6 m&e equipment and hydraulic steel structures · 6 m&e equipment and hydraulic steel...
TRANSCRIPT
Contents
6 M&E Equipment and Hydraulic Steel Structures ................................................. 6-1
6.1 Hydraulic Machinery ........................................................................................... 6-1
6.2 Main Electric Equipment and Main Electrical Connection ............................... 6-27
6.3 Control, Protection and Instrumentation ............................................................ 6-85
6.4 Hydraulic Steel Structures ................................................................................. 6-96
6.5 Ventilation and Air Conditioning .................................................................... 6-123
6.6 Fire Protection Design ..................................................................................... 6-132
6-1
6 M&E Equipment and Hydraulic Steel Structures
6.1 Hydraulic Machinery
The Paklay Hydropower project (HPP) lies on the junction of Sayaboury Province and
Vientiane Province in Laos, about 50 km away from the border of Thailand. Main function
of the HPP is power generation, followed by development assignment for comprehensive
utilization such as ship transport and fishery. The Paklay HPP has a normal pool level of
240.00 m a.s.l. with a corresponding storage of 890.1 million m3 and a minimum pool level
of 239.00 m a.s.l. with a regulating storage of 58.4 million m3. The HPP has a design
installed capacity of 770 MW, average annual energy output of 4124.8 GW·h, and annual
operating hours of installed capacity of 5,357 h. A small portion of electrical power is
supplied to Laos, and the other portion is supplied to Thailand.
6.1.1 HPP Basic Parameters
a) Upstream water level
Check flood level (0.01%) 240.23 m a.s.l.
Design flood level (0.05%) 238.86 m a.s.l.
Normal pool level 240.00 m a.s.l.
Minimum pool level 239.00 m a.s.l.
b) Tail water level
Check flood level (0.01%) 236.49 m a.s.l.
Design flood level (0.05%) 235.50 m a.s.l.
Tail water level (whole plant in full load) (Q=6101.2m3/s) 224.14 m a.s.l.
c) Hydroenergy
Installed capacity 770 MW
Average annual energy output 4124.8 GW·h
Annual operating hours 5357 h
d) Turbine net head
6-2
Maximum (gross) head 20.00 m
Rated head 14.50 m
Weighted average head 15.9 m
Minimum (gross) head 7.5 m
e) Discharge
Average annual discharge 4100 m3/s
f) Sediment data
Average annual sediment concentration 509 g/m3
6.1.2 Selection of Rated Head
The Paklay HPP has the low head and large discharge, with a reservoir drawdown
depth of only 1 m and relatively small change in reservoir water level. The power
generation head of the HPP is closely related to the change of downstream water level. The
Sanakham HPP is the downstream connection cascade of the Paklay HPP, with a normal
pool level of 220.00 m a.s.l., connecting with the normal pool level of the Paklay HPP. In
view of impact from backwater jacking of the Sanakham HPP, change of the downstream
water level of the Paklay HPP dramatically reduces. The power generation head of the
Paklay HPP mainly ranges from 14.00 m to 18.00 m. The head duration of this range is
about 80% of the total duration. The Paklay HPP is a low-head hydropower project with a
relatively poor regulating performance. Low head generally occurs in the flood period.
Therefore, if the selected rated head is too high, the output of the Paklay HPP will be
decreased dramatically in the flood period. According to simulation results of power
generation operation of the HPP, in flood season, the reservoir water level of the Paklay
HPP is basically kept at the normal pool level, with a head about of 15.50 m corresponding
to power generation at full load. Therefore, in this stage, under the premise that power
generation at full load will not be disabled at the normal pool level, the disabled probability
and capacity in flood season shall be as less as possible. The rated head of the HPP is
selected at 14.50 m based on a head dependability of about 88%.
6-3
6.1.3 Selection of Turbine Type
The head range of the HPP is 7.5 m ~ 20.0 m, and the turbine types suitable for this
head range are axial flow turbine and the tubular turbine. The tubular turbine consists of
shaft-extension tubular turbine, pit turbine, bulb turbine and straight flow turbine. The
shaft-extension tubular turbine is suitable for the HPP with a runner diameter less than 3 m.
The pit turbine is only applicable to the HPP with low head and small capacity, with a
maximum unit capacity of 3,000 kW and runner diameter of 3 m. The straight flow turbine
has an extra high requirement for the sealing technology; therefore, it is only applied to the
small HPPs. The HPP has a medium unit capacity and a runner diameter about of 6.90 m;
therefore, the bulb turbines and axial flow turbines are selected for comparison. According
to the installed capacity of the HPP, two alternatives are preliminarily proposed for
comparison, i.e., fourteen 55 MW bulb turbines and eight 96.25 MW Kaplan turbines.
Main parameters of the above two alternatives are listed in the following table.
Table 6.1-1 Comparison of Turbine Types
Description Bulb Turbine Axial Flow Turbine Difference
Turbine model GZ-WP-690 ZZ-LH-1020
Rated output of turbine (MW) 56.4 98.7
Runner diameter (m) 6.90 10.20
Rated speed (r/min) 93.75 62.5
Rated discharge (m3/s) 435.8 788.6
Unit discharge (m3/s) 2.404 1.99
Efficiency at rated point (%) 91.0 88.0%
Specific speed (m·kW) 787 694
Specific speed coefficient 2997 2643
Weight of a single turbine (t) 756 1550
Weight of a single generator (t) 460 1150
Weight of a single unit (t) 1216 2700
Total weight of all units (t) 17024 21600 -4576
Setting elevation (m) 208.5 217.0 -8.5
Elevation of draft tube base
plate (m) 203.0 186.4 16.6
Clear length of powerhouse (m) 391.0 364.0 27
6-4
Description Bulb Turbine Axial Flow Turbine Difference
Clear width of powerhouse (m) 21.0 31.2 -10.2
Compared with the axial flow turbine, for this project the bulb turbine has advantages
as follows:
a) High efficiency. The bulb turbine has a straight and smooth water passage, with
relatively well-distributed flow fields; therefore, its hydraulic efficiency is relatively high
and its high efficiency area is flat and wide. Optimum efficiency of a bulb turbine model is
about over 1% higher than that of an axial flow turbine model, with HPP weighted average
efficiency about 2% ~ 3% higher.
b) High unit parameter level of turbine. The discharge capacity of a bulb turbine is
greater than that of an axial flow turbine. The unit discharge of the bulb turbine adopted by
the HPP is about 20% higher than that of an axial flow turbine, with specific speed and
specific speed coefficient about 13% higher.
c) Less investment on M & E equipment. Because a bulb turbine has advantages of
high parameter level, high speed, small size, and light weight, total weight of all units in
the plant of bulb turbine alternative is 4,576 t less than that of the axial flow turbine
alternative.
d) Less investment on civil works. If the axial flow turbine alternative is adopted,
length of the powerhouse can be reduced, which is in favor of project layout. However, the
clear width of the powerhouse will be about 50% greater than that of the bulb turbine
alternative and clear plane size of the powerhouse will be about 40% greater than that of
the bulb turbine alternative. Although the setting elevation of a bulb turbine is lower than
that of an axial flow turbine, its draft tube is arranged horizontally and no elbow draft tube
is provided, thus the elevation of draft tube base plate is 16.6 m higher than that of an axial
flow turbine. In this way, the bulb turbine alternative has dramatically less foundation
excavation works. Generally speaking, the bulb turbine alternative can reduce foundation
excavation works and control dimensions of the powerhouse, so as to reduce investment on
civil works.
e) Shorter construction period. Because the bulb turbine alternative has no
6-5
construction of curved passages such as a spiral case and elbow draft tube, its civil
construction period can be shortened. In addition, after the main shaft is installed, the
turbine and the generator can be installed at the same time, which further reduces the
construction period of the HPP.
f) In favor of design of system connection and main electrical connection.
According to the design requirement of grid connection, about 100 MW capacity of the
HPP will supply power to Laos, and the other capacity will supply power to Thailand.
In addition, national power grids of Laos and Thailand are not connected for operation.
For the alternative of fourteen 55 MW bulb turbines, the scheme of output of 12 units
being transmitted to Thailand and that of 2 units to Laos can be adopted. For the
alternative of eight 96.25 MW Kaplan turbines, the scheme of output of 7 units being
transmitted to Thailand and that of 1 unit to Laos can be adopted. In the latter case,
when the unit to supply power to Laos is in maintenance, the HPP cannot supply power
to the Laos power grid, which would affect the power grid greatly.
According to Electrical-Mechanical Design Code of Hydropower Plants (DL/T
5186-2004), tubular turbines should be preferably for a run-of-river hydroelectric plant
with a maximum head less than 20 m.
In conclusion, for this project, the bulb turbine has advantages of high efficiency, high
parameter level, less investment on M & E equipment and civil works, shorter construction
period, being in favor of design of system connection and main electrical connection, etc.
Therefore, it is recommended to select the bulb turbine.
6.1.4 Selection of Turbine Model Parameters
a) Selection of specific speed
Both specific speed and specific speed coefficient of a turbine are the aggregative
indexes for turbine technical parameters. High specific speed and specific speed coefficient
can reduce size of the units and powerhouses and investment, which will enhance
economic benefit of the HPP. However, improvement of the specific speed and specific
speed coefficient is limited by turbine strength, cavitation performance, sediment abrasion,
operational stability and others. To meet safe and reliable operation of a unit, both specific
6-6
speed and specific speed coefficient should be controlled within a rational and practicable
range based on practice; namely, specific speed and specific speed coefficient should not
be set too high.
See Table 6.1-2 for the rated specific speed and specific speed coefficient (K) of a
turbine calculated by the relevant statistical formula. See Table 6.1-3 for the specific speed
and specific speed coefficient of some bulb turbines put into operation, with similar head
section as that of the HPP.
Table 6.1-2 Computation Sheet for Specific Speed and Specific Speed Coefficient
(K)
Common Statistical Formula Specific Speed ns(m-kW)
ns=(2700~3100)/H0.5 709~814 2700~3100
ns=2438.1/Hr0.433 766 2917
702 2672
762 2900
Table 6.1-3 Parameters of Some Bulb Turbines Put into Operation
Description Unit
Output (MW)
Maximum Head
(m)
Rated Head (m)
Rated Speed (r/min)
Rated Specific Speed
(m-kW)
Specific Speed
Coefficient K
Unit Discharge
(m3/s)
Number of
Blades
Hongjiang HPP
45 27.3 20 136.4 695 3107 1.892 5
Qiaogong HPP
57 24.3 13.8 83.3 757 2813 2.254 5
Kangyang HPP
40.75 22.5 18.7 125 655 2831 1.868 5
Julongtan HPP
30 18 14.2 125 798 3005 2.318 4
Bailongtan HPP
32 18 9.7 93.75 995 3099 2.959 4
Nina HPP 40 18.1 14 107.1 801 2996 2.346 4
Changzhou HPP
40 16 9.5 75 931.4 2871 2.873 4
Jirau HPP (DEC)
75 19.6 15.2 85.71 789 3076 2.23 4
Jirau HPP (ALSTOM)
75 19.6 15.6 94.7 872.7 3402 2.46 4
According to Table 6.1-3, the turbines with similar parameters as those of the HPP
6-7
have the specific speed of about 650 m-kW~800 m-kW and specific speed coefficient of
about 2800~3100.
The technical schemes for the HPP prepared by major host equipment manufacturing
plants at home and abroad show that the specific speed is 787 m-kW and corresponding
specific speed coefficient is 2998. According to the experience formula, parameter level of
the similar HPPs constructed or under construction, and parameter level stated in
recommendations from host equipment manufacturing plants, the HPP shall have a specific
speed coefficient of about 3000 and a corresponding specific speed of about 788 m-kW.
b) Selection of unit parameter
Because the bulb turbine has many advantages in the low head range and its
operational stability is constantly proved by practice, in recent years, more and more
research works have been focused on the bulb turbine. The applied head may be extended
up and down based on 5 m to 18 m for 4-bladed runner, i.e., 16 m to 30 m for 5-bladed
runner, and 3 m to 12 m for 3-bladed runner. See Table 6.1-4 for main performance
parameters and applicable head range of a tubular runner.
Table 6.1-4 Main Technical Parameters of Bulb Runner
5-bladed Runner 4-bladed Runner
Operating head 16~30m 5~18m
Optimum operating conditions
n10 ~140r/min ~160r/min
Q10 ~1.7m3/s ~1.8m3/s
η0 ~94.2% ~94%
Rated operating conditions
n11 160r/min~170r/min 180r/min~200r/min
Q11 2.2m3/s~2.3 m3/s 2.9m3/s~3.1 m3/s
η ~90% ~88%
Applicable to the HPP or not Applicable Applicable
The HPP has a maximum gross head of 20 m and proposed unit capacity of 55 MW.
According to Table 6.1-4 as well as investigation and research made for the HPP
constructed and discussion results with host equipment manufacturers, in this stage, it is
recommended to adopt the 4-bladed runners temporarily.
See Table 6.1-5 for the unit speed and unit discharge calculated by the relevant
6-8
statistical formulas.
Table 6.1-5 Computation Sheet for Unit Speed and Unit Discharge
Experience Formula Specific Speed
ns
(m-kW)
Unit Speed n11
(r/min)
Unit Discharge Q11
(m3/s)
Formula I 788 169 2.43
Formula II 788 169 2.35
Formula III
788 170.8 2.41
According to Table 6.1-5, the unit discharge of the turbine at the rated point should be
about 2.35 m3/s ~ 2.43 m 3/s, with a unit speed of about 170 r/min.
For a tubular turbine, its unit discharge (Q11) under the rated operation conditions
shall be a value with the medium efficiency and proper cavitation factor (not too large).
The reason is as follows: selection of unit discharge is directly related to the
turbine-generator unit and civil quantities; when the unit discharge is large, the turbine size
and plan view size of the powerhouse will be small and the turbine construction cost will
be low; in addition, the large unit discharge will increase the cavitation factor, which will
decrease the setting elevation of turbine and increase excavation quantities. By reference to
the similar HPPs and in view of consulting results from the host equipment manufacturers,
the unit discharge at the rated operating point shall be 2.4 m3/s with a unit speed of 170
r/min.
c) Turbine efficiency
By reference to the efficiency level of the bulb model turbine developed at home and
abroad and the prototype turbine put into operation, it is preliminarily proposed to set the
rated turbine efficiency of the HPP not less than 91.0%.
d) Cavitation performance
In comprehensive consideration of the specific speed and unit parameter of turbines of
the HPP and model runner parameter currently applicable to the HPP, the critical cavitation
6-9
factor (to the vertex position of a turbine runner) of turbines should be about 1.3. Because
the HPP has a relatively large sediment concentration, the ratio (k) of cavitation factor of
the HPP to critical cavitation factor of the model shall be 1.13, based on which the
corresponding static suction head and setting elevation can be obtained by calculation.
6.1.5 Number of Units and Unit Capacity
The HPP is proposed to have an installed capacity of 770 MW and adopt the bulb
turbine-generator unit. Because the HPP has a relatively large installed capacity, to reduce
quantity of the units, it should increase the unit capacity as far as possible. The Jirau HPP
(Brazil) has an installed capacity of 4,800 MW, with 64 bulb turbine-generator units of
which the unit capacity is 75 MW and the runner diameters are 7.5 m (7.9 m). These units
are the bulb turbine-generator units with the largest unit capacity at present. The first unit
was put into operation in the end of August 2013. The Guangxi Qiaogong HPP (China) has
8 bulb turbine-generator units with the unit capacity of 57 MW and the runner diameters of
7.45 m, which are the units with the largest unit capacity in China and the second largest in
the world at present. The Changzhou HPP has 15 bulb turbine-generator units with the unit
capacity of 42 MW and the runner diameters of 7.50 m, which are the units in operation
with the largest runner diameter in China at present. In case the HPP is equipped with 12
bulb turbine-generator units with the unit capacity of 64.17 MW, the corresponding runner
diameter will be 7.5 m and the total capacity of 10 units transmitting power to Thailand
will be 641.7 MW. According to the design and manufacturing level of the units at present
and in consideration of the grid connection mode of the HPP (about 100 MW energy
output for Laos and the rest for Thailand), in this stage, it is proposed to compare the
scheme involving 13 the units with the unit capacity of 59.23 MW with the scheme
involving 14 the units with the unit capacity of 55 MW. See Table 6.1-6 for main technical
and economic indexes of the units in both schemes.
Table 6.1-6 Technical and Economic Indexes Corresponding to Schemes of Unit Quantity
Description Unit Number of Units
13 14
Turbine Unit capacity MW 59.23 55
6-10
parameter Rated head m 14.5 14.5
Rated discharge of single unit m3/s 469.3 435.8
Rated Speed r/min 88.24 93.8
Runner diameter m 7.2 6.9
Specific speed m·kW 768.6 786.9
Specific Speed Coefficient - 2927 2997
Energy index
Average annual energy output GW·h 4143.4 4143.4
Primary energy (PE) GW·h 2886.6 2886.6
Secondary energy GW·h 1054.4 1054.4
Excess energy (EE) GW·h 202.4 202.4
Equivalent energy (PE + 0.6 x SE) GW·h 3519.2 3519.2
Utilization ratio of water resource % 85.52 85.52
Annual operating hours of installed capacity h 5381 5381
Economic indexes
Project cost on Hydroproject million yuan 9984.38 9975.89
Project cost per kilowatt Yuan/kW 12967 12955
Project cost per kilowatt hour Yuan/kW·h 2.42 2.42
Project cost per KWH for equivalent energy Yuan/kW·h 2.425 2.422
Total project cost difference million yuan -8.49
In terms of the energy indexes, the Paklay HPP has the same comprehensive
efficiency and basically uniform energy indexes in both schemes.
In terms of the project cost, quantity of the units increases to 14 sets from 13 sets,
which slightly increases the excavation works for the powerhouse but slightly decreases
the total weight of the units. In terms of the total project cost, the scheme involving 14 sets
can save RMB 8.49 million compared to the scheme involving 13 sets, which has better
economical efficiency.
In terms of the manufacturing level and operational conditions of the units, the unit
capacity and runner diameter in both scheme do not exceed those used for the units of the
Jirau HPP (Brazil). However, the scheme involving 13 sets uses a runner diameter of 7.2 m
and unit capacity of 59.23 MW, which is more difficult in unit manufacturing; the scheme
involving 14 sets uses a runner diameter of 6.90 m and unit capacity of 55 MW, which has
successful manufacturing and operating experience in China at present. Therefore, in terms
6-11
of design and manufacturing difficulty of the units, the scheme involving 14 sets will be a
better choice.
Based on the comprehensive comparison, in this stage, it is recommended to adopt the
scheme involving 14 units with the unit capacity of 55 MW for the Paklay HPP.
6.1.6 Unit Parameter of the Recommended Scheme
a) Turbine parameter recommended by manufacturers
In this stage, technical communication has been made with the unit manufacturers;
there are 3 manufacturers provide their preliminary technical schemes with the
recommended turbine parameters as shown in Table 6.1-7.
Table 6.1-7 Turbine Technical Parameters Recommended by Host Equipment
Manufacturers
Manufacturer
Turbine Parameter Manufacturer A Manufacturer B Manufacturer C
Model GZ-WP-690 GZ-WP-690 GZ-WP-690
Rated output of turbine (MW) 56.4 56.4 56.4
Rated head (m) 14.5 14.5 14.5
Runner diameter (m) 6.90 6.90 6.90
Quantity of runner blade 4 4 4
Rated speed (r/min) 93.75 93.75 93.75
Rated discharge (m3/s) 420 424.23 417.7
Unit speed at rated point (r/min) 170 170 170
Unit discharge at rated point (m3/s) 2.32 2.34 2.304
Specific speed (m·kW) 787 787 787
Specific speed coefficient 2998 2998 2998
Efficiency at rated point (%) 94.8 93.9 94.92
Maximum efficiency (%) 95.8 95.33 96.19
Critical cavitation factor at rated
point 1.3
Static suction head (to the unit
centerline) (m) -13.5 -14.5 -13.66
Weight of turbine (t) 731.4 700 860
b) Runner diameter
6-12
According to the unit discharge at the rated operating point (2.4 m3/s) and the
parameters recommended by the manufacturers, in this stage, it is proposed to adopt a
runner diameter of 6.9 m.
c) Rated speed
According to the unit speed at the rated operating point (170 r/min), the HPP has a
calculated speed of 93.81 r/min. In this stage, it is proposed to select three synchronous
speeds, including 88.24 r/min, 93.75 r/min and 100 r/min for comparison. The scheme
involving 88.24 r/min has a corresponding specific speed of 741 m-kW and specific speed
coefficient of 2820. The scheme involving 93.75 r/min has a corresponding specific speed
of 787 m-kW and specific speed coefficient of 2998. The scheme involving 100 r/min has
a corresponding specific speed of 839 m-kW and specific speed coefficient of 3196.
According to the comparison, the scheme involving 93.75 r/min has a relatively suitable
specific speed and specific speed coefficient. In addition, the rated speed of 93.75 r/min is
adopted in the technical schemes provided by 3 manufacturers.
According to the selected specific speed and unit parameter level and in view of the
turbine parameters recommended by the manufacturers, in this stage, it is proposed to
adopt the rated speed of 93.75 r/min for the turbines. Accordingly, the specific speed (ns) at
the rated operating point shall be 787m·kW, the specific speed coefficient (K) shall be
2998, the unit discharge shall be 2.404 m3/s, and the unit speed shall be 170 r/min.
d) Static suction head and setting elevation
According to the selected cavitation factor and safety factor, the static suction head
can be calculated by the rated head. In view of consulting results from the manufacturers,
the HPP shall have a cavitation factor of 1.47, an allowable static suction head (to the
vertex position of a runner blade of a turbine) of -11.61 m, and an allowable static suction
head (to the turbine center) of -15.34 m. The design tail water level shall be the tail water
level (whole plant in full operation) of 224.14 m a.s.l.; the setting elevation of the unit shall
be 209.08 m a.s.l., rounded to 208.50 m a.s.l. in this stage.
e) Turbine parameter of the recommended scheme
6-13
See Table 6.1-8 for main turbine parameters recommended.
Table 6.1-8 Main Turbine Parameters in Recommended Scheme
Description Parameter Value
Turbine model GZ-WP-690
Rated output of turbine (MW) 56.4
Maximum head/rated head/minimum head (m) 20/14.5/7.5
Runner diameter (m) 6.90
Rated speed (r/min) 93.75
Rated discharge (m3/s) 435.8
Unit speed at rated point (r/min) 170
Unit discharge at rated point (m3/s) 2.404
Specific speed under rated operating condition
(m·kW) 787
Specific speed coefficient 2997
Efficiency at rated point (%) 91.0
Static suction head (calculated to the unit
centerline) (m) -15.34
Setting elevation (m) 208.50
Weight of turbine (t) ~756
6.1.7 Governing System
The governing system of the units has an operating oil pressure of 6.3 MPa, and the
DWST-150-6.3 model dual-regulating microcomputer electro-hydraulic governor is
adopted. The counter weight is provided for accident shutdown. In case of accident, the
governing system can adjust oil pressure through the relief valve of the counter weight and
shut down the unit by the dead load of the counter weight. Type of the oil pressure unit is
HYZ-15-6.3 and the pressure level is 6.3 MPa.
6.1.8 Design of Regulation Guarantee
a) Unit information
The HPP adopts the tubular turbine-generator unit, with a runner diameter of 6.9 m,
rated speed of 93.75 r/min, and runaway speed of 290 r/min. The moment of inertia of a
generator is about 5,500 t m2; the moment of inertia of a turbine and water body is about
6-14
2,500 t m2; the moment of inertia of the unit and water body is about 8,000 t·m2 in total;
the inertia time constant of the unit is 3.42 s.
b) Calculation control value for hydraulic transition process
According to the relevant codes, in the HPP, the maximum speed rising rate of the
units should be less than 65%; the guarantee value of the maximum pressure rising rate in
front of a guide vane should be less than 70%~100%; during load dump, the maximum
vacuum guarantee value at the draft tube inlet section shall not be greater than 0.07 MPa.
c) Closure rule
In this stage, the 6s linear closure law shall be used for calculation. After relevant
parameters such as the unit manufacturing plant and turbine model characteristic curve are
determined, recalculation for the hydraulic transition process shall be carried out.
d) Calculation results and analysis of transition process
In this stage, calculation only applies to the transition process with large fluctuation.
The operating conditions of the rated load dump at the rated head and those at the
maximum head shall be used for preliminary calculation. See the table below for the
calculation results.
Table 6.1-9 Calculation Results of Transition Process
Parameter Unit Design Head
Operating Condition
Maximum Head
Operating Condition
Pressure rising absolute value in
front of guide vane mH2O 16.94 22.33
Pressure rising rate in front of
guide vane % 53.8 70.9
Pressure at draft tube inlet section mH2O -2.41 -4.39
Rising speed (β) % 65 50
According to the calculation results, the maximum pressure rising in front of the guide
vane and the minimum pressure at the draft tube inlet section both occur at the rated load
dump at the maximum head, with the maximum pressure rising rate in front of the guide
vane of 70.9% and minimum pressure at the draft tube of -4.39 mH2O. The maximum
speed rising occurs at the rated load dump at the rated head, with the maximum speed
6-15
rising rate of 65%. All of above conditions meet the requirement for calculation control
value for hydraulic transition process.
e) Determination of design value for regulation guarantee
For determination of design value for regulation guarantee, the calculation error and
pressure fluctuation shall be used for correction based on the calculation value of
hydraulic transition process. Based on the above calculations and corrections and
characteristics of the HPP, the design values for regulation guarantee in accordance with
the relevant codes and temporary provisions are as follows:
1) The maximum pressure in front of a guide vane is 58 mH2O;
2) The minimum hydrodynamic pressure at the draft tube inlet is -6 mH2O;
3) The maximum speed rising of the units is 65%.
In this stage, it lacks of relevant parameters such as the characteristic curve of the
units and the moment of inertia of the units and water body, the transition process is
calculated by linear closure law based on relevant experience formulas. After relevant
parameters such as the unit manufacturing plant and turbine model characteristic curve are
determined, recalculation for the hydraulic transition process shall be carried out, in order
to optimize the closure law. In this way, the design value for regulation guarantee of the
HPP can meet requirements for safe and reliable operation.
6.1.9 Transport of Heavy Equipment
The heavy equipment consists of a main transformer, generator rotor, turbine runner,
bridge crane girder and others. The main transformer and generator rotor are the key
equipment in the transport control. See Table 6.1-10 for the transport characteristic values.
Table 6.1-10 Characteristic Values for Transport of Heavy Equipment
Description of
heavy-big piece Unit Qty. Transport Size (m)
Weight of A Single
Piece (t)
Turbine hub Set 14 φ3.0x5.0 (D×H) 65
Inner guide ring Nr. 14 φ5.076×2.695m (D×H) 17.5
Enclosure Nr. 56 10.479×3.9×3.92 m (L×
W×H) 11
6-16
Rotor support Set 14 5.2x5.2x2.2 (L×W×H) 40
Bridge crane girder Pcs. 4 22.0x3.0x3.0 (L×W×H) 60
Main transformer Set 6 6.5x4x6.8 (L×W×H) 100
After dredging and channelized waterway works were carried out to the upstream
basin of the Mekong River, the 71 km long waterway connecting the Jinghong Port with
the China - Myanmar No. 243 boundary monument is Grade V, with a single-ship
navigation capacity of 300 t ~ 500 t. The 331 km long waterway connecting the China -
Myanmar No. 243 boundary monument with Houayxay section, Laos has a perennial
navigation capacity of 200 t ~ 300 t ships, with a navigation period of 10 ~ 11 months. The
section from Houayxay to Luang Prabang is an original river course with a length of about
300 km and navigation capacity of 150 t ships. The waterway at the lower reaches of
Luang Prabang has a relatively poor navigation capacity.
There are two national trunk highways passing through the vicinity of the project site.
One of them is the No. 11 highway from Vientiane, capital of Laos, to Pak Lay, and the
other one is the No. 4 highway connecting the Luang Prabang City with Loei, Thailand.
The above two highways meet each other in the Pak Lay Town. There is a rural road of
about 20 km long connecting the Pak Lay Town to the dam site, in which a section of
about 7 km long has been upgraded and reconstructed so that it can meet transport of large
equipment.
According to the site access conditions of the Project, it is preliminarily proposed that
M & E equipment and heavy-big piece will be transported to the Luang Prabanngd Port via
water transport and then transported to the site via highway. Some equipment can be
transported to the site directly via water transport.
6.1.10 Auxiliary Equipment of Hydraulic Machinery
6.1.10.1 Selection of hoisting equipment for powerhouse
The largest heavy piece inside the powerhouse is the weight of rotor with shaft, with a
hoisting weight of about 230 t. There are 14 units in the whole plant. Given that installation
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and maintenance will be simultaneously applied to 2 units as well as in view of turnover
requirement of large equipment, 2 single-trolley electric double-beam bridge cranes (250
t/30 t/10 t) will be adopted, with the span of 21.0 m. Both bridge cranes are arranged in the
same unit. The main hook has a hoisting height of 30 m while the secondary hook has a
hoisting height of 40 m.
6.1.10.2 Cooling water supply system
Service t water supply of the whole plant consists of cooling water for a generator air
cooler, cooling water for a bearing, sealing water for a main shaft, cooling water for a
water-cooled main transformer, lubricating water for a deep well pump, cleaning water,
domestic water and others.
The generator air cooler uses a closed circulation and secondary cooling water supply
method. It is designed by the unit manufacturers and will not be included to the total
amount of cooling water supply.
According to the preliminary estimate, the water consumption for each part of the
units is as follows:
Cooling water for a bearing: 55m3/h
Sealing water for a main shaft: 6m3/h
Other main cooling water supply in the powerhouse is as follows:
Cooling water for a main transformer: 50m3/h x 5
Utilities water: 25m3/h
Total cooling water of the whole plant 1129 m3/h
The HPP is a low-head and run-of-river hydropower project, with a head range of 7.5
m ~ 20.0 m. According to different requirements for water quality and reliability of water
source, the whole plant is equipped with a cooling water supply system and a cleaning
water supply system.
The cooling water supply system will supply cooling water for unit bearings, cooling
water for main transformers, water for utilities, domestic water and others; meanwhile, it
will serve as the standby water source for sealing of main shafts. The cooling water supply
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system takes its water source from the reservoir and drains the wastewater to the tail water.
It adopts water supply by gravity flow in groups. In one group, 7 units and 3 main
transformers will share 2 routes of intake pipelines in front of dam, standby for each other;
in another group, 7 units and 2 main transformers will share 2 routes of intake pipelines in
front of dam, standby for each other. Each route is provided with an automatic water filter
and a spiral flow filter, with the design discharge of 600 m3/h. To ensure stable hydraulic
pressure of the cooling water supply, the whole plant is provided with 2 pressure
stabilizing pools with an effective volume of 100m3.
The cleaning water supply system will supply cooling water for sealing of main shafts,
water supplement for cooling expansion tank of air cooler, etc. The water source is
upstream reservoir. The wastewater is discharged into the leakage water dewatering pit and
then discharged into the downstream via a leakage drainage pump. Water supply by gravity
flow in groups is adopted. Every 7 units shares 2 water intake pipelines in front of the dam,
standby for each other. Each route is provided with an automatic accurate water filter and a
spiral flow filter, a design discharge of 100 m3/h. To ensure water quality of sealing water
for a main shaft, the water inlet pipe of the main shaft shall be equipped with an accurate
water filter.
See "Paklay-FS-EM-Machinery-01" for details of the Cooling water Supply System
Drawing.
6.1.10.3 Dewatering and drainage system
The dewatering and drainage system of the HPP consists of two parts, including a
dewatering system for unit maintenance and a drainage system for the powerhouse
leakage.
a) Dewatering system
It adopts an indirect dewatering mode. When a unit is under maintenance,
accumulated water in the passage will be drained to the dewatering sump through the
drainage gallery, and then drained to tail water by the deep well pump.
One drain valve will be set at the lowest position of upstream and downstream
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passages in each unit bay. Steel pipes are embedded behind the valves and lead to the
dewatering sump at the erection bay. A sealing head cover is provided on the top of the
sump and an air vent is provided as well.
The water to be discharged involves accumulated water to be drained in the inlet
passage and outlet passage during maintenance. According to the preliminary calculation,
quantity of the accumulated water in the passages is 6000 m3. During unit maintenance, the
total water leakage through upstream and downstream gates is about 90 m3/h.
Dewatering duration shall be calculated based on emptying accumulated water in 4 h
~ 5 h. The pump lift shall be sum of difference between the water level at shutdown of
pump and downstream head and frictional loss in the pipeline. It adopts 4 deep well pumps
with a pump discharge of 370 m3/h and head of 48 m.
To drain out the settled sewage in the sump, 1 submersible sewage pump shall be set,
with a discharge of 90 m3/h and head of 47 m.
After the passages are completely drained out, the dewatering sump will be used for
storing the leakage water from upstream and downstream gates, in order to make the
drainage pump to continuously operate. The effective volume of the sump shall be 90 m3
based on the discharge obtained by a drainage pump operating for 15 min. For leakage
water of the gates, a level controller is used for automatically controlling startup and
shutdown of a drainage pump. A level transmitter is provided in the sump, leading to the
central control room.
b) Drainage system
Leakage water in the powerhouse mainly comes from leakage water of hydraulic
structures in the powerhouse, cooling water for bearings and main transformers, sealing
leakage water for main shafts, valve leakage water of each pipeline, cleaning water etc. By
reference to the similar HPPs, powerhouse leakage water shall be 60 m3/h, and the
maximum discharge for sealing water of main shafts shall be 84 m3/h. In view of other
discharge in the powerhouse, the total discharge shall be 200 m3/h.
A drainage gallery throughout the whole plant is set under the passage base plate. All
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leakage water is drained to the drainage gallery through floor drains and vertical drain
pipes. The leakage water flows into the leakage water dewatering sump by gravity and then
be drained to the downstream tail water through deep well pumps.
The capacity of the leakage water dewatering sump shall be calculated based on the
total leakage water amount in the powerhouse within 37.5 min, with an effective volume of
100 m3.
Four vertical deep well pumps are provided, 2 for use and 2 for standby. The pump
discharge shall be calculated based on the effective volume of the emptying drainage sump
in 20 min. The pump lift shall be determined based on sum of difference between the
maximum tail water level and the water level at shutdown of pump and the frictional loss.
The pump discharge is finally determined as 370 m3/h, with a pump lift of 54 m. Startup or
shutdown of a drainage pumps is automatically controlled by a level controller. A level
transmitter is provided in the sump, leading to the central control room.
To drain out the settled sewage in the sump, 1 submersible sewage pump shall be set,
with a discharge of 90 m3/h and head of 47 m.
See "Paklay-FS-EM-Machinery-02" for Drawing of Dewatering and Drainage
System.
6.1.10.4 Compressed air system
The compressed air system of the HPP consists of a powerhouse mediate-pressure
(MP) compressed air system and a powerhouse low-pressure (LP) compressed air system.
a) Powerhouse MP compressed air system
The MP compressed air system is used for air inflation into a pressure oil tank after
installation or maintenance of a pressure oil supply unit in the governing system and for
supplement of air consumption in the pressure oil tank during operation. Rated oil pressure
of the pressure oil supply unit in the HPP is 6.3 MPa. Air supply under first-stage pressure
is adopted in the design. Air supply of pressure oil tank is carried out via pipelines.
The production rate of a MP air compressor shall be determined based on air inflation
capacity and duration of the pressure oil tank. Three MP air compressors are selected, with
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an air displacement of 1000 L/min and a working pressure of 8.0 MPa. Among them, 2 are
used as the main air compressors and 1 is used for standby.
The compressed air silo volume shall be determined based on the air supplement
quantity required by oil level rising of 150 mm ~ 250 mm in the pressure oil tank.
According to calculations and by reference to the similar HPPs, it is determined that 2 x
3.0m3 compressed air silos with a pressure of 8.0 MPa will be adopted.
b) Powerhouse LP compressed air system
The LP compressed air system of the HPP is 0.7 MPa. The LP compressed air system
supplies air for unit braking, maintenance, purging air, air shroud, etc. Because the HPP
has many units, an air supply system for brake and main shaft sealing and a maintenance
air supply system are provided in the whole plant, in order to prevent each part requiring
air supply of the LP compressed air system from interacting with each other. A non-return
valve is set between the above two systems; the maintenance air supply system can supply
air to the air supply system for brake and main shaft sealing.
According to the main electrical connection mode, the air supply system for brake and
main shaft sealing is configured as follows: 3 units shall brake simultaneously; duration for
restoration of operating pressure of a compressed air silo shall be 10 min; 2 LP air
compressors with an air discharge of 1.4 m3/min and operating pressure of 0.85 MP and 2
x 5.0 m3 compressed air silos with a pressure of 0.8 MPa shall be provided.
Configuration of the maintenance air supply system shall be that 2 air compressors
simultaneously operate to meet requirement of the maximum air demand for maintenance.
By reference to the similar HPPs, the configuration details shall be as follows: 2 LP air
compressors with an air discharge of 10.0 m3/min and operating pressure of 0.85 MPa and
1 x 5.0 m3 compressed air silo with a pressure of 0.8 MPa shall be provided. In addition,
another 1 portable air compressor with an air discharge of 0.28 m3/ min and operating
pressure of 0.7 MPa will be provided as well.
Each air compressor of the MP and LP compressed air systems in the powerhouse will
automatically control startup and shutdown of the air compressors based on the pressure
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settings. A safety valve and pressure signal controller will be installed on the compressed
air silo.
See "Paklay-FS-EM-Machinery-03" for Drawing of MP and LP Compressed Air
Systems in the Powerhouse.
6.1.10.5 Oil system
It consists of a turbine oil system and an insulating oil system.
a) Turbine oil system
The turbine oil system mainly supplies unit lubricating oil and mechanical
hydraulic oil. Based on estimation, the maximum oil consumption of 1 unit is 30.4 m3.
According to requirements of relevant codes and HPP operation, 2 x 20 m3
uncontaminated oil tanks and 2 x 20 m3 operating oil tanks shall be provided.
Each oil pump shall have a capacity of filling up oil for 1 unit within 5 h. Two gear oil
pumps (2CY-6/3.3-1) shall be adopted, with an oil delivery quantity of 6 m3/h and the
maximum operating pressure of 0.33 MPa.
The oil treatment equipment shall have a capacity of filtering oil for 1 unit within 8 h.
One pressure oil filter (LY-100) with production rate of 100 L/min shall be adopted. In
addition, 1 turbine oil filter (ZJCQ-4) with production rate of 4,000 L/h and operating
vacuum (P) not greater than 3,500 Pa shall be adopted.
b) Insulating oil system
It mainly supplies cooling oil for main transformers. Based on estimation, the
maximum oil consumption of 1 main transformer is 56 m3. According to requirements of
relevant codes and HPP operation, 2 x 35 m3 uncontaminated oil tanks and 2 x 35 m3
operating oil tanks shall be provided.
Each oil pump shall have a capacity of filling up oil for 1 unit within 6 h. Two gear oil
pumps (2CY-12/3.3-1) shall be adopted, with an oil delivery quantity of 12 m3/h and the
maximum operating pressure of 0.33 MPa.
The oil treatment equipment shall have a capacity of filtering oil for 1 unit within 24 h.
One pressure oil filter (LY-100) with production rate of 100 L/min shall be adopted. In
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addition, 1 vacuum oil-filter (ZJB-3KY) with production rate of 3,000 L/h and operating
vacuum (P) not greater than 0.5MPa shall be adopted.
See "Paklay-FS-EM-Machinery-04" for Drawing of Oil System
6.1.10.6 Hydraulic monitoring system
Configuration of the hydraulic monitoring system shall meet requirements for safe,
reliable and economic operation, automatic control and test measurement of a
turbine-generator unit. It consists of two parts, including plant monitoring and unit bay
monitoring.
The plant monitoring includes upstream/downstream water level, HPP gross head and
reservoir water temperature.
The unit bay monitoring includes the following items: trash rack differential pressure,
pressure balancing on both sides of the intake gate and draft tube gate, passage inlet
pressure, draft tube outlet pressure, operating head, unit discharge, pressure in front of
guide vane, runner chamber pressure, vibration and throw of units etc.
See "Paklay-FS-EM-Machinery-05" for Drawing of Hydraulic Measuring System.
6.1.10.7 Layout of main hydraulic mechanical equipment
The HPP powerhouse lies at the left bank, including a powerhouse (comprising a host
equipment section and an erection bay) and auxiliary plant. The powerhouse has a total
length of 400.0 m, in which the host equipment section is 301.0 m long. Because the HPP
has many units, 2 erection bays are provided. The main erection bay is 52.0 m long,
arranged at the left side of the powerhouse; the auxiliary erection bay is 41.0 m long,
arranged at the right side of the powerhouse. Area of the erection bays can meet erection
progress that 2 units can be put into operation every 3 months. According to the head cover
of unit passage, turbine lifting holes and equipment layout, the powerhouse has a clear
width of 21.0 m.
Units have a setting elevation of 208.5 m a.s.l. and the ground elevation of the host
equipment floor and auxiliary erection bay is 222.5 m a.s.l.; according to flood control
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requirement of the powerhouse access road, the main erection bay has a ground elevation
of 228.5 m a.s.l.; according to turnover requirement for the largest equipment and outer
gate barrel, a crane has a track top elevation of 240.5 m a.s.l.
The air delivery conduit of the powerhouse is arranged inside the head bay wall of the
powerhouse. The oil-water-air pipeline and the air compressor room are arranged on the
hydraulic mechanical equipment floor at an elevation of 222.50 m a.s.l. in the downstream
auxiliary plant; the governor and oil pressure unit are arranged in the upstream first
quadrant of the host equipment floor of an elevation of 222.5 m a.s.l. in the powerhouse.
The drainage pump house and dewatering pump house are arranged in the auxiliary
plant at an elevation of 216.5 m a.s.l. below the erection bay of the powerhouse.
The turbine oil storage room and its oil treatment room as well as the insulating oil
storage room and its oil treatment room are arranged in the auxiliary plant of an elevation
of 216.5 m a.s.l. at the lower position of the auxiliary erection bay. The insulating oil depot
and the oil treatment room are arranged in the auxiliary plant at an elevation of 228.50 at
the downstream side of the powerhouse.
The instruments and pressure balancing pipeline of draft tube gate are arranged in the
downstream auxiliary plant of an elevation of 219.0 m a.s.l.
6.1.11 List of Main Hydraulic Mechanical Equipment
See Table 6.1-10 for main hydraulic mechanical equipment.
Table 6.1-10 Main Hydraulic Mechanical Equipment.
S/N Description Model, Specification and
Parameter Unit Qty. Remarks
1 Turbine
GZ-WP-690, Hr=14.5m,
N=56.4MW,
nr=93.75r/min, D1=6.9m
Set 14
2 Governor DWST-150-6.3 Set 14
3 Oil pressure unit HYZ-15-6.3 Set 14
4 Crane
4.1 Single-trolley bridge crane 250t/30t/10t, span of
21.0 m Set 2 Powerhouse
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4.2 Single-trolley bridge crane 10t, span of 14.4 m Set 1 500kV GIS room
5 Cooling water supply system
5.1 Vertical centrifugal pump Q=600m3/h, H=20m Set 4 N=55kW
5.2 Full-automatic water filter DN350, Q=600m3/h,
PN1.0 MPa Set 4
5.3 Water treatment equipment Q=10m3/h Set 4
5.4 Pump control valve DN350, PN1.0 MPa Set 4
5.5 Hydrocyclone DN350, Q=600m3/h,
PN1.0 MPa Set 4
6 Unit dewatering system and powerhouse drainage system
6.1 Deep well pump Q=370 m3/h, H=48 m,
N=75 kW Set 4 Dewatering
6.2 Deep well pump Q=370 m3/h, H=48 m,
N=75 kW Set 4 Drainage
6.3 Submersible sewage pump Q=90 m3/h, H=47 m Set 2
6.4 Piezoresistive level transmitter Set 2
6.5 Ball float type level transmitter Set 2
7 MP/LP compressed air system
7.1 MP air compressor Q=1.0 m3/min P=8.0
MPa Set 3 N=11kW
7.2 MP compressed air silo V=3.0 m3 P=8.0 MPa Set 2
7.3 MP freezer dryer 8MPpa Set 3
7.4 Pressure-reducing-stabilizing
valve
DN40 P=8.0MPa/
7.0MPa Set 1
7.5 LP air compressor Q=10.0 m3/min P=0.85
MPa Set 2 N=55kW
7.6 LP air compressor Q=1.4 m3/min P=0.85
MPa Set 2 N=11kW
7.7 LP compressed air silo V=5.0 m3 P=0.8 MPa Set 3
7.8 Portable air compressor Q = 0.28 m3/ min P =
0.7 MPa Set 1 N=2.2kW
7.9 LP freezer dryer 0.8MPa Set 2
8 Oil system
8.1 Indoor oil tank 20m3 Nr. 4 Turbine oil system
8.2 Gear oil pump 2CY6/3.3-1 Q=6 m3/h
H=0.32 MPa N=3kW Set 2 Turbine oil system
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8.3 Pressure oil filter LY-100 Q=100 L/min
N=2.2kW Set 2 Turbine oil system
8.4 Turbine oil filter
ZJCQ-4 Q=4000 L/h,
P≤0.33 MPa
N=30.49kW
Set 1 Turbine oil system
8.5 Indoor oil tank 35m3 Nr. 4 Insulating oil
system
8.6 Gear oil pump 2CY12/3.3-1 Q=12 m3/h
H=0.33 MPa N=4kW Set 2
Insulating oil
system
8.7 Pressure oil filter LY-100 Q=100 L/min
N=2.2kW Set 2
Insulating oil
system
8.8 Two-stage high-vacuum oil filter
ZJA-3KY Q=3000 L/h,
P≤0.5 MPa
N=52.35kW
Set 1 Insulating oil
system
8.9 Filter paper oven 1kW Set 2
9 Hydraulic measurement system
9.1 Water-level gauge Measuring range: 0 m ~
30 m Pcs. 2
For measuring
water level at upper
and lower reaches
9.2 Deep water thermometer Measuring range: 0°C ~
40°C Pcs. 1
For measuring
reservoir water
temperature
9.3 Pressure transmitter Measuring range: 0 MPa
~ 0.6 MPa Pcs. 98
9.4 Vacuum pressure transmitter Measuring range: -0.1
MPa ~ 0.6 MPa Pcs. 48
9.5 Oscillatory pressure transmitter Pcs. 32
9.6 Differential pressure transmitter Pcs. 81
For measuring
gross head and
available head
9.10 Manometer YB-150, PN0~0.6 MPa Set 104
9.11 Vacuum manometer YZ-150,
PN-0.1~0.6MPa Set 48
9.12 Measuring equipment for
vibration and throw of units Set 16
For measuring
vibration and throw
of units
10 "Machine maintenance equipment shall be determined via negotiation with the Employer in the
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future.
6.2 Main Electric Equipment and Main Electrical Connection
6.2.1 Design of Grid Connection
6.2.1.1 Power Supply Range
The Paklay Hydropower Project (HPP) is located in Laos, which lies in the north of
Indo-China Peninsula, bordered by China on the north, Cambodia on the south, Vietnam
on the east, Myanmar and Thailand on the northwest and southwest respectively. The
national territorial area of Laos is 236.8 x 103 km2. Mountains and plateaus account for
80% and most of them are covered by forests. Currently, the population in Laos is about 6
million. Laos' economy is dominated by its agriculture, its industrial base is weak, and its
economic development level is backward. Since 1988, Laos has gradually completed its
market economic system via implementation of reform and opening policies, improvement
of investment environment, and adjustment of economic structure. In addition, its
economic society has developed rapidly. In 2010, Laos' GNP was USD 5.97 billion with a
year-on-year growth of 7.9%, and the GDP per capita was nearly USD 1,000. Although the
level of national economy and social development in Laos has been improved dramatically
in recent years, the power demand in Laos is still not large. Laos enjoys very rich
hydropower resources. According to relevant planning results from the electric power
department in Laos, even without the hydropower resources of main stream of the Mekong
River, the available hydropower resources in Laos still reach 18,000 MW. In addition to 5
HPPs, including Pak Beng HPP, Luang Prabang HPP, Xayaboury HPP, Paklay HPP and
Sanakham HPP, planned on the main stream of the Mekong River, the total available
hydropower resources in Laos are more than 23,000 MW.
In recent years, with the increase of investments from China, Japan, Thailand and other
countries in Laos' hydropower projects, the hydropower development in Laos has entered
an unprecedented development stage. In the next decade, the installed capacity of
hydropower to be put into operation in Laos is expected to be millions kilowatts. The
power demand in Laos cannot consume such rich electrical energy. Therefore, Laos'
electric power will mainly be exported to countries with more developed economy, such as
China and Thailand.
Laos is located in the middle of Southeast Asian countries and bordered by China,
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Myanmar, Thailand, Cambodia and Vietnam. Geographically, it has advantages in electric
power export. According to the relevant planning results, the Lao Government plans to
export about 8,000 MW of electric power to its neighbors in 2020. The main object of
electric power export is Thailand. The Lao Government signed a memorandum of
understanding on power cooperation with the Thai Government in December, 2007. Both
parties agreed that 3,000 MW ~ 5,000 MW of electric power will be supplied from Laos to
Thailand before 2015, and 5,000 MW ~ 7,000 MW of electric power after 2015.
The Paklay HPP is about 50 km away from the borderline of Thailand in a straight-line
distance, so it has geographical advantages in electric power export to Thailand. In view of
the analysis results of electricity market space in Thailand, in 2020, the electricity market
space in Thailand will be large enough to consume the electric power delivered from the
Paklay HPP. Therefore, Thailand is within the power supply range of the Paklay HPP.
6.2.1.2 Scheme of Grid Connection
The Paklay HPP has an installed capacity of 14 × 55 MW and a total installed capacity of
770 MW. For the HPP, it is proposed to connect 2 circuits of 500 kV transmission lines
with a conductor cross-section of LGJ-4×300 to the 500 kV combined switchyard owned
by Laos and located at the Laos ~ Thailand border. Electric power from Laos will be
delivered to Thailand through the combined switchyard. See Fig. 6.2.1-1 for the
connection diagram of Laos power grid in terms of geographical location in 2020.
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Fig. 6.2.1-1 Connection Diagram of Laos Power Grid in Terms of Geographical Location
In 2020
6.2.2 Main Electrical Connection
The main electrical connection shall be safe, reliable, flexible and economical. The
specific design principle is as follows:
(1) Safe and reliable power supply
Because the 500 kV transmission line plays an important role in the electric power
system, it is required to employ a main electrical connection scheme of which the power
supply has high reliability.
(2) Flexible operation, convenient maintenance, and easy startup and shutdown
In the design of main electrical connection, frequent operation of HPP shall be fully
taken into account. When the operation mode changes, startup and shutdown operations
shall be as easy as possible and such operations shall not affect the continuous operation of
the station service system and other elements.
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(3) Easy connection, convenient transition, and compact and clear arrangement
The main electrical connection shall be easy and reliable as far as possible. The
quantity of elements in the main electrical connection shall be as less as possible, and the
arrangement of these elements shall be compact and clear, in favor of operation monitoring,
maintenance and accident handling. Staged transition shall not cause great changes in the
arrangement of electrical equipment or secondary circuit; in addition, the staged transition
shall be in favor of extension.
(4) Simple and reliable relay protection and control
(5) Advanced technology and rational economic efficiency
In model selection of equipment, electrical equipment with mature and advanced
technology shall be adopted as far as possible to minimize the investment and loss of
electric energy as long as the reliability of main electrical connection can be guaranteed.
6.2.2.1 Combination Mode of Generator and Main Transformer
In view of operating characteristics, quantity of units and unit capacity of the HPP,
role of the HPP played in the power system, design requirement and transport conditions
related to connection of the HPP to the electric system, the combination mode of
generators and main transformers shall be one of the following three schemes for technical
and economic comparison. Combination mode of generators and main transformers are as
follows:
a) Scheme 1: Single-bus circuit breaker sectionalized connection of
multi-generator-transformer unit
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Figure 6.2.2-1 Single-bus Circuit Breaker Sectionalized Connection of
Multi-Generator-Transformer Unit
Four generators and two main transformers are connected to form a single-bus
sectionalized circuit-breaker connection. This mode of connection is simple and distinct,
with flexible operation and easy protective relaying and control loop. In case any section of
a bus (or any one of main transformers) fails or is under maintenance, only 2 generators
will be affected, with a small shutdown range and high reliability. Disadvantages of the
scheme are as follows: ① Quantity of incoming lines at the 500 kV side is large and switch
quantity required by the HV side is large, which increases investment on the 500 kV switch
apparatuses; ② Quantity of main transformers is large, which increases investment on the
main transformers. ③ To meet requirements for economic-type generator circuit breaker
(GCB with the rated short-circuit breaking current below 80kA), the section circuit
breakers need to be connected with current limiting reactors in series, which increases
electric energy loss and equipment failure rate. ④ Generator switchgear installation has
many elements, which increases equipment investment and maintenance works.
Paklay Hydropower Project Feasibility Study Report
6-32
b) Scheme 2: connection of multi-generator-transformer unit - united
generator-transformer unit
Figure 6.2.2-2 Connection of Multi-Generator-Transformer Unit - United
Generator-Transformer Unit
Four generators and two main transformers are respectively connected to form
connection of two multi-generator-transformer units; the two expanded unit connections
are in parallel connected with each other at the HV side of the main transformers to form
connection of one multi-generator-transformer unit - united generator-transformer unit.
Compared with the scheme 1, advantages of the scheme are as follows: ① Quantity of
incoming lines at the 500 kV side is less and switch quantity required by the HV side is
②less, which decreases investment on the 500 kV switch apparatuses. Rated short-circuit
breaking current ( 80kA) ≯ can easily meets the demands, no additional current limiting
reactors are required, which decreases electric energy loss and equipment failure rate.
Disadvantages are as follows: in case the bus of united generator-transformer unit
fails or is under maintenance, capacity of 4 generators will be impacted; therefore, the
impact scope is larger; operation flexibility and manipulation convenience both are poorer
than those in scheme 1.
c) Scheme 3: connection of multi-generator-transformer unit
Paklay Hydropower Project Feasibility Study Report
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Figure 6.2.2-3 Connection of Multi-Generator-Transformer Unit
Three generators and one main transformers are connected to form one connection of
multi-generator-transformer unit. Compared with the scheme 1, advantages of the scheme
①are as follows: Quantity of incoming lines at the 500 kV side is less and switch quantity
required by the HV side is less, which decreases investment on the 500 kV switch
②apparatuses. Generator switchgear installation has less elements, which increases
③equipment investment and maintenance works. Rated short-circuit breaking current
( 80kA)≯ of the generator circuit breaker can easily meets the demands, no additional
current limiting reactors are required, which decreases electric energy loss and equipment
④failure rate. Quantity of main transformers is less, which decreases investment on the
main transformers. Disadvantages are as follows: in case the main transformer fails or is
under maintenance, capacity of 3 units will be impacted; therefore, the impact scope is
larger; operation flexibility and manipulation convenience both are poorer than those in
scheme 1.
Compared with the scheme 2, advantage is that this connection mode requires less
main transformer, which reduces investment on the main transformer. Disadvantage is that
quantity of incoming lines at the 500 kV side is large and switch quantity required by the
HV side is large, which increases investment on the 500 kV switch apparatuses.
d) Techno-economic comparison
See Table 6.2.2-1 for the summary of techno-economic comparison between different
combination modes of generator-main transformer.
Table 6.2.2-1 Summary for Technical Comparison Between Different Combination
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Modes of Generator-Main Transformer
S/
N Item
Sectionalize
d Single-bus
Connection
Multi-United
Generator-Transforme
r Unit Connection
Multi-generator-transforme
r Unit Connection
1
Quantity of
main
transformer
7 7 5
2
Quantity of
current-limitin
g reactor
3 / /
3
Quantity of
incoming
circuit at the
500 kV side
7 4 5
4
Investment in
electrical
equipment
Maximum Large Small
5 Reliable power
supply
In case of
failure or
maintenance
of any bus
section (any
main
transformer),
the capacity
of 2 units
will be
restricted
In case of failure or
maintenance of a bus
in the united
generator-transformer
unit connection at the
HV side of main
transformer, the
capacity of 4 units
will be restricted and
the influence is
relatively large.
In case of failure or
maintenance of main
transformer, the capacity of
3 units will be restricted
and the influence is
relatively small.
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and the
influence is
smallest.
6 Operation
flexibility Best Poor Good
e) Conclusion
According to the above technical and economic analysis, the scheme 3 has advantages
of high reliability, relatively flexible operation, convenient repair and maintenance. In
addition, this scheme requires less incoming lines at the 500 kV side and less main
transformers; therefore, it is also better in terms of cost. To sum up, the combination mode
of generators and main transformers shall be the scheme 3; namely, the connection of
multi-generator-transformer unit with 3 generators and 1 main transformer.
6.2.2.2 Electrical connection at 500 kV
The 500 kV switchyard of the HPP has 5 incoming circuits and 2 outgoing circuits,
according to the quantity of 500 kV outgoing circuit proposed for the HPP and the
recommended scheme for the combination mode of generator and main transformer
(multi-generator-transformer unit connection). The following 3 connection options are
preliminarily proposed for techno-economic comparison:
Figure 6.2.2-4 Dual-bus Connection
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Figure 6.2.2-5 3/2 Circuit Breaker Connection + Dual Circuit Breaker Connection
Figure 6.2.2-6 Single-bus Sectionalized Connection
a) Scheme 1: dual-bus connection
The dual-bus connection mode has distinct connection; each incoming and outgoing
line will be connected to one group of circuit breakers respectively, free from mutual
impact. In case one group of bus and relevant equipment connected fail, switch over the
circuit connected with the failed bus to another group of bus and then power can be
supplies again, without any influence on the other group of bus; therefore, this mode has
relatively high flexibility. According to line load conditions, switchover of two groups of
bus can basically balance the load distribution on two groups of bus. Switch quantity in
this mode is less than that required by 3/2 connection mode, which decreases equipment
investment.
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Disadvantages are as follows: transfer switching operation of the isolators is very
complicated; in this scheme, in case any one of elements on the bus fails, all elements on
the bus have to be removed; when a bus tie circuit breaker fails, power failure will be
applied to the whole plant in short time.
b) Scheme 2: 3/2 circuit breaker connection + dual circuit breaker connection
The mode of 3/2 circuit breaker connection + dual circuit breaker connection has high
reliability in power supply. Each incoming and outgoing line will be connected to two
groups of circuit breakers respectively. In case a line or a main transformer fails, the failed
element will be deactivated by transfer switching operation and then power supply in other
circuits can be guaranteed. In case any groups of bus or a circuit breaker is under
maintenance, the relevant circuit needs no switchover and operation of isolator is not
frequent, which decreases possibility of misoperation, convenient for operation and
maintenance.
Disadvantages are as follows: protective relaying and control loop are relatively
complicated; switch quantity required is more than that in the scheme of dual-bus
connection, which increases equipment investment.
c) Scheme 3: single-bus sectionalized connection
This mode has simple and distinct connection, with 7 groups of circuit breakers,
simple protective relaying configuration and secondary connection, and distinct equipment
layout. Each incoming and outgoing line will be connected to 1 group of circuit breakers.
In case a main transformer fails, other circuits can properly operate. This mode has flexible
operation and convenient manipulation, which can meet all operating conditions of the
HPP. It is convenient for putting in operation in stages for transition and further expansion.
It has the minimum investment in equipment.
Disadvantages are as follows: in case any one circuit of circuit breakers is under
maintenance or fails, power failure has to be applied to the relevant connected circuit; in
case a bus tie circuit breaker fails or is under maintenance, a short-time shutdown has to be
applied to the whole plant.
d) Techno-economic comparison
See Table 6.2.2-2 for the techno-economic comparison between each connection
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option at the 500 kV side.
Table 6.2.2-2 Techno-Economic Comparison Between Each Connection
Option at the 500 kV Side
Item Name
Option 1:
Double-bus
Connection
Option 2: 3/2
Connection
Option 3:
Sectionalized
Single-bus
Connection
Connection diagram
Quantity of circuit
breaker/disconnectin
g switch
8/23 11/29 8/16
Investment in
electrical equipment Large Maximum Small
Operation
Each circuit is
respectively
connected with 1
group of circuits.
Normal operation is
carried out by a
circuit breaker; in
addition to
maintenance and
isolation, a
disconnecting switch
Each circuit is
respectively
connected with 2
groups of circuit
breakers. Normal
operation is carried
out by a circuit
breaker, and a
disconnecting switch
is only used for
maintenance and
Each circuit is
respectively
connected with 1
group of circuit
breakers. Normal
operation is
carried out by a
circuit breaker,
and a
disconnecting
switch is only
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is also used for
transfer switching;
therefore, operation
in this option is
complex.
isolation. Therefore,
operation in this
option is relatively
simple.
used for
maintenance and
isolation.
Therefore,
operation in this
option is simple.
Arrangement
This option needs
many circuit
breakers and
disconnecting
switches, so the
arrangement is
relatively complex.
This option needs
many circuit breakers
and disconnecting
switches, so the
arrangement is
complex.
This option needs
a few of circuit
breakers and
disconnecting
switches, so the
arrangement is
simple.
Safe power supply
Reliable power supply:
In case of failure or
maintenance of one
group of bus and
equipment connected
with the bus, power
supply of another
bus will not be
influenced. After the
circuit connected
with the failed bus is
switched over to
another group of bus,
power restoration is
achieved.
In case of failure or
maintenance of any
bus and equipment
connected with the
bus, and in case of
maintenance of any
circuit breaker,
normal power supply
of any circuit will not
be influenced.
In case of failure
or maintenance of
one bus section
and equipment
connected with
the bus section,
power supply of
another bus
section will not be
influenced but 1/2
of the plant
capacity will be
restricted.
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Affected range of power cut:
In case of
maintenance of a
circuit breaker at any
incoming or
outgoing circuit,
power cut will only
be carried out for the
circuit under
maintenance and
other power supply
circuit will work
properly. In case of
failure of bus tie
circuit breaker,
power cut is required
to be carried out for
the whole plant, and
power restoration
will be conducted
after the failure is
eliminated.
In case of failure of
circuit breaker at each
circuit connected with
a bus, only short-time
power supply of the
circuit subjected to
the failure will be
influenced. In case of
failure of
interconnection
circuit breaker
between two circuits,
only short-time power
supply of these two
circuits will be
influenced.
In case of
maintenance of a
circuit breaker at
any incoming or
outgoing circuit,
power cut will
only be carried out
for the circuit
under
maintenance and
other power
supply circuit will
work properly. In
case of failure of
sectionalized
circuit breaker,
power cut is
required to be
carried out for the
whole plant, and
power restoration
will be conducted
after the failure is
eliminated.
Probability for power cut of whole plant:
In case of this
option, the
Power cut of whole
plant will not occur in
When a bus tie
circuit breaker
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probability for power
cut of whole plant is
small.
the following
conditions: a circuit
fails when one bus is
under maintenance (in
the single-bus
operation mode) and
the circuit breaker
fails to operate; a bus
fails in the single-bus
operation mode; two
buses fail at the same
time in the double-bus
operation mode.
fails, power cut
will be carried out
for the whole
plant.
Relay protection
Relay protection and
control circuit are
both complex, not in
favor of automation
or telemechanization.
Relay protection and
control circuit are
relatively complex.
Relay protection
and control circuit
are both simple.
e) Conclusion
According to the above technical and economic comparison, the scheme 1 has
relatively lower investment and flexible operation but its operation and manipulation are
relatively complicated; the scheme 2 has high reliability but its investment is relatively
higher. The scheme 3 has the lowest investment but its reliability is the poorest. In view of
the installed capacity of the HPP and the role and function of the HPP in Thailand power
grid, it is recommended to adopt the scheme 1 for connection at the 500 kV HV side;
namely, the dual-bus connection mode at the 500 kV side.
6.2.3 Station Service System and Power Supply System at Dam Area
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6.2.3.1 Features of Station Service System and Power Supply System at Dam Area
⑴ The range of power supply is wide, load points are decentralized, and the farthest
power supply point is about 1.0 km ~ 2 km away.
⑵ Power supply loads are large and the maximum station service load is about 8,000
kVA.
6.2.3.2 Design Principle
Because the HPP plays an important role in the electric power system, the station
service system of the HPP is required to have high reliability of power supply. According
to Code for Designing Auxiliary Power System of Hydro-power Station (NB/T35044-2014)
and Electrical-mechanical Design Code of Hydropower Plant (DL/T5186-2004), the
design principle for the service power of plant of the HPP is as follows:
a) Arrangement principle for station service power supply
When all units are under operation, at least 3 station service power supplies shall be
provided. When only some units are under operation, at least 2 station service power
supplies shall be provided. When all units are shut down, at least 2 reliable power supplies
shall be provided but one of them is allowed to stand by.
b) Selection principle for voltage class of service power of plant
Loss of electric energy and equipment investment shall be reduced as far as possible,
while considerations shall be given to the voltage class of station service motor with a
large capacity.
c) Design principle for station service connection:
⑴ The connection shall meet the requirements for sectionalized power supply of
each load center.
⑵ The connection shall be as simple as possible, in favor of relay protection system
used for service power of plant and spare power source automatic switch.
⑶ The connection shall meet the power supply requirements in staged construction
or continuous construction and shall be convenient for transition.
⑷ The common power system of the whole plant and the auxiliary power supply
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system of units shall be fed separately. The auxiliary power supplies of units shall be
independent, so that frequent startup or shutdown of units will not influence the continuous
power supply of the common power system of the whole plant, in favor of rapid power
restoration.
⑸ The connection shall meet the power supply requirements for startup and
shutdown of units. Switching operation for service power of plant shall be reduced as far as
possible.
⑹ The lighting power supply system shall be equipped with a lighting transformer
independently.
⑺ In view of flood control by the dam, a diesel generator unit shall be arranged on
the dam crest as the safety emergency power supply when the dam is used for flood
releasing.
⑻ The powerhouse shall be equipped with a diesel generator unit as the safety
emergency power supply of the HPP powerhouse, to prevent the powerhouse from
inundation.
6.2.3.3 Leading of Station Service Power Supply
According to Article 3.1.1 of Code for Designing Auxiliary Power System of
Hydro-power Station (NB/T35044-2014), the leading mode and arrangement of the
working power supply used for the service power of plant shall meet the requirement of
"When the voltage circuit of generator is equipped with a generator circuit breaker, the
working power supply used for service power of plant shall be arranged between the
generator circuit breaker and the LV side of main transformer" in Paragraph 4. Because all
units of the HPP are equipped with a generator circuit breaker, the station service power
supply shall be arranged at the LV side of main transformer. Normally, the units will feed
the service power of plant. In case of shutdown, the electric power system can reversely
feed the service power of plant. This scheme is characterized by highly reliable power
supply, simple connection, convenient arrangement, and good economic efficiency.
Therefore, it can be applied to the main power supply used for service power of plant of
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the HPP.
Because the HPP is a Grade I large (1) scale HPP, an external power supply shall be
arranged and used as the spare station service power supply, so as to improve the reliability
and continuity of the service power of plant. For the HPP, the external power supply can be
provided as follows:
Mode 1: The service power of plant can be supplied reversely from the electric power
system through the main transformer.
Mode 2: A diesel generator unit shall be arranged.
Therefore, the leading scheme for station service power supply is as follows: The
whole plant is equipped with 4 HV station service transformers, and the main power
supplies used for service power of plant are respectively led from the LV sides of main
transformers TM1~TM4. For the spare station service power supply, in addition to reverse
power transmission from the electric power system through main transformers, 1 diesel
generator unit is respectively arranged on the dam crest and in the powerhouse, serving as
the safety emergency power supply for flood releasing by dam and the safety emergency
power supply of powerhouse.
6.2.3.4 Voltage Selection for Service Power of Plant
The HPP is of a water-retaining type powerhouse on the ground. Because the plant
area is relatively large, the power transmission distance is relatively long, and the load
capacity is relatively large, the station service system shall be of the two-stage voltage
power supply. According to the design principle specified in Article 3.2.2 of Code for
Designing Auxiliary Power System of Hydro-power Station (NB/T35044-2014) that "The
HV service power voltage should be 10 kV and the LV service power voltage should be
0.4 kV" and Article 3.3 that "According to Code for Design of AC Electrical Installations
Earthing (GB/T 50065), the grounding mode of LV station service system should be of the
TN-S or TN-C-S system", the station service system of the HPP shall be of the two-stage
voltage power supply (10 kV and 0.4 kV), the LV distribution system shall be of the
three-phase four-wire system, and the neutral point shall be directly grounded.
6.2.3.5 Connection mode for station service power
The Paklay HPP respectively supplies power to the unit service power, common
power demand of plant and lighting power. Connection mode for station service power
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adopts single-bus sectionalized connection.
a) Power supply mode at 10.5 kV voltage level
The bus at 10.5 kV voltage level of the station service power consists of 4 sections, in
① ② ③ ④2 groups. Bus sections and constitute 1 group while sections and constitute
another 1 group. The THA1 HV station service transformer connected to the LV side of the
TM1 main transformer suppl ①ies power to the bus section . The THA2 HV station service
transformer connected to the LV side of the TM2 main transformer supplies power to the
②bus section . ① ②A bus tie switch is set for the bus sections and . The THA3 HV
station service transformer connected to the LV side of the TM3 main transformer supplies
③power to the bus section . The THA4 HV station service transformer connected to the
LV side of the TM4 ④main transformer supplies power to the bus section . A bus tie
switch is set for the bus ③ ④sections and .
During normal operation, 4 HV station service transformers will respectively supply
power to operate the station service loads in the whole plant. In case any one section of bus
① ②in the bus sections and loses its voltage, automatic bus transfer equipment will
automatically operate via the bus tie switch and then 1 HV station service transformer will
① ②drive the bus sections and for operation. In case any one section of bus in the bus
③ ④sections and loses its voltage, automatic bus transfer equipment will automatically
operate via the bus tie switch and then 1 HV station service transformer will drive the bus
③ ④sections and for operation.
See Fig. 6.2.3-1 for the schematic diagram of HV station service connection.
Fig. 6.2.3-1 Schematic Diagram of HV Station Service Connection
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b) Power supply mode at 0.4 kV voltage level
1) Common power system of whole plant
The bus at 0.4 kV voltage level of the common power demand of plant consists of 4
sections, in 2 groups. Bus sections I and III constitute 1 group while sections II and IV
①constitute another 1 group. The bus section I is connected to the bus section at 10.5 kV
voltage level via the TLA1 common transformer. The bus section III is connected to the
bus section ③ at 10.5 kV voltage level via the TLA3 common transformer. A bus tie
switch is set for the bus sections I and III. The bus section II is connected to the bus section
② at 10.5 kV voltage level via the TLA2 common transformer. The bus section IV is
④connected to the bus section at 10.5 kV voltage level via the TLA4 common
transformer. A bus tie switch is set for the bus sections II and IV.
2) Lighting power system
The bus at 0.4 kV voltage level for lighting power consists of 2 sections. Bus section I
②is connected to the bus section at 10.5 kV voltage level via the TL1 lighting transformer.
③Bus section II is connected to the bus section at 10.5 kV voltage level via the TL2
lighting transformer. A bus tie switch is set for the bus sections I and II.
3) Auxiliary power supply system of units
The 0.4 kV bus connected with the main panel of auxiliary power supply of unit
consists of 6 sections, namely, section I, section II, section III, section IV, section V, and
section VI. The 0.4 kV bus is connected with the 10.5 kV bus as follows:
The bus section I of the main panel ①is connected to the bus section at 10.5 kV
voltage level via the TLP1 unit service power transformer; the bus section II of the main
panel is connected to the bus section ③ at 10.5 kV voltage level via the TLP2 unit service
power transformer; the bus section III of the main panel ①is connected to the bus section
at 10.5 kV voltage level via the TLP3 unit service power transformer; the bus section IV of
the main panel is connected to the bus section ③ at 10.5 kV voltage level via the TLP4
unit service power transformer; the bus section V of the main panel is connected to the bus
section ② at 10.5 kV voltage level via the TLP5 unit service power transformer; the bus
section VI of the main panel is connected to the bus section ④ at 10.5 kV voltage level
via the TLP6 unit service power transformer
The connection mode of No. 1 ~ No. 5 multi-generator-transformer units is as
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follows:
⑴ No. 1 multi-generator-transformer unit connection
The bus section I of main panel is connected with the load point of auxiliary power supply
of G1 unit. The bus section II of main panel is connected with the load point of auxiliary
power supply of G2 unit. The bus sections I and II of main panel are equipped with a bus
tie switch to ensure that both G1 and G2 units have 2 main power supply points.
⑵ No. 2 multi-generator-transformer unit connection
The 0.4 kV bus connected with the sub-panel of auxiliary power supply of No. 2
multi-generator-transformer unit consists of 3 sections that are respectively connected with
the load points of auxiliary power supply of G3, G4 and G5 units. The 0.4 kV bus of
sub-panel is equipped with two power supplies that are respectively connected with bus
sections III and IV of main panel, so as to ensure that G3, G4 and G5 units have 2 main
power supply points.
⑶ No. 3 multi-generator-transformer unit connection
The 0.4 kV bus connected with the sub-panel of auxiliary power supply of No. 3
multi-generator-transformer unit consists of 3 sections that are respectively connected with
the load points of auxiliary power supply of G6, G7 and G8 units. The 0.4 kV bus of
sub-panel is equipped with two power supplies that are respectively connected with bus
sections III and IV of main panel, so as to ensure that G6, G7 and G8 units have 2 main
power supply points.
⑷ No. 4 multi-generator-transformer unit connection
The 0.4 kV bus connected with the sub-panel of auxiliary power supply of No. 4
multi-generator-transformer unit consists of 3 sections that are respectively connected with
the load points of auxiliary power supply of G9, G10 and G11 units. The 0.4 kV bus of
sub-panel is equipped with two power supplies that are respectively connected with bus
sections V and VI of main panel, so as to ensure that G9, G10 and G11 units have 2 main
power supply points.
⑸ No. 5 multi-generator-transformer unit connection
The 0.4 kV bus connected with the sub-panel of auxiliary power supply of No. 5
multi-generator-transformer unit consists of 3 sections that are respectively connected with
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the load points of auxiliary power supply of G12, G13 and G14 units. The 0.4 kV bus of
sub-panel is equipped with two power supplies that are respectively connected with bus
sections V and VI of main panel, so as to ensure that G12, G13 and G14 units have 2 main
power supply points.
4) Protective load power system
The bus at 0.4 kV voltage level for protective load consists of 1 section. Dual power
supply is adopted for the bus section for power supply and the bus section is respectively
connected to the bus sections ② and ③ at 10.5 kV voltage level via TLA5 and TLA6
common transformers. In addition, a 0.4 kV 800 kW diesel generator unit shall be provided
for the HPP as the emergency power supply.
5) Power supply system at dam area
According to the dam crest load information upon preliminary estimates, the
utilization voltages of electrical equipment on the dam crest shall all be 380/220 V.
Therefore, the dam crest power supply system shall supply 0.4 kV primary voltage. The
dam crest connection is of single-bus sectionalized connection mode. Bus section I is
connected to the bus section ② at 10.5 kV voltage level via the TLA7 dam crest
transformer. Bus section II is connected to the bus section ④ at 10.5 kV voltage level via
the TLA8 dam crest transformer. A bus tie switch is set for the bus sections I and II, to
ensure 2 main power supply points for the crest power consumption. In addition, a 0.4 kV
800kW diesel generator unit shall be provided as the emergency power supply for flood
releasing on the dam.
6.2.4 Type Selection for 500 kV HV Switchgear Installation
6.2.4.1 Construction Scale for 500 kV Switchyard
The 500 kV switchyard of the Paklay HPP has 5 incoming lines and 2 outgoing lines. See
Table 6.2.4-1 for the construction scale.
Table 6.2.4-1 Construction Scale for 500 kV Switchyard
S/N Item Name Construction Scale (Equipment
Quantity)
1 500 kV incoming line
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1.1 Incoming circuit breaker bay of No. 1 main
transformer 1
1.2 Incoming circuit breaker bay of No. 2 main
transformer 1
1.3 Incoming circuit breaker bay of No. 3 main
transformer 1
1.4 Incoming circuit breaker bay of No. 4 main
transformer 1
1.5 Incoming circuit breaker bay of No. 5 main
transformer 1
2 500 kV outgoing line
2.1 Circuit breaker bay of 500 kV outgoing line I 1
2.2 No. 1 line trap 3
2.3 Capacitor voltage transformer at No. 1 line 3
2.4 Arrester at No. 1 line 3
2.5 Circuit breaker bay of 500 kV outgoing line II 1
2.6 No. 2 line trap 3
2.7 Capacitor voltage transformer at No. 2 line 3
2.8 Arrester at No. 2 line 3
3 Bus tie circuit breaker bay 1
4 Bus PT&LA bay
4.1 1M PT&LA bay 1
4.2 2M PT&LA bay 1
6.2.4.2 Selection Principle for 500 kV Equipment
According to relevant electric power export plan made by the Lao Government, upon the
completion of the Paklay HPP, the electric power will be completely exported to Thailand
and play a very important role in the Thailand power grid. The operation management of
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the HPP is "unmanned-on-duty" (few-on-duty). Selection of 500 kV switchgear installation
shall comply with the following basic principles:
⑴ In the service environment, the equipment shall meet the requirements for proper
operation, maintenance, short circuit and over-voltage; in addition, long-term development
shall also be taken into account.
⑵ The equipment shall have mature operation experience and advanced technology.
⑶ The equipment shall have safe and reliable operation and convenient maintenance,
being adaptive to the management mode of the HPP, which is "unmanned-on-duty"
(few-on-duty).
⑷ In the design level year, the rated short-time withstand current for electrical equipment
at a 500 kV switchyard shall be temporarily considered as 50kA/2s.
6.2.4.3 Preliminary Determination of Switchyard Site
a) Considerations for site selection
With respect to a 500 kV switchyard, the following factors shall be taken into account for
its site selection:
⑴ Topographic conditions: Civil excavation and backfilling shall be carried out as less as
possible to avoid occurrence of a high slope.
⑵ Geological conditions: shall meet the foundation requirements for switchyard
equipment and framework.
⑶ Incoming and outgoing lines: The outgoing line corridor of transmission line shall be
as open as possible, in favor of arrangement of outgoing line.
⑷ 500 kV HV outlet: The length of outlet at the HV side of main transformer shall be as
short as possible.
⑸ The switchyard site shall be convenient for operation management and close to the
powerhouse as much as possible.
⑹ The site shall be away from the vibration area of tailrace platform as far as possible.
b) Preliminarily determined site scheme
According to the combination mode of generator and transformer as well as the quantity of
outgoing circuit of transmission line, the 500 kV switchyard has 5 incoming lines and 2
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outgoing lines in total and its connection at the 500 kV side is of the double-bus connection
mode. The HPP is of a water-retaining type hydroelectric station and the powerhouse is
arranged in a compact manner.
⑴ Option 1: GIS switchyard site for auxiliary plant
According to the arrangement of electromechanical equipment in auxiliary plant, if an SF6
gas insulated switchgear (GIS) is adopted, the GIS switchyard can be arranged at the
downstream auxiliary plant (E.L. 245.50 m) at the No. 3 ~ No. 5 unit bay. Meanwhile, the
GIS is directly connected with main transformers through an SF6 tubular bus.
⑵ Option 2: Right-bank AIS switchyard site
According to topographical conditions of the site area, if the air insulated switchgear (AIS)
is adopted, the AIS switchyard can be arranged on the bottomland on the right bank of the
river. However, main transformers are far away from the switchyard, with limited outgoing
line gallery; the HV side of the main transformers shall be connected to the switchyard via
a 500 kV HV cable. Therefore, it requires an additional 500 kV HV cable of about 7.5 km
in length and 30 cable heads.
6.2.4.4 Equipment model selection and arrangement in GIS option
In the GIS option, the 500 kV GIS circuit breaker is of a horizontal double-break type; the
GIS is connected with main transformers and outgoing bushing through an SF6 tubular bus.
The GIS switchyard is arranged as follows:
The GIS switchyard is arranged in 2 layers. The first layer is the SF6 tubular bus layer and
the second layer contains a GIS room and a 500 kV open-type outgoing line platform.
The plane arrangement dimension of the GIS room and the 500 kV open-type outgoing line
platform is 138.90 m × 21.40 m. The plane dimension of the GIS room at the left side is
68.50 m × 17.40 m. The GIS room is mainly equipped with 5 circuit breaker incoming
bays, 2 circuit breaker outgoing bays, 1 circuit breaker bus tie bay, and 2 PT&LA bays.
The plane dimension of the 500 kV open-type outgoing line platform at the right side is
70.50 m × 21.40 m. The platform is mainly equipped with 6 traps, 6 capacitor voltage
transformers, and 6 arresters.
6.2.4.5 Equipment model selection and arrangement in AIS option
The 500 kV AIS mainly consists of HV distribution equipment and outgoing line
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equipment. The HV distribution equipment includes circuit breaker, disconnecting switch
(including grounding switch), current transformer, voltage transformer, arrester and bus.
The outgoing line equipment includes line arrester, voltage transformer and so on. The
circuit breaker is of the SF6 insulation porcelain stanchion type and the disconnecting
switch is of the single-arm folded structure. The AIS switchyard has a plane arrangement
dimension of 250 m × 100 m and an occupied area of about 25,000 mm2. The 500 kV AIS
is arranged as follows:
A suspended tubular bus is employed, porcelain stanchion circuit breakers are arranged in
a single row, and both the incoming and outgoing lines are arranged at a single side. Facing
the outgoing line side, bays are arranged from left to right as follows: No. 1 incoming bay
(to the TM1 main transformer), No. 2 incoming bay (to the TM2 main transformer), No. 3
outgoing bay, No. 4 incoming bay (to the TM3 main transformer), No. 5 bus tie bay, No. 6
incoming bay (to the TM4 main transformer), No. 7 outgoing bay, and No. 8 incoming bay
(to the TM5 main transformer).
6.2.4.6 Technical Comparison for AIS Option and GIS Option
In conclusion, both AIS switchyard and GIS switchyard can meet the technical
requirements of the Project. Technical analysis and comparison of the GIS switchyard and
AIS switchyard are as follows:
a) Reliability and safety
Generally, a GIS is more reliable and safer than an AIS in terms of operation because
the GIS has a lower failure rate. The GIS has advantages in reliability and safety as
follows:
(1) Electrical equipment in the GIS is more reliable than that in the AIS in terms of
insulating property.
(2) Contact resistance at the connection part of the GIS conductors is less than that of
the AIS conductors.
(3) Personal injury accidents: according to the statistical data, personal injury
accidents caused by the AIS occur every 1,000 station years, while those caused by the GIS
occur every 4,000 station years.
b) Maintenance management and repair
(1) The GIS is nearly free from maintenance, with a small quantity of maintenance
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works.
(2) Most elements of the AIS are susceptible to environmental conditions, with a large
quantity of maintenance works.
(3) The GIS has a heavy maintenance cycle of 15~20 years, with a relatively longer
maintenance time; the AIS has a shorter heavy maintenance cycle, with more frequent
maintenance works. According to the statistical data, the ratio of the AIS maintenance
cycle to the GIS maintenance cycle is 1:5.
c) Installation
Generally, the GIS has complete components and its parts and components are
model-building blocks; therefore, the GIS has convenient site installation and
commissioning. However, the AIS has relatively conditions, with longer installation and
commissioning time.
d) Seismic resistance
The GIS elements are enclosed inside a shell and the whole switchgear installation is
connected to be an integrated structure; in addition, its height is lower than that of the AIS;
therefore, it has better integral rigidity and seismic resistance than the AIS.
e) Electrostatic Induction and radio interference level
Most GIS elements are installed inside an enclosed shell that is grounded. Based on
shielding effect of the shell, it is much better than the AIS in terms of electrostatic
induction and radio interference level.
f) Internal fault test
The structure of GIS equipment is highly intensive; therefore, fault of one element
inside may impact other elements. Compared with the AIS, the GIS has a larger fault
impact scope and it is more difficult to find out the failed element in the GIS.
g) Civil construction period and difficulty of the switchyard
In case of the AIS option, it will be arranged on a bottomland on the right bank of the
river, with an occupied area of about 150.0 m x 70.0 m. In case of the GIS option, the GIS
will be arranged in the auxiliary plant downstream at an elevation of 245.50m in the
section of No. 3~5 units and the GIS room will have an area of 68.50m×17.40. Therefore,
the AIS switchyard has a larger occupied area than the GIS switchyard, with more civil
works. Compared with the GIS switchyard, the AIS has disadvantages as follows:
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(1) The AIS switchyard has a longer civil construction period.
(2) The AIS switchyard has a larger civil works.
(3) The AIS switchyard requires an additional investment on the electrical equipment
such as 500 kV HV cables.
(4) The AIS switchyard is of decentralized layout of equipment, with inconvenient
operation and maintenance.
In conclusion, the GIS scheme is better than the AIS scheme technically.
6.2.4.7 Economic Comparison for AIS Option and GIS Option
According to the quantities of civil works and relevant investment amounts provided
by the powerhouse discipline, the investment comparison for civil works of 500 kV
switchyard is listed in Table 6.2.4-2, the investment comparison for main electrical
equipment is listed in Table 6.2.4-3, and the comparison for comprehensive investment is
listed in Table 6.2.4-4.
Table 6.2.4-2 Investment Comparison for Civil Works of 500 kV Switchyard
S/N Item Name Unit GIS AIS Unit Price
(USD)
Total
Price of
GIS
(USD)
Total
Price of
AIS
(USD)
Differenc
e Value
(USD)
GIS-AIS
1 Open earth
excavation m3 / 221902 3.31 / 734939 -734939
2 Open rock
excavation m3 /
125744
3 9.08 / 11417582
-1141758
2
3 Shotcrete m3 / 3008 201.17 / 605119 -605119
4
Anchor rod
(Ф25, L=6
or 8m)
Nr. / 2228 89.978 / 200471 -200471
5
C20
structure
concrete
m3 / 15000 121.03 / 1815450 -1815450
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6
C25
structure
concrete
m3 5400 / 138.49 747846 / 747846
7 Reinforcem
ent t 648 750 1585.36 1027313 1189020 -161707
8
Drainage
hole (D56,
L=3m)
m / 3759 41.07 / 154382 -154382
9 Total (USD
103) 1775 16117 -14342
Remarks: Investments in the above table are all based on the approximate price in September
2013.
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Table 6.2.4-3 Investment Comparison for Electrical Equipment of 500 kV Switchyard
S/N Description Main Electrical Equipment Unit Qty. Price (USD)
I Option 1: GIS switchyard for auxiliary plant
1 500kV GIS
GIS circuit breaker bay Nr. 8 1.1 million/bay
GIS PT&LA bay Nr. 2 400,000/bay
2 500kV
open-type equipment
Capacitor voltage
transformer Set 6 12,500/set
Zinc oxide arrester Set 6 6,000/set
Trap Set 3 46,000/set
3 Investment in
electrical equipment 9.849 million
II Option 2: Right-bank AIS switchyard
1 500kV AIS
AIS circuit breaker bay Nr. 8 460,000/bay
AIS PT&LA bay Nr. 2 80,000/bay
2 500kV
open-type equipment
Capacitor voltage
transformer Set 6 12,500/set
Zinc oxide arrester Set 6 6,000/set
Trap Set 3 46,000/set
3 500 kV HV cable
500kV XLPE m 7500 385/m
GIS cable terminal Nr. 15 61,500/Nr.
AIS cable terminal Nr. 15 61,500/Nr.
4 500kV GIB 500kV Set 5 230,000/set
5 Investment in
electrical equipment 9.9715 million
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Table 6.2.4-4 Comparison for Comprehensive Investment of 500 kV Switchyard
103 (USD)
S/N Item Name Option 1: GIS Switchyard for
Auxiliary plant
Option 2: Right-bank AIS
Switchyard
1 Investment in civil works 1775.0 16117.0
2 Investment difference in civil
works 0.00 +14342
3 Investment in electrical
equipment 9849.0 9971.5
4 Investment difference in
electrical equipment 0.00 +122.5
5 Total project investment 11624.0 26088.5
6 Total investment difference 0.00 +14464.5
6.2.4.8 Conclusion
According to the above techno-economic analysis and comparison, it is recommended that
the 500 kV HV distribution equipment of the HPP should be of the GIS option and the GIS
switchyard shall be arranged at the downstream auxiliary plant (E.L. 245.50 m). Reasons
①are as follows: The investment in the GIS option is USD 14.4645 million less than that
in the AIS option, because a GIS switchyard occupies less land and has a lower cost of
②civil works. It is easy to implement "unmanned-on-duty" (few-on-duty) management
mode for a GIS, due to its high power supply reliability, small workload of maintenance
work, convenient management and easy centralized monitoring.
6.2.5 Position Selection for 500 kV GIS Switchyard
6.2.5.1 Determination of GIS Arrangement Scheme
The review meeting for the feasibility study report on Paklay HPP at the Mekong River in
Laos was held on April 21~22, 2014. In the meeting, the technical parts of the Project were
reviewed. Review comments on the 500 kV HV distribution equipment are as follows: It is
rational to adopt the GIS scheme for the 500 kV HV distribution equipment. However, it is
suggested that the GIS arrangement position should be further studied to make proper
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adjustment because the tailrace platform will suffer from vibrations when a GIS room is
arranged at the unit bay. According to the review comments from experts, 3 GIS
arrangement options are proposed for technical comparison as follows:
Option 1: The 500 kV GIS room is arranged at the downstream auxiliary plant (E.L.
245.50 m) at the No. 3 ~ No. 5 unit bay, while the 500 kV open-type outgoing line
platform is arranged side by side at the No. 1 ~ No. 2 unit bay ①and at the erection bay of
downstream auxiliary plant (E.L. 245.50 m).
②Option 2: The 500 kV GIS room is arranged at the erection bay of downstream auxiliary
plant (E.L. 245.50 m), while the 500 kV open-type outgoing line platform is arranged side
by side at the downstream auxiliary plant (E.L. 245.50 m) at the No. 11 ~ No. 14 unit bay.
①Option 3: The 500 kV GIS room is arranged at the erection bay of downstream auxiliary
plant (E.L. 245.50 m), while the 500 kV open-type outgoing line platform is arranged on
the roof of GIS room (E.L. 260.50 m).
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6.2.5.2 Technical Comparison
See Table 6.2.5-1 for the summary of technical comparison between each GIS arrangement
option.
Table 6.2.5-1 Technical Comparison for GIS Arrangement Options
Item
Name Option 1 Option 2 Option 3
500 kV
outgoing
line
corridor
The 500 kV open-type
outgoing line platform is
arranged against the left
bank of the Mekong River.
The span and deflection
angle between the outgoing
line framework and the
terminal tower are both
small. The outgoing line
corridor is relatively wide.
To sum up, this option is in
favor of the design of
transmission line.
The 500 kV open-type
outgoing line platform is
arranged in the middle of the
riverbed, far away from both
banks. Therefore, a terminal
tower is needed to be
arranged on the retaining
wall at the dredging area.
However, the elevation of the
retaining wall at the dredging
area is relatively low, and it
is difficult to deal with the
tower foundation, and the
quantities of tower are
relatively large. To sum up,
this option is not in favor of
the design of transmission
line.
The 500 kV open-type
outgoing line platform is
arranged against the left
bank of the Mekong River.
The span and deflection
angle between the
outgoing line framework
and the terminal tower are
both small. The outgoing
line corridor is relatively
wide. To sum up, this
option is in favor of the
design of transmission
line.
Vibration
Vibration of tailrace platform:
The 500 kV GIS is arranged
at the downstream auxiliary
plant at the No. 3 ~ No. 5
unit bay. When water flow
passes through the units, the
GIS structure will suffer
from vibrations which will
vibrate the electrical
equipment. To sum up,
The 500 kV GIS is arranged
at the ② erection bay of
downstream auxiliary plant.
In flood season, the whole
plant will be shut down when
the bottom discharge orifice
is used for flushing. To sum
up, equipment vibration does
not exist in this option.
The 500 kV GIS is
①arranged at the erection
bay of downstream
auxiliary plant. The
substructure is free of
discharging facilities. To
sum up, equipment
vibration does not exist in
this option.
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equipment will suffer from
vibrations in this option.
Solutions:
1. The 500 kV GIS circuit
breaker should be of the
horizontal type. In addition,
expansion joints in a proper
number shall be provided
for connections of 500 kV
GIS SF6 tubular bus, 13.8
kV isolated-phase bus and
relevant equipment, so as to
improve the anti-vibration
performance of equipment.
2. In the design, a flexible
circuit conductor shall be
used for fixture wire and
equipment connections as
far as possible, and the
flexible circuit conductor
shall be long enough, so as
to improve the anti-vibration
performance of equipment.
3. A connection terminal
with spring fasteners should
be used as the secondary
connection terminal, to
avoid disconnection of the
secondary connection and to
improve the anti-vibration
performance of equipment.
Equipment vibration does not
exist in this option.
Equipment vibration does
not exist in this option.
Examples
Refer to the Taoyuan HPP,
the Feilaixia Hydropower
Project, and the Shihutang
Navigation and Hydropower
Examples for arrangement of
switchyard on the tailrace
platform in the middle of
riverbed are seldom.
A tubular HPP complex
generally has a wide
landform. In most cases, a
switchyard is arranged at
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Complex Project for
arrangement of switchyard
on the tailrace platform at
the side of river bank.
the erection bay of
downstream auxiliary
plant at the side of river
bank, and the switchyard
and the outgoing line
platform are arranged at
one elevation.
Structure
pattern
The space of downstream
auxiliary plant is fully used
to arrange the switchyard
and open-type outgoing line
equipment. To sum up, the
structure pattern is relatively
rational.
The space of downstream
auxiliary plant is fully used
to arrange the switchyard and
open-type outgoing line
equipment. To sum up, the
structure pattern is relatively
rational.
For the Project, if the
switchyard is arranged at
①the erection bay of
downstream auxiliary
plant, the switchyard and
the outgoing line platform
shall be arranged in a
stagger manner because
①the end of the erection
bay is a high slope. To
sum up, the structure
pattern is irrational.
6.2.5.3 Conclusion
According to the above technical comparison, option 1 is in favor of the arrangement
of 500 kV outgoing line of switchyard and its structure pattern is rational. Therefore,
option 1 is the recommended GIS arrangement scheme of the HPP.
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6.2.6 Selection of Main Electrical Equipment
6.2.6.1 Estimate of short circuit current
Because of lack of relevant data to connect to the power system, it is temporarily
consider the short circuit current of the HV bus at 500 kV side to be 50 kA and the power
supply to be infinite. Upon estimate, the short circuit current at the generator outlet of the
multi-generator-transformer unit is less than 80 kA.
6.2.6.2 Main electrical equipment
a) Turbo- generator
Model: SFWG55-64/8000
Quantity: 14
Type: Three-phase, horizontal type, bulb, closed forced circulation, air-cooling and
synchronous generator
Rated capacity: 55 MW
Rated voltage: 13.8 kV
Rated current: 2422.1 A
Rated power factor: 0.95
Rated frequency: 50 Hz
Rated speed: 93.8 r/min
Direct-axis subtransient reactance X"d 0.≮ 21 (tentative)
Insulation grade: F
Brake mode: mechanical
Excitation mode: self-shunt thyristor static excitation mode
Fire control method: fixed water spray
b) Generator voltage switchgear installation
(1) Generator voltage bus
From the generator main outlet to the 13.8 kV switchgear, the generator voltage bus is of
the common enclosure bus or the insulating tubular bus with a rated current of 3,150 A and
a thermal stability current/time of 80kA/2s. From the 13.8 kV switchgear to the LV side of
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main transformer, the generator voltage bus is of the isolated-phase bus with a rated
current of 8,000 A and a thermal stability current/time of 80kA/2s. Main technical
parameters are as follows:
Type: common enclosure bus or the insulating tubular bus/isolated-phase bus
Cooling mode: natural cooling
Conductor type: Copper conductor/tubular aluminum conductor
Rated voltage: 13.8kV
Maximum voltage: 15.8kV
Rated current: 3150A/8000A
Rated frequency: 50Hz
Thermal stability current (2s):
Main circuit (effective value) 80kA
Branch circuit (effective value) 125kA
Dynamic stability current:
Main circuit (peak value) 200kA
Branch circuit (peak value) 315kA
⑵ Generator outlet circuit breaker
The HPP is of the multi-generator-transformer unit connection. The generator has a rated
capacity of 55 MW, a rated voltage of 13.8 kV and a rated current of 2422.1 A. The
corresponding generator outlet circuit breaker shall have a rated current of 3,150 A and a
rated short-circuit breaking current of 80 kA, and its main technical parameters shall be as
follows:
Type: SF6 generator circuit breaker
Insulating medium: SF6
Rated voltage: 13.8kV
Rated current: 3150A
Rated frequency: 50Hz
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Rated short-circuit making current (peak value): 220kA
Rated peak withstand current: 220kA
Rated short-time withstand current (effective value)/time: 80kA/3s
Rated short-circuit breaking current 80kA
(3) 13.8 kV switchgear installation
The HV station service circuit is proposed to be equipped with an HV current limiting
fuse cabinet. Normal operation (breaking of rated current) is implemented by a load switch.
In case of short circuit, the HV current limiting fuse will provide corresponding protection
for the circuit. A potential transformer, current transformer, surge arrester and others are all
installed inside a fully-closed metal-armored cabinet. All electrical cabinets are of three
phases. Grounding of the generator neutral point is realized by the grounding transformer.
c) Main transformer
The multi-generator-transformer unit connection is adopted for the combination mode of
generator and main transformer. If the multi-generator-transformer unit connection consists
of 3 generators and 1 transformer, in 4 groups, the rated capacity (180 MVA) of main
transformer shall match with the rated capacity of 3 generators. If the
multi-generator-transformer unit connection consists of 2 generators and 1 transformer, in
1 group, the rated capacity (120 MVA) of main transformer shall match with the rated
capacity of 2 generators. Selection for type and parameters of main transformer:
1) Type of main transformer
⑴ Transport of heavy-big piece
Transport scheme of heavy-big piece for the HPP: The transport of heavy-big piece is
carried out by water, rail and road together. Restricted by the load standard of rail tunnel
and road bridge, the transport dimension of the biggest piece shall be within the level-2
over-limit range of railway and the maximum weight shall not exceed 100t.
According to the data on main transformers provided by manufacturers, the transport
weight of common three-phase transformer with nitrogen is beyond the transport
conditions for heavy-big piece of the HPP. Therefore, the following 2 options (i.e.
single-phase transformer bank and combined three-phase transformer) shall be taken into
account for the type of main transformer.
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Option 1: single-phase transformer bank
In this option, three common single-phase transformers are combined into one three-phase
transformer, featuring mature design and fabrication experience, small transport weight
and dimension, short installation period, and rich operation experience. However, the
arrangement area in this option is relatively large.
Option 2: combined three-phase transformer
Upon study and analysis, the combined three-phase transformer composed of three special
single-phase transformers is characterized by mature design and fabrication experience and
wide application. The special single-phase transformer has a structure basically the same as
that of the common one. In combination, independent oil tanks are adopted and only a lead
conduit is used to connect three transformers as a whole. Namely, oil lines of three
independent single-phase transformers are connected as a whole. In this option, the
transport weight, transport dimension and occupied area of arrangement are small, and the
installation period is relatively short.
⑵ Technical analysis
◇ Single-phase transformer bank:
① Reliability
The single-phase transformer bank is composed of three single-phase transformers. In
general, three transformers are respectively arranged in an independent room so their oil
lines are totally separated. Therefore, three-phase short circuit will not occur and reliability
of HPP operation will be improved.
② Arrangement
The single-phase transformer bank is composed of three single-phase transformers. In
general, three phases are arranged separately. According to the typical fire law for
electrical equipment in China, a transformer of which the oil amount is 2,500 kg or above
must be arranged separately; a fire partition shall be used for separation if the interval is
less than 10 m (500 kV). The oil amount of single-phase transformer at an ultra-large type
HPP far exceeds the value specified in the fire law, so the transformers must be arranged
and installed separately and the occupied area is large accordingly.
③ Spare phase
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Application of single-phase transformer bank to a large HPP is to ensure the reliability of
HPP operation. When the quantity of transformer is relatively large, a spare phase shall be
used to improve the reliability of HPP operation and reduce the outage cost. The
replacement of spare phase of single-phase transformer bank shall be convenient.
Specifically, a faulted phase can be taken out from the connecting part between HV side
and LV side and then the spare phase is installed at the connecting part and then the HV
and LV sides are connected again and finally corresponding tests are made.
◇ Combined three-phase transformer:
① Reliability
With the continuous development of design, fabrication and installation technologies of
transformer, the combined three-phase transformer is of independent oil tanks and only a
lead conduit is used to connect three phases as a whole. Namely, oil lines of three
independent single-phase transformers are connected as a whole. In addition, the workload
of site installation is reduced as much as possible. Meanwhile, with the continuous
improvement of construction means and installation process, the reliability of HPP
operation can be guaranteed as long as the field construction management and supervision
are strengthened.
Moreover, after the combined three-phase transformer is assembled on the site, it can work
as a three-phase transformer, sharing one set of oil protection and cooling system.
Therefore, the total quantity of coolers, medium-pressure and low-pressure bushings, and
oil conservators will be reduced, in favor of equipment arrangement and cost reduction. At
present, many HPPs in China have been equipped with the combined three-phase
transformer (such as Lingtan HPP and Xiluodu HPP), and rich experience in both
fabrication and operation has been accumulated.
To sum up, the combined three-phase transformer is inferior to the single-phase
transformer in terms of reliability, but it still can meet the requirements for safe operation
of HPP.
② Arrangement
The combined three-phase transformer has a simplified arrangement mode and less
occupied area. A lead conduit is used to connect three single-phase transformers as a whole.
The single-phase transformers have nearly the same arrangement mode as the three-phase
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transformer. Compared with the single-phase transformer bank, the combined three-phase
transform ① ②er has the following advantages: small occupied area; simple connection
with isolated- ③phase bus at generator outlet; reduction in dimension of auxiliary plant for
arrangement of auxiliary equipment of main transformer, reducing the quantities of civil
works. Therefore, technically and economically, the combined three-phase transformer is
more rational than the single-phase transformer bank in terms of transformer arrangement.
⑶ Conclusion
According to the above factors, in view of reliability and operation and maintenance of
main transformers, the single-phase transformer bank has slightly higher reliability, easier
installation, shorter replacement period of spare phase and easier replacement process than
the combined three-phase transformer. However, the single-phase transformer bank has a
relatively large occupied area and project cost. Therefore, it is recommended that the type
of main transformer of the HPP should be of the combined three-phase transformer to
follow the principle of less project investment.
2) Cooling mode of main transformer
The ODWF and OFAF are both feasible technically for the main transformer. However,
the design of ventilation system will be difficult if the air cooling mode is adopted because
the HPP is of a water-retaining type hydroelectric station and the main transformers are
arranged inside the main transformer room of auxiliary plant. Based on advantages of
convenient water taking at the HPP, mature technology of water cooler and good water
quality of river, it is recommended that the cooling mode of transformers at the HPP
should be of the water cooling mode, so as to simplify the design of ventilation and heat
dissipation and to reduce noise.
3) Technical parameters of main transformer:
The combined three-phase, dual-winding, ODWF, copper winding, non-excitation
voltage-regulation boosting power transformer is selected as the main transformer. Its main
parameters are as follows:
Type: SSP-H-180000(120000)/500
Rated capacity: 180,000 kVA/4 sets
Rated capacity: 120,000 kVA/ 1 set
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Rated transformation ratio: 525±2×2.5%/13.8kV
Rated frequency: 50Hz
Connection symbol: YNd11
Short-circuit impedance: Uz=14%
Connection mode of incoming line at the LV side: connected with IPB
Connection mode of outgoing line at the HV side: connected with GIB
Transport weight of biggest piece: ~100t
d) 500 kV HV distribution equipment
1) 500 kV GIS
The indoor SF6 GIS is proposed to be used as the 500 kV switchgear. The GIS
switchyard is arranged at the downstream auxiliary plant (E.L. 245.50 m). Main
parameters are as follows:
Rated voltage: 550kV
Rated current: 3150A
Rated frequency: 50Hz
Rated short-circuit breaking current: 50 kA (effective value)
Rated making current: 125kA
Rated short-time withstand current/time 50kA/3s
2) 500 kV open-type outgoing line equipment
The outdoor open-type outgoing line equipment of the HPP mainly includes a capacitor
voltage transformer, an arrester, a trap and so on. The open-type outgoing line
equipment is arranged at the downstream auxiliary plant and its platform has an
elevation of 245.50 m a.s.l.
⑴ Voltage transformer at the 500 kV outgoing line side
It is recommended that the voltage transformer at the 500 kV outgoing line side should
be of the capacitor voltage transformer. Compared with the electromagnetic voltage
transformer, the capacitor voltage transformer is of the capacitor divider and
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characterized by less internal insulating oil, high operation reliability, small workload
of maintenance. In addition, the capacitor voltage transformer can also be used as
carrier coupling capacitor of power line. Main technical parameters of capacitor voltage
transformer are as follows:
Type Capacitive
Transformation ratio 550/ 3 /0.1/ 3 /0.1/ 3 /0.1kV
Accurate degree 0.1/0.5/0.5/3P
Capacity 5VA/50VA/50VA/100VA
⑵ 500 kV line arrester
The line arrester is of the zinc oxide arrester for over-voltage protection against
lightning invasion wave and over-voltage protection against operation. Main technical
parameters are as follows:
Type zinc oxide arrester (MOA)
Rated voltage 444kV
System voltage 500kV
Continuous operating voltage 324kV
Nominal discharge current grade 20kA
DC lmA, reference voltage ≤597kV
Switching impulse-current residual voltage (peak value) ≤907kV
Residual voltage under lightning impulse current (peak value) ≤l106kV
Residual voltage under steep current impulse (peak value) ≤1238kV
2 ms rectangular wave current (peak value) 2,000 A, 20 times
⑶ Line trap
The line trap is of the outdoor seat-type trap, with main technical parameters as
follows:
Model XZF-2000-1.0/50
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Rated voltage 550/ 3 kV
Rated frequency 50Hz
Rated working current 2000A
2s rated thermal stability current (effective value) 50kA
Peak value of short-circuit current 125kA
Rated inductance (it will be adjusted after specific frequency range is determined)
1mH
Allowable deviation ±5%
Bandwidth (it will be adjusted after specific frequency range is determined)
64~464kHz
Wave form: Approximate to sine wave
Quality factor of main coil (at 100 kHz) ≥30
e) Electrical equipment of station service system
The electrical equipment of station service system shall be selected based on the station
service connection and estimated loads of service power of plant.
⑴ HV station service transformer
The HV station service transformer is of 4 dry-type transformers, in 2 groups. The
capacity is under the consideration that 2 transformers back up each other. Namely, the
capacity of each group of transformer is half of the whole plant load (8,000 kVA). Main
technical parameters are as follows:
Type SCB11-4000/13.8
Rated capacity 4000kVA
Transformation ratio 13.8±2×2.5%/10.5kV
Impedance voltage 7%
Type of voltage regulation no-load voltage regulation
⑵ Station service transformer
Type SCB11-2000/10.5
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Rated capacity 2000kVA
Transformation ratio 10.5±2×2.5%/0.4kV
Impedance voltage 6%
Type of voltage regulation no-load voltage regulation
⑶ Unit service transformer
Type SCB11-1600(500)/10.5
Rated capacity 1,600 kVA (4 in total)/500 kVA (2 in total)
Transformation ratio 10.5±2×2.5%/0.4kV
Impedance voltage 6%
Type of voltage regulation no-load voltage regulation
⑷ Lighting transformer
It is recommended that a lighting transformer should be arranged independently and the
on-load voltage regulation should be adopted, so as to prevent lighting quality from
being affected by fluctuation of station service supply voltage cause by drastic changes
in station service loads. Main technical parameters are as follows:
Type SCB11-400/10.5
Rated capacity 400kVA
Transformation ratio 10.5±4×2.5%/0.4kV
Impedance voltage 4%
Type of voltage regulation on-load voltage regulation
⑸ Dam crest transformer
Type SCB11-1000/10.5
Rated capacity 1000kVA
Transformation ratio 10.5±2×2.5%/0.4kV
Impedance voltage 6%
Type of voltage regulation no-load voltage regulation
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⑹ In-plant emergency transformer
Type SCB11-630/10.5
Rated capacity 630kVA
Transformation ratio 10.5±2×2.5%/0.4kV
Impedance voltage 6%
Type of voltage regulation no-load voltage regulation
⑺ Diesel generator unit
A diesel generator unit is arranged on the dam crest to serve as the emergency power
supply for flood control by dam. The capacity of diesel generator unit shall comply
with the maximum quantity of flood gates opened at the same time. A diesel generator
unit is arranged in the powerhouse to serve as the emergency power supply for
powerhouse and to meet the requirements for earthquake resistance and prevention of
powerhouse and leakage water dewatering pump. Main technical parameters are as
follows:
Capacity 800 kW (powerhouse)/800 kW (dam)
Voltage 380V/220V
Frequency 50Hz
⑻ HV station service switchgear
The 10.5 kV station service system will be of the indoor metal armored movable
switchgear inside which a vacuum circuit breaker will be provided.
⑼ LV station service switchgear
The 0.4 kV station service system will be of the MNS drawer type switchgear.
6.2.7 Over Voltage Protection (OVP) and Grounding
6.2.7.1 Principle of Insulation Coordination
The design of over-voltage protection and insulation coordination shall be carried out
according to Insulation Co-ordination — Part 2: Application Guide (GB311.2-2013), Code
for Design of Overvoltage Protection and Insulation Coordination for AC Electrical
Installations (GB/T 50064-2014) [clause explanations are attached], and Overvoltage
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Protection and Insulation Coordination Design Guide for Hydro-power Station (NB/T
35067-2015). The Principle of insulation coordination is as follows:
⑴ Under each over-voltage, the insulation strength of electrical equipment shall be
higher than the voltage level and have proper margins.
⑵ The resonance over-voltage shall be avoided and eliminated during design and
operation.
6.2.7.2 Neutral Point Grounding Mode
⑴ Generator neutral point
The grounding of generator neural point will be achieved by a grounding transformer.
⑵ Main transformer neutral point
Because no special requirements are proposed in the design of grid connection, the
500 kV main transformer neutral point of the HPP is temporarily of the direct grounding
mode.
6.2.7.3 Direct lightning protection
The roof lightning strips of powerhouse and auxiliary plant of the HPP are used to prevent
them from direct lightning. The 500 kV open-type outgoing line platform is equipped with
a framework lightning rod and a lightning conductor, which will work together to prevent
the platform from direct lightning. The whole 500 kV transmission line is equipped with
double lightning conductor to prevent the whole line from direct lightning.
6.2.7.4 Lightning invasion wave OVP1) Arrangement scheme of arrester
According to Overvoltage Protection and Insulation Coordination Design Guide for
Hydro-power Station (NB/T 35067-2015), the arrangement scheme of 500 kV arrester of
the HPP is as follows:
(1) Each circuit of 500 kV outgoing lines shall be equipped with 1 group of zinc
oxide arresters aside;
(2) Each group of 500 kV GIS bus shall be equipped with 1 group of zinc oxide
arresters;
⑶ The 13.8 kV bus at the LV side of each main transformer is equipped with 1 group
of zinc oxide arresters, to prevent the LV winding insulation of main transformer from
being damaged by the electrostatic component of lightning coupling over-voltage
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generated at the HV winding of main transformer.
2) Lightning over-voltage simulation
The calculation for the over-voltage protection against lightning invasion wave is
carried out based on the EMTP software, to check if the arrangement scheme of arrester is
rational or not. According to the diagram of main electrical connection of the HPP, the
operation mode suffering from the severest over-voltage is "single transformer ~ single
line". Therefore, the shortest route is as shown in Fig. 6.2.6-1
(LA1→CVT1→ABS1→CB1→MVT1→LA2→CB2→TR1).
Fig. 6.2.7-1 Simulation Calculation Equivalent Circuit Diagram
The ground capacitance model is applied to a capacitor voltage transformer, a GIS circuit
breaker assembly unit, an electromagnetic voltage transformer, and a main transformer.
The wave impedance model is applied to an overhead transmission line and a GIS SF6
tubular bus.
◇ Parameters of line arrester
Rated voltage 444kV
Maximum continuous operating voltage 324kV
8/20μs residual voltage under lightning impulse (20 kA) 1106kV
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30/60μs residual voltage under switching impulse (2 kA) 907kV
◇ Parameters of GIS bus arrester
Rated voltage 420kV
Maximum continuous operating voltage 318kV
8/20μs residual voltage under lightning impulse (20 kA) 1046kV
30/60μs residual voltage under switching impulse (2 kA) 858kV
See Table 6.2.7-1 for volt-ampere characteristics of arrester.
Table 6.2.7-1 Volt-Ampere Characteristics of 500 kV Zinc Oxide Arrester
I(kA) 0 1 5 10 20 40 1mA(DC)
U(kV) Line side 0 950 1009 1050 1106 1212 597
Bus 0 891 946 984 1046 1136 565
◇ Parameters of lightning invasion wave
In the calculation of traveling wave protection, the lightning invasion wave form is of the
oblique-angled and flat-topped wave, and only lightning stroke within 0.2 km (the first
base tower) is taken into account. The lightning invasion wave has an amplitude of
U0=2450kV and a wave head of τ=2.6μs.
◇ Analysis of calculated results
Under the "single line ~ single transformer" operation mode (the worst case), the
maximum voltage value and equipment insulation level in case of nearby lightning stroke
are listed in Table 6.2.7-2 and the simulation waveform is as shown in Fig. 6.2.7-2.
Table 6.2.7-2 Comparison for Maximum Over-voltage Value and Insulation Level of
Equipment
Node
No. Equipment Name
Equipment
Code
Maximum Voltage In Case of
Nearby Lightning Stroke
Equipment
Insulation Level
(kV)
1 Zinc oxide arrester at the
line side LA1 835 1675
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Node
No. Equipment Name
Equipment
Code
Maximum Voltage In Case of
Nearby Lightning Stroke
Equipment
Insulation Level
(kV)
2 Capacitor voltage
transformer CVT1 840 1675
3 SF6/air bushing + SF6
conduit ABS1 842 1550
4 GIS circuit breaker
assembly unit CB1 846 1550
5 Electromagnetic voltage
transformer MVT1 1036 1550
6 Zinc oxide arrester at the
GIS bus LA2 1048 1675
7 GIS circuit breaker
assembly unit CB2 1112 1550
8 Main transformer TR1 1132 1550
Fig. 6.2.7-2 Simulation Waveform for Lightning Over-voltage
3) Conclusion
Under the "single line ~ single transformer" operation mode suffering from the severest
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lightning over-voltage, the arrangement scheme of arrester meets the requirements as
follows: the lightning over-voltage level on the 500 kV distribution equipment and main
transformer does not exceed the equipment insulation level; both the insulation
coordination and the insulation protection margin comply with relevant design codes and
specifications.
6.2.7.5 Grounding Design of HPP
a) Principle of grounding design
The working grounding, protective grounding and lightning protection grounding of the
HPP share one integral grounding device. The grounding design complies with Ground
Design Guide for Hydro-power Station (NB/T 35050-2015) and Code for Design of AC
Electrical Installations Earthing (GB 50065-2011).
Lacking of relevant data on grid connection, the allowable value of grounding resistance is
temporarily designed as 0.5 Ω. The design principle of grounding system of the HPP is as
follows:
⑴ Make full use of the underwater structural reinforcement for ground connection with a
natural grounding body, and erect a reservoir grounding grid as the main grounding grid.
⑵ Arrange a voltage balancing net to ensure that neither the contact potential difference
nor the step potential difference of the grounding grid will exceed the specified value in
relevant codes and specifications.
⑶ Arrange a centralized grounding device near the grounding point with a large earth
current, such as main transformer neutral point, grounding point of outgoing line portal
framework, grounding point of lightning conductor or grounding point of downlead of
open lightning strip, and grounding point of arrester.
⑷ Take the aperiodic component of short-circuit current into account, to prevent 6 kV ~
10 kV arrester from operation or explosion under the effect of power-frequency transient
reverse over-voltage.
⑸ Carry out corresponding grounding grid treatment if the measured grounding
resistance of the whole plant cannot meet the design requirements for allowable value of
grounding resistance.
b) Constituent parts of grounding grid
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According to the layout of hydroproject of the HPP, the grounding system of the whole
plant is mainly composed of three parts, including reservoir area grounding grid in front of
dam, underwater grounding grid behind dam, and grounding grid used for powerhouse,
auxiliary plant and ship lock. The grounding grids at each position are interconnected with
each other in a multiple manner. According to relevant calculation, the grounding
resistance of the HPP is about 0.48 Ω. The constituent parts of the grounding grid at each
position are as follows:
⑴ The reservoir area grounding grid in front of dam is composed of reservoir grounding
grid in front of dam, grounding grid of dam upstream face and so on.
⑵ The underwater grounding grid behind dam is mainly composed of tailrace grounding
grid, grounding grid at dredging area, stilling basin grounding grid after dam, tailrace
system grounding grid and so on.
⑶ The grounding grid used for powerhouse, auxiliary plant and ship lock is mainly
composed of such natural grounding bodies as grounding steel flat, structural
reinforcement mesh of hydraulic structure, and gate slot.
c) Voltage balancing measures
Because grounding grids at each position have different current divergence effects, current
shunt will be a major means for the grounding system of the HPP. Because grounding grids
are connected via long grounding wires, in case of grounding fault, a large fault current
will pass through grounding wires between grounding grids, generating a relatively large
voltage drop. In this case, reduction in grounding resistance only cannot achieve the
purpose of reduction of grounding grid potential, contact potential and step potential.
Therefore, the calculation of contact potential and step potential must be conducted based
on the arrangement conditions of grounding grids at each position. In addition, various
measures shall be taken to ensure personnel safety of operators at the HPP.
In view of actual conditions of the HPP, the following measures will be taken
comprehensively:
⑴ Design of voltage balancing net
The grounding grid used for powerhouse and auxiliary plant of the HPP is composed of
special grounding sheet flat and structural reinforcement mesh of structures. The structural
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reinforcement meshes are welded with each other to form small mesh openings. The
grounding grid made of special grounding sheet flats is reliably welded and connected with
the structural reinforcement mesh, to connect the grounding grids at each structure as a
whole. In this way, a voltage balancing net with good effects can be obtained without
increase of steel consumption. In addition, the voltage balancing net can reduce the
distribution gradient of potential for each grounding grid.
⑵ Control of transfer potential
The control of transfer potential at the HPP is mainly of the high potential isolation,
focusing on the communication line and neutral line of LV distribution system.
An isolation transformer and equipment with good insulation performance are used for the
communication line, to avoid personal injury or damage of weak current equipment caused
by high voltage of communication equipment and line.
If a metal pipe coming out from a grounding grid is an exposed pipe, insulated isolation
measures shall be taken for the flange connections.
⑶ Fast fault clearing
Fast fault-clearing measures shall be taken to shorten the duration of grounding fault, to
meet the requirements for step potential and contact potential in the guide, to ensure
personnel safety. In addition, such measures can reduce difficulties in grounding design
and material consumption.
⑷ Multipoint grounding protection and equipotential connection
The LV distribution system of the HPP is of the multipoint grounding mode. Namely,
equipotential connection shall be applied to the PE line and neutral line of distribution
equipment, grounding main line of electrical equipment, metal case of equipment, metal
pipe and metal members of structures. The above items shall be connected with the
grounding system. In this way, the personnel safety of operators can be guaranteed.
⑸ Model selection for 10 kV arrester
In model selection of 10 kV arrester, the aperiodic component of short-circuit current
shall be taken into account to prevent 6 kV ~ 10 kV arrester from operation or explosion
under the effect of power-frequency transient reverse over-voltage.
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6.2.8 Layout of Electrical Equipment
The HPP is of a water retaining ground powerhouse, with a powerhouse being 402.0
m in total length and 22.5 m in width, with a main erection bay being 52.0 m in length and
22.5 m in width, with an auxiliary erection bay being 42 m in length and 22.5 m in width,
and with downstream auxiliary plant being 376.0 m in length and 23.4 m in width.
The generator operation floor is at the elevation of 222.50 m a.s.l. in the powerhouse,
with a unit spacing of 21.5 m. It mainly consists of a governor, oil pressure unit and so on.
The main erection bay has an elevation of 228.5 m a.s.l. and the auxiliary erection bay has
an elevation of 222.5 m a.s.l. Both main and auxiliary erection bays are provided with 3
positions for stator field assembly, 2 positions for rotor field assembly, 2 positions for field
assembly of gate operating mechanism, 2 positions for runner field assembly, 2 positions
of field assembly of bulb head, 2 positions for field assembly of cooling jacket, and 2
positions for field assembly of main shaft. The pipeline - bus floor is at the elevation of
219.0 m a.s.l., mainly equipped with such equipment as non-segregated phase enclosed bus
(or insulated tubular bus).
Auxiliary plant is arranged closely to the downstream side of the powerhouse. The
generator voltage switchgear installation floor is at the elevation of 222.5 m a.s.l., mainly
equipped with a VT & LA arrester cabinet, enclosed bus, excitation transformer and others.
The main transformer floor is at the elevation of 228.5 m a.s.l., mainly equipped with a
main transformer room, HV control room of service power, LV control room of service
power, 13.8 kV switch gear and others. The main transformer transport passage is at the
downstream side of the main transformer room. The SF6 pipeline floor is at the elevation
of 240.5 m a.s.l., mainly equipped with an SF6 pipeline. The GIS switchyard and opened
outgoing line platform are set at a floor of an elevation of 245.5 m a.s.l. The outgoing line
platform is mainly equipped with an SF6/air bushing, arrester, high frequency wave trap,
capacitor voltage transformer, outgoing line framework and others.
6.2.9 List of Main Primary Electrical Equipment
See Table 6.2.9-1 for List of Main Primary Electrical Equipment
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Table 6.2.9-1 Main Primary Electrical Equipment
S/N Description Main
Equipment Parameter Unit Qty. Remarks
1
Gen
erat
or a
nd g
ener
ator
vol
tage
sw
itch
gear
ins
tall
atio
n
Generator SFWG55-64/8000 55MW Set 14
Excitation
transformer 13.8kV Set 14
VT cabinet 13.8kV Nos. 14
VT & LA
cabinet 13.8kV Nos. 5
SF6 gas circuit
breaker of
generator
13.8kV 3150A 80kA Set 14
Grounding
transformer 13.8/ 3 kV Set 14
Isolated-phase
enclosed bus
QZFM-13.8/8000
13.8kV 8000A 80kA m 300
HV current
limiting fuse
cabinet
13.8kV Nos. 4
Non-segregated
phase enclosed
bus (or
insulated
tubular bus)
13.8kV 3150A 63kA m 1250
Isolation switch
cabinet 13.8kV Nos. 5
2
Pow
er
tran
sfor
m
er
Main
transformer
SSP-H-180000/500
180000kVA
525±2×2.5%/13.8kV
Set 4 Combined
3-phase
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Ud=14% YNd11 transformer
Main
transformer
SSP-H-120000/500
120000kVA
525±2×2.5%/13.8kV
Ud=14% YNd11
Set 1
Combined
3-phase
transformer
3
500k
V
GIS
Circuit breaker 500kV 3150A 50kA Set 8
Isolator 500kV 3150A 50kA Group 23
Including
earthing
switch
Electromagnetic
voltage
transformer
500kV Set 6
GIS SF6 arrester YH10W-444/1050 Set 6
4
500
kV o
pene
d ou
tgoi
ng l
ine
equi
pmen
t
SF6/air bushing 500kV 3150A 50kA Nr. 6
High frequency
wave trap 500kV Set 6
Capacitor
potential
transformer
500kV Set 6
Zinc oxide
arrester YH10W-444/1065 Set 6
5
Sta
tion
serv
ice
pow
er
equi
pmen
t HV station
service
transformer
SCB10-4000/13.8
13.8±2x2.5%/10.5kV
Set 4
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Dam crest
transformer
SCB10-1000/13.8
13.8±2x2.5%/0.4kV Set 2
Unit service
power
transformer
SCB10-500/10.5
10.5±2x2.5%/0.4kV
Set 2
Unit service
power
transformer
SCB10-1600/10.5
10.5±2x2.5%/0.4kV
Set 4
Diesel generator
unit at dam 0.4kV 800kW Set 1
Transformer for
common power
demand of plant
SCB10-2000/10.5
10.5±2x2.5%/0.4kV Set 4
Protective load
transformer
SCB10-630/10.5
10.5±2x2.5%/0.4kV Set 2
Transformer
special for
lighting
SCB10-400/10.5
10.5±2x2.5%/0.4kV Set 2
HV switchgear 10.5kV 630A 31.5kA Nos. 35
Isolation
cabinet 10.5kV Nos. 2
VT & LA
cabinet 10.5kV Nos. 4
LV switchgear 0.4kV MNS3.0 Nos. 180
Diesel generator
unit for
powerhouse
0.4kV 800kVA Set 1
6 Cable 13.8 kV cable 13.8kV YJV22-3x35 m 4000
LV cable Item 1
7 Grounding Item 1
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8 Lighting Item 1
9 Bridge Item 1
10 Fire
Protection Item 1
6.3 Control, Protection and Instrumentation
6.3.1 Control
The Paklay HPP is the first cascade HPP proposed to be developed on the main
stream of the Mekong River in Laos, with a planned total installed capacity of 770 MW
and 14 sets of 55 MW bulb turbine-generator units. The HPP plays an important role in the
electric power system. Due to lack of relevant data about the electric power system at
present, in the follow-up design, relevant codes and design information of the system
connection shall be used for defining the dispatching management relationship, telecontrol
and other information exchange. At present, it is temporarily determined that the 500 kV
system shall be dispatched by Laos Power Dispatching Center.
6.3.1.1 Plant centralized computer monitoring system
The plant is proposed to operate with no fulltime personnel on duty (a few people on
watch) and be monitored in centralized manner by computer monitoring. The computer
monitoring system shall be of an open network architecture distributed in layers. The
system shall consist of a main control level and a local control level. Ethernet with 100M
redundancy shall be used for communication between the upper and lower levels. The
network topology of the main control level shall be of a twin-stelliform network while that
of the local control level shall be of a double loop network. Main control level equipment
shall use twisted pair cables as its communication media while local control level
equipment shall use optical fibers as its communication media. See attached drawing -
PAKLAY-EM-ES-01 for structural configuration of the computer monitoring system.
The main control level equipment of the computer monitoring system shall consist of
2 historical database servers, 1 set of disk arrays, 2 application program servers, 2 operator
workstations, 1 engineer workstation, 1 training workstation, 1 plant intercommunication
server, 2 remote communication servers, 1 voice alarm and report forms workstation, 1 set
of mimic board and drive device, 2 sets of network equipment, 2 network printer, 1 set of
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clock synchronization system, 2 sets of UPS power supplies and so on. The main control
level equipment shall be used for monitoring the whole plant. Operating crew can monitor
main M & E equipment in the whole plant via the mimic board in the central control room,
liquid crystal display (LCD), keyboard, mouse and others in the operator workstations. The
2 remote communication servers shall be used for communication with Laos Power
Dispatching Department, in order to achieve remote dispatch. The plant
intercommunication server shall be used for communication with fire alarm system, MIS
system of the HPP etc., in order to achieve information exchange. A unit emergency
shutdown button and an emergency incident shutdown button shall be provided for the
mimic board, independent of the monitoring system, in order to achieve manual operation
in case of emergency.
In view of each unit, 500 kV switchyard, station service power, plant utilities and dam
gates, the local control level shall consist of 18 local control units (LCU), including 14
LCUs for the units, 1 LCU for the 500 kV switchyard, 1 LCU for the station service power,
1 LCU for the utilities and 1 LCU for the dam gates. The micro-computer governor,
micro-computer excitation device, micro-computer relay protection device and
micro-computer monitoring instrument of units shall communicate with their
corresponding LCUs.
Unit auxiliary equipment, plant utilities and others shall respectively adopt an
independent programmable logic controller (PLC) so as to independently achieve
automatic control based on their own control programs; in addition, the above items shall
be able to communicate with their corresponding LCUs. The LCU shall be used for
implementing process control for the controlled objects, collecting and processing data,
and carrying out accident detecting and alarming.
Each dam crest flood gate shall be provided with 1 local control cabinet, composed of
a PLC and a motor starter. Ethernet shall be used for communication between the dam
gates and LCU.
The main control level equipment of the whole plant shall be respectively arranged in
the computer room and central control room; the unit control level equipment shall be
respectively arranged beside each unit and in the corresponding relay protection room.
The HPP shall be provided with 1 monitoring system for flooding of powerhouse.
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Both ends of the gallery floor of the powerhouse shall be equipped with one water level
annunciator, which will transmit alerting signals in case of water and shall be connected to
the computer monitoring system.
6.3.1.2 Automation of unit
The self-shunt thyristor rectifier static excitation system is adopted for the excitation
system, which is composed of an excitation transformer, three-phase full-control power
rectifier unit, micro-computer excitation regulator, magnetic field circuit breaker, AC/DC
overvoltage and incomplete phase protection, excitation build-up device current
transformer and potential transformer for measurement, etc. The excitation system is of a
micro-computer excitation regulator with two channels. Each channel is provided with an
automatic voltage regulator (AVR) unit and an automatic current regulator (ACR) unit.
Interface for communication with LCU of the computer monitoring system unit is adopted
for the micro-computer excitation regulator to achieve monitoring and regulation of the
generator excitation via the monitoring system. Normal shutdown is achieved by inverse
de-excitation, while emergency shutdown is achieved by a DC de-excitation switch plus
oxidizing nonlinear resistor de-excitation.
To ensure units, relevant auxiliary equipment and plant utility system can safely
operate, the selected automation elements shall be able to correctly and reliably monitor
the operating parameters and conditions of oil, gas, water and important parts such as
bearing and generator stators, in order to provide reliable and accurate information for the
computer monitoring system and form a reliable hydraulic mechanical protection system.
Non-electric quantity items mainly consist of temperature, discharge, pressure, liquid level,
etc. A resistance temperature detector (RTD) of the computer monitoring system is used
for directly sampling so as to measure the unit temperature. Other non-electric quantity
items are collected by a transmitter and transformed to be 4 ~ 20 mA of analog signals and
finally transmitted to the computer monitoring system.
6.3.2 Protective Relaying
6.3.2.1 Protective relaying of main equipment
Protective relaying of all equipment in the HPP adopts digital protection equipment,
with each level of protection function in accordance with relevant standards and provisions.
In view of specific characteristics of main electrical connection of the Paklay HPP, single
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protection configuration is applied to the generators; electric quantity protection of main
transformers, protection of 500 kV lines, and protection of 500 kV bus all adopt duplex
configuration. See attached drawing - PAKLAY-EM-ES-02 for details.
It is preliminarily to provide the generators with the following protections: completely
longitudinal differential protection, zero-sequence current transverse differential protection,
LV over-current protection with current memory, over-load protection of stator, protection
for loss of excitation, negative-sequence over-current protection, stator grounding
protection, one-point grounding protection of rotor, stator OVP protection, shaft-current
protection, over excitation protection, excitation winding overload protection, reverse
power protection, CT break-wire protection, PT break-wire protection, etc.
It is preliminarily to provide the 500 kV main transformer with the following
protections: longitudinal differential protection, zero-sequence current protection,
over-current protection of compound voltage, CT break-wire protection, PT break-wire
protection and over excitation protection. Non-electric protection of the transformers
includes gas protection, gusty pressure relief protection, temperature protection, abnormal
oil level protection, cooler failure protection, etc.
Bus protection: each 500 kV bus is provided with two sets of bus differential
protection.
Line protection, protection of a 500 kV line shall be configured according to the
relevant provisions and requirements of the electric power system.
Excitation transformer protections consist of cut-off protection, over-current
protection and temperature protection.
Station service transformer protections consist of cut-off protection, over-current
protection and temperature protection.
Protection of station service power: digital protection equipment is provided in
corresponding switchgear and communicates with the LCU of the station service power.
6.3.2.2 Fault recorder and automatic safety device
For the convenience of fault analysis, the 500 kV switchyard is provided with 2 sets
of micro-computer fault recorders, while the 220 kV switchyard is provided with 1 set of
micro-computer fault recorders. Configuration of the automatic safety device shall meet
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requirements of the electric power system.
6.3.3 Secondary Connection
To meet measuring, metering and synchronizing requirements of the HPP, 0.5-level
current transformers for measurement are respectively configured at the HV side of the
excitation transformer and at the HV side of the station service transformer; 0.2-level
current transformers for measurement are configured for the 500 kV circuit breaker etc.; a
0.2-level current transformer for metering and measurement is configured at the generator
terminal; 0.2S-level current transformers for metering are configured at the HV side of
main transformers and 500 kV outgoing lines; corresponding potential transformers are
configured for the generator terminal, generator voltage bus, 500 kV bus and line etc.
6.3.3.1 Measurement
Electric quantity of the station service power, DC system, and switchgear installation
of the HPP is measured by a transmitter and collected by an AC sampling device. The
electric quantity then will be transformed to be 4 mA ~ 20 mA of analog quantity or
transmitted to the computer monitoring system via data communication mode. Water level,
pressure, discharge, temperature etc. of the HPP are measured by a transmitter or directly
collected by a RTD, and then transformed to be 4 mA ~ 20 mA of analog quantity or
directly transmitted to the computer monitoring system via the RTD temperature
measurement module.
6.3.3.2 Synchronization system
Microcomputer-based automatic precise synchronizing device is selected as the main
synchronization method of the HPP. Manual precise synchronization with asynchronous
blocking is provided as a back-up synchronization method. Each generator circuit breaker
and 500 kV circuit breaker will serve as synchronizing points. Each unit is equipped with 1
set of single-object synchronizing device and the 500 kV switchyard is equipped with 1 set
of multiple-object synchronizing device.
6.3.3.3 Signal
No routine central alarm signal is set in the central control room of the HPP. An alarm
is given by voice alarm device of the computer monitoring system and displayed by the
operator workstation. To meet requirements of local control and monitoring, each LCU is
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equipped with a LCD. The local control cabinet of all equipment is equipped with signal
lights for equipment status and monitoring of power supply.
6.3.3.4 Operation and locking
The computer monitoring system in the central control room can be used for
centralized monitoring of all HV circuit breakers, 500 kV isolators and earthing switches,
circuit breakers at the LV side of station service transformers, station service bus
sectionalizing circuit breakers and others of the HPP. Local control is set for other isolators,
earthing switches, outgoing breakers of 400 V station service power, etc.
Status signal indication is set for all circuit breakers on the local control cabinet,
which can be controlled manually. Necessary locking function is set at tripping and closing
circuits of the isolators and earthing switches to prevent from misoperation.
The mimic board in the central control room is equipped with simply measuring
meters, equipment status signal device and emergency operation button, etc.
6.3.4 Control Power Supply System
The HPP has a large powerhouse area and decentralized layout of M & E equipment.
To reduce distance and scope of power supply, the control power supply system shall be
arranged in a properly decentralized manner, so as to reduce the impact scope related to
power failure or maintenance, and improve reliability of the control power supply system.
The HPP is proposed to employ 4 sets of 220 V AC/DC control power supply systems.
Fourteen units, accident lighting, utilities and station service power system will share 2 sets
of the control power supply systems. Unit control, protection and operation, station service
power, utilities control and accident lighting in the No. 1 ~ No. 7 unit bays will share 1 set
of control power supply system. Unit control, protection and operation, station service
power, utilities control and accident lighting in the No. 8 ~ No. 14 unit bays will share 1
set of control power supply system. Switchyard and central control room will share 1 set of
control power supply system. In addition, dam site will be provided with 1 set of control
power supply system. Each set of DC power supply system shall employ two groups of
batteries, in order to ensure safe operation of the HPP and be convenient for maintenance.
All DC systems shall adopt single-bus sectionalized connection. Each section of bus shall
be connected with one group of battery and one set of float charging device. Normally, a
battery operates in float charging mode and two groups of batteries stand up for each other.
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The battery shall be valve-controlled sealed lead-acid battery, with a rated voltage of 2 V.
Each group of batteries of the 4 sets of control power supply systems respectively has a
capacity of 600 Ah, 600 Ah, 600 Ah and 200 Ah. See attached drawing -
PAKLAY-EM-ES-03 for the control power supply system.
6.3.5 Communication
The HPP communication consists of dispatching communication of the electric power
system, HPP internal dispatching and administrative management communication,
communication with local telephone department, etc.
The dispatching communication of the electric power system shall be set according to
requirements of the electric power system. Due to lack of relevant data about the electric
power system at present, it is temporarily considered to use two types of communication
channels, with a main communication channel using the OPGW optical fiber and a standby
communication channel using the power line carrier.
The HPP internal dispatching and administrative management communication shall
use 1 set of dispatching communication equipment and 1 set of administrative
communication equipment, equipped with corresponding intelligent dispatching console,
attendant desk, digital recording system, maintenance and charging terminal, wiring
devices, etc. It shall also be equipped with 1 set of in-plant addressable broadcast system
and 1 set of in-plant wireless intercom system.
Communication with the local telephone department shall be set according to the
existing local conditions. At present, it is temporarily proposed to use digital relay lines for
connecting the digital program-controlled exchangers with program-controlled switching
equipment of the local telephone department.
The HPP is equipped with 2 sets of power supply units for communication. Each set
consists of 2 groups of high-frequency switch rectifiers, 2 groups of valve-controlled
sealed lead-acid battery of 48 V/200 Ah, etc. AC power of the high-frequency switch
rectifiers comes from the station service power.
Emergency communication of the HPP is temporarily proposed to use 2 satellite
phones.
6.3.6 Industrial Television Monitoring System
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One set of all-digital industrial television monitoring system shall be provided, which
includes two areas - the HPP area and navigation lock area. Each area shall be equipped
with an independent server, hard disk video, monitoring terminal, camera, switching
control device, exchanger, etc., which will form two area systems operating independently.
Network shall be used for communication between the two systems; important video
images can be uploaded to the central control room of the HPP. The industrial television
monitoring scope involves the powerhouse, switchyard, control building, dam crest,
navigation lock, important safety exits, etc. The system transmits the camera video signal
and control signal via Ethernet. It is able to carry out digital coding, compressing, picture
recording, monitoring, multi-picture separating and controlling for video signals. In
addition, it is also able to interlock with the fire alarm system and monitoring system for
flooding of powerhouse.
At present, the HPP is proposed to employ 80 cameras, a hard disk video with
128-channel capacity, 2 serves, 1 monitoring terminal and 1000M backbone network. The
ship lift is proposed to employ 20 cameras, a hard disk video with 32-channel capacity, 1
serve, 1 monitoring terminal and 100 M backbone network. A 100M Ethernet is used for
connecting the HPP with the ship lift area.
The monitoring terminals are installed in the central control room and navigation lock
control room. The servers, hard disk videos and main network equipment panels are
installed in the relay protection room. The cameras and front-end accessory equipment etc.
are installed on site. Power supply of all cameras and front-end accessory equipment is
taken nearby where they are installed.
6.3.7 Electrical testing laboratory
Electrical testing consists of HV test, relay protection test, automation test,
electrotechnical instrument verification, etc. Selected instrument and testing apparatuses
shall meet requirements of operation and maintenance, acceptance and preventive test,
general test, supervising verification and adjustment test, repair, element test, etc.
Equipment for electrical testing laboratory shall be provided as per Grade-I electrical
testing laboratory.
6.3.8 Navigation Control System of Navigation Lock
Navigation control of the navigation lock is achieved by a navigation lock control
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system focused on a computer. The system consists of 1 set of upstream gate control unit, 1
set of downstream gate control unit, and 1 set of centralized control unit. Ethernet with
100M redundancy is used for communication between each unit. The network topology is
of a twin-stelliform network and equipment communication media is optical fiber. The
control system and gate hoisting device are equipped with 1 set of independent AC/DC
control power supply system.
The fire alarm and joint control devices as well as communication devices in the
navigation lock area are all included in the fire fighting system and communication system
of the HPP.
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6.3.9 List of Main Secondary Electrical Equipment
See Table 6.3.9-1 for List of Main Secondary Electrical Equipment
Table 6.3.9-1 Main Secondary Electrical Equipment
S/N Description of Equipment Qty. Remarks
I Automatic system of unit
1 Control cabinet for unit governor and oil pressure unit 14 x 1 Included in the unit governor
2 Unit excitation system 14 x 1
3 Control system of auxiliary equipment 14 x 1 Included in the unit
II Computer monitoring system
1 Historical database server 2
2 Disk array 1
3 Application server 2
4 Operator workstation 2
5 Engineer workstation 1
6 Simulation training workstation 1
7 Voice alarm and report forms workstation 1
8 Mimic board and drive device 1
9 Remote communication server 2
10 In-plant communication server 1
11 Network printer 2
12 Double-seat console 1
13 Ethernet network device 2
14 Clock synchronization system 1
15 LCU for unit (including synchronizing devices, etc.) 14 x 1
16 LCU for switchyard (including synchronizing devices,
etc.) 1
17 LCU for dam gate 1
18 LCU for utilities 1
19 LCU for station service power 1
20 Utilities control system (including drainage and
compressed air system, etc.) 1
21 Monitoring system for vibration and throw of unit 14 x 1 Included in the unit
22 Local control cabinet of dam flood gate Included in the complete hoist equipment
23 Ventilation control system 1 III Relay protection and automatic safety device
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S/N Description of Equipment Qty. Remarks
1 Generator protective equipment 14 x 1 2 Transformer protective equipment 5 x 2 3 500 kV line protective equipment 2 x 2 4 500 kV bus protective equipment 2 5 500 kV fault recorder 1
6 Automatic safety device for 500 kV system 1 Configured as per requirements of the electrical power system
7 10 kV protective equipment and automatic bus transfer equipment
Included in the switchgear
8 400 V protective equipment and automatic bus transfer equipment
Included in the switchgear
IV Control power supply system
1 AC/DC control power supply in No. 1 ~ No. 7 unit bays 1 With 2 groups of batteries being 600 Ah and 2 groups of float charging devices
2 AC/DC control power supply in No. 8 ~ No. 14 unit bays
1 With 2 groups of batteries being 600 Ah and 2 groups of float charging devices
3 220 V control power supply for GIS switchyard and central control room
1 With 2 groups of batteries being 600 Ah and 2 groups of float charging devices
4 220 V control power supply of dam gate 1 With 2 groups of batteries being 200 Ah and 2 groups of float charging devices
5 UPS for Main control level of computer monitoring system
2 30 kVA, free of battery
V Communication system 1 Carrier communication equipment 2 2 Optical fiber communication equipment 1
3 In-plant administrative communication equipment 1 Including navigation lock part
4 Dispatching communication equipment 1 5 In-plant addressable broadcast equipment 1 6 In-plant wireless intercom equipment 1 7 Communication power supply equipment 2 8 Communication cable 50km 9 Emergency communication equipment 1 2 hand-held satellite phones
VI Industrial TV system 1 Equipped with 100 cameras (including navigation lock part)
VII Automatic fire control and alarm system 1 Including navigation lock part
VIII Electric energy metering system 1 Including 4 gateway energy meters
IX Navigation lock control system 1
X AC/DC control power supply system for navigation lock
1
XI Control cable
Estimated as per 8 x 1.5 cables 500km Armored, fire-proof and overall shield
XII Others Electrical testing equipment 1
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6.4 Hydraulic Steel Structures
Hydraulic steel structure equipment of the Paklay HPP is mainly distributed in the
flood discharging system, headrace and power generation system, navigation lock system
and fish pass structure. Work amount of the hydraulic steel structures is 23,170 t in total.
See Table 6.4-1 - Summary Sheet of Main Metal Structure Equipment of the Paklay HPP
for details.
6.4.1 Metal Structure Equipment of Flood Release System
According to project layout, the flood releasing and flushing system structures are
provided with 2 flushing bottom outlets, 3 low-level surface bays (the low-level surface
bays are set for the purpose of flood releasing and sediment discharge) and 11 high-level
surface bays in sequence from left to right.
The hydraulic steel structure equipment of the flood releasing and flushing system is
composed of the upstream bulkhead gate and service gate of the release sluice, downstream
bulkhead gate of the release sluice, the emergency bulkhead gate, service gate and outlet
bulkhead gate of the flushing bottom outlets, as well as the corresponding hoists. For the
details of arrangement, please refer to the Layout Plan for Gates and Hoists of the Flood
Releasing & Flushing System (Drawing No.: Paklay-FS-MS-01 (1/5)), the Layout for
Gates and Hoists of Low-level Surface Bays of the Flood Releasing & Flushing System
(Drawing No.: Paklay-FS-MS-01 (2/5)), the Layout for Gates and Hoists of High-level
Surface Bays (with stilling basin) of the Flood Releasing & Flushing System (Drawing No.:
Paklay-FS-MS-01 (3/5)), the Layout for Gates and Hoists of High-level Surface Bays
(without stilling basin) of the Flood Releasing & Flushing System (Drawing No.:
Paklay-FS-MS-01 (4/5)) and the Layout for Gates and Hoists of Flushing Bottom Outlets
of the Flood Releasing & Flushing System (Drawing No.: Paklay-FS-MS-01 (5/5)).
6.4.1.1 Upstream Bulkhead Gate for Low-Level Surface Bay of Flood Discharge Gate
The upstream bulkhead gate for the low-level surface bay of the flood discharge gate
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is set at the upstream side of the service gate for the low-level surface bay. There are 3
outlets in total. For the bulkhead gate, the orifice width is 16.0m, the normal pool level is
240.000m, the design flood level is 239.020m, the check flood level is 240.530m. For the
low-level surface bay, the crest elevation is 212.000m, the elevation of sill is 212.000m,
the design water head is 28.0m and the gate height is about 29.0m. The gate shall be the
emerged plane stoplog sliding gate supported by a high-strength and low-friction
composite slide block. The gate is closed in static water and lifted by filling water between
segments. The gate is operated by the gantry crane main hook on the dam crest of release
sluice dam monolith through the automatic hydraulic pick-up beam. The gate is normally
locked at the top of gate slot with flashboard locking device. One segment is locked in
each orifice. The gate leaves exceeding the number of gate slot orifices shall be locked on
the dam crest between oil cylinder trunnion of high-level surface bays and downstream
pedestrian bridge.
6.4.1.2 Upstream Bulkhead Gate for High-Level Surface Bay of Release Sluice
The upstream bulkhead gate for the high-level surface bay of release sluice is set at
the upstream side of the service gate for the high-level surface bay. There are 11 outlets in
total. For the bulkhead gate, the orifice width is 16.0m, the normal pool level is 240.000m,
the design flood level is 239.020m, the check flood level is 240.530m. For the high-level
surface bay, the crest elevation is 220.000m, the elevation of sill is 220.000m, the design
water head is 20.0m and the gate height is about 20.3m. The gate shall be the emerged
plane stoplog sliding gate supported by a high-strength and low-friction composite slide
block. The gate is closed in static water and lifted by filling water between sections. The
gate is operated with the gantry crane main hook on the dam crest of the release sluice dam
monolith through the automatic hydraulic pick-up beam. One upstream bulkhead gate is set
for the high-level surface bay and the gate is normally locked at the top of gate slot with
flashboard locking device. Each gate segment leaf is exchangeable with each segment leaf
of the upstream bulkhead gate for the low-level surface bays. The 14 crest overflowing
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outlets share 2 bulkhead gates. The gate is normally locked at the top of gate slot with
flashboard locking device.
6.4.1.3 Dam Crest Gantry Crane of Release Sluice
One two-way gantry crane with a downstream cantilever is provided on the top of
flood releasing dam monolith. It is mainly used to hoist the upstream and downstream
bulkhead gates of the release sluice and for the erection, examination and repairing of the
service gate of the release sluice and its hoists. The main hook capacity of the dam crest
two-way gantry crane is 2×800kN. An auxiliary trolley, with hoisting capacity of 2×400kN,
is provided on the downstream cantilever of the gantry crane. The track gauge of the gantry
crane is 32.5m, the main hook lift is 50.0m and the secondary hook lift is 58.0m.
6.4.1.4 Service Gate for Low-level Surface Bay of Release Sluice
The low-level surface bay of the release sluice is provided with 3 service gates, each
outlet is provided with 1 service gate. There are 3 service gates in total. Given the radial
gate of the release sluice has no gate slot, with good flowing condition and small vibration
upon partial lifting of the gate, the radial gate is adopted as the service gate. The width of
gate orifice is 16.0m, the normal pool level is 240.000m, the design flood level is
239.020m and the check flood level is 240.530m. For the low-level surface bay, the crest
elevation is 212.000m. And for the service gate, the elevation of sill is 212.000m, the
design water head is 28.0m, the gate height is about 28.5m and the panel curvature radius
is 31.0m. The elevation of the radial gate trunnion is decided as 235.000m as per the
principle that the trunnion shall not be impacted while discharging a 100-year flood. Three
main beam and oblique supporting arms structure is employed for the radial gate structure.
And the spherical sliding bearing is adopted for trunnion bearing. It is designed to be lifted
and closed in dynamic water and to allow partially lifting for flow regulation. When the
radial gate is fully opened, the bottom edge of the gate is preliminarily considered to be at
an elevation of 241.000m; this ensures that the radial gate will not be subject to the strike
of the water flow or the floating debris during flood release at check flood level.
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6.4.1.5 Service Gate Hoist for the Low-level Surface Bay of the Release Sluice
Each service gate with the low-level surface bay is provided with 1 set of hoist. Since
the hydraulic hoist is characterized by simple structure, small volume, stable transmission,
such advantages as no adoption of high bent frame, convenience of remote control and
good-looking arrangement of dam surface, it is used for the service gate. The hoist for the
radial gate with the low-level surface bay has a capacity of 2×6500kN with an operating
stroke of about 13.0 m. The hoist for the radial service gate with the low-level surface bay
is suspended, with the upper bearings of the two oil cylinders being respectively fixed onto
the side walls of the left and right gate piers and the lower ends being connected to the gate
lifting eye on the rear flange of the lower main beam. Each set of hydraulic hoist shall be
provided with a pump station and the hoist shall be controlled both locally and remotely.
6.4.1.6 Service Gate for the High-level Surface Bay of the Release Sluice
At the right side of the low-level surface bay of the release sluice, 11 high-level
surface bays are provided, each outlet is provided with 1 service gate. There are 11 service
gates in total. The crest elevation is 220.000m. And for the gate, the elevation of sill is
220.000m, the design head is 20.0m, the gate height is about 20.5m and the panel curvature
radius is 25.0m. The elevation of the radial gate trunnion is decided as 235.000m as per the
principle that the trunnion shall not be impacted while discharging a 100-year flood.
Double main beam and oblique supporting arms structure is employed for the radial gate
structure. And the spherical sliding bearing is adopted for trunnion bearing. It is designed
to be lifted and closed in dynamic water and to allow partially lifting for flow regulation.
When the radial gate is fully opened, the bottom edge of the gate is preliminarily
considered to be at an elevation of 241.000m; this ensures that the radial gate will not be
subject to the strike of the water flow or the floating debris during flood release at check
flood level.
6.4.1.7 Service Gate Hoist for the High-level Surface Bay of the Release Sluice
One set of hydraulic hoist with hoisting capacity of 2×3800kN and working stroke of
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about 10.0m is provided for each service gate. The radial service gate hoist for the
high-level surface bay shall be hanging mounted. The upper bearings of the two oil
cylinders shall be fixed on the side walls of the left and right gate piers of the gate,
respectively, while the lower ends shall be connected with the gate hoist eye of the lower
main beam rear wing plate of the gate. Every set of hydraulic hoist shall be equipped with
1 pump station. The hoist shall be controlled by the combination of local control and
remote control.
6.4.1.8 Downstream Bulkhead Gate of the Release Sluice
At the downstream of each service gate for release sluice, a 1-orifice bulkhead gate
slot shall be provided. There are 14 orifices in total. The orifice width of the bulkhead gate
is 16.0m. The elevation of sill for the downstream bulkhead gate of the low-level surface
bay is 204.201m, while that for the 5 high-level surface bays at left is 212.206m and that
for the 6 high-level surface bays at the right is 220.000m. One downstream bulkhead gate
is provided by taking the tailwater level of 224.140m when the unit is at full load as the
downstream service level. The bulkhead gate, with a height of about 20.9m and design
water head of about 19.939m, is provided for service gate and gate slot repairing and
maintenance. For low-level surface bays, 11 segments shall be used; for high-level surface
bays with stilling basin, 7 segments shall be used; for high-level surface bays without
stilling basin, 3 segments shall be used. The gate shall be the emerged plane stoplog sliding
gate. It is supported by a high-strength and low-friction composite slide block. Each leaf of
gate segments are exchangeable and 1 bulkhead gate is shared by 14 outlets. The gate is
closed in static water and lifted by filling water between sections. The gate is normally
locked by segment on the platform with an elevation of 245.000m above the downstream
side orifice of the downstream track of the dam crest gantry crane at the high-level surface
bay dam monolith.
6.4.1.9 Downstream Bulkhead Gate Hoist of the Release Sluice
The downstream bulkhead gate of the release sluice is operated with the secondary
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hook of downstream cantilever on the dam crest two-way gantry crane at the release sluice
dam monolith through the hydraulic automatic pick-up beam.
6.4.1.9 Emergency Bulkhead Gate of the Flushing Bottom Outlet
Two flushing bottom outlets share 1 emergency bulkhead gate. The emergency
bulkhead gate is of plane fixed wheel gate for closing in dynamic water in case of service
gate accident, and for orifice closing during service gate and gate slot maintenance; for the
gate, the orifice size is 10.0m×12.1m, the elevation of sill is 205.000m and the design
water head is 35.0m. The emergency bulkhead gate adopts the form of upstream board and
upstream water stop. And the gate is closed by dead weight of itself. A filling valve is
equipped at the top of the gate for gate lifting in static water after the pressure is balanced
by water filling of the filling valve. The gate is normally locked at the top of the gate slot.
6.4.1.10 Emergency Bulkhead Gate Hoist of the Flushing Bottom Outlet
The emergency bulkhead gate of the flushing bottom outlet is operated with the
platform hoist set on the dam crest bent. For the platform hoist, the hoisting capacity is
2500kN and the lift is about 42.0m.
6.4.1.11 Service Gate of the Flushing Bottom Outlet
The service gate is arranged at the downstream outlet of the flushing bottom outlet
with 1 service gate for each flushing bottom outlet. There are 2 service gates in total. The
gate is of plane fixed wheel gate with an orifice dimension of 10.0m×10.0m, the elevation
of sill of 205.000m and the design water head of 35.0m; to prevent sediment deposition in
the tunnel and beam grillage of the gate, the service gate adopts the form of upstream
board and upstream water stop. The gate is lifted and closed in dynamic water and the
maximum head difference during operation in dynamic water is about 20m.
6.4.1.12 Service Gate Hoist of the Flushing Bottom Outlet
The service gate of the flushing bottom outlet is operated with the stationary winch
hoist set on the dam crest bent. For the hoist, the hoisting capacity is 3200kN and the lift is
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about 34.0m. A bridge crane with capacity of 30kN shall be set on the top of the hoist
room for maintenance of the hoisting equipment for the service gate of the flushing bottom
outlet.
6.4.1.13 Outlet Bulkhead Gate of the Flushing Bottom Outlet
As the sill is submerged in the downstream water level of the flushing bottom outlet
for a long time, for the maintenance of the waterway, tunnel and embedded parts of the slot,
1 bulkhead gate slot shall be provided at the downstream side of the service gate slot at the
outlet of each flushing bottom outlet. There are 2 outlets in total which share 1 bulkhead
gate. For the gate, the orifice dimension is 10.0m×10.0m, the elevation of sill is 205.000m,
the design water level is 235.600m which is also the downstream design flood level and the
design water head is 30.6m. The gate is of plane sliding gate supported by a high-strength
and low-friction composite slide block. And the simple supporting side wheels are used to
serve as the lateral support. The gate closed in static water is lifted when the pressure is
balanced by water filling of the filling valve set on the top of the gate. The gate is normally
locked on the top of the gate slot in two segments.
6.4.1.14 Outlet Bulkhead Gate Hoist of the Flushing Bottom Outlet
Lifting and closing of the outlet bulkhead gate of the flushing bottom outlet are
realized by tailrace 2×1600kN gantry crane through the hydraulic automatic pick-up beam.
6.4.2 Hydraulic steel Structure Equipment of Headrace and Power Generation System
The headrace and power generation system is equipped with 14 units in total and each
unit is equipped with a single headrace tunnel and a single draft tube. Hydraulic steel
structure equipment of headrace and power generation system mainly consists of an intake
trashrack, intake trash rack, intake bulkhead gate, tailrace emergency gate and
corresponding hoists. For the details of arrangement, please refer to the Layout Plan for the
Trashrack of the Headrace and Power Generation System (Drawing No.:
Paklay-FS-MS-02(1/2)) and Layout for Gates and Hoists of the Headrace and Power
Generation System (Drawing No.: Paklay-FS-MS-02(2/2)).
6.4.2.1 Intake trashrack and embedded parts
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One trashrack guide slot column is provided on the guide wall between the flushing
outlet dam monolith and the power station dam monolith and one provided at the place
about 610m upstream of the power station on the left bank. Between the aforementioned
two trashrack guide slot columns, another two trashrack guide slot columns are arranged to
divide the whole trashrack into 3 sections. 3 sets of trashracks are furnished. Each set of
trashrack is composed of the pedestals with floating camel at both ends and several floating
caissons which are interconnected with tie bars. Pedestals with floating camel at both ends
shall be restrained in the guide slot arranged in vertical and lifted up and down along the
guide slot track through rollers. Grids are welded at the upstream face of the floating
caisson, allowing the whole trashrack to go up and down along with the water. The trash
before the trashrack shall be cleaned manually with wastes cleaning boats.
The reason why trash cleaning boat is used to remove the trashes in front of the trash
boom rather than setting a flap gate in the radial service gate of flood discharging for
surface trash discharging is mainly based on the following consideration: during the
non-flood season, the surface trashes are comparatively of small quantity and frequent
discharge of the trashes is not good for concentrative cleaning and will affect the
downstream environment. Besides, the discharge of the trashes from the trash boom does
not ensure the thorough cleaning and trash cleaning boat may still be needed. During the
flood season, in case of the occurrence of a 2-year flood or flood with longer return period,
there will be a lot of surface trashes. For this case, as the flood discharge is realized by
fully opening the gate, the trashes could be discharged to the downstream as well with the
fully-opened radial gate.
6.4.2.2 Intake trash rack
An intermediate pier is set at the water intake of each unit, which evenly divides the
water intake to be 2 orifices and 2 trash racks are provided. The 14 units are corresponding
to 28 orifices; therefore, 28 trash racks are required in total. The trash rack has an orifice
width of 6.65 m and orifice height of 28.0 m, all of which are arranged vertically. All trash
racks are designed as per a head difference of 4.0 m. The composite sliding block is
employed for both reverse guide and support of the trash rack, connected to the dam crest
by a tie bar for locking. A cleaning guide slot is set in front of a trash rack slot. The
cleaning grab bucket is operated by the dam crest gantry crane at the intake monolith to
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remove trash of the trash rack. When a trash rack needs to be maintained, a dam crest
gantry crane at the intake monolith is used for hoisting the trash rack onto the dam crest.
6.4.2.3 Intake bulkhead gate
Behind each intake trash rack slot, 1 intake bulkhead gate slot is set. The 14 units are
corresponding to 14 orifices in total; after power generation by the first generator unit,
intakes shall be closed for installation of other units; therefore, 14 bulkhead gates are
needed in total, including 4 permanent bulkhead gates and 10 gates for temporary water
retaining during construction. The bulkhead gates have an orifice width of 15.1 m, height
of 16.3 m, sill elevation of about 201.020 m a.s.l., normal pool level of 240.000 m a.s.l.,
design flood level of 239.020 m a.s.l., and design head of 38.98m. The gate type is of the
down-hole plane sliding stoplog gate, supported by high-strength low-friction composite
steel slide blocks. Gates are opened and closed in still water. Pressure balancing method of
gates is that a filling valve on the top of gate is used for filling water so as to balance
pressure. Pressure balancing is carried out by the automatically hydraulic pick-up beam
operated by the dam crest gantry crane at the intake monolith. At ordinary times, gates are
placed inside a gate chamber.
6.4.2.4 Temporary Water Retaining Gate at the Intake
Given that water inlets shall be sealed for installation of other units after power
generation of the first unit, 10 temporary water retaining gates are provided for water
retaining during project construction. For the temporary water retaining bulkhead gate, the
orifice width is 15.1m, the height is 16.3m, the elevation of sill is 201.020m, the normal
pool level is 240.000m, the design flood level is 239.020m and the design water head is
38.98m. The gate shall be the down-hole sliding plane stoplog gate supported by a
high-strength and low-friction composite slide block. The gate is lifted and closed in static
water. The pressure is balanced by water filling of the filling valve provided on the top of
the gate. The operation is carried out with the dam crest gantry crane at the intake dam
monolith through the hydraulic automatic pick-up beam. Gates are normally stored in the
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gate chamber. After the gate is used, it is properly stored in some place at the station or
will be recycled.
6.4.2.5 Dam crest gantry crane at intake monolith
One two-way gantry crane is installed on the dam crest at the intake monolith, mainly
used for hoisting the intake trash rack and intake bulkhead gate as well as cleaning the
intake trash rack. The two-way gantry crane has a main hook capacity of 2 x 1000 kN,
auxiliary hook capacity of 2 x 400kN, gantry crane track gauge of 15.0 m, and head of
main and auxiliary hooks is about 55 m.
6.4.2.6 Tailrace emergency gate
Draft tube outlet of each unit is equipped with 1 tailrace emergency gate slot. The 14
units are corresponding to 14 orifices in total; after power generation by the first generator
unit, draft tubes shall be closed for installation of other units; therefore, 14 tailrace
emergency gates are needed in total, including 5 permanent emergency gates and 9 gates
for temporary water retaining during construction. The gates have an orifice width of 13.6
m, orifice height of 10.88 m, sill elevation of 203.060 m a.s.l., downstream design flood
level of 235.600 m a.s.l. and design head of 32.54 m. The above permanent gates are
down-hole plane gates, with two-way water seal. The gates are supported by high-strength
low-friction composite steel slide block on the upstream side and fixed roller on the
downstream side, closed in flowing water (maximum head difference at lowering of gate is
20 m) and opened in still water. The gates used for temporary water retaining are
down-hole plain sliding gates, supported by high-strength low-friction composite steel
slide blocks, opened and closed in still water. Pressure balancing method of gates is that a
filling valve on the top of gate is used for filling water so as to balance pressure. Pressure
balancing is carried out by the automatically hydraulic pick-up beam operated by the
tailrace gantry crane. At ordinary times, gates are locked at the top of gate slots.
6.4.2.7 Temporary Water Retaining Gate of the Tail Water
For the temporary water retaining gate, the orifice width is 13.6m, orifice height is
10.88m and the elevation of sill is 203.060m. And the design level is 232.980m as per the
downstream flood level specified in the construction and flood control standard of
100-year flood, while the design water head is 29.92m. The temporary water retaining gate
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shall be the down-hole plane sliding gate supported by a high-strength and low-friction
composite slide block. The gate is lifted and closed in static water. The pressure of the gate
is balanced by water filling of the filling valve provided on the top of the gate. The
operation is carried out through the hydraulic automatic pick-up beam of the tailrace gantry
crane. The gate is normally locked on the top of the gate slot. After the gate is used, it is
properly stored in some place at the station or will be recycled.
6.4.2.8 Tailrace gantry crane
One single-way gantry crane is installed on the tailrace platform, with a capacity of 2
x 1600 kN, track gauge of 6.5 m, and head of about 36.0 m. It is mainly used for hoisting
the permanent tailrace emergency gates, gates used for temporary water retaining and
bulkhead gate at the sediment releasing bottom outlet.
6.4.3 Hydraulic steel Structure Equipment of Navigation Lock System
The navigation lock is the one-stage type, arranged on the right side of riverbed, with
a lock chamber width of 12.00 m, upstream check flood level of 240.530m m a.s.l.,
upstream maximum stage of waterway of 240.000 m a.s.l., upstream minimum stage of
waterway of 239.000 m a.s.l., downstream maximum stage of waterway of 229.600 m a.s.l.,
and downstream minimum stage of waterway of 219.000 m a.s.l. The navigation lock is
composed of an upstream approach channel, upper lock head, lock chamber, lower lock
head, downstream approach channel, etc. The main hydraulic steel structure equipment of
navigation lock system mainly includes emergency bulkhead gate and service gate of the
upstream lock head, service gate and bulkhead gate of the downstream lock head, bulkhead
gate and service gate for water conveyance gallery at upstream and downstream lock heads,
corresponding hoists and floating makefast in the gate chamber. For the details of
arrangement, please refer to the Layout for the Gates and Hoists of the navigation lock
system (Drawing No.: Paklay-FS-MS-03).
6.4.3.1 Gates and Hoists of the Upstream Lock Head
a) Emergency bulkhead gate of the upstream lock head
One emergency bulkhead gate of upper lock head is set at the upstream side of the
upper lock head, with an orifice width of 12.0 m, height of about 5.73 m, sill elevation of
235.000 m a.s.l., and design head of 5.53 m. The gate type is of the emersed plane sliding
gate, supported by steel-based high-strength low-friction composite sliding blocks. The
gates are opened and closed in still water. In case of emergency, the gates can be closed in
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flowing water as well. At ordinary times, the gates are placed inside the gate chamber for
the bulkhead gate of upper lock head.
b) Emergency bulkhead gate hoist of the upstream lock head
The emergency bulkhead gate for the upstream lock head is operated with the
platform hoist with capacity of 2×400kN at the dam crest of the upstream lock head dam
monolith through the hydraulic automatic pick-up beam.
c) Service gates of the upstream lock head
Miter gates or submergence gates are adopted as service gates of the lock head. At
present, the service gates for domestic medium-high water head navigation lock are
generally miter gates, while the service gates for the low water head navigation lock are
generally miter gates, lateral drawing gates and submergence gates. However, most of the
service gates are miter gates. When the miter gate is adopted, small capacity of the hoist is
required with easy control and convenient maintenance, while the hoist for submergence
gate requires large capacity, high degree of synchronization and complicated control. The
miter gate basically adopts rigid water seal as it show excellent water stop effect, long
service life and short navigation interference time. The water seal of the submergence gate
has short service life and overall poor sealing and water stop effect. It also shows high
maintenance frequency, long maintenance duration and long navigation interference time.
The miter gates are generally arranged horizontally with relatively complicated civil
structure and relatively large gate structure weight. The hoist of the submergence gate is
set on the top of the gate with simple civil structure, gate structure and low construction
cost. For the convenience of future maintenance and minimize the influence of equipment
maintenance on navigation, the service gates of the upstream lock head of navigation lock
shall adopt miter gate. For the miter gate, the orifice width shall be 12.0m and the height
shall be about 6.0m. Pedestrian steel bridge and guardrail shall be provided on the top of
gate. The elevation of threshold is 235.000m and the design water head is 5.0m. The miter
gate adopts the beam structure with the fixed bottom pintle hinged with the frame-type top
pintle. The continuous support pillow spacers serve as support and water stop. And
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prestress diagonal tie bars are adopted for torsion resistance.
d) Service gate hoist of the upstream lock head
The miter gate of the upstream lock head shall be lifted and closed in static water with
the 2×320kN horizontal hydraulic hoist (a water head difference of 0.2m is allowed during
operation).
6.4.3.2 Hydraulic steel structure equipment of lower lock head
a) Service gates of the downstream lock head
The service gate of lower lock head is a mitre gate, with an orifice width of 12.0 m,
height of about 26.0 m, sill elevation of 215,000 m a.s.l., and design head difference of
21.0 m. The mitre gate is of a cross beam structure, with the pedestrian steel bridge and
guardrail on the top, as well as a fixed bottom pintle, and a top pintle in hinged frame
manner. Bolsters and cushion blocks are continuously used for support and water seal. A
pre-stressed diagonal draw bar is used for torsion resistance.
b) Service gate hoist of the downstream lock head
The miter gate of the downstream lock head shall be lifted and closed in static water
with the 2×1250kN horizontal hydraulic hoist (a water head difference of 0.2m is allowed
during operation).
c) Bulkhead gate of the downstream lock head
At the downstream side of the downstream lock head, 1 bulkhead gate of the
downstream lock head shall be provided. For the bulkhead gate, the orifice width is 12.0m,
the height is about 9.64m, the elevation of the sill is 215.000m, the downstream
maintenance water level is 224.140m and the design water head is 9.14m. The gate shall be
the emerged plane sliding gate supported by a high-strength and low-friction composite
slide block. The gate shall be lifted and closed in static water. The gate is normally locked
on the dam crest of the downstream lock head with flashboard locking device. The bottom
elevation of the gate leaf shall not affect ship navigation. The control elevation is
238.000m.
d) Bulkhead gate hoist of the downstream lock head
The bulkhead gate of downstream lock head shall be operated through the stationary
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winch hoist with capacity of 2×630kN on the dam crest bent of the downstream lock head.
6.4.3.3 Gates and Hoists of the Water Conveyance Gallery
a) Trash racks of the water conveyance gallery of the upstream lock head
Trash racks are provided at the left and right inlets of the water conveyance gallery of
the upstream lock head. Every water conveyance gallery inlet is divided into 5 sections
with separating piers. There are 10 sections in the left and right water conveyance galleries.
And 10 stationary trash racks are provided. For the trash racks, the orifice width is 2.3m,
the orifice height is 3.3m and the design water head difference is 5.0m.
b) Bulkhead gates of the water conveyance gallery of the upstream lock head
One set of bulkhead gate for water conveyance gallery is arranged at the downstream
side of trash rack at the left and right water conveyance gallery of the upstream lock head,
respectively. There are 2 sets in total. For the gate, the orifice width is 2.2m, the height is
3.3m, the elevation of sill is 226.200m and the design water head is 14.33m. The gate shall
be the down-hole plane sliding gate which is closed in static water and lifted in static water
after small lifting of the gate for water filling and pressure balancing. The gate is normally
locked on the top of the gate slot.
c) Bulkhead gates hoist of the water conveyance gallery of the upstream lock head
The bulkhead gate for the left and right water conveyance galleries of the upstream
lock head is operated with the platform hoist with capacity of 2×400kN at the dam crest of
the upstream lock head dam monolith through tie bars.
d) Service gates of the water conveyance gallery of the upstream lock head
One set of service gate is arranged for the left and right water conveyance galleries of
the upper lock head, respectively. There are 2 sets in total. Service gates commonly used
for the water conveyance gallery are of two types, i.e. reverse radial gates and plane gates.
For water head larger than 15m, the adoption of plane gates may cause gate vibration and
slot cavitation. The reverse radial gates are normally provided as the service gates for the
water conveyance gallery of navigation lock with higher water head. Without the
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interference of gate slot, it provides relatively good hydraulic conditions. With small
hoisting force, light water fluctuation and vibration, the water entering the gate chamber is
in good state of flow. Therefore, reverse radial gates are adopted as the service gates of the
water conveyance gallery. The orifice width of the gate is 2.2m, the height is 2.6m, the
elevation of sill is 209.700m, the design retaining water head is 30.83m and the dynamic
operation water head is 30.3m. The gate is lifted in dynamic water and closed in static
water (closing in dynamic water is allowable in emergency conditions).
e) Service gate hoists of the water conveyance gallery of the upstream lock head
The water conveyance gallery of the upstream lock head shall be operated with the
630kN hydraulic hoist through tie bars.
f) Bulkhead gates beside the service gate chamber for the water conveyance gallery
One bulkhead gate slot is provided beside the upstream and downstream service gate
chambers of the left and right water conveyance galleries, respectively. There are 4
bulkhead gate slots in total. For the convenience of repair and maintenance of the service
gates for the water conveyance gallery, 2 bulkhead gates are provided beside the service
gate chamber of the water conveyance galleries. For the gate, the orifice width is 2.2m, the
height is 3.3m and the elevation of sill is 211.90m. The design water level of the gate is
240.000m, which is also the maximum upstream stage of waterway. The design water head
for the gate is 28.1m. The gates shall be the down-hole plane sliding gates supported by a
high-strength and low-friction composite slide block. The gates are closed in static water
and lifted in static water after small lifting of the gate for water filling and pressure
balancing. The gate is normally locked on the top of the gate slot.
g) Bulkhead gate hoists beside the service gate chamber for the water conveyance
gallery
The bulkhead gate beside the service gate chamber of the water conveyance gallery
shall be operated with a temporary floating crane with a hoisting capacity equal to or larger
than 400kN.
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h) Service gates of the water conveyance gallery of the downstream lock head
Left and right water conveyance galleries of lower lock head are respectively equipped
with 1 service gate of water conveyance gallery, 2 in total. The gate has an orifice width of
2.2 m, height of 2.6 m, sill elevation of 209.700 m a.s.l., and design head difference of 21.0
m. The gate type is of reversed radial gate and is opened in flowing water and closed in
still water. In case of emergency, it can also be closed in flowing water.
i) Service gate hoists of the water conveyance gallery of the downstream lock head
The service gate of the water conveyance gallery for the downstream lock head shall be
operated with the 630kN hydraulic hoist through tie bars.
j) Bulkhead gates of the water conveyance gallery of the downstream lock head
Downstream sides of the service gates of the left and right water conveyance galleries of
lower lock head are respectively equipped with 1 bulkhead gate of water conveyance
gallery, 2 in total. The gate has an orifice width of 2.2 m, height of 3.3 m, sill elevation of
209.700 m a.s.l., downstream water level during maintenance of 224.140 m a.s.l., and
design head of 14.44 m. The gate type is of down-hole plain sliding gate. The operating
condition of the gate is as follows: the gate is closed in still water; the gate is then slightly
opened for water filling and pressure balancing, after which the gate is completely opened
in still water. At ordinary times, gates are locked at the top of the gate slot.
k) Bulkhead gate hoists of the water conveyance gallery of the downstream lock head
The bulkhead gates of the left and right water conveyance galleries for the downstream
lock head shall be operated with a stationary winch hoist with capacity of 250kN on the
bent at the top of gate chamber.
6.4.3.4 Floating makefast of lock chamber
There are 12 floating makefasts in total at both sides of the lock chamber. The floating
makefast is of floating camel structure. Upper part of the floating camel is equipped with a
double-deck floating makefast. There are 6 sets of rollers provided respectively at three
positions including upper, intermediate and lower parts. The floating camel can go up and
down along the guide slot based on change of water level.
6.4.3.5 Anticollision device and hoisting equipment of gate chamber
To avoid the clash on the service gate of lower lock head by the ships due to their
failure in speed control, a set of anticollision device is provided in front of the service gate.
This anticollision device uses steel wire rope as the ship holding rope, which goes across
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the gate chamber, with both ends of the rope tied to the buffering device of the butterfly
spring at the lifting platform in both sides of the gate wall slot. The anticollision device
could withstand a max. striking energy of 250kNm from the ships, having a max. buffering
distance of around 2.32m. The anticollision device is operated by the 2×200kN (lifting
force)/2×300kN (holding force) stationary winch-type hoist set on the bent frame at the top
of the gate wall.
6.4.4 Hydraulic steel Structure Equipment of Fish Pass Structure
The fish pass structures shall be arranged at the left side of the powerhouse dam
monolith. The hydraulic steel structure equipment for the fish pass structures include
upstream flood control service gates, downstream flood control gates and corresponding
hoists.
6.4.4.1 Service Gates of Upstream Flood Control
One service gate slot for flood control and one service gate for flood control shall be
provided at the fishway entrance in front of the dam. For the service gate, the orifice width
is 6.0m, the height is 3.3m, the elevation of sill is 237.240m and the design water head is
about 3.29m. The gate shall be emerged plane sliding gate supported by a high-strength
and low-friction composite slide block. The gate shall be lifted and closed in dynamic
water. For maintenance of service gate slot for flood control, water retaining shall be
carried out by sandbag cofferdams.
6.4.4.2 Service Gate Hoists of Upstream Flood Control
The service gate for upstream flood control shall be operated through the stationary
winch hoist with capacity of 2×100kN set on the dam crest bent.
6.4.4.3 Service Gates and the Hoists for Downstream Flood Control
According to the requirements of the fish pass structure arrangement, 1 flood control
gate is arranged at the middle section of the fishway close to the access road on the left
bank of the power station. For the gate, the orifice width is 6.0m, the height is 3.0m, the
elevation of sill is 232.140m, the downstream design flood level is 235.500m and the
design water head is about 3.46m. The gate shall be the down-hole plane sliding gate
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supported by a high-strength and low-friction composite slide block. The gate shall be
lifted and closed in dynamic water.
6.4.4.4 Service Gate Hoists of the Downstream Flood Control
The service gate for downstream flood control shall be operated through the stationary
winch hoist with capacity of 2×100kN set on the bent of the platform with an elevation of
237.500m on the top of gate slot.
6.4.5 Correction Protection Scheme for Hydraulic steel Structure Equipment
The correction protection scheme for hydraulic steel structure equipment of the
Project mainly consists of four classifications as follows:
a) Except structural components for the temporary gates, all other structural
components for trash racks, gates, exposed surface (unfinished surface) of embedded parts,
and hoists shall be sprayed with zinc for corrosion prevention. The minimum partial
thickness of zinc spraying shall be 120 μm. After zinc spraying, seal coat, intermediate
coat and finishing coat shall also be painted. The seal coat is 30 μm thick epoxy primer, the
intermediate coat is 50 μm thick epoxy micaceous iron antirust paint and the finishing coat
is 60 μm ~ 100 μm thick chlorinated rubber pain.
b) Structural components for the temporary gates shall be applied with coatings for
corrosion prevention. The coatings consist of epoxy asphalt antirust primer with a
thickness of 125 μm and epoxy asphalt antirust finishing coat with a thickness of 125 μm.
c) Surface of non-fit mechanical components of hoists shall be applied with coatings
for correction prevention. The coatings consist of epoxy zinc-rich primer with a thickness
of 70 μm at the bottom course, epoxy micaceous iron antirust paint with a thickness of 80
μm at the intermediate course, and chlorinated rubber paint with a thickness of 70 μm at
the surface course.
d) Embedded parts of all gate slots, rack slots and guide slots in concrete shall be
painted with cement mortar for corrosion prevention.
6.4.6 Summary Sheet of Main Hydraulic steel Structure Equipment of Paklay HPP
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Table 6.4-1 Summary Sheet of Main Hydraulic steel Structure Equipment of Paklay HPP
S/N Description Type Specification Qty. Unit Unit
Qty. Subtotal Remarks
(t) (t)
1. Flood Releasing System
10458
1.01
Upstream
Bulkhead Gate
of the Release
Sluice (I)
Plane
stoplog
sliding gate
16.0m×29.0m-28.000m 1 Set 500 500
1.02
Embedded
Parts of
Upstream
Bulkhead Gate
of the Release
Sluice (I)
3 Orifice 30 90
1.03
Upstream
Bulkhead Gate
of the Release
Sluice (II)
Plane
stoplog
sliding gate
16.0m×20.3m-20.00m 1 Set 350 350
1.04
Embedded
Parts of
Upstream
Bulkhead Gate
of the Release
Sluice (II)
11 Orifice 23 253
1.05
Upstream
Bulkhead Gate
Hoist of the
Release Sluice
Two-way
gantry crane 2×800kN/2×400kN 1 Set 650 650
1.06
D a m C r e s t
Gantry Crane
Track of the
Release Sluice
QU120 1 Set 105 105
Single track has a
length about 285m,
two tracks
1.07
Service Gate
for the
Low-level
Surface Bay of
Radial gate 16.0m×28.50m-28.000m 3 Set 550 1650
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the Release
Sluice
1.08
Embedded
Parts of the
Service Gate
for the
Low-level
Surface Bay of
the Release
Sluice
3 Orifice 40 120
1.09
Service Gate
Hoist for the
Low-level
Surface Bay of
the Release
Sluice
Hydraulic
hoist 2×6500kN 3 Set 110 330
1.10
Service Gate
for the Surface
Outlet of the
Release Sluice
Radial gate 16.0m×20.5m-20.000m 11 Set 330 3630
1.11
Embedded
Parts of the
Service Gate
for the Surface
Outlet of the
Release Sluice
11 Orifice 29 319
1.12
Service Gate
Hoist for the
Surface Outlet
of the Release
Sluice
Hydraulic
hoist 2×3800kN 11 Set 70 770
1.13
Downstream
Bulkhead Gate
of the Release
Sluice
Plane
stoplog
sliding gate
16.0m×20.9m-19.939m 1 Set 330 330
1.14
Embedded
Parts of
Downstream
Bulkhead Gate
of the Release
3 Orifice 29 87
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Sluice (I)
1.15
Embedded
Parts of
Downstream
Bulkhead Gate
of the Release
Sluice (II)
5 Orifice 23 115
1.16
Embedded
Parts of
Downstream
Bulkhead Gate
of the Release
Sluice (III)
6 Orifice 15 90
1.17
D o w n s t r e a m
Bulkhead Gate
Ho i s t o f th e
Release Sluice
Two-way
gantry crane
Shared dam crest
gantry crane
1.18
Emergency
Bulkhead Gate
of the Flushing
Bottom Outlet
Plane
fixed-roller
gate
10.0m×12.1m-35.0m 1 Set 165 165
1.19
Embedded
Parts of
Emergency
Bulkhead Gate
of the Flushing
Bottom Outlet
2 Orifice 50 100
1.20
Emergency
Bulkhead Gate
Hoist of the
Flushing
Bottom Outlet
Platform
hoist 2500kN 1 Set 110 110 Including track
1.21
Service Gate of
t h e F lu sh in g
Bottom Outlet
Plane
fixed-roller
gate
10.0m×10.0m-35.0m 2 Set 140 280
1.22
Embedded
Parts of Service
Gate of the
Flushing
2 Orifice 42 84
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Bottom Outlet
1.23
Service Gate
Hoist of the
Flushing
Bottom Outlet
Stationary
winch hoist 3200kN 2 Set 75 150
1.24
Maintenance
Crane of the
Service Gate
Hoist Room of
the Flushing
Bottom Outlet
Electric
block 30kN 1 Set 10 10
1.25
Bulkhead Gate
of the Flushing
Bottom Outlet
Plane
sliding gate 10.0m×10.0m-30.6m 1 Set 110 110
1.26
Embedded
Parts of
Bulkhead Gate
of the Flushing
Bottom Outlet
2 Orifice 30 60
1.27
Bulkhead Gate
Hoist of the
Flushing
Bottom Outlet
One-way
gantry crane
Shared tailrace gantry
crane
2. Headrace and power generation system
11354
2.01 Intake
Trashrack 3 Set 300 900
2.02
Guide Slot of
the Intake
Trashrack
3 Set 20 60
2.03 Intake trash
rack
Plane
vertical
trash rack
6.65m×28.0m-4.0m 28 Set 55 1540
2.04
Embedded
Parts of the
Intake Trash
Rack and
Embedded
Parts of the
28 Orifice 25 700
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Cleaning Guide
Slot
2.05 Intake
Bulkhead Gate
Plane
stoplog
sliding gate
15.1m×16.3m-38.98m 4 Set 260 1040
2.06
Temporary
Water
Retaining Gate
at the Intake
Plane
stoplog
sliding gate
15.1m×16.3m-38.98m 10 Set 260 2600
2.07
Embedded
Parts of the
Intake
Bulkhead Gate
14 Orifice 33 462
2.08
Embedded
Parts of Intake
Bulkhead Gate
Chamber
14 Orifice 5 70
2.09
Dam Crest
Gantry Crane at
Intake
Two-way
gantry crane 2×1000kN/2×400kN 1 Set 360 360
Including cleaning
equipment
2.10 Intake Gantry
Crane Track QU100 1 Set 100 100
Single track has a
length about 345m,
two tracks
2.11
Tail Water
Emergency
Gate
Plane
fixed-roller
gate
13.6m×10.88m-32.54m 5 Set 190 950 Maximum gate closing
water head 20m
2.12
Temporary
Water
Retaining Gate
of the Tail
Water
Plane
sliding gate 13.6m×10.88m-29.92m 9 Set 172 1548
2.13
Embedded
Parts of the Tail
Water
Emergency
Gate
14 Orifice 41 574
2.14 Tailrace Gantry
Crane
One-way
gantry crane 2×1600kN 1 Set 320 320
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2.15
Tail Water
Gantry Crane
Track
QU120 1 Set 130 130
Single track has a
length about 345m,
two tracks
3. Navigation Lock System
1328
3.01
Emergency
Bulkhead Gate
of the Upstream
Lock Head
Plane
sliding gate 12.0m×5.73m-5.53m 1 Set 42 42
3.02
Embedded
Parts and
Chamber of the
Emergency
Bulkhead Gate
of the Upstream
Lock Head
1 Orifice 15 15
3.03
Emergency
Bulkhead Gate
Hoist of the
Upstream Lock
Head
Platform
hoist 2×400kN 1 Set 70 70
3.04
Platform Hoist
Track of the
Upstream Lock
Head
QU80 1 Set 12 12
Single track has a
length about 44m, two
tracks
3.05
Service Gates
of the Upstream
Lock Head
Mitre gate 12.0m×6.0m-5.0m 1 Set 70 70
3.06
Embedded
Parts of the
Service Gate of
the Upstream
Lock Head
1 Orifice 8 8
3.07
Service Gate
Hoist of the
Upstream Lock
Head
Hydraulic
hoist 2×320kN 1 Set 8 8
3.08
Service Gates
of the
Downstream
Mitre gate 12.0m×26.0m-21.0m 1 Set 290 290
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Lock Head
3.09
Embedded
Parts of the
Service Gate of
the
Downstream
Lock Head
1 Orifice 25 25
3.10
Service Gate
Hoist of the
Downstream
Lock Head
Hydraulic
hoist 2×1250kN 1 Set 25 25
3.11
Bulkhead Gate
of the
Downstream
Lock Head
Plane
sliding gate 12.0m×9.64m-9.14m 1 Set 58 58
3.12
Embedded
Parts of the
Bulkhead Gate
of the
Downstream
Lock Head
1 Orifice 20 20
3.13
Bulkhead Gate
Hoist of the
Downstream
Lock Head
Stationary
winch hoist 2×630kN 1 Set 25 25
3.14
Trash Racks
and Embedded
Parts of the
Water
Conveyance
Gallery Inlet of
the Upstream
Lock Head
Stationary
type 2.3m×3.3m-5.0m 10 Set 2.5 25
3.15
Bulkhead Gates
of the Water
Conveyance
Gallery of the
Upstream Lock
Head
Plane
sliding gate 2.2m×3.3m-14.33m 2 Set 8 16
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3.16
Embedded
Parts of the
Bulkhead Gates
of the Water
Conveyance
Gallery of the
Upstream Lock
Head
2 Orifice 6 12
3.17
Bulkhead Gates
beside the Gate
Chamber for
the Water
Conveyance
Gallery
Plane
sliding gate 2.2m×3.3m-28.1m 2 Set 9 18
3.18
Embedded
Parts of the
Bulkhead Gates
beside the Gate
Chamber for
the Water
Conveyance
Gallery
4 Orifice 9 36
3.19
Bulkhead Gates
of the Water
Conveyance
Gallery of the
Downstream
Lock Head
Plane
sliding gate 2.2m×3.3m-14.44m 2 Set 8.5 17
3.20
Embedded
Parts of the
Bulkhead Gates
for the Water
Conveyance
Gallery of the
Downstream
Lock Head
2 Orifice 9 18
3.21
Bulkhead Gate
Hoists of the
Water
Conveyance
Gallery of the
Stationary
winch hoist 250kN 2 Set 5 10
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Downstream
Lock Head
3.22
Service Gates
of the Water
Conveyance
Gallery of the
Upstream and
Downstream
Lock Head
Reverse
radial gate 2.2m×2.6m-30.83m 4 Set 32 128
3.23
Embedded
Parts of the
Service Gates
for the Water
Conveyance
Gallery of the
Upstream and
Downstream
Lock Head
4 Orifice 50 200
3.24
Service Gate
Hoist of the
Water
Conveyance
Gallery of the
Upstream and
Downstream
Lock Head
Hydraulic
hoist 630kN 4 Set 8 32
3.25 Floating
Makefast 12 Set 2.5 30
3.26
Embedded
Parts of the
Floating
Makefast
12 Orifice 6.5 78
3.27
Anticollision
device of gate
chamber
Butterfly
spring
buffering
type ship
holding
rope
1 Set 25 25
3.28
Embedded
parts of
anticollision
device of gate
chamber
1 Set 6 6
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3.29
Hoist of
anticollisio
n device of
gate chamber
Stationary
winch type
hoist
2×200kN (lifting force)/2×300kN (holding force)
1 Set 9 9
4. Fish Pass System 30
4.01
Service Gates
of Upstream
Flood Control
Plane
sliding gate 6.0m×3.3m-3.29m 1 Set 6 6
4.02
Embedded
Parts of the
Service Gates
for Upstream
Flood Control
1 Set 4 4
4.03
Service Gate
Hoists of
Upstream Flood
Control
Stationary
winch hoist 2×100kN 1 Orifice 5 5
4.04
Service Gates
of Downstream
Flood Control
Plane
sliding gate 6.0m×3.0m-3.46m 1 Set 6 6
4.05
Embedded
Parts of the
Service Gates
for
Downstream
Flood Control
1 Orifice 4 4
4.06
Service Gate
Hoists of the
Downstream
Flood Control
Stationary
winch hoist 2×100kN 1 Set 5 5
5. Total 23170
6.5 Ventilation and Air Conditioning
6.5.1 Overview
The Paklay HPP is in Laos, where the climate is hot, and annual average temperature
is 25.3 °C, extreme maximum temperature is 40.5 °C, and extreme minimum temperature
is 1.3 °C.
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The HPP is of a water retaining powerhouse. Main auxiliary plant is composed of
powerhouse and downstream auxiliary plant. Generator floor, busbar floor, and operation
gallery floor are set for the powerhouse only. Floors of the downstream auxiliary plant
from bottom to top are busbar cable floor, power distribution device floor, SF6 pipeline
floor, GIS floor, outgoing line platform floor. Two erection bays, which are 1# erection
bay (at left side of the powerhouse) and 2# erection bay (between the 11# 12# units), are
set for the HPP. The central control building is at left side of the downstream auxiliary
plant and downstream side of the 1# erection bay.
6.5.2 Design Parameters of Indoor Air
a) Summer
Generator floor ≤33 °C 75%
Main transformer room <40 °C
Station service transformer room ≤35 °C
Turbine oil depot and insulating oil depot ≤33 °C 80%
Air compressor room ≤35 °C 75%
Cable room (passage) ≤35 °C
Central control room and computer room ≤28 °C 60%±5%
Local panel room, relay protection room, storage room, etc. ≤28 °C 60%±5%
Office, meeting room, etc. ≤28 °C 60%±5%
b) Winter
Generator floor ≥10 °C
Main transformer room ≥10 °C
Central control room and computer room ≥20 °C
Oil disposal room ≥10 °C
Air compressor room ≥12 °C
Office, meeting room, etc. ≥18 °C
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6.5.3 Preparation of System Scheme
Location of the HPP is of a hot climate. According to meteorological and local
conditions, etc., method of mechanical ventilation (the major part) supported by multi-split
air condition is adopted for design scheme of ventilation and air conditioning of the whole
plant. Mechanical ventilation is adopted for the powerhouse, electrical equipment room for
the main transformer, station service transformer, etc. Multi-split central air conditioning
system is adopted for rooms of the central control building and equipment rooms (such as
local panel room) which are within the unit bay scope and have high requirement for
temperature and moisture while holding a heavy thermal load. Ventilation method of
natural air intake and mechanical air exhaust is adopted for GIS room and pipeline floor.
Independent air exhaust system of natural air intake and mechanical air exhaust is adopted
for the battery room, which is of maintenance-free type.
6.5.4 Organization and Systematic Design of Ventilation Air
According to layout of the electromechanical equipment, method of air blown from
upstream and exhausted from d ①ownstream is adopted for the whole plant. Blower room
② ③is set at upstream side at left of the powerhouse, and blower rooms and are set at
②upstream side of the erection bay . Unit bay ⑫~⑭ ①is air supply area of blower room
and unit bay ①s ~⑪ is air su ② ③pply area of blower rooms and . One air blow gallery of
powerhouse is set in wall at upstream of the powerhouse as channel to blow outdoor fresh
air to operation floor and busbar floor by centrifugal fan. An air exhaust interlayer is set at
downstream side of the downstream auxiliary plant as channel to exhaust the air to outside
by 5 exhaust fans set at downstream side of the main transformer floor.
As the GIS and pipeline floor is above ground outside, wall axial flow fan is adopted
to exhaust the air to outside of downstream.
Unit battery room is at downstream side with an elevation of 228.50 m a.s.l. of the
downstream auxiliary plant. Natural air flows into the lower auxiliary access gallery and is
exhausted outside by explosionproof axial flow fan set in the battery room via
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umbrella-shaped vent cap at roof.
Multi-split central air conditioning system is adopted for rooms of the central control
building and equipment rooms (such as local panel room) which are within the unit bay
scope while holding a heavy thermal load. The outside unit is set at an elevation of 236.50
m a.s.l. of the tailrace platform.
a) Air blow system of powerhouse
Outside air is induced and sent to operation floor and busbar floor of powerhouse
via upstream air blow gallery by blower. Total air capacity of the system is 320000 m3/h;
air capacity of the operation floor and busbar floor are 160000 m3/h respectively.
The 1# blower room is provided with 1 dual-inlet centrifugal fan of 4-79No.2-12E
model with air capacity of 80000 m3/h; 2# and 3# blower rooms are provided respectively
with 1 dual-inlet centrifugal fan of 4-79No.2-14E model with air capacity of 120000 m3/h.
b) Air exhaust system of downstream auxiliary plant
Air of busbar floors of powerhouse and downstream auxiliary plant, as well as
downstream equipment rooms (water supply room and circuit breaker room) of operation
floor of the downstream powerhouse are all exhausted to the air exhaust interlayer of
downstream auxiliary plant, which has a total air capacity of 215000 m3/h and exhausts air
to outside via its downstream exhaust fan of the operation floor (elevation of 228.50 m
a.s.l.). There are 5 blower rooms in total and 1 dual-inlet centrifugal fan of 4-79No.2-10E
model is set for each blower room.
c) Air exhaust system of oil depot and oil disposal room
Blower rooms are set at downstream side of the insulation oil room and oil disposal
room, and turbine oil depot and oil disposal room. Air ducts are embedded in upstream
wall of the oil depot as channel to exhaust air of the oil depot and oil disposal room outside
via blower room. Air capacities of air exhaust systems of the insulating oil and turbine oil
are both 10000 m3/h, with blower model of B4-79 No.8D, and each system has 1 blower.
d) Air exhaust system of GIS room
Ventilation method of natural air intake and mechanical air exhaust is adopted for the
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GIS room. Lower part of the upstream wall is set with air intake window and axial flow
fans are set for upper and lower parts of the downstream wall. The upper axial flow fan is
used for ventilation and the lower one is used for emergency ventilation. Total air capacity
of the system is 100000 m3/h and 20 axial flow fans of BFT35-11No.5 model are adopted.
e) Air exhaust system of pipeline floor
Ventilation method of natural air intake and mechanical air exhaust is adopted for the
pipeline floor. Air is taken from upper large space of the generator floor. Lower part of the
upstream wall of pipeline floor is set with air intake window and upper part of the
downstream wall is set with axial flow fan. Total air capacity of the system is 35000 m3/h
and 12 axial flow fans of T35-11 No.4 model are adopted.
f) Air exhaust system of main transformer and station service transformer room
Ventilation method of natural air intake and mechanical air exhaust is adopted. Air
flows from operation floor of the powerhouse and exhausted to outside of the downstream
side via axial flow fan. Total air capacity of the system is 150000 m3/h and 20 axial flow
fans of T35-11 No.5.6 model are adopted.
g) Air exhaust of switchgear room, DC panel room, etc. of downstream auxiliary
plant
Ventilation method of natural air intake and mechanical air exhaust is adopted. Air
flows from transportation channel of the main transformer and exhausted to outside of the
downstream side via axial flow fan. Total air capacity of the system is 50000 m3/h and 5
axial flow fans of T35-11 No.6.3 model are adopted.
h) Air exhaust from battery room
No. 1, No. 2, and No. 3 batteries of the unit are all at downstream side with an
elevation of 228.50 m a.s.l. of the downstream auxiliary plant. Natural air flows into the
lower auxiliary access gallery and is exhausted outside by explosionproof axial flow fan
set in the battery room via umbrella-shaped vent cap at roof. Air capacity of each battery
room is 2000 m3/h and each room is provided with 1 axial flow fan of BT35-11 No.3.55
model.
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6.5.5 Dehumidification in Plant
Inside of the plant is set with 10 mobile dehumidifiers for dehumidification of wet
districts (such as operation gallery) in the plant. Dehumidifying capacity of the
dehumidifier is 5 kg/h. The dehumidifiers can be set in flexible way as required and can be
moved.
6.5.6 Smoke Exhaust of Main and Auxiliary plants
According to requirements of the specification, smoke exhaust system should be set
for generator floors of the main and auxiliary plants and transportation channel of main
transformer.
Smoke exhaust system of generator floor: smoke exhaust pipes are set in central part
of the upper part of generator floor; smoke exhaust holes are set on the pipes, which are
closed under common condition and opened automatically upon fire. Axial flow fan for
smoke exhaust connects with the smoke exhaust pipe directly and are mounted under the
arc crown. Smoke is directly exhausted to upstream outside of 2# erection bay when there
is a fire. Smoke exhaust capacity of the system is 60000 m3/h. There are only 1 smoke
exhaust fan with model of HTF-11.2-I.
Smoke exhaust system of transportation channel of main transformer: smoke exhaust
pipes are set at upper part of transportation channel of the main transformer; smoke
exhaust holes are set on the pipes, which are closed under common condition and opened
automatically upon fire. Axial flow fan for smoke exhaust connects with the smoke
exhaust pipe directly. Smoke is directly exhausted to downstream outside when there is a
fire. Smoke exhaust capacity of the system is 15000 m3/h. There are only 1 smoke exhaust
fan with model of HTF-8-I.
6.5.7 Main Equipment of HVAC System
Refer to Table 6.5-1 for main equipment of the HVAC system.
Table 6.5-1 Main Equipment of HVAC System
S/N Description Model Specifications Unit Qty. Remarks
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S/N Description Model Specifications Unit Qty. Remarks
1 Centrifugal fan 4-79No.2-14E
L=123000m3/h
H=431Pa
n=460rpm
N=22kW
Set 2 Air blown to
powerhouse
2 Centrifugal fan 4-79No.2-12E
L=82600m3/h
H=451Pa
n=520rpm
N=15 kW
Set 1 Air blown to
powerhouse
3 Centrifugal fan 4-79No.2-10E
L=45000m3/h
H=657Pa
n=660rpm N=15
kW
Set 10
Air exhausted
from
downstream
auxiliary plant
4 Centrifugal fan B4-72-8D
L=11000m3/h
H=480Pa
n=730rpm N=3 kW
Set 2 Air exhausted
from oil depot
5 Axial flow fan T35-11No.6.3
L=11534m3/h
H=114Pa
n=960rpm N=0.75
kW
Set 5
Air exhausted
from switchgear
room
6 Axial flow fan T35-11No.5.6
L=8100m3/h H=90Pa
n=960rpm N=0.37
kW
Set 20
Air exhausted
from
transformer
room
7 Axial flow fan T35-11No.4
L=3505m3/h
H=76.2Pa
n=1450rpm
N=0.18 kW
Set 12
Air exhausted
from pipeline
floor
8 Axial flow fan T35-11No.5
L=5235m3/h
H=63.5Pa
n=960rpm N=0.37
kW
Set 20 Air exhausted
from GIS room
9 Axial flow fan T35-11No.3.55
L=2692m3/h
H=69.7Pa
n=1450rpm
N=0.09 kW
Set 30 Air blown to
busbar floor
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S/N Description Model Specifications Unit Qty. Remarks
10 Axial flow fan T35-11No.3.55
L=2692m3/h
H=69.7Pa
n=1450rpm
N=0.09 kW
Set 30
Air blown to
water supply
room and
circuit breaker
room
11 Axial flow fan T35-11No.3.15
L=2078m3/h
H=61.7Pa
n=1450rpm
N=0.09 kW
Set 14
Air blown to
operation
gallery
12
High-temperature
smoke exhaust fan
box
HTF-11.2-Ⅰ
L=59007m3/h
H=593Pa
n=1450rpm N=22
kW
Set 1
Smoke
exhausted from
generator floor
of powerhouse
13
High-temperature
smoke exhaust fan
box
HTF-8-Ⅰ
L=14336m3/h
H=508Pa
n=1450rpm N=4
kW
Set 1
Smoke
exhausted from
transportation
channel of main
transformer
14 Explosionproof
axial flow fan BT35-11No.3.55
L=2683m3/h H=75Pa
n=1450rpm
N=0.12kW
Set 3
Air exhausted
from battery
room
15 Axial flow fan T35-11No.3.55
L=2692m3/h
H=69.7Pa
n=1450rpm
N=0.09 kW
Set 30 Auxiliary fan
16 Mobile
dehumidifier 5 kg/h Set 10
17
Outdoor machine
of multi-split air
conditioning unit
Refrigerating
capacity QL: 75 kW Set 4
Air condition of
central control
room
18
Outdoor machine
of multi-split air
conditioning unit
Refrigerating
capacity QL: 80 kW Set 7
Air conditions
of equipment
rooms such as
local panel
room
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S/N Description Model Specifications Unit Qty. Remarks
19
Outdoor machine
of multi-split air
conditioning unit
Refrigerating
capacity QL: 40 kW Set 1
Air conditions
of equipment
rooms such as
local panel
room
20 Indoor unit Set
Air conditions
of areas of
central control
room, local
panel room, etc.
21 Fire damper Pcs.
22 Smoke exhaust
damper Pcs.
23
Opposed
multi-blade
damper
Pcs.
24
Aluminium air
hole of window
blind
Pcs.
25 Galvanized iron air
duct m2
Manufacturing
including the
air duct
18
Outdoor machine
of multi-split air
conditioning unit
Refrigerating
capacity QL: 40 kW Set 1
Air conditions
of equipment
rooms such as
local panel
room
19 Indoor unit Set
Air conditions
of areas of
central control
room, local
panel room, etc.
20 Fire damper Pcs.
21 Smoke exhaust
damper Pcs.
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S/N Description Model Specifications Unit Qty. Remarks
22
Opposed
multi-blade
damper
Pcs.
23
Aluminium air
hole of window
blind
Pcs.
24 Galvanized iron air
duct m2
Manufacturing
including the
air duct
6.6 Fire Protection Design
6.6.1 Project Overview
6.6.1.1 Overview
The Paklay HPP has storage of 0.89×109 m3 corresponding to normal pool level of
240.00 m a.s.l. and of 904.4×106 m3 corresponding to check flood level of 240.23 m a.s.l.,
with total installed capacity of 770 MW (14×55 MW). The hydraulic structures mainly
consist of the flood releasing and energy dissipation (sediment releasing) structure, water
retaining structure, powerhouse, navigation lock and fish way. The non-overflow dam
section on the left bank, water retaining powerhouse dam section, sediment releasing
bottom outlet dam section, low-level surface bay, overflow surface bay dam section (11 in
total, with underflow for the energy dissipation downstream for the 5 bays on the left),
navigation lock dam section and the non-overflow dam section on the right bank are
arranged in sequence from left to right.
6.6.1.2 General Layout of Powerhouse
a) Layout of powerhouse area
Main structures in the powerhouse area include the powerhouse, auxiliary plant, GIS
room of main transformer switchyard, outgoing line platform, central control building,
entrance channel, tailwater canal, access road, etc.
Main unit bay of the powerhouse is located on the main riverbed of the left bank with
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a total length of 301.00 m. For the main unit bay, its left end is connected with the
non-overflow dam section and its right end is connected with the bottom outlet dam section.
The total width of the powerhouse dam section along the water flow direction is 83.05m.
Water retaining type intake is arranged on the upstream side of the generator hall, while the
downstream side of the generator hall is provided with downstream auxiliary plant. The
GIS switchyard and outgoing line platform are provided on the top of unit ① ~ unit ⑤
in downstream auxiliary plant. One erection bay is provided on the left and the right ends
of the generator hall respectively. Auxiliary erection bay is located on the sediment
releasing bottom outlet at the right end of generator hall, while the main erection bay is
located on the left end of generator hall. Auxiliary plant of central control building is
located 26 m downstream of the main erection bay on the right side, and turnaround is
located 26 m on the left side. Powerhouse access road leads to the site horizontally from
the downstream and connects with the turnaround. Direct access to the floor of main
erection bay can be realized through the turnaround.
Sand-guide sill and trashrack are arranged in front of the powerhouse dam section.
Upstream guide wall is arranged on the right side slope of the entrance channel. After
extending upstream 60.00 m, the upstream guide wall will extend upstream 50.00 m
along the sand-guide sill.
b) Layout of intake
Each unit is set with 1 intake. Elevation of foundation surface of the intake is 194.02
m a.s.l.; dam crest elevation of the intake is 245.20 m a.s.l.; height of the intake is 50.98 m.
Width of each intake front is 21.50 m and thickness of abutment pier is 3.20 m. To reduce
span of trash rack, an intermediate pier which is 1.80 m thick is set at the intake. Abutment
pier at intake and water retaining wall at upstream of the generator hall integrate as a whole.
Thickness of the water retaining wall is 6.00 m. Air delivery conduit and air vents for
emergency gate are set in the wall. Platform at top of the intake is 30.05 m long along the
flow direction, which is set with an 8-meter-wide road, upstream track of gantry, trash rack,
emergency gate chamber and slot, and downstream track of gantry. A breast wall
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connecting the abutment piers and intermediate pier is set between trash rack slot and
emergency gate slot. Base plate elevation of the intake is 201.02 m a.s.l. Grouting and
drainage gallery is set in the base plate of the intake.
One gantry is set at top of the intake to lift the trash rack and emergency gate. A
highway bridge of dam crest connecting the overflow monolith and non-overflow monolith
is set at front of the dam crest.
c) Layout of powerhouse
The powerhouse consists of generator hall and erection bay, with a dimension of
400.00m×22.50m×52.44m (length×width×height). The distance between generator units is
21.50m. Two single-trolley bridge cranes are set in the powerhouse, with the rated lifting
capacity per crane of 2500 kN; the span is 21.00 m, and elevation of rail top is 240.50 m.
The crane can operate between erection bay and generator hall. In the powerhouse, bottom
elevation of the roof is 246.50 m a.s.l, and elevation of the foundation surface is 194.06 m
a.s.l.
The generator hall has a length of 301.00 m and a net width of 21.00 m. The generator
hall consists of operation floor, pipeline floor, and flow passage floor from top to bottom.
Ground elevation of operation floor is 222.50 m a.s.l. and this floor is set with oil pressure
apparatus, governor, generator and turbine lifting holes at the upstream and downstream
sides. The pipeline floor has a ground elevation of 219.00 m. Pipe gallery and cable gallery
are set respectively at both sides of the pipeline floor to connect with the generator lifting
hole and turbine lifting hole. Setting elevation of the unit is 208.50 m a.s.l. An access
gallery running through the whole powerhouse is set below the runner room. Bottom
elevation of the gallery is 198.06 m a.s.l., and the gallery connects with tubular shaft of the
unit.
The auxiliary erection bay has a length of 47.00 m, a net width of 21.00 m and a
ground elevation of 222.50 m, same as that of the operation floor. It is the place for unit
installation and maintenance. Two sand releasing bottom outlets are arranged at the lower
part of the auxiliary erection bay.
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The main erection bay has a length of 52.00 m, a net width of 21.00 m and a ground
elevation of 228.50 m, 6.00m higher than that of the operation floor. At 26.00m on the left
end of main erection bay, the lower part is solid concrete. The place of 26.00m on the right
end is a 3-layer reinforced concrete structure. The top floor is the place for unit installation
and maintenance. Middle floor with a ground elevation of 222.50 m is equipped with an air
compressor room. The ground floor with an elevation of 216.50 m is equipped with a
turbine oil depot and a pump house for leakage water drainage sump and maintenance
drainage sump. Such two drainage sumps are arranged below the pump house. The
elevation of drainage sump bottom is 192.00 m.
d) Layout of auxiliary plant
The auxiliary plant consists of downstream auxiliary plant and auxiliary plant of the
central control building. The downstream auxiliary plant, which is 21.40 m wide, is set at
downstream side of generator hall and is a 5-storey reinforced concrete structure. The
bottom is pipeline floor with an elevation of 219.50 m a.s.l. Local panel room and power
distribution room are set at the elevation of 222.50 m a.s.l. The generator floor consisting
of main transformer room, switchgear room, station service transformer room, exhaust fan
room, and main transformer transportation rail, etc. is set at the elevation of 228.50 m a.s.l.
SF6 pipeline floor is set at the elevation of 240.50 m a.s.l. with the roof elevation of 245.50
m. 500 kV GIS room with a plan size of 64.50m×17.40m (L×W) is arranged at the section
of units ③~⑤, and 1 bridge crane of 150 kN is set indoor. The GIS room has a roof
elevation of 260.50 m and outgoing line platform with a plan size of 69.00 m×23.40 m
(L×W) ① ②is formed jointly by section of units ~ and roof of auxiliary plant of central
control building.
Auxiliary plant of central control building is arranged at downstream of the main
erection bay, with the plan size of 26.00 m×21.40 m (L×W); it is of a 5-storey reinforced
concrete structure. Elevation of the ground floor is 216.50 m a.s.l. with turbine oil
treatment room, powerhouse drainage sump and sewage pool arranged. Drainage pump
room, sewage pump room, air conditioning equipment room and HV laboratory, etc. are
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arranged at an elevation of 222.50 m a.s.l. Relay protection room and diesel engine room
are arranged at an elevation of 228.50 m a.s.l. Central control room and computer room are
arranged at an elevation of 234.50 m a.s.l. Battery room, tool room, communication
equipment room and communication power supply room of the central control building are
set at an elevation of 240.50 m a.s.l.; and the outgoing line platform is arranged at the roof
elevation of 245.50 m.
Exhaust fan room is arranged in the space between main erection bay and upstream
non-overflow dam, with a plan dimension of 11.00 m×7.00 m (length×width) and a ground
elevation of 228.50m. Fire pump house and public auxiliary panel cabinet are arranged in
the space at the downstream part of auxiliary erection bay.
e) Internal and external access of the powerhouse
Internal access of the powerhouse: 1 staircase is set at upstream of main erection bay
of the powerhouse to connect with each floor and the deep well pump house. Manholes for
dewatering sump and leakage drainage sump are set in the deep well pump house at the
lower part. At the downstream auxiliary plant, 1 staircase is arranged respectively at ③,
⑥, ⑨, ⑪, ⑭ unit bays and bottom outlet dam section end, to connect to each floor.
Staircase and elevator are set at the downstream side of the central control room to connect
to each floor. Meanwhile, door opening is set for foundation wall at downstream between
the powerhouse and auxiliary plant for horizontal transportation of each floor and ensure
easy operation management.
External access of the powerhouse: horizontal access to the powerhouse is adopted.
Access road of the powerhouse is set along hillside toe at left bank of downstream of the
powerhouse. One end of the access road connects with downstream of the turnaround loop
and the other end connects with outside highway at downstream of the powerhouse. The
access road is 8 m wide and about 150 m long, with average longitudinal slope of 6.07%.
Drainage ditches are set at both sides of the road; the left side is excavated side slope, and
the right side is gravity retaining wall.
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6.6.2 Design Basis and Principle for Fire Protection
6.6.2.1 Overview
a) Scope and key point of design
Fire protection design of the Paklay HPP includes the powerhouse area (including
powerhouse, auxiliary plants, 500 kV switchyard, insulating oil disposal room, and tailrace
platform) and head structure (including dam crest at intake and dam crest of spillway).
Design of the powerhouse area is key point of fire protection of the Project.
b) Fire extinguishment method
Fire hydrant, water spray, and dry powder fire extinguisher are adopted for fire
protection of the station. As water yield of the HPP is sufficient, fire extinguishment with
water is the main fire protection way.
Fire hydrant is adopted for fire extinguishment with water and ammonium phosphate
dry powder extinguisher (MFA type) is adopted.
c) Design of fire protection of powerhouse area
Design of fire protection of powerhouse area includes buildings such as powerhouse,
auxiliary plants, 500 kV switchyard, insulating oil disposal room, and tailrace platform, as
well as their electromechanical equipment inside. Fire hydrant is adopted for fire
protection of buildings of the plant area; fixed system for fire extinguishment of water
spray is adopted for fire protection of the generator; ammonium phosphate dry powder
extinguisher is adopted for fire protection of the central control room, relay protection
panel room, computer room, tailrace hoist room, etc.
d) Head works
Fire protection of head works includes buildings and electromechanical equipment.
Dry powder extinguisher is adopted for fire protection of electromechanical equipment of
power distribution room at dam crest of the head, diesel engine room, hydraulic hoist room,
etc.
e) Design basis
Design for fire protection of the Paklay HPP is based on following latest rules and
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codes issued by the People’s Republic of China and the industry.
1) Fire Control Law of the People's Republic of China
2) Code of Design on Building Fire Protection and Prevention
3) Code for Design of Fire Protection of Hydraulic Engineering
4) Typical Rules of Fire Protection for Electric Power Installations
5) Code of Design for Water Spray Extinguishing Systems
6) Code of Design for Carbon Dioxide Fire Extinguishing Systems
7) Code for Design of Extinguisher Distribution in Buildings
8) Code for Design of Automatic Fire Alarm Systems
9) Code for Design of Heating, Ventilation, and Air Conditioning
10) Design Code for Heating, Ventilation and Air Conditioning of Power House of
Power station
11) Electrical-mechanical Design Code of Hydropower Plant
6.6.2.2 Design Principle
Fire control design of the Project should be implemented on the basis of "prevention
first, combination of prevention and elimination", ensuring key points, giving
consideration to general points, easy management, and economical and practical.
Provisions of current regulations and specifications should be strictly followed during the
design. Comprehensive fire control technical measures should be adopted for the fire
control. Functions of the fire control system requires complete consideration of fire control,
monitoring, alarm, control, fire extinguishment, fume exhaust, life saving, etc. to achieve
“prevention before a fire starts”. And fire can be extinguished in short time once it happens
to minimize fire damage.
Allocation of fire control facilities is based on fire self-rescue. In general layout of the
project, fire lane, fire separation distance, emergency exits and signs should all be arranged
to meet the requirements of specifications. Fire protection devices and apparatuses should
be allocated according to production significance and risk level of the fire. Special fire
control measures should be adopted for special parts according to fire control specification.
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Monitoring apparatus of automatic fire alarm system should be set in the central control
room.
Fire control products to be used should all be safe and reliable, easy for use,
economical, with advanced technology, and meet special requirements of the Project. All
the products should be qualified by related national quality supervision and inspection
departments. Water spray, fire hydrant, dry powder fire extinguisher, and CO2 fire
extinguishment are adopted. Fire protection water is taken from the upstream reservoir
with sufficient and reliable water. Double-circuit independent power supply is used as the
fire protection power supply. Ventilation and smoke exhaust system after fire protection
should be set. Electrical equipment using nonflammable or flame-retardant materials as
insulating medium should be used if possible. Apparatus rooms with fire risk should be
insulated by fire-proof materials; holes and cable channels should be blocked by fire-proof
materials. Fire separation zones should be set to prevent fire spreading.
6.6.3 Design for Fire Protection of the Project Buildings
6.6.3.1 Fire Risk Classification and Fire Resistance Rating of Workshop
a) Fire risk of workshops is classified as Class C, Class D, or Class E according to
principles of Code of Design on Building Fire Protection and Prevention (GB
50016—2006).
b) According to the hydro-project layout and production characteristics, fire
protection zones of buildings and structures of the workshops are naturally divided to the
powerhouse and erection bay, auxiliary plant, busbar floor, main transformer floor, 500 kV
switchyard, inlet and water intake of flood release and desilting buildings, dam area, etc.
c) According to stipulations of Code for Design of Fire Protection of Hydraulic
Engineering (GB50872-2014), fire risk classification, fire resistance rating, and fire
protection measures of buildings and structures are classified as what are shown in Table
6.6-l.
Table 6.6-1 Fire Risk Classification, Fire Resistance Rating, and Fire Protection
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Measures of Buildings and Structures
S/N
Buildings, Structures,
and Electromechanical
Equipment
Fire Risk
Classification
Fire
Rating Fire Protection Measures
1 Powerhouse and erection bay
1.1 Generator floor and
erection bay Class D II
Wheeled and portable fire
extinguisher and fire hydrant
1.2 Hydraulic generator Class D II System for fire extinguishment of
water spray
1.3 Busbar floor Class D II Portable fire extinguisher and fire
hydrant
1.4 Cable floor Class C II
Layered arrangement of cables;
fireproof bulkhead, coating, gas
mask, cable-type thermal detector,
portable fire hydrant, system for fire
extinguishment of water spray
1.5 HV cable adit and shaft Class D II Portable fire extinguisher and fire
hydrant
1.6 Turbine floor Class D II Portable fire extinguisher and fire
hydrant
1.7 Operation gallery Class D II Portable fire extinguisher
1.8 Air compressor room Class D II Portable fire extinguisher
1.9 Deep-well pump house of
powerhouse Class D III Portable fire extinguisher
1.10 Bridge crane of
powerhouse Class D II Portable fire extinguisher
2 Auxiliary plant
2.1
Central control room,
relay protection room,
computer room, etc.
Class C II
Automatic alarm, fire extinguishing
system of IG541 mixed gas, and
portable fire extinguisher
2.2 10 kV station service HV
switchgear room Class D II Portable fire extinguisher
2.3 0.4 kV station service LV
switchgear room Class D II Portable fire extinguisher
2.4
Generator voltage
distribution equipment
room
Class D II Portable fire extinguisher
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S/N
Buildings, Structures,
and Electromechanical
Equipment
Fire Risk
Classification
Fire
Rating Fire Protection Measures
2.5 Power cable floor Class C II
Layered arrangement of cables;
fireproof bulkhead, coating, gas
mask, cable-type thermal detector,
portable fire hydrant, system for fire
extinguishment of water spray
2.6 Control cable floor Class C II
Layered arrangement of cables;
fireproof bulkhead, coating, gas
mask, cable-type thermal detector,
portable fire hydrant, system for fire
extinguishment of water spray
2.7 Turbine oil depot and oil
treatment room Class C II
Automatic alarm, portable fire
extinguisher, sand box, and system
for fire extinguishment of water
spray
3 Isolated-phase enclosed
bus Class D II
Portable fire extinguisher and fire
hydrant
4 Main transformer
4.1 Main transformer room Class C I Water spray extinguishing system
5 Insulating oil tank room,
oil disposal room Class C II
Portable fire extinguisher, system for
fire extinguishment of water spray,
fire hydrant, and sand box
6 Oil testing room Class C II Portable fire extinguisher and sand
box
7 500 kV cable adit and
cable shaft Class D II
Portable fire extinguisher and fire
hydrant
8 500KV switchyard
8.1 Indoor switchgear of
500kV SF6 GIS Class D II
Ammonium phosphate fire
extinguisher of trolley type, gas
mask, and fire hydrant
8.2 500 kV cable floor Class D II
Automatic alarm, portable fire
extinguisher, and water spray
extinguishing system
8.3 Outgoing line platform Class D II
Ammonium phosphate fire
extinguisher of trolley type, and fire
hydrant
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S/N
Buildings, Structures,
and Electromechanical
Equipment
Fire Risk
Classification
Fire
Rating Fire Protection Measures
9 Dam area and parts outside the plant
9.1 Power distribution room
at dam crest Class D II Portable fire extinguisher
9.2 Diesel generator room Class C I Portable fire extinguisher and fire
hydrant
9.3 Hoist room Class D II Portable fire extinguisher
10 Equipment repairing
workshop Class D III
Portable fire extinguisher and fire
hydrant
6.6.3.2 Fire Protection Zones and Emergency Exit
According to stipulation of Article 3.2.1 of Code of Design on Building Fire
Protection and Prevention, there is on limit for maximum allowable floor area of fire
protection zones with production category of Class D, fire resistance rating of Grade II,
and multilayer. Thus, powerhouse of the Paklay HPP can be divided to 2 fire protection
zones. The powerhouse and auxiliary plant are set as two independent fire protection zones;
firewalls, fireproof doors, and wall-type fire dampers are adopted to segregate the big
space in the powerhouse.
According to stipulations of clauses of Article 4.2 of Code for Design of Fire
Protection of Hydraulic Engineering, two emergency exits are set for operation floor of the
powerhouse, and at least two evacuation exits are set for each floor such as generator floor,
cable floor, and operation gallery. Only 1 evacuation exit is set for the central control
building as the floor area of each floor is less than 800 m2 and number of staff on duty is
not more than 15.
For each floor, distance between the farthest work place and nearest evacuation exit
should be not more than 60.0 m. Net width of evacuation door, which opens towards
evacuation direction, is not less than 0.9 m. Net width of corridor is not less than 1.2 m.
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Net width of staircase is not less than 1.1 m and slope gradient of the staircase is not more
than 45°. Fireproof doors and firewalls are set between the underground buildings and
ground buildings for segregation.
Number of staircase and safe evacuation distance should both meet requirements of
the Codes.
6.6.3.3 Fire Lane
a) Fire lane outside the plant
Permanent access road can lead to the generator floor and head structures. Both the
permanent access road and dam crest road can be used as fire lane.
b) Fire lane inside the powerhouse
The station is of a ground-type powerhouse; the fire truck can reach to powerhouse
via access road and do fire protection operation. Turnaround loop, which can also be used
as turnaround loop for fire truck, is set before the plant gate.
6.6.3.4 Fire Water Supply and Design of Water Supply System
Water source of the HPP is abundant. Upstream reservoir is the source of fire water
supply and direct water supply system of pressurization of water pump is adopted.
Capacity of fire pump is not less than sum of maximum water yield of water spray and fire
water yield of hydrant; the sum is 360 m3/h by calculation. Elevation of the water pump
should ensure that pressure at outlet of water sprayer at highest place should be not less
than 0.35 MPa (35.7 mH2O) stipulated in the Code, and that value is 50 mH2O by
calculation. Two water supply pumps are provided (one for use and one for standby).
Circular pipe for water supply of fire protection should be set crossing the whole plant.
Water is led by branch pipes of the circular pipe to each water consumption system.
According to requirement of the Code, sectionalized valves should be set on the circular
pipe. When a section is damaged, fire hydrants out of work should be not more than 5 in
same floor.
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6.6.3.5 Design for Fire Control of Main Electromechanical Equipment
a) Turbine generator
Water spray should be adopted for fire extinguishment of generators according to the
capacity, scale, and fire protection technology at present. Detectors for temperature sensing
and smoke sensing should be set in foundation pit of generators. When the fire alarm of
generator gives alarm signal to fire control centers of whole plant, staff on duty should
confirm the alarm and then connect the separated hoses of fire hydrant of the generator
manually to open the water supply valve to put out fire.
b) Main transformer
Independent water spray extinguishing system should be adopted for each main
transformer. When the transformer is on fire, the sprayer seals both its body and oil sump
in the water spray, and extinguishes fire by cooling down and asphyxiating effects. Oil
discharging pipe is set at bottom of the oil storage pit to discharge fire protection water and
transformer oil which may overflow to the emergency oil pool. Capacity of emergency oil
pool is sum of transformer oil capacity and water yield of fire protection for 24 min. The
sum is 195.4 m3. Capacity of emergency oil pool of main transformer is 200 m3.
c) Turbine oil depot and oil disposal room, insulating oil depot and oil disposal room
The turbine oil depot and oil disposal room, and insulating oil depot and oil disposal
room are all set at the floor with an elevation of 216.500 m a.s.l. below the central erection
bay. Two fireproof doors opening outward are set at that floor. Firewalls with fire
endurance of 4 h are set for the oil depots and oil disposal rooms. Explosionproof electric
appliances are provided for the oil disposal room.
Fixed fire extinguishment appliance for water spray is adopted for fire protection of
the oil depot and oil disposal room. Complete set of deluge valves, which are set outside
the turbine oil depot, is adopted as operation valves for inflow of fire protection water.
Detectors for temperature sensing and smoke sensing are set in the oil depots to send alarm
to the fire control center automatically when there is a fire. At that time, the fire damper
will close automatically, the exhaust fan stops exhausting immediately, deluge valves start
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spraying water to put out fire, and the exhaust fan starts exhausting after the fire is put out.
d) Central control room, computer room, and relay protection room
Fixed fire extinguishment system of CO2 is adopted for this part. Combined and
distributed pipeline system is adopted and one set of storage vessel is adopted. Design
capacity of the system is determined as per demand capacity of the biggest central control
room and a standby capacity of 8% should be considered. By calculation, 22 storage
cylinders are adopted. The cylinders are controlled by fire alarm control panel. Point-type
temperature and smoke sensing detectors as well as audible and visual alarms should be set
in fire extinguishing districts. Gas indicators should be set at upper parts outside the doors,
which should be provided with emergency interrupting boxes. When the temperature and
smoke sensing detectors give alarms simultaneously, the controller will stop air
conditioners and fans of the district immediately, and the audible and visual alarms give
alarms to alert people to evacuate immediately. After a time delay of 30 s (adjustable), the
fire protection door will be closed and fire extinguishing apparatus will be used. Cylinders
will be started by solenoid valve to start the CO2 storage cylinders. When the gas indicators
are on, it means that the fire extinguishing system is working. Supporting sprayers of the
fire extinguishment system are adopted as sprayers of the protection zone. Number of both
kinds sprayers are 8 respectively. When the staff on duty finds a fire, he must press the
emergency interrupting box, and then the fire extinguishment appliance will start to work
immediately. Or if the staff finds that the alarm is a false one during time delay before
the gas is emitted, he can press the emergency interrupting box to stop the fire
extinguishment appliance.
e) Cable
Flame retardant cables should be adopted to prevent and reduce occurrence and
spreading of fire disasters. Temperature sensing cables are laid for each floor of enclosed
cable bridge.
Fire resistant plates should be set for spaces between the power cable floors and
control cable floors in the enclosed cable bridge. Fire retardant sections should be set at
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appropriate position. Fire proof materials should be adopted to seal holes on walls, floors,
etc. those are crossed by cables, and ends of cables.
Fire extinguishment appliances of water spray are set for main cable channels such as
those of the central control room, cables of the powerhouse, etc.
Combining layout of equipment and cables, cable zones without fixed fire
extinguishment systems of water spray should be set with portable fire extinguishers at
certain interval distances. Fire protection sealing measure, as well as sand boxes and
portable fire extinguishers, etc. is set at entrances and outlets where cables are centralized.
6.6.3.6 Electrical Works for Fire Control
a) Power Distribution for Fire Fighting
Electrical fire fighting equipment includes smoke exhaust fans, fire dampers, fire and
smoke exhaust dampers, automatic fire alarm control system, safety evacuation
identifications and emergency lightening, etc.
Power supply for the electrical fire fighting equipment is provided with second class
load through independent power supply circuit. The arrangement ensures the availability of
fire fighting power supply in case of a fire. And the power distribution equipment is
provided with the sign of “Dedicated Equipment for Fire Fighting”.
The power station is equipped with dedicated fire fighting power panel. The power
supplies come from the II-section and III-section bus of the public power supply for the
whole powerhouse, respectively to ensure 2 reliable power supplies for the electrical fire
fighting equipment.
The emergency system is powered by the AC and DC switching system. In normal
conditions, AC power supply shall be used for supplying power. If the AC power supply is
out of service, switch to the DC power supply system to convert DC power supply into AC
power supply. Under normal conditions, AC power supply shall be used for supplying
power for evacuation indicator lights. If the AC power supply is out of service, batteries of
the lights shall be used for supplying power.
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Evacuation indication lighting and emergency lighting are also the emergency lighting
in case of fire. Continuously supplying power of the fire emergency lighting and
evacuation signs shall not be less than 30 min.
Cables for power supply of the fire fighting power supply system, emergency lighting
system and evacuation indication lighting shall adopt fire resisting cables and be laid in
conduit.
b) Fire emergency lighting, evacuation sign indication and lamps
Main evacuation exits, staircases, emergency exits are provided with fire
emergency lighting and emergency sign indication lighting with minimum illumination
no less than 0.5Lux.
The emergency lighting lamps are mounted on wall or ceiling. Evacuation lighting of
the emergency exits shall be mounted on the top. Evacuation indication signs of the
evacuation corridor shall be mounted on the wall with a distance of 0.5m to the ground
(floor). The distance between the signs shall not be larger than 20m.
The emergency lighting and evacuation indicator lights shall be equipped with
protection covers made of glass or other refractory materials.
6.6.3.7 Smoke Prevention and Exhaust System
a) Fire protection plan for ventilation system
According to requirements of fire protection code, fire protection design of ventilation
system of the whole plant conforms to the following principles.
Open fire heating is prohibited at parts such as oil depots, oil disposal room, places
neat to the oil pipes and their accessories, battery room, etc.
Fire dampers are set for spaces of different fire protection zones, for spaces between
important equipment rooms and the outside, and for areas among different fire ratings for
segregation.
Independent exhaust systems are set for equipment rooms with superior fire ratings,
such as oil depots, battery rooms, etc.
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Based on the above principles, fire dampers are adopted for exhaust outlets set at
exhaust interlayer of the downstream auxiliary plant to complete fire protection function of
the ventilation system, for exhaust inlets for fire protection, alarm, and air volume
regulation, for air inlets and exhaust outlets of main transformer room of the exhaust
system for main transformers to separate the main transformers with other zones, separate
the transformers with each other to prevent spreading of fire, for air inlets and exhaust
outlets of oil depots and battery room to prevent and cut off fire. The exhaust fan is of
direct-connection explosionproof type and axial exhaust fan of SF6 switchyard is of
explosionproof type.
Galvanized iron-sheet air hose with good fireproof performance is adopted for all air
ducts of the plant to eradicate fire risk.
Joint control is carried out for the fire dampers and their corresponding exhaust fans.
When there is a fire, the fire damper will start to work and send electric signal to stop its
corresponding exhaust fan. After the fire is put out, fire damper will open again to start the
exhaust fan to exhaust smoke after the fire.
b) Design of smoke prevention and exhaust of whole plant
According to requirements of the Code, mechanical smoke exhaust system is set for
generator floor of the powerhouse and transportation channel of main transformer, as the
HPP is of a ground-type powerhouse.
Smoke exhaust system of generator floor: smoke exhaust pipes are set in central part
of the upper part of generator floor; smoke exhaust holes are set on the pipes, which are
closed under common condition and opened automatically upon fire. Axial flow fan for
smoke exhaust connects with the smoke exhaust pipe directly and are mounted under the
arc crown. Smoke is directly exhausted to upstream outside of 2# erection bay when there
is a fire. Smoke exhaust capacity of the system is 60000 m3/h. There are only 1 smoke
exhaust fan with model of HTF-11.2-I.
Smoke exhaust system of transportation channel of main transformer: smoke exhaust
pipes are set at upper part of transportation channel of the main transformer; smoke
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exhaust holes are set on the pipes, which are closed under common condition and opened
automatically upon fire. Axial flow fan for smoke exhaust connects with the smoke
exhaust pipe directly. Smoke is directly exhausted to downstream outside when there is a
fire. Smoke exhaust capacity of the system is 15000 m3/h. There are only 1 smoke exhaust
fan with model of HTF-8-I.
Air exhaust system of downstream auxiliary plant exhausts smoke as well. When
there is a fire, fans of related parts should be stopped; after the fire disaster, fans should be
started to exhaust smoke. Twenty axial flow fans with model of T35-11No.5 are set at
upper and lower parts (10 for the upper part and 10 for the lower part) of downstream wall
of GIS room. The upper fans can exhaust smoke and the lower fans can exhaust SF6 gas
leaked when putting out the fire.
For areas such as generator floor of powerhouse and transportation channel of main
transformer that are set with immediate smoke exhaust facilities, their smoke exhaust
dampers are interlocked with corresponding exhaust fans so that when the smoke exhaust
damper is started (via the fire control center), the exhaust fan will operate automatically.
For areas set with emergency exhaust facilities, fire alarm controller will automatically
close the corresponding fire dampers and stop corresponding exhaust fans via joint module
when there is a fire. Fire dampers will be open to start smoke exhaust fan after the fire is
put out.
6.6.3.8 Fire Alarm Control System
A set of automatic fire alarm and fire joint control cabinet and fire monitoring
computer (including professional fire monitoring software) is set in the control room to
achieve fire detection, audible and visual alarm, joint control of fans and air conditioners,
join control of smoke prevention and exhaust, joint control of fire extinguishment, etc. of
the HPP and monitoring scope within the navigation lock. The fire monitoring computer
can monitor, deal with, store, and print all alarm information to display the system status
via plane graph, as well as control all controllable fire extinguishment apparatuses. Each
one regional fire alarm and fire joint control cabinet is set for the dam area and navigation
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lock. Coaxial cables or optic fiber communication is adopted for all control cabinets.
The alarm and joint control apparatus connects with the fire monitoring computer via
communication interface, connects with the computer monitoring system via I/O interface
to send general alarm information to the computer monitoring system, and connects with
industrial television monitoring system via I/O interface and communication interface to
link with facility of the industrial television monitoring system to achieve automatic
tracking and video recording of the alarm site. Operators in the control room can operate
the facility of the industrial television monitoring system to carry out remote monitoring to
area with the scope of fire protection monitoring of the HPP and facilities.
Detectors are installed at areas where important facilities are set and places where fire
may occur easily. Detectors, manual fire alarm buttons, etc. are set according to Code for
Design of Automatic Fire Alarm Systems (GB50116-98) and actual layout of the HPP.
Joint control modules are provided according to requirement of automatic control of fire
extinguishment apparatus. Point-type smoke sensing detectors are provided for areas (such
as hydraulic generator room, central control room, relay protection panel room, computer
room, communication facility room, and main transformer room) where important and
common facilities are set. Explosionproof infrared-beam smoke sensing detectors are
provided for turbine oil depot and oil disposal room. Point-type and cable-type temperature
sensing detectors are provided for areas where fixed fire extinguishment apparatus of water
spray are set. Manual alarm buttons, audible and visual alarms are provided for important
transportation channels, evacuation channels, galleries, stairs, and main facilities.
Complete administration and dispatching communication facilities are set in the HPP
to cover the area of fire monitoring system, thus, there is no need to set fire protection
communication facilities. Fireproof treatment is carried out to communication line
according to laying requirement of fire protection line. Meanwhile, a number of wireless
intercoms are provided for the HPP as standby communication for the wire
communication.
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6.6.4 Fire Protection Design for Finishing Works of Buildings
6.6.4.1 Overview
Design for finishing works of the HPP should not only meet the requirement of
operation function, pay attention to appearance, but also meet the requirement of durability,
anti-corrosion ability, and good fireproof performance. Therefore, materials which are
non-inflammable and fire-retardant should be used as finish to meet the architectural effect
and prevent flame. In addition, fire protection zones should be set reasonably at the same
time.
Suspended ceiling is an important part of the finishing. As many lighting lines are set,
the suspended ceiling is a part where fire may occur easily. Therefore, suspended ceilings
of important places and provided with light-steel keel and aluminium alloy perforated plate
(with requirement of sound absorption) should be paved with mineral cotton with thickness
of 50 mm. Thus, requirement of sound absorption and flame prevention can be met. In
addition, constant temperature sensing detectors should be laid at the suspended ceiling.
Interior wall is plastered by cement mortar, whitened after leveling, and finished by
environmental wall paint.
Except the computer room, communication room, etc. which are paved by aluminium
alloy antistatic floor, other grounds are paved by granite, floor tile, cement floor, cement
mortar, and terrazzo.
Class A or Class B fireproof doors are adopted for windows and doors of partition
walls according to fire ratings of rooms. Fireproof materials are adopted to seal facility
holes which cross the walls.
6.6.4.2 Powerhouse
Generator hall and erection bay are key places of interior safety design of the
powerhouse. White wall paints are adopted as finish of the wall. Magenta marble boards
which are 2000 mm high are adopted for wainscot. The 1000×1000 copper bar frames of
cast-in-situ terrazzo are adopted for the generator hall and erection bay. Color plate
arc-shaped roof is adopted as the roof. Stainless-steel metal guard rods which are 1050
mm high are adopted for interior surrounding of the generator hall. Cover plates are
adopted to seal the lifting holes.
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6.6.4.3 Downstream Auxiliary plant and Central Control Building
Class A fireproof doors are adopted for power distribution room, 10 kv switchgear
room, central control room, communication power supply room, communication facility
room, relay protection room, and battery room of the downstream auxiliary plant and
central control building as safety design measure of fire protection. Double-layer
fireproof glass windows are adopted for windows of the central control room.
Architectural finishing: white wall paints are adopted for walls of the power
distribution facility room, station-service power distribution panel room, 10 kv
switchgear room, local small room, duty room, office, galleries, relay protection room,
and shift room as finish. In addition, tiles with skirting which is 150 mm high, 600×600
anti-skidding floor tiles of the ground, and white aluminium alloy light-steel keel for the
suspended ceiling is adopted for the above rooms.
The 600×600 antistatic floors are adopted for the central control room,
communication power supply room, and communication facility room. White wall paint
is adopted as finish and white aluminium alloy light-steel keel is adopted for the
suspended ceiling.
White wall paint is adopted for the exhaust fan room, cable floor, and pump room as
finish. Cement mortar with skirting which is 150 mm high is adopted and cement mortar
is adopted for the ground.
Acid-proof floor tiles are adopted for the battery room. Acid-proof tile with
wainscot which is 1.5 m high is adopted and other wall surfaces should be of cement
mortar top with white paint. Enamel paint is adopted for the ceiling as finish after it is whitened.
6.6.4.4 Other Rooms
White wall paint is adopted for other rooms. Cement mortar with skirting which is
150 mm high is adopted and cement mortar is adopted for the ground.
6.6.5 Summary Sheet of Fire protection Apparatus
Refer to Table 6.6-2 for main fire protection apparatuses of the HPP.
Table 6.6-2 Summary Sheet of Fire protection Apparatus
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S/N Description Specification Unit Qty.
1 Fire pump Q=360m3/h H=50m Set 2
2 Pump control valve DN250, PN1.6MPa Nr. 2
3 Fire fighting device of generator Set 14
4 Y-type filter DN200 PN1.6MPa Nr. 39
5 Automatic water filter Q=360m3/h P=1.0MPa Nr. 2
6 Ball valve DN250 PN1.6MPa Nr. 4
7 Ball valve DN65 PN1.6MPa Nr. 33
8 Butterfly valve DN150 PN1.6MPa Nr. 11
9 Butterfly valve DN100 PN1.6MPa Nr. 6
10 Water spray nozzle ZSTWB-40-90 Nr. 2140
11 Water spray nozzle ZSTWB-160-120 Nr. 240
12 Deluge valve DN200 Nr. 39
13 Indoor fire hydrant SN65 Nr. 58
14 Signal butterfly valve DN200 PN1.6MPa Nr. 78
15 Check valve DN200 PN1.6MPa Nr. 4
16 Check valve DN150 PN1.6MPa Nr. 4
17 Pump adapter DN200 PN1.6MPa Nr. 4
18 Pump adapter DN150 PN1.6MPa Nr. 4
22 Start cylinder V=70L PN=15MPa Nr. 2
23 Portable dry powder fire extinguisher
MFA6 Nos. 92
24 Wheeled dry powder fire extinguisher
MFAT35 Nos. 4
25 Gas mask Set 20
26 Anti-fire plug (fast solidification)
SFD-II type t 4.5
27 Anti-fire plug (fast solidification)
XFD type t 1.5
28 Anti-fire plug (soft) DFD-III(A) type t 12
29 Fireproof coating G60-3D type t 4.5
30 Fireproof bag of expansible PFB-720 type m3 30
Paklay Hydropower Project Feasibility Study Report
6-154
S/N Description Specification Unit Qty.
cable
31 Fireproof bulkhead EFW-A type m2 150
32 Fireproof bulkhead EFF-C type m2 200
33 Fireproof tray ESW-Z type m2 450
34 Power distribution panel for fire protection
400 V Nos. 2
35 Emergency lighting 25 W Pcs. 180
36 Exit indicator light 13 W Pcs. 110
37 Emergency light 2×32 W Pcs. 100
38 Fire alarm and control system
39 Monitoring computer and software for fire protection
Set 1
40 Fire alarm and joint controller Set 1
41 Point-type smoke and temperature sensing detectors
Nr. 300
42 Infrared beam smoke sensing detector
Pair 20
43 Cable type temperature sensing detector
km 5
44 Manual alarm button Nr. 40
45 Isolator and connector modules Nr. 100
46 Audible and visual alarm Nr. 40
47 Alarm and control signal line and power line
km 10
48 Protection casing of flame-retardant flexible metal cable
km 8
49 Sand box 2m3 Pcs. 6
50 Explosionproof axial flow fan Set 3
51 Fire damper Nr. 20