ehv substation planning prdc

8/12/2019 Ehv Substation Planning Prdc

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SUBSTATION PLANNING

By

D.Chethan.

Asst. Executive Engineer (Ele),

Planning Section, KPTCL.


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SUBSTATION

A Substation is an assembly of

apparatus which transform the

characteristics of electrical energyfrom one form to another.

A Substation is a link between the

generation of power and the

ultimate consumer.


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ALL-INDIA(as on 31-03-2007)

Energy Requirement (MU) 690587

Energy supply (MU) 624495

Energy Shortage 9.6%

Peak Demand (MW) 100715

Peak Demand met (MW) 86818

Peak Deficit 13.7 %


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ALL-INDIA(11thPlan & 12thPlan Period)

Year Energy

Requirement (BU)

Peak

Demand

(MW)

2011-12 1038 1,52,000

2016-17 1470 2,18,200


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POWER SECTOR REFORMS INKARNATAKA

Karnataka Electricity Reforms Act, 1999 was passedand came into force with effect from 01.06.1999.

Karnataka Electricity Board restructured in 1999, new

successor entities

KPTCL and V V N L

incorporated.

Karnataka Electricity Regulatory Commission

established and made functional from November 1999.

Memorandum of Agreement entered into withGovernment of India to implement Power Sector

Reforms.


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Detailed Policy Statement issued in January 2001,which mentions that Distribution Companies will be

privatized.

Independent Power Producers Policy also announced.

Distribution unbundled from KPTCL. Four Distribution

Companies, namely, BESCOM, MESCOM, GESCOM and

HESCOM were formed and made operational from

01.06.2002.

To enable the ESCOMs to start operations with cleanbalance sheets, Government took over Rs. 1050 crores

of long-term loans and Rs. 866 crores of bad and

doubtful consumer receivables of KPTCL.


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MINISTRY OF POWER(JUNE 2006)

1. Andhra Pradesh

2. Gujarat

3. Delhi

4. Karnataka

This is based on a Study made by

CRISIL and ICRA


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PERFORMANCE RATING OF KARNATAKAs POWERSECTOR BY MINISTRY OF POWER(JUNE 2006)

1.

Andhra Pradesh2. Gujarat

3. Delhi

4. Karnataka

This is based on a Study made by

CRISIL and ICRA


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PROBLEMS FACING THE POWER SECTOR

GENERATION

Difficulties faced by KPCL in getting domestic coal

Protests against proposed new power projects by environmentalistsand local people

ALLOCATION OF POWER FROM CENTRAL GENERATING STATIONS

Allocation to Karnataka in CGS power is disproportionately small

Reduction of Karnatakas share in unallocated quota


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TRANSMISSION AND DISTRIBUTION

AT&C losses of 33.2 % and T&D losses of

29.68% are too high

FINANCIAL PROBLEMS

Non-payment of dues by IP set consumers and Gram

Panchayats

Capital expenditure financed solely by borrowings (except

for works under Rajiv Gandhi Grameen Vidyutikaran Yojana)

Unfavourable Tariff Orders passed by KERC

hardly any increase in tariffs

With increasing consumption of power by IP sets and no

increase in IP set tariff, subsidy burden will not come down


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Structure of Power Sector

Generation KPCL IPPS NCE Projects PCKL

KPTCL

400 kV (4 nos)

220 kV (61 nos)

110 kV (233 nos)66 kV (400 nos)

Construction

&

Maintenance

Divisions

BESCOMCESCMESCOMHESCOMGESCOMHUKKERI

33 kV

Substations(283 nos) ,

Lines &

11 KV Lines

Consumers

Operation &

Maintenance

Divisions

Transmission

Distribution

CGS

Inst. Cap. 8154 MWas on 31.08.2007

Handled 40380 MU

in 2006-07

Energy Sales

28454 MUs in

2006-07

1.46 Crs.


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Power Sector Companies in Karnataka

KPCL Karnataka Power Corporation Limited

PCKL Power Company of Karnataka

KREDL Karnataka Renewable Energy

Development Corporation Ltd.

KPTCL Karnataka Power Transmission

Corporation Limited

BESCOM Bangalore Electricity Supply

Company

MESCOM Mangalore Electricity Supply

Company

CESC Chamundeshwari Electricity SupplyCorporation

HESCOM Hubli Electricity Supply Company

GESCOM Gulbarga Electricity Supply Company

Govt. of Karnataka

owned Companies

G i I ll d C i


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Generator-wise Installed CapacityAs on 26.12.2007

NCE18%

IPPs &Others

4%

KPC-

Hydel

42%

CGS

16%

KPC-

Thermal21%

Source Inst.Cap.

(MW)

%

KPC-Hydel 3392 41

KPC-Thermal 1598 20

CGS (alln. Only) 1315 16

NCE 1543 19

IPPs & Others 346 4

Total 8194 100

Break-up for NCE Projects (MW)

Wind 838

Co-gen. 355

Mini-Hydel 253

Bio-Mass 97
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7620

7353

70076

085

6085

5939

12

00

85

8

1431

47

3

64

0

1134

0%

10%20%

30%

40%

50%

60%

70%

80%

90%

100%

02-03 03-04 04-05 05-06 06-07 07-08

MWs

Unrestricted Demand Shortage

Demand shortage

16%10%

7%

17%10% 16%

84% 90% 93% 83% 90% 84%


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7620

7353

70076

085

6085

5939

12

00

85

8

1431

47

3

64

0

1134

0%

10%20%

30%

40%

50%

60%

70%

80%

90%

100%

02-03 03-04 04-05 05-06 06-07 07-08

MWs

Unrestricted Demand Shortage

Demand shortage

16%10%

7%

17%10% 16%

84% 90% 93% 83% 90% 84%


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41075

40379

34641

33110

31210

29279

5651

3634

5533

4515

3439

4538

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

02-03 03-04 04-05 05-06 06-07 07-08

MUs

Energy Met / Estimated Shortage

Energy shortage

13%10%

12%14%

8% 12%

87% 90% 88% 86% 92% 88%

Capacity Addition Programme (


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Capacity Addition Programme (Projects in KARNATAKA)

KPCL Projects Capacity (MW)

1 BTPS unit I & II - Thermal project 1000

2 RTPS 8thUnitThermal Project 250

3 Varahi IIHydel Proejct 230

4 GundiaHydel Project 400

5 Bidadi Combined Cycle Plant 1400

6 Kalgurki _ Thermal Project 1000

7 YermarasThermal Project 10008 AnnechakanahalliThermal Project 1000

9 YadgirThermal Project 1000

10 EdlapurThermal Project 500

11 BTPS unit IIIExpansion Project 500

12 Kudathini - Thermal Project 1500

PCKL Projects

13 Chamalapura 1000

14 Jewargi 1000

15 Ghataprabha 1000

TOTAL 12780

During 11thPlan PeriodFY2008FY 2012

NOTE: Above capacity addition doesnt include share in CGS Projects


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Capacity Addition Programme

IPPs Capacity (MW)

16 Nagarjuna 1015

17 Euro India Power Canara 500

TOTAL 1515

GRAND TOTAL 14295

S b t ti & T Li


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As on 01.01.2008

Voltage Level No. of stationsTr. Line in

CKMs

400 kV 4 1978220 kV 63 8656

110 kV 242 7606

66 kV 415 8306

33kV 285 7468

Total 1009 34014

Substations & Tr Lines

T&D L R d ti


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T&D Loss Reduction

27.21

38.02

35.50

35.86

31.95

30.88

29.44

29.38

29.68

25

30

35

40

99-2000 2000-01 2001-02 2002-03 2003-04 2004-05 2005-06 2006-07 2007-08

(in%)

projected

A T & C L


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A T & C Loss

42.3

36.38 36.99

32.3

43.31

25

30

35

40

45

50

2002-03 2003-04 2004-05 2005-06 2006-07

(in%)

Overall

SECTOR

B
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Revenue & Expenditure Growth

8773

7933

69406295

10550

9475

79917918

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

2003-04 2004-05 2005-06 2006-07

(Rs.Crs.)

Revenue Expenditure

KPTCL & ESCOMs

ompany w se apex


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ompany-w se apex

0

100

200

300

400

500

600

700800

900

1000

KPTCL BESCOM MESCOM HESCOM GESCOM

(Rs.Crs.)

2004-05 2005-06 2006-07

Year KPTCL BESCOM MESCOM & CESC HESCOM GESCOM TOTAL

2004-05 472 334 61 213 90 1170

2005-06 479 432 127 199 128 1365

2006-07 870 563 310 307 171 2221


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Capex plan2007-08 to 2009-10

YearTransmission Distribution Total

2007-08 2400 3997 6397

2008-09 2100 1716 3816

2009-10 1600 2171 3771

TOTAL 6100 7884 13984

Rs. Crores

Capex

incurred(till Nov 07)

1067 700 1767


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Purpose & Necessity

Generated power to be evacuated to

load centers for consumption.

Generating stations are far of from loacenters.

The process of

Generation Transmission Consumption

(in 10s kV) (in 100s kV) (in 100s V)

Needs Substation at various points


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Classification

Substations are classified into

Generating Substations.

Grid Substation mainly 400kV &220kV class.

Distribution Substationmainly of

110kV,66kV,33kV class

Generating Substation are step-upstations


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Classification

Grid Substations are mainnodal stations betweenGenerating Substations &Distribution Substation.

Grid Substation may be

Switching Substations

Step-down stations Distribution Substations are

step down stations


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Substation Planning

AIM

To minimize constructional

and operational cost.To minimize loss.

To supply power safely

and reliably to theconsumer


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Substation Planning..

Sub-station planning considers

the location, size,voltage,

sources, loads and ultimatefunction

Lack adequate planning

results in unnecessary andcostly modifications


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Planning Process Long range planning

Detailed load forecasting

Locating load centers

Identifying Substation location and voltage

class Developing upstream network

Detailed Planning

Valid requirements & criteria

Appropriate guidelines Construction drawings & associated

documentation

The planning would test the engineersability to find an acceptable design from

diverse constraints


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Long Range Planning

Long range plan identifies therequirement of sub-station not for

its initial use but also for some

years in future

It will consider ultimaterequirements in the initial design

itself

It would make economic

comparison to discover what

provisions are necessary for ease

of addition


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Planning methods

Substation & associated network

planning method can be classified

into Heuristic

Mathematical Optimization


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Heuristic method

Based on Intuitive analysis i.e.,

Experience and analysis

Not a strict Mathematical Optimization

It is widely used due to its straight

forwardness, flexibility, speed of

computation & easy involvement of

personnel in decision making

Has ability to obtain a comparatively

optimal solution which meets practical

engineering requirements.


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Mathematical Optimization

Formulation of design requirements

as an operational mathematical

planning model and solved by anoptimization algorithm.

It posses more strictness in theory

Very difficult to solve a large scale

planning problem due to largenumber of planning variables and

complex constraints


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Perspective Planning

The present practice is to combine

both heuristic and Mathematical

optimization methods Perspective planning followed in

KPTCL is combination of Heuristic

and Horizon year planning method


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Perspective Planning

The Horizon year is so selected

that projected demand &

generation availability are knownreasonably well

Planning is based on guidelines

prescribed by CEA, Regulatory

Commission and Utilities


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Planning criteria

Substation capacity should not

exceed the limit set

If peak load of the station exceeds90%

New stations are to be proposed

Upgraded to higher voltage


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Table 1 : Substation Maximum Capacity

SL.

No

Voltage Ratio

(kV)

By KPTCL in

MVA

By KERC in

MVA

1. 400/220 1000 1000

2 220/110, 220/66 300 320

3 110/33 40 150*

4 110/11 20 150*

5 66/11 63** 75

6 33/11 10 --

* The combined capacity of 110/33kV and110/11kV levels.

** - 63MVA in case of Urban areas, 25MVA in

case of Semi-urban and 12.6/16MVA in rural

areas

Pl i it i


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Planning criteria Size & Number of ICTs

Outage of single unit should notoverload the remaining ICTs orunderlying system

Size & Number of HT/EHTTransformer

Outage of single unit should notlimit the supply of 80% station load

By not overloading the remainingtransformer

By interconnection with adjacentsubstations

The distance between twosubstation is dependent on density

of load


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Reactive Power Compensation

Table 2 : Shunt capacitor compensation

MVA at

11kV Bus

Shunt Compensation

MVA MVA

< 30

1 x 5 MVAr (at12.1 kV) for each transformer at

11 kV Bus

MVA > 30 1 x 20 MVAr (at 72 kV) at 66kV Bus , 1 x 20

MVAr (at 121 kV) for 110 kV Bus

Pl i C it i N t k


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Planning Criteria -Network

Addition of Network to avoid overloading Incase the Substation is to be uprated to

higher voltage at a later date the

network be built for that higher voltage

If 110kV or 66kV station be uprated to220kV station at a later date, the

addition line be of 220kV class but

charged on 110kV or 66kV

If three or more circuits of same voltage

class is envisaged Next higher voltage

may be considered

Every station be fed by a D/C line orshall

have provision for alternate feeding


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Voltage limits as per CEATable 3 : Specified Voltage Limits

Voltage Minimum

(pu)

Minimum

(kV)

Maximum

(pu)

Maximum

(kV)

400 kV 0.95 380 1.05 420

220 kV 0.9 198 1.11 244.2

110 kV 0.924 101.64 1.0985 120.835

66 kV 0.924 60.984 1.0985 72.501

33 kV 0.909 29.997 1.09 35.97

11 kV 0.909 9.999 1.09 11.99


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Perspective planning

process Planning process consists of

Preparation of data

Identification of load center andthe substation

Planning upstream network and

grid substation

Planning grid network

Staging study for intermediate

year


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Preparation of Data

Load forecasting

Load forecasting at macro levelwill be carried out by CEA

The micro level shall be carriedout by the utilities

In the absence of loadforecasting, historical demand &

load growth may be considered

The Initial network should beproperly represented

Id tifi ti f l d t


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Identification of load centerand the substation

Peak demand recorded in eachsubstation in a particular year is takenas base and to which load growth beapplied OR the results of the demand

forecast study be used The new substation location is

identified

Based on peak load of the existing

stations Based on Substation planning criteria

The loads of existing substations arere-distributed to the new substation

based on their location & distance


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Sub-transmission Network

Load flow study is conducted in

islanded mode with each grid

substation as a slack bus

Violation of any planning criteria

Network is strengthened

New grid substation is added to

form additional island


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Grid substation Network

The interconnected network tobe represented completely

Generation schedule for the

system peak conditions are

drawn

The load flow study is carriedout by scaling down the load to

match system peak demand



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The Load flow study is repeatedforDifferent combination of

generation schedule

With change in diversity factor indifferent areas for the samesystem peak like

Diversity factor 1 in north and

increased diversity in other areasto match the system peak

Combination of above



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The network should not be

overloaded and shall meet theplanning criteria in all the studies

The network should meet the security

guidelines (both steady state and

transient state) Ex:N-1 contingency

checking

Short circuit, Transient and Voltage

stability studies shall be carried out

If any of the criteria not met, the

network expanded with additional

line.

Staging study


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Staging study This is the study for ascertaining

the substation & network additionsfor the intermediate years

For example, if the horizon year is

2008, the staging studies in the

order of 2007,2006,2005,2004shall be carried out

This is done running DC load flow

to identify the substation to be

removed

AC load flow is run to check the

planning criteria

Staging study


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Staging study

In case criteria is not met, then oneor more substations removed is put

back

The study for ascertaining the grid

substation network is for the

System peak condition for that

year is repeated

The process is continued for other

year also

Conclusion


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Conclusion

The proposed approach is being

followed in KPTCL and the resultsare encouraging

The Horizon year selected for thestudy is 2007 (terminal year of 10th

plan) and 2012 (terminal year of11thplan)

The staging studies for the period2007 to 2012 is carried out in detail

The overall network design for theyear 2017 is carried out withoutstaging studies


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Conclusion

The KPTCL network is represented

upto 11kV bus and complete

southern region network (400 &220kV) with real power injection for

HVDC import


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Loss figures in KPTCL

0.001.00

2.00

3.00

4.00

5.00

6.007.00

8.00

Year

2002-03

Year

2003-04

Year

2004-05

Year

2005-06

Year

2006-07

Peak Power Losses

Tr. N.L Loss

33 kV

66 kV

110 kV

220 kV400 kV


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Loss figures in KPTCL

0.001.00

2.00

3.00

4.00

5.00

6.00

7.00

Year

2002-03

Year

2003-04

Year

2004-05

Year

2005-06

Year

2006-07

Energy Losses

Tr. N.L Loss

33 kV

66 kV

110 kV

220 kV400 kV


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Present planning process

The process is based on

The field report to overcome

the overloading and poor

voltage

Demand from local

consumers

Influence from various

quarters


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Present planning process..

Disadvantages

System improvement in

isolated pocketsDelay in execution

Improper upstream

network

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