highvoltage dclandandsubmarine cablesystem ......with dc, the things for the cable system are much...
TRANSCRIPT
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
HIGH VOLTAGE DC LAND AND SUBMARINECABLE SYSTEM
Ernesto Zaccone
Practical Considerations
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
HVDC cables are mainly used for submarineapplications were overhead lines cannot be used
HVDC overhead lines are more common for landapplications but some important HVDCunderground cables land connections have beenrealized and are also planned for the nearfuture.
THE USE OF HVDC CABLES
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
WHY TO USE HVDC TRANSMISSION
The electric power transmission started more than 1century ago with DC but AC soon offered some betterpractical applications.
The approximative relation for the transmissiblepower is:
sin21
X
VVP
R
VVP
2
22
21
For AC
For DC
The line factor that is limiting the DC power transmissionis the conductor resistance R
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Cables arecylindricalcapacitors
A cable under AC voltage is subject to a capacitive current that is proportionalto the frequency f[Hz], to the voltage V[V], to the unitary capacitance C[μF/km] and to the cable length L[km]: I = 2·π· f · C · V · LCables for HV-AC transmission typically have a capacitance of the order of0,2-0,3 [μF/km] therefore require capacitive currents of 10 to 25 [A/km],depending on system voltage and frequency.
For short lengths (few kilometers) this is not a problem, but for long lengths,e.g. above 60-80 km depending on the voltage, the capacitive current becomesimilar in magnitude (even if in quadrature) to the active current that the cableis asked to transmit: losses are very much increased and consequently actualcable rating is reduced.
AC TRANSMISSION
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
With DC, the things for the cable system are much simpler: f = 0;Consequently, capacitive current and main effects relevant to reactances areeliminated. Only conductor resistance plays the major role.
Transmission (Joule) losses are: W [W] = R · L · I 2 (+ W Earth Return)and Voltage Drop: ΔV [V] = R · L · I (+ ΔV Earth Return)
Practically, there are no limits for the Transmission Length, quite independentlyfrom transmission Voltage and Power.
DC TRANSMISSION
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Systems are operated in AC; therefore DC transmission shall be associatedwith AC-DC Converter Stations at both ends.
The two networks are not required to be syncronised; they can have differentfrequency and voltage.
The system, overall, acts like aGenerating Power Station that isinjecting power into the receivingnetwork.
PP
AC Networke.g. 345 kV, 60 Hz
PG
AC-DC CONVERSION
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Conventional High-Power Converters useTyristors (controlled Diodes): the currentflows in one direction only and the polarityreversed Line Commutated Converter (LCC).
Therefore, when the power flow is reversed, also the polarity on the HVDCcable is reversed: here an example:
+HVDC CABLE
P
i
i
GROUND RETURN
+HVDC CABLE
P
i
i
GROUND RETURN
+HVDC CABLE
P
i
i
GROUND RETURN
Transferring power from side A to B,clockwise direction of current, cableis at positive voltage (+)
Transferring power from side B to A,to keep same direction of current,cable is at negative voltage (-)
_
i
iA B
+_
i
i+_
+A B
_
i
iA B
+_
_
i
iA B
+_
ii
iiA B
+_
ii
ii+_
++A B
LINE COMMUTATED CONVERTER
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
The New Generation of Converters (VSC – VoltageSource Converters) use use IGBT Transistors. TheAC voltage is ‘built’ as liked; there are no constraintson current direction and therefore there is nonecessity to reverse the polarity when the power flowis reversed
Therefore, when the power flow is reversed, the direction of current isreversed but the polarity of the HVDC cables is the same: here an example:
Transferring power from side A to B,clockwise direction of current, onecable is at positive (+) and one atnegative (-) voltage
Transferring power from side B to A,to keep same polarity of cables butwith anticlockwise direction ofcurrent
i
iA B
ii
ii+A B
VOLTAGE SOURCE CONVERTERS
P/2
P/2HV_
HV+
P/2
P/2HV_
HV+
+
-
-
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Higher conversion losses
Limited experience
Limited power
Can feed isolated loads (oil platforms,wind parks, small islands, etc.), mediumpower
Modularity, short deliv.time
Small space and envir.impact
No polarity reversal
Standard equipment
Needs strong AC networks
Cannot feed isolated loads
Polarity reversal
Large space occupied
Special equipment (trafo, filters)
Less no. of cables, lighter
No limits in length
Low cable and conv. Losses
Power flow control
Very high transmiss. power
Heavy cable
Length (50-150 km)
Rigid connection/Power control
Require reactive compensation
High short circuit currents
Simple
No maintenance
High Availability
Drawbacks/LimitationsAdvantagesTransmission Solution
ACAC
AC
ACAC
DC - LCCConventional
ACAC
DC - VSC
Higher conversion losses
Limited experience
Limited power
Can feed isolated loads (oil platforms,wind parks, small islands, etc.), mediumpower
Modularity, short deliv.time
Small space and envir.impact
No polarity reversal
Standard equipment
Needs strong AC networks
Cannot feed isolated loads
Polarity reversal
Large space occupied
Special equipment (trafo, filters)
Less no. of cables, lighter
No limits in length
Low cable and conv. Losses
Power flow control
Very high transmiss. power
Heavy cable
Length (50-150 km)
Rigid connection/Power control
Require reactive compensation
High short circuit currents
Simple
No maintenance
High Availability
Drawbacks/LimitationsAdvantagesTransmission Solution
ACAC
AC
ACAC
DC - LCCConventional
ACAC
DC - VSC
Some Considerations on Transmission Systems
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
TYPICAL HVDCCONFIGURATIONS
MONOPOLE (WITH METALLIC RETURN)
MONOPOLE
+
CABLEi
M.V. RETURN CABLE
Laid Separatedor bundled
(Hokkaido-Honshu 1;
Moyle;SVE-POL;Basslink;Neptune)
P+
CABLEi
M.V. RETURN CABLE
Laid Separatedor bundled
(Hokkaido-Honshu 1;
Moyle;SVE-POL;Basslink;Neptune)
P
BIPOLE WITH EMERGENCY ELECTRODES
BIPOLE WITHOUT METALLIC RETURN
( Majority ofOld Systems:
SA.CO.I;ITA-GREECE;
Fennoskan;Baltic Cable )
+
CABLE i
Cathode Anode
+i
PSEA RETURN
( Majority ofOld Systems:
SA.CO.I;ITA-GREECE;
Fennoskan;Baltic Cable )
+
CABLE i
Cathode Anode
+i
PSEA RETURN
HV
(Cook-Strait;Vancouver 1;Skagerrak;
Haenam-Cheju)
HV+P/2
2 . v
P/2
_ HV
(Cook-Strait;Vancouver 1;Skagerrak;
Haenam-Cheju)
HV+P/2
2 . v
P/2
_
BIPOLE WITH METALLIC RETURN
HV+P/2
2 . v
P/2HV
v
v
(Hokkaido-Honshu 2;Gotland 2)
_
BIPOLE WITH METALLIC RETURN
HV+P/2
2 . v
P/2HVHV
v
v
(Hokkaido-Honshu 2;Gotland 2)
_
P/2
P/2HV_
HV+ (CrossChannel;Nor-Ned;
Transbay)
P/2
P/2HV_
HV+ (CrossChannel;Nor-Ned;
Transbay)
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
300
400
525
600
D.C.Fluid FilledCable Systems
ROUTE LENGTH kmA.C. one 3-phase system D.C. one bipole
SYSTEM
VOLTAGE
kV
1200 MW
1000 MW
800 MW
600 MW
400 MW
No Theoretical limit for D.C.
Mass-impregnatedTraditional or PPL insulatedD.C. Cable Systems
> 2400 MW3500 MW
120 140
A.C./D.C. Fluid FilledCable Systems
A.C. Extruded Insulation Cable Systems10
60
150
0 40 60 80
230
100
Extruded D.C. Cable Systems(or conventional MI)
AC vs. DC - TRANSMISSION OPTIONS
A.C. Extruded or Fluid Filled Cable Systems
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
CABLES
A (FUNDAMENTAL) COMPONENTOF HVDC SYSTEMS
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Copper conductor
Semiconducting paper tapes
Insulation of paper tapes impregnated with viscous compound
Semiconducting paper tapes
Lead alloy sheath
Polyethylene jacket
Metallic tape reinforcement
Syntetic tape or yarn bedding
Single or double layer of steel armour (flat or round wires)
Polypropylene yarn serving
Typical Weight = 30 to 60 kg/m
Typical Diameter = 110 to 140 mm
Copper conductor
Semiconducting paper tapes
Insulation of paper tapes impregnated with viscous compound
Semiconducting paper tapes
Lead alloy sheath
Polyethylene jacket
Metallic tape reinforcement
Syntetic tape or yarn bedding
Single or double layer of steel armour (flat or round wires)
Polypropylene yarn serving
Typical Weight = 30 to 60 kg/m
Typical Diameter = 110 to 140 mm
Mass Impregnated Cables are the most used; they are in service for morethan 40 years and have been proven to be highly reliable. At present used forVoltages up to 500 kV DC. Conductor sizes typically up to 2500 mm2.
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Self Contained Fluid-Filled Cables are used for very high voltages (they are qualifiedfor 600 kV DC) and for short connections, where there are no hyd raulic limitations inorder to feed the cable during thermal transients; at present used for Voltages up to 500kV DC. Conductor sizes up to 3000 mm2.
Conductor of copper or aluminium wires or segmental strips
Semiconducting paper tapes
Insulation of wood-pulp paper tapes impregnated with lowviscosity oil
Semiconducting paper tapes and textile tapes
Lead alloy sheath
Metallic tape reinforcement
Polyethylene jacket
Syntetic tape or yarn beddings
Single or double layer of steel armour (flat or round wires);sometime copper if foreseen for both AC and DC use, in orderto reduce losses in AC due to induced current
Polypropylene yarn serving
Typical Weight = 40 to 80 kg/m
Typical Diameter = 110 to 160 mm
Conductor of copper or aluminium wires or segmental strips
Semiconducting paper tapes
Insulation of wood-pulp paper tapes impregnated with lowviscosity oil
Semiconducting paper tapes and textile tapes
Lead alloy sheath
Metallic tape reinforcement
Polyethylene jacket
Syntetic tape or yarn beddings
Single or double layer of steel armour (flat or round wires);sometime copper if foreseen for both AC and DC use, in orderto reduce losses in AC due to induced current
Polypropylene yarn serving
Typical Weight = 40 to 80 kg/m
Typical Diameter = 110 to 160 mm
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
In fact, an Extruded Insulation(generally PE based) can besubjected to an uneven distributionof the charges, that can migrateinside the insulation due to theeffect of the electrical field.
It is therefore possible to have anaccumulation of charges inlocalised areas inside the insulation(space charges) that, inparticular during rapid polarityreversals, can give rise to localisedhigh stress and bring toaccelerated ageing of theinsulation.
Extruded Cables for HVDC applications are still under development; atpresent they are used for relatively low voltages (up to 300 kV DC), mainlyassociated with Voltage Source Converters, that permit to reverse the powerflow without reversing the polarity on the cable.
Conductor
Semiconducting compound
Extruded insulation
Semiconducting compound
Lead alloy sheath
Polyethylene jacket
Syntetic tape or yarn beddings
Steel armour
Polypropylene yarn serving
Typ. Weight = 20 to 35 kg/m
Typ. Diameter= 90 to 120 mm
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Conductor
Semiconducting compound
Extruded insulation
Semiconducting compound
Water swellable tape
Metallic screen
Polyethylene jacket
Typ. Weight = 10 to 30 kg/m
Typ. Diameter= 40 to 120 mm
EXTRUDED INSULATION HVDC LAND CABLE
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
- Cu Conductor: 1500 mm2- Insulation: Mass impregnated paper- Armour: Galvanized steel- Overall diameter: 121 mm- Weight of cable: 43 kg/m
CABLE SYSTEM - HVDC 400 KV MI CABLES
- Cu Conductor: 2000 mm2- Insulation: Mass impregnated paper- Overall diameter: 121 mm- Weight of cable: 38.5 kg/m
Submarine HVDC Cable Land HVDC Cable
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
TURNTABLE
CONDUCTOR STRANDING
TURNTABLE
IMPREGNATION VESSEL PAPER LAPPING MACHINE
LEAD EXTRUDER
PE SHEATH EXTRUDERARMOURING MACHINE
TURNTABLES
Typical Manufacturing Flow Diagram of a submarine cables. Main differenciesbetween Mass Impregnated Cables and Extruded Cables are highlighted inthe yellow coloured area.
FactoryJoint
EXTRUSION LINE (CCV)DE-GASSING TANK
PAPER CABLE
EXTRUDED CABLE
OR
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
CONDUCTOR ON TURNTABLE BEFORE INSULATION
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Paper lapping line
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Impregnation vessel
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
MI COMPOUND VISCOSITY
10
100
1000
10000
100000
0 20 40 60 80 100 120 140
temperature °C
visc
osity
cSt
Properties of the MI Compound
The compound used for the mass impregnated HVDC powercables is solid at working temperatures
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
.
A new insulation system consisting of PaperPolypropylene Laminate (PPL) has beendeveloped for HVDC applications (after longexperience of this kind of insulation for ACapplications).
Extensive qualifications carried out forsystem voltages up to 600 kV havedemonstrated capability to safely operate ata temperature of 85 °C
Test loop atCESI, h=21m
High Performances MI Cable
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
SUBMARINE CABLES – TYPES OF CONDUCTORS
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
I c amb W d 0.5 T 1 T 2 T 3 T 4
R ac 10 3 T 1 1 1 T 2 1 1 2 T 3 T 4
I c amb W d 0.5 T 1 T 2 T 3 T 4
R ac 10 3 T 1 1 1 T 2 1 1 2 T 3 T 4
AC AND DC CABLES CURRENT RATING
The current rating of underground and submarine cables is mainly affected bythe losses in the conductor. For the AC cables there are additionally losses inthe other cable components that may strongly affect the cable current rating.
I c amb
R dc 10 3 T 1 T 2 T 3 T 4
AC cables
DC cables• Rac: the AC resistance of conductor is approx 5-20%
higher than the DC resistance• Wd: the dielectric losses are voltage depending and may
be 5-10% of the conductor losses• λ1: The losses in the metallic screen may be of 10%
and may be higher both for submarine and land cablesdepending on the cable design and installation mode.
• λ2: The losses in the metallic armor are applicable tosubmarine cables only and may be very high, generallythe design of the cable is selected in order not tooverpass the conductor losses.
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
BASIC REQUIREMENTS OF SUBMARINE CABLES
• Long continuous lengths
• High level of reliability with practical absenceof expected faults
• Good abrasion and corrosion resistance
• Mechanical resistance to withstand all laying andembedment stresses
• Minimized environmental impact
• Minimized water penetration in case of cable damage
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
• Power to be Transmitted
• Route Selection - Seabed Geology, Thermal Resistivity of Seabed
• Length of Cable
• Water Depth
• Protection Requirements - Burial Depth, Fishing Activity, Marine Activity
• Security of Supply
• Environmental Considerations
• Economic Viability
KEY POINTS TO CONSIDER WHEN
SELECTING A SUBMARINE CABLE
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Mechanical Protection – Armour Design
SINGLE ROUND WIRE ARMOUR(it covers the vast majority of the submarine installation requirements,including windmill applications)
DOUBLE ROUND WIRE ARMOUR (uni-directional)
DOUBLE ROUND WIRE ARMOUR (contra-directional)
ROCK ARMOUR
PLASTIC COATED WIRES
STEEL TAPE ARMOUR PLUS WIRES
DOUBLE STEEL STRIP ARMOUR
NON-MAGNETIC ARMOUR
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
CONSIDERATION ON SUBMARINE CABLES ARMOUR DESIGN
Key requirements: Robustness, abrasion and corrosion resistance
The cable shall be capable of withstanding all the mechanical stresses due to storage,handling, installation, burial on the sea bottom but also recovery in case of damage andre-deployment and burial/protection after repair.
Traditionally and confirmed by the experience, the submarine cables shall bearmoured with one layer, called SWA (more common design for shallow waterapplications), or two layers, called DWA (deep water applications and special increasedprotection against outer injuries, bottom roughness and abrasion) of metallic wires.
Mostly used materials for armour are:
- Hot dip galvanised low carbon steel (BL~400-500 Mpa) for HVDC cables and low-rating 1-core AC cables
- Hard drawn copper for 1-core high rating AC cables
- rarely, stainless steel wires or high carbon, high tensile steel
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Rock Armour; 7mmangle 50degRock Armour; 7mmangle 50deg
Individually PE covered 4mm wiresIndividually PE covered 4mm wires
Sometime armour wires are required tobe covered by a plastic sheath, eitherindividually (each wire) or overall, inparticular for offshore use when theplatform is actively cathodicallyprotected.
A specially resistance armour to abrasionand crushing is the so called ‘rock type’.The outer layer is applied with a short pitch(typically angle of 45 to 60 deg), made ofbig wires (e.g. 6-7 mm), over a thick PPyarn bedding (4-5 mm).
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
The HVDC Cable System is typically made by:
End Terminations,Outdoor or Indoor type
Submarine andLand Cable
Intermediate andtransition Joints
In general, an HVDC System includes converter stations and a transmission linewhich can be composed by various sections, sometime including OHL lines, landand submarine cable.
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
MONOPOLE LAND INSTALLATION
BIPOLE LAND INSTALLATION
TYPICAL HVDC LAND CABLE INSTALLATION
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Road Level
500
1400
500
600
100
300
400 kV DC SCFF Cable
Weak Mix
MV Return Cables
Triple Duct
Pilot Cable
Backfilling
ITALIAN LAND SECTION (43 KM LONG) 100% UNDERGROUND CABLEITALIAN LAND SECTION (43 KM LONG) 100% UNDERGROUND CABLE
1 HV CABLE, 2 MV RETURN CABLES, 1 PILOT CABLE, 1 TRIPLE DUCT IN1 HV CABLE, 2 MV RETURN CABLES, 1 PILOT CABLE, 1 TRIPLE DUCT IN THE SAME TRENCHTHE SAME TRENCH
MECHANIZED LAYING SYSTEM USED OUTSIDE URBAN AREAS, WITH THE ADVAMECHANIZED LAYING SYSTEM USED OUTSIDE URBAN AREAS, WITH THE ADVA NTAGE OF:NTAGE OF:
LIMITED IMPACT ON PUBLICLIMITED IMPACT ON PUBLIC TRAFFICTRAFFIC
NO PULLING TENSION EVEN FOR LONGNO PULLING TENSION EVEN FOR LONGLENGTHS OF CABLE (UP TO 1200 m)LENGTHS OF CABLE (UP TO 1200 m)
SAFE CABLE HANDLINGSAFE CABLE HANDLING
SIMULTANEOUS LAYINGSIMULTANEOUS LAYINGAND PROTECTIONAND PROTECTION
ItalyItaly –– Greece, land cable installationGreece, land cable installation
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
ItalyItaly –– Greece, land cable installationGreece, land cable installationMechanized layingMechanized laying
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
In the Land (Underground) sections, Installation is generally done from largedrums, in excavated trenches, being the cable directly buried or pulled inplastic pipes.
Unloadingfrom Drum
Lay inTrenchLay inTrench
PullingWinchPullingWinch
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Limit is determined by transportation, both in terms ofdimensions and weight. Usually for trucks on roadmax. width is 2,5 m and height 3,5 m. Using specialcarries it is possible to use 4,2 m flange. For largedrums, there are no protection battens. For drums ofland cables, or everytime a protection is required,battens are applied (either steel or wood for thesmallest); increase of dimension is from 0 to 0,1 mmax. on overall diameter.
Wooden battensWooden battens
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
LAND SECTIONS INSTALLATIONLAND SECTIONS INSTALLATIONrural and urban zonesrural and urban zones
Transportation and trenchingTransportation and trenching
Neptune: New JerseyNeptune: New Jersey –– Long Island (NY)Long Island (NY)
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Parameters:T = tension at ships sheave, (kN)To= bottom tension, (kN)S = length of suspended cable, (m)X = distance to touch down point (m)H = the water depth, (m)W = unit weight of cable (in water) (kN/m) = the angle of the cable at sheaveC = min bending radius at touch down
(catenary constant)
T
To
Xθ
H
C
S
T
To
Xθ
H
C
S
Practical formulae to use:T = W·H + To = W·(H + C) ·To= W·CS = T·sin / w = C·tanX = C·sinh -1 (S/C) = tan -1(S/C) = cos -1(C/(H+C)) = cos -1(S·C/T) = tan -1(W·S/T)C = T·cos /W
Nominal Laying tensile forces. The cable suspended from the shipassumes the configuration of a Catenary :
HVDC SUBMARINE CABLE INSTALLATION
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Nominal Laying tensile forces: Test forces according to Cigre ELECTRA 171:
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
SeaSea--Trial (example of the SAPEI 500 kV project)Trial (example of the SAPEI 500 kV project)
• Lay of 6 km of cable including a repair joint and an earthingconnection at maximum depth (1620 m)
• Stay for 6 days st-by with cable suspended at max.depth• Recovery of all cable and un-load back to factory• HV test at 720 kV• Inspection of most significant parts of cable and accessories
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
HVDC MONOPOLE INSTALLATION
Typical bundle installation of a monopoleHVDC cable system in shallow water
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
GIULIO VERNE
B0040030
BUNDLE OF TWO SUBMARINE CABLES
ACCURATEPOSITIONING
SIGNALFROM
SATELITEFOR
POWER CABLE
ROPEPOLYPROPYLENE
POWER CABLE
HVDC BIPOLE BUNDLE INSTALLATION
• The cables will be simultaneously laid and buriedin a Bundle configuration wherever possible
• Minimal environmental impact
• The Cable bundle is taken to the trench bottom bya stinger
200 kV dcXLPE Cable
Fibre OpticCable
Lead+PE Sheath
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Shore Crossings - Horizontal Directional Drilling
BoreHole
Duct
HVDC Cable
Bore Hole
DuctElectrode cable
Duct
F.O. cable
5-6 m
Drilling the pilot hole Hole reaming
Duct installation
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Planning of installation activities
• Offshore activities and hazards
• Weather and oceanographic factors (climatology, tides, currents, waves,water temperature, etc.)
• Seismicity
• Identification of local facilities, local hazards at landing sites
• IS and OOS utilities location
• Bathymetry
• Morphology and nature of the seabed
• Sub-bottom characteristics (mainly necessary in case cable burial isforeseen)
• Permitting (planned developments along the route, marine delimitations,permits and regulations)
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Survey Charts
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
First Panel: Bathymetry
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Second Panel: Superficial Features
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Third Panel: Profile
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Initial and Final Cable landing
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Inshore & Shore End Works
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Burial EquipmentBurial Equipment -- HydroplowHydroplow
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Burial EquipmentBurial Equipment -- Jetting MachinesJetting Machines
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Burial EquipmentBurial Equipment –– Trenching MachinesTrenching Machines
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Sand/Cement Bags ProtectionSand/Cement Bags Protection
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Mattresses ProtectionMattresses Protection
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Cast Iron Shell ProtectionCast Iron Shell Protection
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Submarine Cables Repair Tecniques
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
SUBMARINE CABLE REPAIR SEQUENCE
Note: The availability of a spare cable strongly reduce the repair time
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
FINAL LAYING OFTHE JOINTEDOR REPAIRED CABLE BY USINGTHE QUADRANT
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
MAINTENANCE
HVDC submarine MI and Extruded cables aremaintenance free the only termiantions may needsome inspections
For HVDC land cables it may be convenient but notmandatory to periodically check the integrity of theouter jacket in order to identify eventual third partiesdamages
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
MAJOR HVDC SUBMARINE
PROJECTS
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
World’s Major HVDC Submarine Cable Links
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
SA.PE.I (Sardinia-Peninsula Italiana)
VOLTAGE 500kV
POWER 1000 MW
Bipolar configuration (2x500 MW)
WATER DEPTH 1650 m
CABLE LENGTH 2x420 km
CABLE TYPE Mass Impregnated
RFS 2008 Pole 1 and
2011 Pole 2
The Deepest HVDC Cable
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
Main reason for choosing HVDC:Long submarine cable distance andnon-synchronous AC systems
NorNed: Norway – The Netherlands HVDC cableTransmission capacity: 700 MWDC Voltage: ± 450 kVLength of DC cable: 2*580 km
The Longest HVDC Cable
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
0
100
200
300
400
500
600
0 200 400 600 800 1000Power per cable [MW]
Ope
ratin
gVo
ltage
[kV]
HVDCExtru
ded HVDC M.I.
(incl. PPL)
HVDC TRANSMISSIBLE POWER – TRENDS
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA
THANK YOU FOR YOUR ATTENTION
any questions?