HIGH VOLTAGE DC LAND AND SUBMARINE CABLE SYSTEM Practical Considerations
Ernesto Zaccone
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA THE USE OF HVDC CABLES
. HVDC cables are mainly used for submarine applications were overhead lines cannot be used
. HVDC overhead lines are more common for land applications but some important HVDC underground cables land connections have been realized and are also planned for the near future.
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA WHY TO USE HVDC TRANSMISSION
. The electric power transmission started more than 1 century ago with DC but AC soon offered some better practical applications. . The approximative relation for the transmissible power is: VV For AC P 21 sin X 2 VV 2 For DC P 1 2 2R . The line factor that is limiting the DC power transmission is the conductor resistance R
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA AC TRANSMISSION
Cables are cylindrical capacitors
A cable under AC voltage is subject to a capacitive current that is proportional to 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 · L Cables for HV-AC transmission typically have a capacitance of the order of 0,2-0,3 [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 become similar in magnitude (even if in quadrature) to the active current that the cable is asked to transmit: losses are very much increased and consequently actual cable rating is reduced.
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA DC TRANSMISSION
With DC, the things for the cable system are much simpler: f = 0; Consequently, capacitive current and main effects relevant to reactances are eliminated. Only conductor resistance plays the major role.
2 Transmission (Joule) losses are: W [W] = R · L · I (+ W Earth Return) and Voltage Drop: ΔV [V] = R · L · I (+ ΔV Earth Return)
Practically, there are no limits for the Transmission Length, quite independently from transmission Voltage and Power.
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA AC-DC CONVERSION
Systems are operated in AC; therefore DC transmission shall be associated with AC-DC Converter Stations at both ends. P
The two networks are not required to be syncronised; they can have different frequency and voltage.
The system, overall, acts like a P Generating Power Station that is G injecting power into the receiving AC Network e.g. 345 kV, 60 Hz network.
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA LINE COMMUTATED CONVERTER
i HVDC CABLE Conventional High-Power Converters use + P Tyristors (controlled Diodes): the current flows in one direction only and the polarity GROUND RETURN reversed Line Commutated Converter (LCC). i
Therefore, when the power flow is reversed, also the polarity on the HVDC cable is reversed: here an example: + A B Transferring power from side A to B, i + clockwise direction of current, cable _ is at positive voltage (+) i
_
A B _ _ _
Transferring power from side B to A, i _
+ + + to keep same direction of current, + cable is at negative voltage (-) i
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA VOLTAGE SOURCE CONVERTERS
P/2 The New Generation of Converters (VSC – Voltage Source Converters) use use IGBT Transistors. The + HV AC voltage is ‘built’ as liked; there are no constraints _ HV on current direction and therefore there is no P/2 necessity to reverse the polarity when the power flow is reversed Therefore, when the power flow is reversed, the direction of current is reversed but the polarity of the HVDC cables is the same: here an example: A + B Transferring power from side A to B, i clockwise direction of current, one cable is at positive (+) and one at i - negative (-) voltage A + B Transferring power from side B to A, i to keep same polarity of cables but with anticlockwise direction of i current -
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA Some Considerations on Transmission Systems
Transmission Solution Advantages Drawbacks/Limitations
Simple Heavy cable AC AC No maintenance Length (50-150 km) High Availability Rigid connection/Power control Require reactive compensation AC High short circuit currents
Less no. of cables, lighter Needs strong AC networks No limits in length Cannot feed isolated loads AC AC Low cable and conv. Losses Polarity reversal Power flow control Large space occupied DC - LCC Very high transmiss. power Special equipment (trafo, filters) Conventional
Can feed isolated loads (oil platforms, Higher conversion losses wind parks, small islands, etc.), medium Limited experience power Limited power Modularity, short deliv.time AC AC Small space and envir.impact No polarity reversal DC - VSC Standard equipment
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA TYPICAL HVDC BIPOLE WITH EMERGENCY ELECTRODES CONFIGURATIONS P/2 + HV (Cook-Strait; MONOPOLE 2 . v Vancouver 1; Skagerrak; CABLE i Haenam-Cheju) ( Majority of _ Old Systems: P/2 HV SA.CO.I; + P ITA-GREECE; SEA RETURN BIPOLE WITH METALLIC RETURN Fennoskan; i + Baltic Cable ) P/2 + HV Cathode Anode (Hokkaido- v . 2 v Honshu 2; v Gotland 2) HVHVHV MONOPOLE (WITH METALLIC RETURN) P/2 _ CABLE (Hokkaido- i BIPOLE WITHOUT METALLIC RETURN Honshu 1; + P P/2 Moyle; (Cross SVE-POL; M.V. RETURN CABLE + HV Channel; Basslink; Nor-Ned; Neptune) Laid Separated _ HV Transbay) or bundled P/2
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA AC vs. DC - TRANSMISSION OPTIONS
> 2400 MW 600 3500 MW S Y D.C.Fluid Filled S Cable Systems T 525 Mass-impregnated 1200 MW Traditional or PPL insulated E D.C. Cable Systems M 1000 MW 400 V A.C./D.C. Fluid Filled O Cable Systems 800 MW L 300 T A 230 600 MW G A.C. Extruded or Fluid Filled Cable Systems Extruded D.C. Cable Systems E 150 (or conventional MI) 400 MW
60 k A.C. Extruded Insulation Cable Systems V 10 0 40 60 80 100 120 140 No Theoretical limit for D.C. ROUTE LENGTH km A.C. one 3-phase system D.C. one bipole
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA CABLES
A (FUNDAMENTAL) COMPONENT OF HVDC SYSTEMS
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA Mass Impregnated Cables are the most used; they are in service for more than 40 years and have been proven to be highly reliable. At present used for Voltages up to 500 kV DC. Conductor sizes typically up to 2500 mm2.
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
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA Self Contained Fluid-Filled Cables are used for very high voltages (they are qualified for 600 kV DC) and for short connections, where there are no hyd raulic limitations in order to feed the cable during thermal transients; at present used for Voltages up to 500 kV 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 low viscosity 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 order to 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 Extruded Cables for HVDC applications are still under development; at present they are used for relatively low voltages (up to 300 kV DC), mainly associated with Voltage Source Converters, that permit to reverse the power flow without reversing the polarity on the cable. In fact, an Extruded Insulation
(generally PE based) can be Conductor subjected to an uneven distribution Semiconducting compound of the charges, that can migrate Extruded insulation inside the insulation due to the Semiconducting compound effect of the electrical field. Lead alloy sheath Polyethylene jacket It is therefore possible to have an Syntetic tape or yarn beddings accumulation of charges in Steel armour localised areas inside the insulation Polypropylene yarn serving (space charges) that, in
particular during rapid polarity Typ. Weight = 20 to 35 kg/m reversals, can give rise to localised Typ. Diameter= 90 to 120 mm high stress and bring to accelerated ageing of the insulation.
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA EXTRUDED INSULATION HVDC LAND CABLE
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
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA CABLE SYSTEM - HVDC 400 KV MI CABLES
Submarine HVDC Cable Land HVDC Cable
- Cu Conductor: 1500 mm2 - Cu Conductor: 2000 mm2 - Insulation: Mass impregnated paper - Insulation: Mass impregnated paper - Armour: Galvanized steel - Overall diameter: 121 mm - Overall diameter: 121 mm - Weight of cable: 38.5 kg/m - Weight of cable: 43 kg/m
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA Typical Manufacturing Flow Diagram of a submarine cables. Main differencies between Mass Impregnated Cables and Extruded Cables are highlighted in the yellow coloured area.
CONDUCTOR STRANDING
TURNTABLE
IMPREGNATION VESSEL PAPER LAPPING MACHINE PAPER CABLE
OR
DE-GASSING TANK EXTRUSION LINE (CCV) EXTRUDED CABLE
LEAD EXTRUDER Factory TURNTABLES Joint
PE SHEATH EXTRUDER ARMOURING MACHINE
TURNTABLE Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA CONDUCTOR ON TURN TABLE 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 Properties of the MI Compound
MI COMPOUND VISCOSITY
100000
10000
1000 viscosity cSt 100
10 0 20 40 60 80 100 120 140 temperature °C
The compound used for the mass impregnated HVDC power cables is solid at working temperatures
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA High Performances MI Cable
A new insulation system consisting of Paper Polypropylene Laminate (PPL) has been developed for HVDC applications (after long experience of this kind of insulation for AC applications). .
Extensive qualifications carried out for system voltages up to 600 kV have demonstrated capability to safely operate at Test loop at a temperature of 85 °C CESI, h=21m
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 AC AND DC CABLES CURRENT RATING
The current rating of underground and submarine cables is mainly affected by the losses in the conductor. For the AC cables there are additionally losses in the other cable components that may strongly affect the cable current rating.
AC cables
c amb W d 0.5 T 1 T 2 T 3 T 4 I 3 R ac 10 T 1 1 1 T 2 1 1 2 T 3 T 4
• Rac: the AC resistance of conductor is approx 5-20% higher than the DC resistance DC cables • Wd: the dielectric losses are voltage depending and may be 5-10% of the conductor losses c amb • λ1: The losses in the metallic screen may be of 10% I 3 and may be higher both for submarine and land cables R dc10 T 1 T 2 T 3 T 4 depending on the cable design and installation mode. • λ2: The losses in the metallic armor are applicable to submarine cables only and may be very high, generally the design of the cable is selected in order not to overpass 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 absence of expected faults
• Good abrasion and corrosion resistance
• Mechanical resistance to withstand all laying and embedment stresses
• Minimized environmental impact
• Minimized water penetration in case of cable damage
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA KEY POINTS TO CONSIDER WHEN SELECTING A SUBMARINE CABLE
• 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
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 and re-deployment and burial/protection after repair.
Traditionally and confirmed by the experience, the submarine cables shall be armoured with one layer, called SWA (more common design for shallow water applications), or two layers, called DWA (deep water applications and special increased protection 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 Sometime armour wires are required to be covered by a plastic sheath, either individually (each wire) or overall, in particular for offshore use when the platform is actively cathodically protected.
Individually PE covered 4 mm wires
A specially resistance armour to abrasion and crushing is the so called ‘rock type’. The outer layer is applied with a short pitch (typically angle of 45 to 60 deg), made of big wires (e.g. 6-7 mm), over a thick PP Rock Armour; 7mm angle 50deg yarn bedding (4-5 mm).
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA In general, an HVDC System includes converter stations and a transmission line which can be composed by various sections, sometime including OHL lines, land and submarine cable. The HVDC Cable System is typically made by:
Intermediate and transition Joints
Submarine and End Terminations, Land Cable Outdoor or Indoor type
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA TYPICAL HVDC LAND CABLE INSTALLATION
MONOPOLE LAND INSTALLATION BIPOLE LAND INSTALLATION
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA Italy –– Greece,Greece, land land cable cable installation installation
ITALIANITALIAN LAND SECTION (43 KM LONG) 100% UNDERGROUND CABLE
1 HV CABLE, 2 MV RETURN CABLES, 1 PILOT CABLE, 1 TRIPLE DUCT IN THE SAME TRENCH
MECHANIZED LAYING SYSTEM USED OUTSIDE URBAN AREAS, WITH THE ADVANTAGE OF:
Road Level LIMITED IMPACT ON PUBLIC TRAFFIC
NO PULLING TENSION EVEN FOR LONG Backfilling NO PULLING TENSION EVEN FOR LONG
500 LENGTHS OF CABLE (UP TO 1200 m)
Triple Duct SAFE CABLE HANDLING MV Return Cables 300
Pilot Cable 1400 SIMULTANEOUS LAYING AND PROTECTION Weak Mix 600 400 kV DC SCFF Cable
500 100
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA Italy – Greece, land cable installation Mechanized laying
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA In the Land (Underground) sections, Installation is generally done from large drums, in excavated trenches, being the cable directly buried or pulled in plastic pipes.
Unloading Lay in from Drum Trench
Pulling Winch
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA Limit is determined by transportation, both in terms of dimensions and weight. Usually for trucks on road max. width is 2,5 m and height 3,5 m. Using special carries it is possible to use 4,2 m flange. For large drums, there are no protection battens. For drums of land cables, or everytime a protection is required, battens are applied (either steel or wood for the smallest); increase of dimension is from 0 to 0,1 m max. on overall diameter.
Wooden battens
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA Neptune: New New Jersey –– Long Island Island (NY) (NY)
LAND SECTIONS INSTALLATION rural and urban zones
Transportation and trenching
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA HVDC SUBMARINE CABLE INSTALLATION Nominal Laying tensile forces. The cable suspended from the ship assumes the configuration of a Catenary :
T X Parameters: θ T = tension at ships sheave, (kN) To= bottom tension, (kN) S = length of suspended cable, (m) X = distance to touch down point (m) H S H = the water depth, (m) W = unit weight of cable (in water) (kN/m) = the angle of the cable at sheave C To C = min bending radius at touch down Practical formulae to use: (catenary constant) T = W·H+To=W·(H+C)· To= W·C S = T·sin / w = C·tan X = 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
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 Sea-Trial (example of the SAPEI 500 kV project)
• Lay of 6 km of cable including a repair joint and an earthing connection 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 testat720 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 monopole HVDC cable system in shallow water
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA HVDC BIPOLE BUNDLE INSTALLATION
Fibre Optic 200 kV dc Cable XLPE Cable
POWER CABLE Lead+PEPOWER CABLE Sheath
S IG N A A C L CU F R RO A M TE SA PO T S EL I I TI T O E N F I O NG R
POLYPROPYLENE ROPE
GIULIO VERNE
• The cables will be simultaneously laid and buried BUNDLE OF TWO SUBMARINE CABLES in a Bundle configuration wherever possible
• Minimal environmental impact
• The Cable bundle is taken to the trench bottom by B0040030 a stinger
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA Shore Crossings - Horizontal Directional Drilling
Drilling the pilot hole Hole reaming
5-6 m
F.O. cable
HVDC Cable
Duct Bore Hole Duct Duct installation Bore Hole Electrode cable Duct
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
• Permitting (planned developments along the route, marine delimitations, permits and regulations)
• Bathymetry • Morphology and nature of the seabed • Sub-bottom characteristics (mainly necessary in case cable burial is foreseen)
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 BurialBurial Equipment Equipment -- HydroplowHydroplow
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA BurialBurial Equipment Equipment -- JettingJetting Machines Machines
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA BurialBurial Equipment Equipment –– TrenchingTrenching Machines Machines
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA Sand/CementSand/Cement Bags Bags Protection Protection
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA MattressesMattresses Protection Protection
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA CastCast Iron Iron Shell Shell Protection 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 JOINTED OR REPAIRED CABLE BY USING THE QUADRANT
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA MAINTENANCE
HVDC submarine MI and Extruded cables are maintenance free the only termiantions may need some inspections
For HVDC land cables it may be convenient but not mandatory to periodically check the integrity of the outer jacket in order to identify eventual third parties damages
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 The Deepest HVDC Cable 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
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA The Longest HVDC Cable NorNed: Norway – The Netherlands HVDC cable Transmission capacity: 700 MW DC Voltage: ± 450 kV Length of DC cable: 2*580 km
Main reason for choosing HVDC: Long submarine cable distance and non-synchronous AC systems
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA HVDC TRANSMISSIBLE POWER – TRENDS
600
500 .I. C M HVD L) 400 ed l. PP ud inc tr ( 300 Ex
Operating Voltage [kV] C VD 200 H
100
0 0 200 400 600 800 1000 Power per cable [MW]
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA THANK YOU FOR YOUR ATTENTION
any questions?
Spring 2010 ICC Education Subcommittee – 24 March, 2010 Nashville, USA