EDIN -Submarine Power Transmission

7/30/2019 EDIN -Submarine Power Transmission

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Leading the Caribbean to a sustainable energy future. 60% by 2025

Submarine Power Transmission

Vahan Gevorgian, NREL

Clinton T. Hedrington, VIWAPA

June 15-16, 2010

St. Thomas, USVI


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Innovation for Our Energy Future


Leading the Caribbean to a sustainable energy future. 60% by 2025 2

Submarine power transmission has been around

for more than a century.

Early usesisolated offshore facilities, lighthouses, etc.

Mid 20th centurypower supply of near-shore islands

Since 1960sconnection of autonomous grids for better stability

and resource utilization, LCC HVDC

Modern daysoffshore wind, longer-distance power transmission,

network interconnections, increased number of islands connected

to mainland grid, HVDC light, etc.

History of Submarine Power Transmission

Mercury Arc Valves

(Source: Wikipedia)
http://en.wikipedia.org/wiki/File:Mercury_Arc_Valve,_Radisson_Converter_Station,_Gillam_MB.jpg


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Existing

Under Construction

Conceptual

Europe

Submarine Transmission Links

North America

TransBay, CA (HVDC, 53 mi, 600 MW, $450 M),

Siemens

Vancouver Island, Canada (DC and AC)

NJ to Long Island (HVDC, 50 mi, 660 MW)

CT to Long Island (HVDC, 25 mi, 330 MW), ABB

Rest of the world

Japaninterisland (50 km HVDC)

Philippinesinterisland (21 km HVDC)

New Zealandinterisland (40 km, HVDC)

AustraliaTasmania (290 km, HVDC)

S. KoreaCheju Island (100 km, HVDC)


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HVAC vs. HVDC


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HVDC Advantages

Advantages

Long-distance transmission with lower costs and losses

No high-capacitance effect on DC (no reactive losses)

More power per conductor, no skin effect, 2 conductors only

Connecting unsynchronized grids, rapid power flow control

Buffer for some disturbances, stabilization of power flows

Multiterminal operation

Good for weaker grids

Helps in integrating large amounts of variable generation

Disadvantages

High cost of power converters

Complexity of control, communications, etc.

Maintenance cost higher than for AC; spare parts needed

HVDC circuit breakers reliability issue


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Submarine Cable Technologies

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Major submarine cable suppliers: ABB, Prysmian, Nexans, Sumitomo, Fujikura

Extruded XLPE cables for AC - 420 kV, 1000 MW

Extruded cables for DC VSC technology (HVDC light) - 300 kV, 1000MW

Mass impregnated paper cables for DC - 600kV, 2000MW bi-pole

HVDC ultra deep technology 1600 m (2000m possible)

Source: ABB

Source: ABB

Source: Prysmian


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Fishing 52%

Dredging /

Drilling 1%

Fish bite 2%

Anchors

18%Earthquakes

3%

Cableship

activities 1%

Suspensions

5%Others 18%

Causes of Submarine Cable Damages

Source: Submarine Power Cables by Thomas Worzyk, Springer, 2009 (page 212)

CIGRE Investigation - 2009

7000 circuit km of submarine

power cables

49 faults reported during

1990-2005

Only 4 faults identified as

internal


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Oahu Wind Integration andTransmission Study (OWITS)

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Oahu Wind Integration and Transmission Study

Hawaii Clean Energy Initiative (HCEI)October 2008

Multiyear initiative

70% clean energy by 2030 (40% by renewables)

Agreement between state of Hawaii and HECO

400 MW wind from Lanai and/or Molokai to Oahu (Stage 1)

100 MW of Oahu on-island wind (Stage 2)

OWITS studies in support of HCEI and HECOFY09/10

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Project Management/Steering

GE Integration Study(HECO, DOE co-funded)

EPS Transient Study(HECO funded)

Electranix Cable Study(DOE funded)

Technical Review Committee (TRC)

AWS Truewind and NREL wind and solar data

HECO study of generator flexibility

Supporting Data


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Inputs to OWITS Cable Study

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Potential cable landing points and inter-

island routes have been identified in Ocean

Floor Survey Report (DBEDT)

Maximum water deptharound 800 m

Sending and receiving end voltages138 kV

PSSE load flow data from HECO

Information from cable manufacturers

Electranix expertise in HVDC technology



OWITS Option Screening Methodology

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Costs (HVAC) Costs (HVDC)

AC cables DC cables

AC substations DC converter stations

Sea/land cable transition Sea/land cable transition

Fixed compensation reactors -

Other components Other components

AC losses (20 years) DC losses (20 years)

Total HVAC cost Total HVDC cost

200 MW

Iwilei

Maui

200 MW Pole - Stage 2

200 MW

Molokai

Koolau

Stage 1

200 MW Symmetrical Monopole

200 MW Pole Lanai

18 options analyzed (AC, DCor combination of both)

Only 6 selected for detailedsimulation (AC and DC) andRFQ



HVAC Simulations

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138 kV bus

230 kV Bus

Fiberoptic link

70 mile AC

undersea cable

34.5 kV bus 600 V bus

200 MW of

wind turbines

Spontaneous

breaker-open

operation

230 kV bus

Operation due

to overvoltage

protection

Receiving end Sending end

230 kV / 733 Athree-core XLPE cable

Not practical for 800m water depths due to heavy weight



HVDC Simulations

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Detailed models of VSC in PSCAD

Traditional control strategy

Sending endfrequency and AC voltage control

Receiving endAC reactive power DC bus voltage control

Contingency and protection scenarios simulations

LVRT/HVRT limits

Time (sec)

Voltage(pu)



OWTIS Budget Pricing Analysis

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Requests were sent to Prysmian, Areva, Siemens, ABB, Sumitomo, Nexans, etc.

200 MW, 40 mi AC 200 MW, 40 mi DCmonopole

Almost same capital cost

3% ($10 M) more losses over 20 years

Final report goes public in July 2010. Contains conclusions, detailed cost and

technical analysis for all preferred options.



OWITS Future Detailed Simulations

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More detailed study is needed for wind farm/VSC converter interactions

Impact of turbines types on proposed cable system

Possibility of wind farms to provide inertial response to the system

Type 3partially rated power converter

Type 4fully rated power converter



Cable Study for USVI Submarine Transmission

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Peak loads: 88 MWSTT, 52 MWSTX

Transmission voltage: 34.5kVSTT

No short undersea route between STT and STX

PREPA5.8 GW generating capacity/3.6 GW peak load

50 mi

80100 mi to stay above

2,000 m depths



USVI Cable StudyNecessary Steps

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Determine power capacity of Puerto Rico-USVI interconnect (several scenarios possible)

Identify potential landing points, study existing infrastructure on both ends

Environmental evaluation (routes, cable burial, sea/land transitions, etc.)

Identify candidate cable configurations

Examine capital costs, losses and reliability for HVDC and AC options

Perform detailed technical evaluation and modeling of preferred options (PSCAD)

Protection, control strategy, synchronization

LVRT, severe contingency disturbances, impact on frequency, voltage stability

Impact of faults on grids at both ends of the cable

Impact of high penetration variable generation on cable operation

Communications between both cable ends

Requests for budgetary price estimates from manufacturers

Final evaluations, report, RFQs



USVI Cable StudyNecessary Steps

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Studies can be done by WAPA/NREL team, or by a consultant

Significant involvement from PREPA is necessary

Models of WAPA and PREPA grids are needed (PSLF or PSSE)

Results of cable study can be used by other working groups

Future cost of energy

Regulation/reserves

Impacts on possible energy storage studies


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Questions?

Source: www.nexans.com

Documents

EDIN -Submarine Power Transmission