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ABB GroupOctober 7, 2011 | Slide 3
History and Introduction
First commercial HVDCtransmission in 1954
(100 kV, 20 MW)
Cable length: 100 km
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ABB the HVDC pioneer
1954 - First commercial HVDC link with mercury-arc valves
1970 - First thyristor valves for HVDC
1980 - The highest power, Itaipu 6.300 MW
1994 - The longest submarine cable, Baltic Cable HVDC Project, 250 km
1997 - First commercial HVDC Light installation
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HVDC characteristics
Why use HVDC instead of AC?
DC decreases total cost for long distance powertransmission with overhead lines
Cables.
DC enables connection between asynchronous AC
networks.
Gives fast and accurate control of the power flow.
ABB GroupOctober 7, 2011 | Slide 5
Generator HVDC transmission system Load
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DC Transmission Line Corridor
ABB GroupOctober 7, 2011 | Slide 7
400 MW AC
2000 MW DC
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Transmission line corridor
AC transmission line require large corridorsDC line transmitting as much powerrequires fewer towers
HVDC conserves forests and saves landHVDC cables
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Lower investment
ABB GroupOctober 7, 2011 | Slide 9
AC Terminal costs
ACLine
Costwith
Series
Co
mpen
satio
n
Total AC costInvestment Costs
Distance
DC terminalCosts
DCLineCost
Total DC Cost
Variables
-Cost of Land- Cost of Materials- Cost of Labour
- Time to Market- Permits
etc.
Critical Distance
AC DC
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Lower losses
ABB GroupOctober 7, 2011 | Slide 10
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ABB GroupOctober 7, 2011 | Slide 12
AC
Charging current consumes capacity,e.g. a 40 km, 230 kV, a.c. cable has a
charging current of 450 A (179 Mvar)
Require shunt reactors due to reactivepower generation
Distance limited to about 50 - 100 km
Three cables or three core cable
DC
No physical distance limitation
No charging current All cable capacityavailable for power transfer
Two cables or dual core cable
Comparison of cable characteristicsHVAC vs. HVDC
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ABB GroupOctober 7, 2011 | Slide 13
Maximum loadability for cable transmissionsHVAC vs. HVDC
Cable transfer capability vs. distance
(1200 A rating)
0
200
400
600
800
1000
1200
0 50 100 150
Distance (km)
Transfercapability
(MW)
230 kV
345 kV
500 kV
320 kV DC
150 kV DC
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Interconnection of power systems
Why use HVDC for interconnections?
Exact power flow control
Interconnected systems maintain their autonomy
Disturbances in one system are not propagated to the other
Efficient use of generating capacity Cable transmission
Stability control
No increase of short circuit currents
Less environmental impact
Low losses for long distance transmissions
Lower investment
ABB GroupOctober 7, 2011 | Slide 15
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ABB GroupOctober 7, 2011 | Slide 16
