1. HVDC High Voltage Direct Current Transmission Adam Holbrook, Kyle Holcomb, Bo Liu, Phillip Pardue, Mitchell Smith, Nina Wong
1 November 2013

2. Outline Background Modern HVDC Impact of HVDC R&D Challenges
History
Basic Theory
Modern HVDC
Impact of HVDC
Advantages
Disadvantages
R&D Challenges
Demonstrated Technologies
Related Published Research

3. The War of Currents
Thomas Edison pioneered DC distribution while Tesla and Westinghouse adopted AC
Voltage conversion was not efficiently possible with the DC grid. Voltage drop, then, wreaked havoc as loads varied and at the ends of lines.
DC distribution was manageable in urban locations but impossible in rural areas due to low customer density.
The majority of loads ran at ~100 volts. Larger loads, though required separate circuits be ran at very high costs.

4. Innovations in DC Technology
Mercury-Arc Tubes and Vacuum Diodes allowed for the rectification of AC to DC
Thyristors and IGBTs allow conversion both to and from DC

5. Increasing Current and voltage capacity
Heated Cathode Rectifier, c. 1930
Mercury-Arc Rectifier, c.1970
Thyristor Rectifier, 2009
Increasing Current and voltage capacity

6. DC Transmission Theory
DC generation is not practical on a large scale due to the need for large permanent magnets or brushes. DC, then, is only viable as a transmission method between AC grids
HVDC lines typically run in the hundreds of kV, generally around 500 kV.

7. Why use DC for Transmission Anyway?
DC is more efficient than AC for transmission. It does not exhibit losses due to skin effect thus conductors can be sized smaller.
DC can serve as a link between non-syncronized AC grids.
Line losses are largely eliminated- capacitive, inductive, radiation.

8. Outline Background Modern HVDC Impact of HVDC R&D Challenges
History
Basic Theory
Modern HVDC
Impact of HVDC
Advantages
Disadvantages
R&D Challenges
Demonstrated Technologies
Related Published Research

9. Modern HVDC
Several different designs which share several qualities.
Innovative field watched closely by the Power Community

10. Thyristor Valve Advances
Thyristor valves have made significant advances in the past ten years
Development of light triggered thyristors
Control unit advancement
Has helped keep electrically triggered thyristors as the popular choice

11. Thyristor Valves from Manitoba Hydro

12. IGBT Valves
Insulated gate bipolar transistor valves allow the current in the lines to be extinguished completely and quickly
This property allows for much more versatility than standard HVDC lines can provide

13. Active DC Filters
Digitally controlled amplifiers actively cancel interfering currents on lines
Compared to the use of shunt filter branches, this is cheaper and easier to maintain and operate

14. Optical Direct Current Transducers
Use high precision shunt at high potential to send signals over glass optical fibers
Allows for much smaller components than the porcelain counterparts
Cheap and effective method for lowering flashover probability.

15. Outline Background Modern HVDC Impact of HVDC R&D Challenges
History
Basic Theory
Modern HVDC
Impact of HVDC
Advantages
Disadvantages
R&D Challenges
Demonstrated Technologies
Related Published Research

16. Most benefits stem from inherently fewer components:
Advantages
Most benefits stem from inherently fewer components:
DC eliminates need for three-phase system
No “skin effect”
Easier repairs in event of outage

17. Lower losses / higher transmission efficiency
Advantages, continued
Lower losses / higher transmission efficiency
Good long-distance underground and underwater transmission
Eliminates need for substations near far-reaching delivery point

18. More complicated switching infrastructure
Disadvantages
Higher cost over short distances
Efficient DC-AC converting stations
Harmonics
System oscillation when integrated with AC networks
Overvoltages
More complicated switching infrastructure
Heat dissipation of breaker

19. Outline Background Modern HVDC Impact of HVDC R&D Challenges
History
Basic Theory
Modern HVDC
Impact of HVDC
Advantages
Disadvantages
R&D Challenges
Demonstrated Technologies
Related Published Research

20. Challenges
Conversion
Switching
Control
Availability
Maintenance

21. Research HVDC Offshore and Onshore Energy Multi Terminal HVDC (MTDC)
Great for long distance energy transmisson.
Wind Power
Solar Power
Hydro Power
Multi Terminal HVDC (MTDC)
Will be the most commonly used in the Future.
Popular for offshore energy networking.
Underwater cables or overhead powerline.

22. Multi Terminal HVDC (MTDC)
Research
Multi Terminal HVDC (MTDC)
Series, Parallel, Hybrids
Parallel systems are becoming the easiest to control because of Voltage Source Convertors.
Area to Area Transmisson

23. Research
HVDC Breakers
Power Flow Control
Automatic Network Restoration
HVDC Converter for the exchange of renewable energies.

24. Development SIEMENS 2015 Offshore HVDC Plus link HelWin2, Germany
2014 Offshore HVDC Plus link SylWin1, Germany
2014 INELFE, France-Spain
2013 Offshore HVDC Plus link HelWin1, Germany
2013 Offshore HVDC Plus link BorWin2, Germany
2010 Trans Bay Cable Project, USA

25. Development ABB 2016 Celio Upgrade, Pacific Intertie, USA
2015 LitPol Link, Lithuania-Poland
2015 Troll A 3&4 offshore, Norway
2015 DolWin2, Germany
2015 NordBalt, Lithuania – Sweden

26. Outline Background Modern HVDC Impact of HVDC R&D Challenges
History
Basic Theory
Modern HVDC
Impact of HVDC
Advantages
Disadvantages
R&D Challenges
Demonstrated Technologies
Related Published Research

27. 1964 saw the first plants to be upgraded rather than shut down.
Demonstrations
First demonstrations in 1882 with single DC machines. Since been dismantled
1964 saw the first plants to be upgraded rather than shut down.
Demonstrations centered around Europe
Early 2000s, China, Japan, and India take over with demonstrations and installed stations

28. Mainly for country-country interconnects Submarine transmission lines
Applications
Mainly for country-country interconnects
Submarine transmission lines
European HVDC
Existing
Under Construction
Considered Projects

29. Regional Transmission System (RTS)
The Neptune Project
Regional Transmission System (RTS)
65 mile, undersea and underground cable
500 kV DC cable
660 MW capability (600,000 homes)
20% of Long Island’s electrical needs
Construction began June 2005, completed June 2007
Ahead of schedule and on budget
Thyristor based system

30. The Neptune Project cont.

31. The Neptune Project Details
No overhead lines
60 miles under water, 15 miles under ground
Three cable bundle
Main 5” 500 kV cable
Medium voltage “return” cable
Fiber-optic cable for system control

32. The Neptune Project Details cont.
One of two identical converter stations with filter banks located outside of the facility.
One in Sayreville, NJ and the other on Duffy Ave in NY
Thyristor valves for power conversion supplied by Siemens.

33. Submarine HVDC cable from Feda, Norway to Eemshaven, Netherlands
NorNed
Submarine HVDC cable from Feda, Norway to Eemshaven, Netherlands
Longest submarine cable in the world, 360 mi
Bipolar HVDC link
±450 kV with 700 MW capacity
300 kV AC on Feda end, 400 kV AC at Eemshaven
Passes under the North sea
Construction began 2006
Commissioned in 2008
Over budget (€550m budget, €600m actual)

34. NorNed cont. Unique construction One 12-pulse converter on either end
Symmetric Monopole configuration
Earthed via high impedance, no earth current

35. NorNed Installation

36. Outline Background Modern HVDC Impact of HVDC R&D Challenges
History
Basic Theory
Modern HVDC
Impact of HVDC
Advantages
Disadvantages
R&D Challenges
Demonstrated Technologies
Related Published Research

37. from HVDC to MTDC
Drive: Interconnection of offshore generation resources (wave and wind)
Increase Reliability
Increase transmission capacity
Cost-effective

38. Challenges of MTDC DC fault current breaking and blocking
ABB hybrid DC breaker, 2012:

39. Challenges of MTDC
2. DC power flow control: in case of overload (VSC and DC line)

40. Thank you!
Questions? Comments?

41. References http://en.wikipedia.org/wiki/HVDC

42. Sources https://en.wikipedia.org/wiki/High-voltage_direct_current

43. References

44. Reference [1]: “HVDC Grid Feasibility Study”, Cigre B4 533, 2013
[2]: ABB, “Proactive Hybrid HVDC Breakers-A key innovation for reliable HVDC grids ”,
2011
[3]: ABB, “The high voltage DC breaker, The power grid revolution ”, 2012
[4]: “Power Flow Analysis in Multi-Terminal HVDC Grid”, 2011
[5]: “Multi-Terminal HVDC Grid with Power Flow Controllability”, Cigre B4-301, 2012