ECE 421
Project 1, Group 3
HVDC
Brian Beilstein, Robert Germick, James Haney,
Alexander Joss, Matt Murphy, Shutang You
History and Basic Theory
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First HVDC link in Sweden
Mercury Arc Rectifiers
Silicon Thyristors
Capacitor Commutated Converter (CCC)
State-of-the-art Design and Products
● DC Breaker
○
Low impedance of HVDC system
■ Faster opening speed
■ Wider air gap
● Thyristor valves
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Can be used to go from AC-DC or DC-AC
Used in renewables
Hybrid DC Breaker
● Used to overcome issues of breaking DC
o
No zero-crossings with voltage as in AC
● In the case of a fault
o
o
o
o
Load-commutating switch directs current to the main
breaker
Arrestor across the main breaker absorbs current
Ultra fast disconnector opens to isolate the LCS
Main breaker opens a number of IGBT bank
depending on whether interruption or limitation is
required
Hybrid DC Breaker Sequence of Events
http://www05.abb.com/global/scot/scot221.nsf/veritydisplay/22d1af449957bf28c1257d070046df97/$file/Technical%20Assessment%20of%20Load%20Commutation%20Switch_IPEC2014.pdf
Thyristor Valve
● Typically will use electronically triggered or
light triggered thyristors for control.
● Thyristors are typically found in large stacks
and are water cooled
http://www05.abb.com/global/scot/scot221.nsf/veritydisplay/3c981b9078f55447c1256feb0022602a/$file/ett%20vs%20ltt.pdf
Impacts - Benefits
● Undersea cables
● Useful in connecting remote areas/plants
o End to end long haul bulk transmission
● Reduced cost in…
o Increasing capacitance of existing grid
o Line cost - less wiring, conductors, and lower pylon profile
● AC systems compatible
o Transmission between unsynchronized AC systems
o Stabilization of AC grid
● Reduced corona losses
Impacts - Concerns
● Higher overall cost
o Expensive inverter stations for connecting to AC grid
o Requires filter and reactive power compensation units
o Design and operational complexity
● Short circuits in connect AC systems causes HVDC faults
● Substation construction limit
o Requires minimal capacity difference
● Creates radio noise in communication lines
● Current causes electro-corrosion of underground metal pipes
● Difficult to ground preventing ‘step voltage’
Challenges
- Cost of HVDC components and availability
- Conversion from AC to DC
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Cost and losses in conversion may not be offset in
by the lower transmission losses and line
construction.
Limited overload capacity
- Complex control needed for Multi Terminal
Systems
R&D Development
- Offshore HVDC
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Useful for offshore wind-farms
- Need for projects with Higher DC voltage
and rating
- Improvements in Converting to HVDC
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Voltage Source Converters (VSC)
- Multi Terminal HVDC systems
- HVDC breakers
Current Applications
North America
Existing - 12
Projects Planned - 4
Projects Under Construction - 3
Europe
Existing - 49
Projects Planned - 0
Projects Under Construction - 2
Current Applications cont.
Asia
Existing - 52
Projects Planned - 0
Projects Under Construction - 0
Red - Existing
Green - Under Construction
Blue - Possible additions
Specific Existing Projects
October 23, 2014 - Alstom announces €800
million in new contracts to build HVDC “Energy
highways”.
South Korea - HVDC Line Commutated
Converter project
India - ~800kV, 3000MW Ultra-high voltage
DC connecting Champa to Kurukshetra
Related Research
Modular Multilevel Converter for HVDC System
SM
OR
SM
SM
a) Half-Bridge Submodule (SM)
b) Full-Bridge Submodule (SM)
Internal structure of typical submodules
HVDC-Station using Modular Multilevel Converter
Ref: Marquardt, R. "Modular Multilevel Converter: An universal concept for HVDC-Networks and extended DC-Bus-applications." Power Electronics Conference (IPEC),
2010 International. IEEE, 2010.
Conventional VSC-HVDC converters
Two-level converter
Ref: http://en.wikipedia.org/wiki/HVDC_converter
Three-level converter
Modular Multilevel Converter for HVDC System
Ref: http://en.wikipedia.org/wiki/HVDC_converter
Modular Multilevel Converter for HVDC System
Two-Level Converter
Two-Level Converter
Modular Multilevel Converter
Modular Multilevel Converter
Comparison of the AC-line voltages of Two-Level
Converter and the M2C
Comparison of the arm currents of Two-Level
Converter and the M2C
Ref: Marquardt, R. "Modular Multilevel Converter: An universal concept for HVDC-Networks and extended DC-Bus-applications." Power Electronics Conference (IPEC),
2010 International. IEEE, 2010.
Application of M2C in multi-terminal HVDC
line-to-line
fault
Station 1
Station 2
A Multi-terminal HVDC Network with 3 branches
Clamp-Doule submodule
Failure current
Station 3
Ref: Marquardt, R. "Modular Multilevel Converter: An universal concept for HVDC-Networks and extended DC-Bus-applications." Power Electronics Conference (IPEC),
2010 International. IEEE, 2010.
Questions?