ECE 421 Project 1, Group 3 HVDC. Brian Beilstein, Robert Germick, James Haney, Alexander Joss, Matt Murphy, Shutang You

Transcription

1 ECE 421 Project 1, Group 3 HVDC Brian Beilstein, Robert Germick, James Haney, Alexander Joss, Matt Murphy, Shutang You

2 History and Basic Theory First HVDC link in Sweden Mercury Arc Rectifiers Silicon Thyristors Capacitor Commutated Converter (CCC)

3 State-of-the-art Design and Products DC Breaker Low impedance of HVDC system Faster opening speed Wider air gap Thyristor valves Can be used to go from AC-DC or DC-AC Used in renewables

4 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

5 Hybrid DC Breaker Sequence of Events

6 Thyristor Valve Typically will use electronically triggered or light triggered thyristors for control. Thyristors are typically found in large stacks and are water cooled

7 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

8 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

9 Challenges - Cost of HVDC components and availability - Conversion from AC to DC - - 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

10 R&D Development - Offshore HVDC - Useful for offshore wind-farms - Need for projects with Higher DC voltage and rating - Improvements in Converting to HVDC - Voltage Source Converters (VSC) - Multi Terminal HVDC systems - HVDC breakers

11 Current Applications North America Existing - 12 Projects Planned - 4 Projects Under Construction - 3 Europe Existing - 49 Projects Planned - 0 Projects Under Construction - 2

12 Current Applications cont. Asia Existing - 52 Projects Planned - 0 Projects Under Construction - 0

13 Red - Existing Green - Under Construction Blue - Possible additions

14 Specific Existing Projects October 23, 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

15 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.

16 Conventional VSC-HVDC converters Two-level converter Ref: Three-level converter

17 Modular Multilevel Converter for HVDC System Ref:

18 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.

19 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.

20 Questions?