| 摘要 |
This application relates to voltage source converters and method of controlling such converters in a DC fault situation. The converter (200; 500) has a plurality of AC terminals (a, b, c) and first and second DC terminals (DC+, DC-) with each AC terminal being connected to the first and second DC terminals via respective first and second converter arms. The converter also comprises a fault controller (205) and a DC breaker (206) connected in series with the first DC terminal. The fault controller is configured to, in the event of a DC fault being detected: control the converter to provide current paths for current flow between the AC terminals that bypass the DC system connected to the DC terminals and also to operate the DC breaker (206). Each converter arm may comprise at least one bypass module (202; 502), which may have switching elements (203, 204) such as thyristors to establish current paths in both directions through the converter arm in a fault situation. Providing such current paths effectively short circuits the AC system and allows the DC breaker (206) to have a lower voltage rating than otherwise would be required. The DC breaker may comprise a low voltage electronic switch (207) in series with a mechanical isolation switch (208) |
