Study on ±800kV UHVDC valve protections and switching sequence strategy

At present, SGCC´s ±800kV HVDC Transmission Project (Fu Feng UHVDC Project) has completed pole I low voltage side system commissioning test and bipolar commissioning test is planned to be completed in June, 2010. Fu Feng UHVDC Project adopted dual-pulse valve 12 in series connection forms. The connection form has a flexible operation mode, which can reduce the insulation level of equipment, be convenient for equipment transportation as well as meet the present demand for high-power transmission. It is just needed to bypass when one 12-pulse vale failed by adopting dual 12-pulse valve series wiring. As a result, the no fault valves are still under normal operation and greatly reduce the rate of monopole block. Based on the parameters of Fu Feng UHVDC Project, this paper conducted a detailed simulation by using RTDS on converter valves zone fault, and a detailed analysis of fault characteristics. According to the analysis results, the 12 pulse valve group´s switching sequence under different faulty conditions is proposed, which is instructional and helpful to practical engineering.