基于耦合负压的改进型多端口中压直流断路器拓扑研究OA

The reliability of VSC DC distribution network is set up on the basis of mature MV circuit breaker and,however,the high cost of DC circuit breaker limits its application in the distribution network.In order to reduce the investment cost of DC circuit breaker in VSC distribution network,a kind of improved multi-terminal hybrid DC cir-cuit breaker is designed based on coupled negative voltage commutation method.First,the topological structure of the existing DC circuit breaker is analyzed.Then,the topological structure of improved multi-port hybrid DC circuit breaker is proposed,and the operation sequence in interrupting the fault is designed.Finally,a four-terminal ring-main VSC DC distribution network is set up on the basis of Pscad/Emtdc,and the transient characteristics of the im-proved multi-terminal hybrid DC circuit breaker during bipolar short circuit fault interruption are analyzed.The dis-tribution of internal voltage and current is obtained and the feasibility of the designed fault isolation sequence is veri-fied.The results show that the improved multi-terminal hybrid DC circuit breaker can interrupt fault current within 3 ms,has low control difficulty and has more economical performance than other types of topology.