具备故障限流和快速故障清除能力的多端口直流断路器拓扑与控制策略

Topology and Control Strategies of a Multiport DC Circuit Breaker Integrating Current-limiting and Fast Fault Clearing Capabilities

为解决直流电网中直流故障快速清除的技术难题,提出了一种同时具备限流和快速故障清除能力的多端口直流断路器,并设计了启动、限流后开断线路和限流后复位3种控制策略。所提拓扑结构通过限流电路实现断路时刻电流值的大幅下降,通过电感旁路电路实现故障清除所需时间的缩短;所提控制策略通过复用拓扑部分回路实现直流电网对断路器电容的预充电,通过初步故障判断与二次确认方式来优化断路器的动作时序,实现断路时刻电流值的进一步下降。在PSCAD/EMTDC中搭建了三端直流电网仿真模型,对断路器的各种工况进行了仿真验证。结果表明该多端口直流断路器在各工况下均可实现多条直流线路的保护、减小断路时刻电流值和减小故障切除所需时间。

In order to solve the technical problems of fast clearing DC faults in DC grid,a multiport DC circuit breaker integrating current-limiting and fast fault clearing capabilities was proposed.Three control strategies were designed,including energization,fault interruption after current limiting and reset after current limiting.The proposed topology realizes a large reduction of current value at break time through a current limiting circuit.The time required for fault clearing is shortened by inductive bypass circuit.The proposed control strategy realizes the pre-charge of circuit breaker capacitor by multiplexing part of the topology loop.The operating sequence of circuit breaker is optimized by the method of preliminary fault judgment and secondary confirmation,and the current value at the break time is further reduced.A three-terminal DC grid simulation model is built in PSCAD/EMTDC,and various operating conditions of circuit breakers are simulated and verified.The results show that the multi-port DC circuit breaker can realize the protection of multiple DC lines,reduce the current value at break time and reduce the time required for fault interruption under all working conditions.