基于直流系统故障保护的三端口直流断路器拓扑研究

Topology research of three-port solid state circuit breaker based on DC system fault protection

由隔离开关和电力电子器件组合而成的混合直流断路器在正常运行下的损耗较低,故障保护时能快速有效地断路,因此已得到普及。然而,在多端直流系统中,每一端都与多条输电线路相连,同一端则需要多个混合直流断路器,混合直流断路器庞大的体积和高昂的成本限制了它在多端直流系统中的应用。为了解决这一问题,提出了一种三端口直流断路器拓扑。这一拓扑将同一端子的三个断路器集成于一个,可减少一半电力电子器件,大大降低断路器的尺寸和成本。同时提出了针对一个端口发生短路故障的故障中断策略,该策略可快速中断短路电流,隔离故障端口,减少故障对直流系统的影响。仿真与实验结果表明,该拓扑与故障中断策略可行。

Hybrid DC circuit breaker, a combination of disconnector and muhiple power electronic devices, has gained popularity for its low-loss at normal operation and its quick and effective circuit breaking during fault protec-／tion. However, its bulkiness threatens to limit its application in multi-terminal DC system, where the terminal is usually connected to more than one transmission lines and hence the circuit breaker tends to appear in clusters. In this context, a three-port DC circuit breaker topology is proposed. The circuit breakers at one terminal is integrated into one. Through this, it is able to cut down by half the number of power electronic devices needed, greatly reducing the size and cost for circuit breaking. At the same time, a fault interruption strategy for short-circuit faults on a port is proposed. This strategy can quickly interrupt the short-circuit current and isolate the faulty ports to reduce the impact of faults on the DC system. Through simulation and experimental verification, the topology and fault in terrupt strategy are feasible.