新型船舶中压直流固态断路器拓扑分析与设计

Topological analysis and design of a new MVDC solid-state circuit breaker for ships

为解决船舶中压直流(medium voltage direct current,MVDC)电力系统直流电流开断困难,以及发生短路时故障电流上升率高且峰值大的问题,提出一种基于耦合电抗器的阻容限流型固态直流断路器拓扑。以晶闸管(silicon controlled rectifier,SCR)作为主开断器件,通过耦合电抗器来辅助晶闸管开断,并在直流系统发生故障时,通过换流过程将阻容限流元件接入,有效限制故障电流上升率和峰值,减少故障开断所需时间。基于所提拓扑设计了6 kV/4.2 kA的直流断路器模型,在PSCAD/EMTDC中进行仿真,并与现有拓扑进行对比分析。仿真结果表明:所设计断路器可针对直流系统不同的运行状态,按照不同的控制策略顺利完成对直流电流的开断,并且在开断速度、限流能力和金属氧化物避雷器(metal oxide arrester,MOA)耗能方面均具有一定优势。

In order to solve the problems of direct current breaking difficulty of the medium voltage direct current(MVDC)power system in ships,as well as the high rise rate and high peak value of fault current in the case of short circuit,a resistance capacitance current-limiting solid-state direct current circuit breaker topology based on coupling reactors is proposed.The silicon controlled rectifier(SCR)is used as the main breaking device,and the coupling reactor is used to assist SCR breaking;in the event of direct current system fault,the resistance capacitance current-limiting element is connected through the commutation process,effectively limiting the rise rate and peak value of fault current,and reducing the time required for fault breaking.A 6 kV/4.2 kA direct current circuit breaker model is designed based on the proposed topology,simulated by PSCAD/EMTDC,and compared with existing topologies.The simulation results show that,the designed circuit breaker can successfully break direct current according to different control strategies for different operating states of the direct current system and has certain advantages in breaking speed,current-limiting ability,and energy consumption of metal oxide arrester(MOA).