具备阻断直流故障电流能力的MMC钳位双电容子模块

A Clamp Dual Capacitor Submodule of MMC With DC Fault Current Blocking Capability

模块化多电平换流器(modular multilevel converter,MMC)是柔性直流输配电领域的优选拓扑之一,但其传统半桥子模块(half-bridgesubmodule,HBSM)不具备阻断直流故障电流的能力。为此,推导了一种基于双向开关的钳位双电容子模块(clamp dual capacitor submodule,CDCSM),该子模块包含两个电容,能够输出3个电平,通过将电容引入故障回路可实现对故障电流的快速阻断。与其他能够阻断直流故障电流的子模块相比,CDCSM具有一定的成本优势,且运行损耗较低。基于Matlab/Simulink的仿真结果表明,CDCSM-MMC可快速阻断直流故障电流,且故障后电容电压较为均衡,有利于MMC的快速重启。

The modular multilevel converter(MMC)is one of the preferred topologies in flexible DC transmission.However,the traditional half-bridge submodule(HBSM)cannot block the DC fault current.Therefore,a clamp dual capacitor submodule(CDCSM)based on bidirectional switch is derived in this paper.The CDCSM contains two capacitors and can output three levels,and possesses the capability of blocking fault current by introducing capacitors into fault circuits.Compared with other submodules that can block DC fault current,CDCSM possesses certain superiorities in investment cost and operation loss.Simulation results based on Matlab/Simulink show that CDCSM-MMC can fast block the DC fault current,and the capacitor voltages of submodules are relatively balanced after the fault,which is beneficial to the rapid restart of MMC.