具有直流故障阻断能力的电容嵌位子模块拓扑及其特性

摘要

针对半桥子模块无法清除直流故障电流的问题,提出了一种具有直流故障阻断能力的新型电容嵌位子模块拓扑.正常运行时,子模块中各IGBT均衡导通,无需采用具有特殊通流能力的附加功率器件;当发生直流故障时,闭锁子模块中所有IGBT通过子模块中的电容提供反向电压来阻断交流系统能量的馈入.IGBT闭锁后,利用二极管的单向导通性抑制桥臂电抗器的续流作用,具有较强的故障电流阻断能力.在PSCAD/EMTDC仿真平台上进行了仿真分析,验证了提出的电容嵌位子模块比全桥子模块、箝位双子模块具有更好的直流故障阻断能力.%Considering the fact that HBSMs(Half-Bridge SubModules) cannot eliminate DC fault current,a novel CESM(Capacitor-Embedded SubModule) topology with DC fault blocking capability is proposed.Under normal conditions,there is no extra requirement for equipments with special flow capacity because of IGBTs'equilibrium conduction.When a DC fault happens,all IGBTs of CESMs block,and submodule capacitors are inserted in series,which can provide a reverse voltage to block the fault current feeding from AC side.When IGBTs block,the after-follow current caused by bridge arm reactor can be suppressed by the unidirectional conductivity of submodule diodes.The simulative results based on PSCAD/EMTDC platform demonstrate that CESMs exhibit superior performance than FBSMs(Full-Bridge SubModules) and CDSMs(Clamp Double SubModules) in aspects of blocking the DC fault current.