集成直流故障换流电路的改进型混合MMCOACSTPCD

Based on full-bridge(FB)and half-bridge(HB)sub-modules(SMs),the conventional hybrid modular multievel converter(MMC)is a typical topology of MMC with DC fault clearing ability.However,the proportion of FB SMs in conventional hybrid MMC is usually greater than 50%,so as to increase the cost and losses.To solve this mentioned issue,a DC fault commutated circuit based on thyristor-switched capacitor(TSC)structure in the hybrid MMC was integrated to reduce the number of FBs,the improved TSC-hybrid MMC was proposed in follows.In TSC-hybrid MMC,HB-MMCs and FB-MMCs were both retained their complete commutated body,and meanwhile,they were connected by a three-winding transformer in AC side and in series with DC side.In particularly,a thyristor-switched capacitor structure was integrated in the DC side of TSC-hybrid MMC to clear the DC fault.According to the analysis,the proportion of FB SMs in TSC-hybrid MMC can be reduced to 10%～25%or even lower(the AC-side voltage quality is a main limiting condition),the cost is reduced as well as the on-state losses.Simulation results validate the correctness of analyses.