MMC型统一电能质量控制器故障分析及保护策略

模块化多电平换流器（modular multilevel converter，MMC）拓扑结构引入统一电能质量控制器（unified power quality conditioner, UPQC），既能够提高UPQC的容量又可以提高UPQC的电压等级，从而扩展了UPQC在中压领域的应用，使UPQC具有更加广阔的适用前景。然而当负载侧出现短路故障时，如何合理地操作保证其安全可靠地运行，不仅是系统对装置的要求，更是装置保护自身的要求。针对上述情况提出了应用于MMC型UPQC（MMC-UPQC）故障保护策略制定的原则，采用反并联晶闸管支路与线路断路器之间的动作配合，将串联MMC与故障线路隔离开，最终实现有效保护装置的目的。PSCAD/EMTDC环境下的仿真结果验证了所提方法的有效性及可行性。

Failure Analysis and Protection Strategy for MMC-UPQC

Applying the topology structure of modular multilevel converter （MMC） in unified power quality controller （UPQC） can improve the applicative capacity and voltage level of UPQC, which can expand the application of UPQC in medium voltage field, and make UPQC has wider application prospects. However, when the short-circuit fault occurs on the load side, how to logically operate to ensure the safe and reliable operation of UPQC, is not only the system requirement for the device, but also its own requirement for the device to protect itself. On this basis, this paper presented the principle of fault protection strategy for MMC-UPQC, which adopts the interaction between the branch of anti-parallel thyristor and circuit breaker to isolate the MMC in series from the fault line, and ensure the effective protection for the device. The simulation results in PSCAD/EMTDC environment have demonstrated the effectiveness and feasibility of the proposed method.