一种模块化多电平换流器新型子模块拓扑

A New Sub-Module Topology in MMC

设计模块化多电平换流器(MMC)时,调整子模块串联的个数可以实现输出电平数以及电压等级的灵活变化,当MMC直流侧发生短路故障时,半桥子模块不具备阻断直流侧短路故障电流的能力。为此提出了一种具有阻断直流侧故障电流能力的MMC新型子模块拓扑,可实现快速阻断直流侧故障电流的目的。最后在PSCAD/EMTDC下搭建MMC-STATCOM仿真模型进行了验证。仿真结果表明,新型子模块在阻断直流故障电流方面是有效的。

Multilevel modular converter（MMC） can achieve flexible changes of the number of the output level and the voltage level due to its modular design, by adjusting the number of sub-modules in series. Currently the submodule commonly used is the half-bridge sub-module, but when there is a short circuit fault happenes at MMC DC side, half-bridge sub-module does not have the capacity to block the DC-side short-circuited. So this paper proposed a new sub-module having the ability to block the DC-side fault current rapidly on the basis of analyzing the existing sub-module topology. Finally, the simulation model of MMC-STATCOM was built in PSCAD / EMTDC to verify the above analysis. The simulation results show the effectiveness of the proposed sub-module in terms of blocking DC fault currents.