基于单相矢量控制的MMC环流抑制策略

摘要

模块化多电平变流器( MMC)在正常运行时子模块和桥臂的电气量存在循环耦合关系,会在相内产生二倍频环流.二倍频环流对MMC输出功率无贡献,却增加了开关管额定容量和通态损耗,也给MMC系统带来高次谐波扰动,影响系统的正常运行.为抑制相内二倍频环流,本文提出了一种基于单相矢量的环流控制方法,控制器输出相应的控制补偿量对MMC桥臂电压进行补偿调制,实现了相内二倍频环流的抑制.最后采用专业软件PSCAD／EMTDC搭建仿真模型,其结果验证了所提控制策略的可行性.%Influenced by the loop of electrical coupling in sub-modules and arms, modular multilevel converter (MMC) will produce the double frequency circulating current.The double frequency circulating current does not contribute to the output power of MMC, but increases the rated capacity and losses of the switch, which also brings higher-order harmonic disturbance to the MMC system and affects the normal operation.In order to eliminate the double-frequency circulating current, a method based on single-phase vector control is proposed in this paper, where the circulating current is eliminated by the output of the single-phase vector controller.Finally, the simula-tion model is built with the professional software PSCAD／EMTDC and the simulation results show the effectiveness of the proposed control strategy.