模块化多电平换流器(MMC)在中高压直流输电中得到了广泛的研究和应用。其内部环流的存在是MMC的一种重要现象。在MMC的拓扑结构及其内部环流产生机理的基础上,利用二倍频负序旋转坐标变换,把换流器内部的三相环流分解为两个直流分量,并提出了相应的环流抑制方法。仿真结果证明,利用坐标变换提出的环流抑制控制器可以有效地消除桥臂电流中的环流分量,减小桥臂电流的畸变程度,同时不会对MMC外部输出的交流电压和电流产生负面影响。

The modular multilevel converter (MMC) had been widely studied and applied in the medium and high voltage direct current (HVDC) transmission system. The existence of internal circulation was an important phenomenon in MMC. According to the mechanism of MMC topology and its internal circulation, its threephase circulation was divided into 2 DC components based on negativesequence coordinate transformation of double fundamental frequency. And a circulating current suppressing controller was designed. The simulation results showed that the cotroller could effectively suppress the circulation of arm current and reduced the distortion of waveform without negative impacts on MMC external output AC voltage and current.

TM 301.2

河北省高等学校科学技术研究项目(ZD2014026);河北省创新协同发展(LJRC003)