模块化多电平变流器孤网运行控制策略研究

Research on the Control Strategy for Isolated Grid Operation of Modular Multilevel Converter

模块化多电平变流器(MMC)以其模块化的结构可使储能单元分散接入的优点,可作为微网系统孤网运行下的储能变流器。由于孤网系统具有大量的单相负荷,会导致输出电压不对称。研究了两相静止坐标系下MMC孤网运行的控制策略,分析了桥臂环流特性,并提出了相应的抑制方法。最后,经过仿真和实验验证了上述控制策略的有效性。

Modular multilevel converter（MMC） has the advantage of its modular structure allows scattered access to energy storage unit, so it can be used as energy storage converter in microgrid system.Due to a large number of single-phase loads in isolated net system, the output voltage is asymmetry.The control strategy of MMC in two-phase synchronous reference frame is studied.The characteristic of circulating current is analyzed,and the suppression control is designed.Finally, simulation and experimental results verify the validity of the control strategy.