基于虚拟电阻的MMC子模块故障容错环流抑制策略

摘要

针对模块化多电平变流器(MMC)子模块故障下容错环流抑制问题,分析了子模块故障状态下的环流特性,进而指出了准比例谐振(PR)控制在子模块故障容错环流控制中的通用优势.通过对采用准PR控制方式的子模块故障容错环流控制器进行分析与改进,提出了一种包含虚拟电阻前馈补偿环节的子模块故障容错环流抑制策略,其在保证实现子模块故障下环流抑制的同时可通过引入的虚拟电阻提高整个控制器的响应速度,使得子模块故障时刻的直流电流以及环流的冲击得到快速、有效的限制,优化了整个系统的性能.仿真与实验结果验证了该环流抑制策略的有效性.%Aiming at the problem of circulating current suppressing of MMC (Modular Multilevel Converter) in submodule fault-tolerant control mode,the fault characteristics are analyzed,and the advantages of quasi PR(Proportion Resonance) control for it are pointed out.The circulating current suppressor with quasi PR controller is modified and a fault-tolerant circulating current suppressing strategy with a virtual resistor feedforward compensation is proposed.It ensures the circulating current suppress and improves the response speed of the entire controller by introducing the virtual resistor,which makes the peak value of the DC and circulating current limited quickly and effectively in periods of sub-module fault.The performance of the entire system is optimized and verified through simulations and experiments to prove the feasibility and effectiveness of the control strategy.