基于虚拟阻抗VPI谐振控制器的MMC环流抑制策略

MMC Circulation Suppression Strategy Based on Virtual Impedance VPI Resonance Controller

针对MMC相间环流包含的二倍频以及偶次高倍频问题,该文提出了基于虚拟阻抗VPI谐振控制器的新型环流抑制策略,该策略通过虚拟阻抗与VPI谐振控制器结合,从而有效抑制环流中二倍频及偶次高倍频。首先建立了模块化多电平换流器(modular multilevel converter,MMC)的数学模型,分析了内部环流;其次将环流二倍频分量利用陷波器精准提取之后采用VPI谐振控制器进行抑制;最后设计了虚拟阻抗,抑制环流中的高频谐波分量。利用Matlab/Simulink搭建三相MMC仿真模型并进行验证。

In response to the issues of double frequency and even-order harmonics in the inter-phase circulating currents of the modular multilevel converter(MMC),this paper proposes a novel circulating current suppression strategy based on the virtual impedance VPI resonance controller.This strategy effectively suppresses the double frequency and even-order high-frequency harmonics in the circulating currents by combining virtual impedance with the VPI resonance controller.Firstly,a mathematical model of the MMC is established to analyze the internal circulating currents.Subsequently,the double frequency components of the circulating currents are accurately extracted using a notch filter and suppressed using the VPI resonance controller,then a virtual impedance is designed to suppress the high-frequency harmonic components in the circulating currents.A three-phase MMC simulation model is constructed using Matlab/Simulink and validated.