基于多通道信号分离器的MMC网侧背景谐波电流抑制策略

针对模块化多电平换流器(Modular Multilevel Converter, MMC)受电网背景谐波影响输出谐波电流的问题提出抑制策略。通过计算子模块能量波动函数得到MMC在背景谐波影响下的输出电压，进而分析了MMC网侧背景谐波电流产生的规律。利用交叉解耦复数滤波器设计了多通道信号分离器，实现了对MMC网侧谐波信号的分离提取。对所分离的各次谐波建立了MMC数学模型，并以此为基础设计了谐波电流抑制器；通过搭建双端HVDC输电模型对理论分析和抑制策略进行了仿真验证。仿真结果表明，MMC网侧输出背景谐波电流规律与理论分析吻合，所提出的抑制策略能有效降低MMC网侧电流中的背景谐波含量。

Suppression strategy for an MMC grid-side background harmonic current based on a multi-channel signal separator

To solve the problem that a Modular Multilevel Converter (MMC) outputs harmonic current affected by background harmonics of a power grid, a suppression strategy is proposed. The output voltage of an MMC when there are background harmonics is obtained by calculating the energy fluctuation function of sub-modules, and then the generation law of background harmonic current at the MMC grid side is analyzed. A multi-channel signal separator is designed by using a cross decoupling complex filter to separate and extract MMC grid-side harmonic signals. An MMC mathematical model is established for separated harmonics, and a harmonic current suppressor is designed based on this. The theoretical analysis and suppression strategy are verified by building a double terminal HVDC transmission simulation model. Simulation results show that the generation law of background harmonic current at the MMC grid side is consistent with the theoretical analysis, and the proposed suppression strategy can effectively reduce the background harmonic content of MMC grid-side current.This work is supported by the Science and Technology Project of the Headquarters of the State Grid Corporation of China (No. 52130419000M).