基于阻抗灵敏度的MMC稳定性主导影响因素分析

Analysis of Dominant Influencing Factors of MMC Stability Based on Impedance Sensitivity

针对模块化多电平换流器的宽频谐振日益突出且涉及影响因素众多,通过参与因子分析难以宽频段定量寻找主导谐振因素的问题,提出模块化多电平换流器阻抗绝对灵敏度及标幺灵敏度的分析方法,来实现宽频谐振主导因素的定量研究,并降低模块化多电平换流器的谐振风险。首先,建立模块化多电平换流器宽频阻抗模型,对延时环节和电流控制参数开展绝对灵敏度分析,来反映参数变化对系统稳定性的影响趋势;然后,对灵敏度比重标幺化消除各因素间量纲的影响,得到模块化多电平换流器互联系统在各频段稳定性的主导因素;最后,通过Matlab/Simulink模型验证了理论分析的正确性。

Since the broadband resonance problem in a modular multilevel converter(MMC)is becoming increasingly prominent and involves many influencing factors,it is difficult to quantitatively determine the dominant factors in the broadband through the analysis of participation factors.To solve this problem,an analysis method for the absolute and per-unit sensitivity of MMC impedance is proposed in this paper,which can realize the quantitative study of dominant factors of broadband resonance and reduce the resonance risk of MMC.First,a broadband impedance model of MMC is established,and the absolute sensitivity analysis of delay link and current control parameters is carried out to reflect the trend of influence of changes in parameters on system stability.Then,the influence of dimension between various factors is eliminated by the per-unit normalization of sensitivity,and the dominant factors of stability of MMC interconnected system in each frequency band are obtained.Finally,the theoretical analysis is verified by a simulation model built on the Matlab/Simulink platform.