Harmonic Impedance Modeling and Oscillation Analysis of Modular Multilevel Converter

模块化多电平换流器谐波阻抗建模与振荡分析

To facilitate rapid analysis of the oscillation stability mechanism in modular multilevel converter-based high voltage direct current(MMC-HVDC)systems and streamline the simulation process for determining MMC impedance characteristics,a simplified mathematical simulation model for MMC closed-loop impedance is developed using the harmonic state space method.This model considers various control strategies and includes both AC-side and DC-side impedance models.By applying a Nyquist criterion-based impedance analysis method,the stability mechanisms on the AC and DC sides of the MMC are examined.In addition,a data-driven oscillation stability analysis method is also proposed,leveraging a global sensitivity algorithm based on fast model results to identify key parameters influencing MMC oscillation stability.Based on sensitivity analysis results,a parameter adjustment strategy for oscillation suppression is proposed.The simulation results from the MATLAB/Simulinkbased MMC model validate the effectiveness of the proposed method.

为快速分析基于模块化多电平换流器的高压直流输电系统(MMC-HVDC)的振荡稳定机理,简化MMC阻抗特性获取过程中的仿真流程,利用谐波状态空间方法建立了考虑不同控制方式的MMC闭环阻抗数学简化仿真模型,包含交流侧阻抗模型和直流侧阻抗模型;根据基于奈奎斯特判据的阻抗分析法研究了MMC交、直流侧的稳定机理;提出了一种基于数据驱动的振荡稳定性分析方法,即基于快速模型的结果利用全局灵敏度算法分析影响MMC振荡稳定的关键参数,并根据灵敏度分析结果,提出振荡抑制的参数调整策略。在MATLAB/Simulink中建立的MMC模型验证了方法的有效性。