Equivalent Impedance Modeling and Stability Analysis of MMC-HVDC with Wind Farm

Abstract

The risk of resonances may exist in the power electronic transmission systems composed of wind farm (WF) and the high-voltage direct-current system consisting of modular multilevel converter (MMC-HVDC). And the oscillation frequency will show coupling characteristics. The frequency dynamic interaction effect causes the WF interconnected with MMC-HVDC system exhibit multiple-input multiple-output (MIMO) characteristics. The stability determination of the system will become very difficult. Therefore, using frequency dynamic interaction effect as one of the constraints, this paper uses the harmonic state space (HHS) method to establish the two-dimensional impedance model of the wind farm side MMC(WFMMC) and the grid-side converter (GSC) of the wind farm, and further an accurate dimensionality reduction method is proposed. Finally, the results of the simulation system built based on MATLAB/Simulink verify the accuracy of the established impedance model and show that using the established model for stability analysis can obtain more accurate analysis results.