DC Impedance Modeling and Stability Analysis of VSC with Consideration of Grid Impedance

This paper investigates the dc impedance modeling and stability analysis of voltage source converter (VSC) with consideration of grid impedance. Based on the developed impedance model, the parameter impact analysis is made and the influence of grid impedance and phase-locked loop (PLL) on dc impedance is revealed. In addition, this paper uses a resistance-inductance-capacitance (RLC) equivalent vector diagram to analyze the dc stability issue, and a virtual capacitor based active damping method is adopted to suppress the oscillation. Simulation results are given to validate the impedance model and stability analysis.