High frequency resonance characteristics analysis of voltage-source virtual synchronous generator and suppression strategy

Abstract

The voltage-source virtual synchronous generator is a grid-forming type power electronic control technology and is able to support converters that have the ability of inertial, primary frequency and voltage regulation. Firstly, the authors build the small-signal model of the voltage-source virtual synchronous generator and conventional converters, compare and analyse the characteristics of the high-frequency resonance modes, the results show that the voltage-source virtual synchronous generator has almost the same high-frequency resonance characteristics as the conventional converter. Secondly, the different control parameters and power grid strength that affect the high-frequency resonance characteristic are analysed with eigenvalue, and the mechanism of voltage-source VSG that caused high-frequency resonance is derived. The leading factor that causes high-frequency resonance is power grid strengths, and the authors proposed introducing virtual impedance into the front-end channel of the current inner loop control strategy to suppress resonance for the voltage-source virtual synchronous generator based on the theoretical analysis with the small-signal model and eigenvalue analysis. In addition, the electromagnetic transient simulation model and RT-LAB controller-in-loop platform are built, and the simulation and experiment results indicate the effectiveness of the virtual impedance control strategy.