Dynamic Impedance Modeling and Stability Analysis of Grid-Forming and Grid-Following Converters

With the increasing proportion of renewable energy and power electronic equipment in power systems, the problems of broadband resonance and harmonic stability caused by the dynamic interaction between grid-connected inverters and the power grid become increasingly prominent. The dq impedance method based on a small signal model in the frequency domain in a synchronous rotating coordinate system is an effective tool for studying broadband harmonic resonance in a three-phase inverter grid-connected system. Given the lack of physical significance of the frequency-domain stability criterion and its derivative methods for the multi-input-multi-output system, In this paper, the dq impedance model of the grid-connected inverter is applied to small signal modeling and equivalent circuit construction of the grid-connected system, dynamic impedance modeling and stability analysis are carried out. Stability tests were carried out on the Simulink simulation to verify the validity of the stability analysis method.