Power Dynamic Modeling and Synchronous Frequency Resonance Analysis of Multi-VSGs Grid-Connected System

The synchronous frequency resonance (SFR) research on a single VSG grid connected system has been widely conducted. However, the situation where multiple VSGs are connected in parallel is more common actually. Currently, there is insufficient research on multi-VSGs grid-connected system. The interaction among VSGs affects the characteristics of SFR. On this basis, a single VSG power loop model is first established with power reference input and power output in this paper. Then, a power dynamic model considering interaction characteristics is established, where output impedance model is introduced. On this basis, the generalized Nyquist criterion (GNC) is adopted to analyze the stability of the model. Simulation results are finally provided to verify the accuracy and effectiveness of the proposed model and the stability analysis.