Modeling for Oscillation Propagation with Frequency-Voltage Coupling Effect in Grid-Connected Virtual Synchronous Generator

This letter proposes a modeling method for mechanism clarification on oscillation propagation in grid-forming virtual synchronous generator (GF-VSG) systems considering the frequency-voltage coupling effect. Specifically, the physical significance of oscillation propagation between frequency and voltage of VSG has been clarified by the proposed self-stability-loop-model and the induced-stability-loop-model. The proposed model and method can fill in the gap that conventional single-input-single-output system cannot identify this oscillation propagation phenomenon. It is also found that frequency oscillations are not always coupled with voltage oscillation especially when the oscillation propagation is suppressed. Finally, the modeling and analysis are validated by simulations and experiments.