Power-frequency admittance model of multi-VSGs grid-connected system considering power coupling

The high penetration of renewable energy decreases the inertia of power systems. The virtual synchronous generator (VSG) control technology has good inertia compensation effect and has attracted considerable attention because of the similar external characteristics of synchronous generators. However, the power and frequency oscillation of multi-VSG grid-connected systems seriously threatens the stability of power system. Existing multi-VSG power frequency admittance (PFA) models ignore the power coupling caused by the large line impedance ratio in medium- and low-voltage microgrids, and the accuracy of these models needs improvement. Thus, this study aims to establish a multi-VSG grid-connected PFA model considering power coupling. The influence of power coupling on model accuracy is analyzed, and the impacts of line impedance and reactive loop coefficient on the power-frequency response characteristics are investigated. Simulation results verify that the proposed model has higher accuracy over existing models.