Analysis of Low-Frequency Oscillation in Dual Virtual Synchronous Generators Parallel System

The virtual synchronous generator (VSG) enhances the inertia of power grid by simulating the dynamic characteristics of a synchronous generator. However, it could induce low-frequency oscillations in VSG power, similar to synchronous generators, threatening system stability. This paper proposes the mechanism of power low-frequency oscillations in dual VSGs parallel system. Firstly, the power system with loads and VSGs are modeled through the system state-space equations. Then, the rise time, peak time, overshoot, and settling time of the transmission power are discussed. Moreover, the parameters affecting power low-frequency oscillations are analyzed, including phase voltage amplitude, power level, line impedance, virtual inertia, and virtual damping. Finally, hardware experiments are conducted to validate the correctness of the theoretical analysis.