Dynamic Coupling Mechanism Analysis Between Voltage and Frequency in Virtual Synchronous Generator System

This letter investigates the dynamic coupling mechanism between voltage and frequency in a virtual synchronous generator (VSG) system, where a unified model is proposed for the analysis of voltage stability, frequency stability and voltage-frequency coupled stability. The results show that voltage/frequency stability is impacted by both self- and coupled-dynamics. Moreover, voltage and frequency oscillate at the same oscillation frequency if the voltage-frequency coupled instability occurs. However, the frequency oscillation occurs while voltage magnitude maintains stability if voltage self-dynamics behaves a negative feedback effect. The time-domain simulation is performed to validate the rationality of the theoretical analysis.