Dynamic Coupling Mechanism Analysis Between Voltage and Frequency in Virtual Synchronous Generator System
Huijie Cheng, Chang Li, Amer M. Y. M. Ghias, Frede Blaabjerg
Abstract
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.