High penetration of inverter-based power sources with VSG control impact on electromechanical oscillation of power system

The virtual synchronous generator (VSG) provides a promising solution to integrate a high penetration of inverter-based sources into the power system without threatening the frequency and voltage stability, which may solve the problem that the traditional maximum power point tracking (MPPT) control cannot provide the necessary ancillary. Due to different design principles, the impact of the VSG on the power system may be quite different compared with the traditional synchronous generators (SGs). This paper aims to study the impact of replacing SGs with VSGs on the electromechanical oscillation of the power system. It starts with the comparison of modeling between VSGs and SGs and establishment of a general small-signal model representing both the SGs and VSGs with frequency and voltage regulation. Accordingly, a comprehensive small-signal analysis is executed in details in order to study the changing of electromechanical dynamics. Finally, simulation results in Matlab/Simulink verify the analysis. It shows how the states of a VSG will influence the electromechanical oscillation by changing the participation factors in those modes.