Transient Stability Analysis of WTs Based on VSG-PMSG Considering the Machine-Side Dynamics

Wind turbines (WTs) using virtual synchronous generator (VSG) technology can effectively improve the voltage/frequency support capability of power grid. But it also brings complex transient stability problems due to dynamic interaction between machine-side and grid-side. In this paper, the transient stability of WTs based on permanent magnet synchronous generator with VSG control (VSG-PMSG) is investigated considering machine-side rotor dynamics. The transient model of VSG-PMSG is first established and then the dynamic response of the VSG-PMSG under frequency fluctuation is analyzed. And excessive damping coefficient or severe frequency drop will increase the risk of synchronous instability of the VSG-PMSG. Moreover, the transient characteristics of VSG-PMSG under voltage drop have also been studied. And the machine-side dynamics will reduce the transient stability margin of VSG-PMSG by changing the acceleration and deceleration area. Finally, the time-domain simulations based on MATLAB/Simulink are given to verify the correctness of the stability analysis.