Transient Stability Analysis and Coordination Control Design for Grid-Forming PMSG Based On Dynamics of DC-Link Capacitor

Large-scale integration of wind turbines (WTs) results in the reduction of the power system inertia and weakens the power grid strength. And permanent magnet synchronous generator(PMSG) with DC voltage self synchronization control, which utilizes the dynamics of the DC-link capacitor to realize gird-forming is an effective measure to solve these problems. However, the complex dynamics of WTs also make their stability characteristics unclear. To deal with these issue, this paper analyzes the transient characteristics of PMSG with DC voltage self synchronization control. The transient instability mechanism due to power imbalance between generator-side and grid-side of PMSG under current saturation is revealed. Further, a transient stability enhanced control strategy of PMSG based power coordination is proposed, which comprehensively considers the performance requirements of WTs such as DC voltage, frequency response, transient ride-through, etc., so that the wind turbine can achieve stable GFM operation. And the simulations by MATLAB/Simulink verify the effectiveness of the proposed strategy.