Transient Stability Analysis and Control Improvement of VSG-VSC System Considering Current Limitation

The transient stabilization of the virtual synchronous generator-voltage source converter (VSG-VSC) system with current limitation is analyzed in this paper. The adverse effect of the current limitation is revealed through both forward instability with a continuously increasing power angle and backward instability with a continuously decreasing power angle. On this basis, the low-pass filter (LPF)-based power angle feedback control is proposed to improve transient stability and eliminate adverse effect of current limitation through the dynamic regulation of the active power, which avoid power swing during fault occurrence. The effectiveness is validated by the phase trajectory method based on the nonlinear state space model. The key parameters are designed based on the critical clearing angle (CCA) and the critical clearing time (CCT) after the fault occurs. In addition, the application of the proposed control in the multi-VSG (MVSG) system is validated by the energy function. Simulation and experimental analysis are performed to verify the correctness of the theoretical analysis and the effectiveness of the proposed control strategy.