Transient Stability Analysis and Improvement of Multi-paralleled Power Conversion System Based on the Lyapunov’s Direct Method

The objective of this study is to analyze the transient stability of a multiparalleled grid-forming (GFM) power conversion system (PCS) under grid fault conditions. In this study, Lyapunov’s direct method is employed to characterize the stability region of a multi-parallel power conversion system. Based on this characterization, the influence mechanism of control parameters on the transient stability is systematically analyzed. Subsequently, a transient switching strategy is proposed to modify the conventional reactive power control loop (RPCL) in the GFM control, with the aim of enhancing the transient stability of the system. By constructing a GFM-PCS simulation model, the results indicate that the proposed method not only suppresses the divergence of the power angle, but also mitigates the oscillations in angular frequency, thereby improving the transient stability of the system during the grid fault condition. This study provides a novel scheme on analyzing the transient stability of multi-paralleled PCS. It also demonstrates the potential for enhancing transient stability through the reconstruction of RPCL, offering a new perspective for improving the transient performance of such systems.