GFM-GFL变流器并联系统暂态同步稳定性分析与提升方法OA

In the parallel system consisting of grid-forming(GFM)and grid-following(GFL)converters,the complex transient interaction mechanisms pose significant challenges to the transient synchronization stability of the system.To investigate the transient synchronization stability mechanism and its enhancement methods for the parallel system with GFM-GFL converters,a voltage-phase angle transient stability surface for the parallel system is first constructed,thereby the influence mechanism of phase angles for two types of converters on bus voltage transient stability is revealed.Subsequently,by considering the difference in synchronization modes and their influence patterns on bus voltage,the transient synchronization stability criteria and critical stability boundaries are derived.Furthermore,the transient stability surface is employed to delineate the transient stability region of the individual converters and the parallel system,and the influence of the GFM converter reactive power control loop on the system transient synchronous stability is analyzed accordingly.On this basis,a virtual capacitor control strategy is proposed with the bus voltage as the compensation target,which effectively supports the bus voltage during faults by releasing the reactive power potential of the GFM converter.Finally,the correctness and effectiveness of the theoretical analysis and proposed strategies are verified through experiments.