考虑暂态模式切换的构网型变换器并联跟网型变换器系统暂态稳定性分析

In the hybrid system consisting of a grid-following voltage source converter (GFL-VSC) and a grid-forming voltage source converter (GFM-VSC), the complex transient interactions make it a challenge to keep the system operating safely and stably. Therefore, it is crucial to clarify the dynamic coupling mechanism between the converters and the effect of the coupling mechanism on the transient stability of the system. The current limiting measure taken in the GFM-VSC leads to the switching of its transient operation mode, which further increases the complexity of the coupling mechanism between the GFM-VSC and the GFL-VSC. To reveal the dynamic coupling mechanism between the GFM-VSC and the GFL-VSC during the transient operation mode switching and the effect of this coupling on the fault recovery process of the GFM-VSC, this paper first establishes a transient coupling model of the hybrid system considering the current limiter of the GFM-VSC. Based on this model, the influence of the parameters of the GFL-VSC on the operation mode switching of the GFM-VSC during the fault and after the fault clearance is analyzed. Then, the operation mode switching process of the GFM-VSC after fault clearance is analyzed in detail for different degrees of grid voltage sag, so as to obtain the critical conditions for successful restoration to normal operation mode in hybrid systems. Finally, the simulation model of the hybrid system is constructed to verify the correctness of the theoretical analysis in this paper.