Cascading Synchronization Instability in Multi-VSC Grid-Connected System

Abstract

In this letter, a cascading synchronization instability phenomenon is reported in a multi-voltage-source-converter (VSC) grid. By adopting the equal area criterion, it is revealed that during the fault transient, there is static interaction that increases equivalent mechanical power for the original stable-operating VSC. Due to the fast power angle swing of the unstable VSC, there is nonnegligible dynamic interaction, which may decrease its synchronization stability margin. The effect of system parameters on synchronization stability is studied, and the simulation and experimental results verify the analysis.