Transient Behavior of Grid-Forming Converters During Phase Jumps

GFM converters could misinterpret phase jumps as rms voltage or frequency variations, leading to the misbehavior in phase jump response. This paper reveals that the behavior of GFM converters during phase jumps can be classified into three typical modes of transient responses: fast recovery, slow recovery, and loss of synchronism. The operational boundary between the three phase jump modes is correlated to the relationship between the actual phase jump angle and its critical value (namely the phase displacement between the normal operating point and the unstable equilibrium point). Influencing factors of the critical angle are identified based on transient stability analysis that incorporates the impact of current limiting design as well as the couplings between active/reactive power controllers. The stability analysis provides guidelines for developing grid specifications and testing requirements of phase jump responses of GFM converters. All given analysis is experimentally verified in a GFM converter system under different phase jump scenarios.