Analysis of Power Swing Characteristics of Grid-Forming VSC System Considering the Current Limitation Mode

This paper investigates power swing characteristics of grid-forming (GFM) voltage source converter (VSC) systems with the current limitation mode in both non-inertial and inertial GFM-VSC systems. Following grid faults, non-inertial GFM VSC systems can re-synchronize with the grid. Still, they may experience significant power swings driven by their control dynamics. In contrast, inertial GFM-VSC systems may exhibit loss of synchronization (LOS), characterised by the divergence of the control-dependent angle from the active power control loop. These behaviours differ from those of conventional synchronous generator (SG)-based systems, in which power swings are typically characterized by physical angle deviations among power sources. Based on these findings, this paper examines the performance of traditional impedance-based swing-detection schemes in GFM-VSC systems. The theoretical analysis is validated through simulations covering both single- and multi machine systems.