Current Limiting Methods for Grid-Forming Converters: Uniting Current Saturation and Virtual Impedance Approaches with Enhancements

Grid-forming (GFM) power converters are considered to play a crucial role in future power systems. They will increasingly take over the tasks of synchronous generators (SGs), such as voltage and frequency regulation and grid stability. GFM converters require power measurements as control feedback. Current limitation thus has a profound impact on the control. Prolonged faults may cause loss of synchronizm, if current limitation is not accounted for. This work therefore focuses on developing a current limitation for balanced and unbalanced faults that minimizes the post-fault resynchronization time.