Transformer inrush current mitigation of GFM inverters in islanded microgrids

Transformer re-energisation in islanded microgrids dominated by Grid-Forming (GFM) inverters may result in severe inrush currents due to core saturation and residual magnetic flux, posing significant challenges to inverter overcurrent tolerance. This paper compares the effectiveness of a range of GFM-based inrush current limiting strategies under identical operating conditions using a saturable transformer model. The mitigation performance is quantitatively assessed in terms of peak inrush current, recovery time, and voltage drop during transformer re-energisation.