Transient Stability Analysis of Grid-Forming Converters With an Elliptical Current Limiter Under Asymmetrical Grid Faults

Under asymmetrical faults, analyzing the transient stability of grid-forming voltage-source converters (GFM-VSCs) becomes essential because their behavior fundamentally differs from that under symmetrical faults. In particular, the point-of-common-coupling voltage of a GFM-VSC contains both positive- and negative-sequence components, and the interaction between these components generates a non-negligible negative-sequence-driven active power. However, the transient stability of GFM-VSCs under asymmetrical faults has not been sufficiently investigated, and the influence of negative-sequence-driven active power remains unclear. Accordingly, this letter derives the$P$-$\delta$curve of a GFM-VSC with an elliptical current limiter under asymmetrical faults by explicitly accounting for negative-sequence effects. This enables a more accurate transient stability assessment when extending convent…