Operational limits and P-Q capability diagram analysis of grid-forming converters in weak grids

This paper investigates the P-Q curve characteristics of grid-forming converters, highlighting their unique constraints from semiconductor properties and grid conditions, unlike the thermal and magnetic limitations of synchronous generators, which are critical for compliance with grid codes. It examines the impact of control strategies, particularly fixed virtual impedance, across varying grid strengths. The results show that while the P-Q curve typically appears circular, it can deviate significantly under certain conditions, forming non-convex regions.