  Grid forming control applied to power converters that interface storage or
renewable generation to the power grid, has been identified as a potential
solution to facilitate a substantial share of converter-based renewable
generation in the power system. Analyzing the response of grid forming
converters (GFC) for large frequency, phase, and voltage events, particularly
when the GFC enters the current limit operation, is very important for system
stability, but studies on this have been limited. This paper presents a
quantitative and illustrative analysis of the impact of the current limit in
GFC on the transient stability of a system comprising of GFC. Furthermore, a
solution based on virtual active power is proposed to improve the transient
stability margin of the GFC when the GFC enters the current limit. Finally, the
analysis and the proposed method to enhance the transient stability are
verified by Power hardware in the loop (PHIL) experimental tests.
