PNNL

Abstract

The critical clearing time is a crucial parameter for assessing the large-signal stability of grid-forming inverters. Variations in current limiters can notably affect the inverter’s transient behavior during large disturbances. This letter introduces a power-angle relationship-based method to evaluate the fault recovery of a droop-controlled grid-forming inverter under a three-phase bolted fault scenario, considering circular current limiter and virtual impedance method. Analytical formulas are presented to estimate the critical clearing time of the grid-forming inverter. High-fidelity simulations are performed to validate the efficacy of the proposed approach in estimating the critical clearing time of the grid-forming inverter.