Virtual impedance technology effectively prevents overcurrent in grid-forming converters during faults

but during the fault recovery stage

there’s a risk of current exceeding limits. This paper analyses this post-fault overcurrent mechanism and discovers that the converter’s overcurrent occurs only if the virtual impedance design value is higher than the grid’s impedance value. Under this condition

the increasing of virtual power angle is the main cause of overcurrent. Accordingly

this paper proposes a current safety control strategy that dynamically adjusts virtual impedance and power command values. This strategy restrains the output current within the safe range while ensuring transient power angle stability. Simulations and experiments confirm the correctness of theory and the effectiveness of proposed strategy.