A control strategy for an island operated LV microgrid under unbalanced faults

This paper proposes an control strategy for the voltage control of an inner current-controlled distributed energy resource units (DERs) in an islanded microgrid to provide overcurrent protection under unbalanced faults. During the unbalanced voltage sag, even though the inner current-controlled limit the current magnitude, the peak phase current may still exceed the limit value. The control strategy scheme detects the fault, limits the phase current magnitude of the DER unit through changing the reference voltage, and restores the microgrid to its normal operating condition subsequent to fault clearance. Digital time-domain simulation studies, in the DIgSILENT/Power-Factory software environment, have demonstrated the feasibility and desirable performance of the proposed strategy.