An islanding microgrid reactive power sharing scheme enhanced by programmed virtual impedances

This paper proposes an improved power control approach to address the load sharing problems in islanded microgrids. The proposed method first estimates distributed generation (DG) unit feeder impedances through measuring low order point of common coupling (PCC) harmonic voltages and DG unit line harmonic currents. With the knowledge of feeder impedances, reactive power sharing performance can be enhanced by the regulation of DG unit output virtual impedance. The proposed method realizes accurate real and reactive power sharing in proportion to DG unit rated power. Simulated and experimental results from a single-phase microgrid are provided to validate the feasibility of the proposed method.