Modified Adaptive Virtual Impedance Method to Compensate Mismatched Line Impedances in Microgrids

Under mismatched line impedance conditions, reactive power sharing performance of droop control tends to be barely satisfactory for the absence of sharing accuracy. Therefore, to realize accurate reactive power sharing of parallel-connected inverters in microgrids, a modified adaptive virtual impedance method is proposed in this paper. Through this method, appropriate virtual impedance of DG units could be obtained to compensate the mismatched line impedances, and extra information from PCC voltage, line impedance or other inverters is not needed. After the compensation, reactive power could be shared naturally and accurately with no impact on voltage regulation. Finally, the effectiveness of proposed method is verified by simulation and experimental results.

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