In this paper, an improved load sharing strategy is proposed for distributed generation units (DGs) connected in a microgrid. Conventional frequency and voltage droop control result in unacceptable active and reactive power sharing. The proposed method formulates a suitable algorithm for load sharing in the islanded microgrid. The feeder power loss and the line impedance voltage drops are minimized so as to regulate the voltage at the point of common coupling (PCC) at its nominal value. The desired DG output voltages are calculated and a linear relationship is obtained between the shared active and reactive powers and the DG output voltages. A master DG controller sets the frequency which is followed by other DG units. The reference powers for the DG units are adjusted so as to maintain the rated PCC voltage. The proposed strategy is verified taking into account the DG ratings, unequal line impedance drops, feeder losses, change in system impedance and effect of DG local loads and formulates an improved power sharing strategy that also facilitates PCC voltage regulation under variable loading conditions. Simulation and experimental results are presented to verify the effectiveness of the proposed method.
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