An Enhanced Droop Control Strategy for Accurate Reactive Power Sharing in Islanded Microgrids

This paper is focused on power sharing among distributed generation (DG) units in islanded microgrids. Due to the unmatched feeder impedances, the conventional droop control strategy is unable to accurately allocate the output reactive power of DG units in proportion to their power ratings. To address this issue, an enhanced droop control strategy is proposed. A first controlled voltage source (FCVS) is inserted into the conventional droop control loop to compensate the feeder voltage drop. Besides, considering that the droop control inevitably leads to the voltage and frequency deviations of common AC bus when load varies, a secondary regulation is supplemented to recover the deviated variables to the rated values. As a result, the effects of unmatched feeder impedances are eliminated, and the accurate power sharing among DG units is realized. Simulations based on Matlab/Simulink have been carried out to verify the effectiveness of the enhanced droop control strategy.