An Improved Reactive Power Sharing Method for an Islanded Microgrid

 Conventional droop control is widely used for achieving proportional power sharing in islanded microgrids. The active power sharing becomes proportional to the ratings of the inverters by applying the conventional droop control. However, reactive power sharing is not proportional because of resistive feeder impedance, unequal feeder lengths, and asymmetric load distribution in the network. In this article, an existing control strategy that has been proposed for improving reactive power sharing is enhanced by removing its dependency on communication. The required synchronization for executing the correction is generated by each inverter locally using a load change detection algorithm. This modification also makes the original control strategy immune to load changes happening during the correction process. An almost accurate reactive power sharing is achieved by applying the proposed modification even for highly resistive networks. Also, a tradeoff required in tuning the controller gain is discussed. The efficacy of the proposed modification has been validated by performing detailed simulation studies and by carrying out exhaustive experimental studies on a laboratory prototype.