An Improved Reactive Power Sharing Method for Islanded Microgrid

Conventional droop control is traditionally used for achieving proportional power sharing in an islanded microgrid. 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 unequal line impedances and asymmetric load distribution in the network. In this paper, an existing control strategy which has been proposed for improving reactive power-sharing is enhanced by removing its dependency on communication. The required synchronisation for executing the correction is generated by each inverter locally by 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. Also, a trade-off 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.