A Self-Adjusting Droop Control Strategy to Improve Reactive Power Sharing in Islanded Microgrid

In this paper, a self-adjusting nominal voltage based modification in the Q - V droop control has been proposed to improve the reactive power sharing amongst distributed generation sources in an islanded microgrid. This is achieved by coupling the nominal voltage calculation with the system frequency, which has an effect of driving the voltage references of all the distributed generators in such a manner so as to improve the network-wide reactive power sharing. An appreciable improvement in reactive power sharing is achieved by using adaptive nominal voltage as compared to fixed nominal voltage. The proposed method neither depends on data exchange among sources nor does it need feeder impedance information. In addition, it is able to improve the sharing in cases of loads located locally or at a distance. The improvement in reactive power sharing does not compromise on voltage magnitude. The viability of the controller has been confirmed from detailed simulation studies and experimental validation on a laboratory prototype.