Reactive Power Sharing in an islanded microgrid

For a coordinated integration of the increasing amount of distributed generators in the distribution network, the microgrid has been presented. For the islanded operating condition of the microgrid, the conventional approaches for grid control are no longer applicable as the microgrid characteristics differ significantly from those of conventional power systems. Therefore, in this paper, the reactive power control by means of a reactive power/frequency droop control strategy is studied in an islanded microgrid. The active power on the other hand, is controlled by using a droop control strategy of the dc-bus voltage to the grid voltage amplitude. It is shown that the combination of the aforementioned control methods gives good results concerning reactive power sharing and avoidance of circulating currents. Also, a reactive power limiting procedure is incorporated in the droop controller.