A New Control Strategy for Voltage Restoration and Voltage Unbalance Compensation in an Islanded Droop-Controlled Microgrid

Abstract

Low voltage microgrids including sensitive loads often face unbalanced load conditions. Therefore, a compensation procedure should be carried out in order to balance and restore sensitive load's voltage. In this paper, an effective voltage control strategy has been proposed for the autonomous operation of microgrids, under unbalanced load conditions. The proposed strategy balances single-phase sensitive loads by compensating the unbalanced voltage drop of the impedance between the outputs of Distribution Generation (DG) to the Point of Common Coupling (PCC). In addition, this scheme has also shown to be capable of restoring sensitive loads' voltage to nominal values. This method also shares the active and reactive load accurately between Distribution Generation (DG) units, based on their capacity. In order to evaluate the performance of the proposed control strategy, several simulations have been conducted under various states in an islanded microgrid prototype. Obtained simulation results demonstrate the effectiveness of the proposed control strategy in compensation of unbalanced load voltage and voltage restoration.