Consensus-Based Distributed Control for Improving the Sharing of Unbalanced Currents in Three-phase Three-wire Isolated Microgrids

Abstract

This paper proposes a secondary distributed control strategy to achieve the sharing of unbalanced currents between 3-leg power converters, operating under droop control, in a three-phase three-wire isolated Microgrid (MG). To this end, a modified $Q$ - $E$ droop controller is used, where new control actions are defined to achieve the unbalanced currents sharing amongst the converters. These control actions are generated, in the secondary control level, by a consensus-based algorithm, where the consensus variables correspond to the single-phase reactive powers of the converters. This paper shows that sharing negative sequence current components amongst the power converters can be managed by achieving a consensus (per phase) of single-phase reactive powers. Extensive simulations demonstrate the excellent performance of the proposed controller.