Triple-harmonic-droop control strategy for accurate harmonic power sharing in low-voltage islanded microgrids

Abstract

This paper proposes a power sharing control scheme for power electronics interfaced distributed generation to attain accurate harmonic power dispatch as well as unbalanced power sharing. The proposed controller is composed of two main blocks: 1) a harmonic power sharing unit, which leads to an accurate harmonic power sharing, and 2) individual triple-droop control units separately applied to the control unit of each phase, which properly provide unbalanced power sharing. For this purpose, a virtual harmonic conductance concept is developed to control the inherent impedance of the inverter under non-linear load conditions. As a result, the fundamental power sharing performance as well as the harmonic power dispatch accuracy is ensured. Simulation results from an islanded microgrid prototype using the CIGRE low-voltage distribution network are provided to validate the effectiveness of the proposed method.