An Accurate Unbalanced Power Sharing Control Method for Islanded Three-Phase Four-Wire Microgrids

This paper addresses the critical power sharing challenges in islanded microgrids employing parallel three-phase four-wire grid-forming inverters, where feeder impedance mismatch severely compromises power sharing accuracy. A novel small-AC-signal (SACS) synchronization-based control method is proposed to achieve accurate unbalanced power distribution under unbalanced load conditions. The method establishes droop relationships between power components and SACS parameters, enabling adaptive virtual impedance adjustment equivalent to feeder impedance compensation. Distinctively, it simultaneously ensures accurate sharing of unbalanced power and positivesequence active power without requiring communication infrastructure or prior feeder impedance knowledge. Comprehensive simulation and experimental validation confirm effectiveness of proposed method.