Decentralized Method for Load Sharing and Power Management in a Hybrid Single/Three-Phase-Islanded Microgrid Consisting of Hybrid Source PV/Battery Units

This paper proposes a new decentralized power management and load sharing method for a photovoltaic (PV)-based, hybrid single/three-phase-islanded microgrid consisting of various PV units, battery units, and hybrid PV/battery units. The proposed method is not limited to the systems with separate PV and battery units, and power flow among different phases is performed automatically through three-phase units. The proposed method takes into account the available PV power and battery conditions of the units to share the load among them. To cover all possible conditions of the microgrid, the operation of each unit is divided into five states in single-phase units and seven states in three-phase units and modified active power-frequency droop functions are used according to operating states. The frequency level is used as trigger for switching between the states. Efficacy of the proposed method in different load, PV generation and battery conditions is validated experimentally in a microgrid lab prototype consisting of one three-phase unit and two single-phase units.