Decentralized Method for Load Sharing and Power Management in a PV/Battery Hybrid Source Islanded Microgrid

This paper proposes a new decentralized power management and load sharing method for a photovoltaic based islanded microgrid consisting of various PV units, battery units and hybrid PV/battery units. Unlike the previous methods in the literature, there is no need to communication among the units and the proposed method is not limited to the systems with separate PV and battery units or systems with only one hybrid unit. 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 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 consisted of three units.