Fuzzy droop control loops adjustment for stored energy balance in distributed energy storage system

The study of isolated AC microgrid has been under high interest due to the integration of renewable energy resources especially for remote areas, or to improve the local energy reliability. The current trend is oriented to distributed renewable energy sources and their corresponding energy storage system, in order to smooth the variations at the prime energy generator. In this paper, a decentralized strategy based on fuzzy logic is proposed in order to balance the state of charge of distributed energy storage systems in low-voltage three phase AC microgrid. The proposed method weights the action of conventional droop control loops for battery based distributed energy storage systems, in order to equalize their stored energy. The units are self-controlled by using local variables, hence, the microgrid can operate without communication systems. Frequency and voltage bus signaling are used in order to coordinate the operation of the microgrid under different stages for charging batteries. Simulation results show the feasibility of the proposed method.