Smart Hybrid Energy Storage for Stand-alone PV Microgrid: Optimization of Battery Lifespan through Dynamic Power Allocation

In islanded microgrid system, the battery tends to be the most vulnerable element in terms of durability. Poorly managed battery charge/discharge process is one of the main life-limiting factors. To improve the battery life, a novel energy storage system topology and a power allocation strategy are proposed in this paper. A standalone 6kW Photovoltaic (PV) microgrid system with hybrid energy storage that combines battery and supercapacitor (SC) is considered. The performance of the proposed system is evaluated via model simulation using Matlab/Simulink. The system is simulated under a typical 24-hours residential load profile and the results demonstrated that the proposed system can provide sufficient power to regulate the fluctuations in supply and load whilst maintaining optimal batteries charged / discharged rate. The batteries were also operated under a low depth-of-discharge which prolongs the battery lifetime.