An Optimal State of Charge Feedback Control Strategy for Battery Energy Storage in Hourly Dispatch of PV Sources

The effects of intermittent cloud and changes in temperature cause a randomly fluctuated output of a photovoltaic (PV) system. To mitigate the PV impacts particularly on a weak electricity network, battery energy storage (BES) system is an effective means to smooth out the power fluctuations. Consequently, the net power injected to the electricity grid by PV/BES systems can be dispatched smoothly such as on an hourly basis. This paper presents an improved control strategy for a grid-connected BES for mitigating PV farm output power fluctuations. A feedback controller for state of charge is proposed where the control parameters are optimized using genetic algorithm. In this way, the optimal size for the BES is also determined to hourly dispatch a 1.2 MW PV farm. The effectiveness of the proposed control scheme is evaluated using PSCAD/EMTDC-based simulation.