Minimized Operational Cost and Enhanced Battery Life in Solar, Battery and Building Integrated EV Charging Station

A reduction in operating cost of electric vehicle (EV) charging station will accelerate the development of EV charging infrastructure. In this paper, an intelligent optimal energy management algorithm is developed to minimize the operating cost of EV charging station. An EV charging station integrated with solar generation, battery energy storage system (BESS) and a building is considered. A diesel generator (DG) is used during unavailability of renewable generation and grid supply. The DG is operated at maximum efficiency by controlling the operating point with help of BESS. For implementing the energy management strategy, the state of charge (SoC) of battery needs to be known accurately. The life of battery depends on variation of its SoC. Battery management system (BMS) must accurately estimate battery SoC to get maximum battery life. As the capacity of battery degrades over time, the updated battery state of health (SoH) is essential for accurate SoC estimation. Simultaneous and real time estimation of battery SoC and SoH algorithm is also developed for the battery management system used in BESS. This algorithm can also be easily used in EVs for improving their battery life. The BMS with accurate SoC estimation is implemented in a building integrated with solar, BESS and DG in India. The results of the implementation are discussed and used for validating the performance of the optimal energy management strategy developed. Further simulation studies are performed with EV charging station integrated in the building and effectiveness of the algorithm is discussed.