Battery Degradation Aware Power Exchange in Grid-Integrated PV- Battery Assisted EV Charging Station

This paper presents a grid electricity price-aware algorithm for charging/ discharging of behind-the-meter battery energy storage system (BTM-BESS) in a building microgrid. An electric vehicle is connected at the point of common coupling which demands a constant load. A super-twisting sliding mode control is developed for the grid-interfacing bidirectional converter to keep DC link voltage within standard limits at varying solar irradiance. The degradation rate of BTM-BESS depends on its depth of discharge and temperature, and more degradation leads to increased maintenance and replacement costs. Therefore, the discharging events of the BTM-BESS should be minimized to reduce its cycle-life degradation. Based on the available power from renewable sources and the step-ahead grid electricity price, a power exchange algorithm is designed for optimized operation of the BTM-BESS. The system with the power exchange algorithm and associated control methods is validated by simulation in the MATLAB® Simulink platform.