Grid-connected Lithium-ion battery energy storage system for load leveling and peak shaving

Load leveling, peak shaving and power demand management are major applications of a grid-connected battery energy storage system (BESS), especially in an autonomous power network. Lithium-ion BESS has started to become one of the most popular options of energy storage systems due to its high charge/discharge efficiency and significant energy density. This paper presents a current control scheme for Lithium-ion BESS that utilizes the state of charge (SOC) of the batteries to satisfy system operation constraints. The output signal of the proposed current loop controller is fed to the PWM generator block to produce the gating signals for the converter semiconductor switches. The control algorithm considers the active and reactive grid reference signals as long as the battery state of charge (SOC) is within the designated upper and lower limits. Detailed simulations are performed and analysed for typical operating conditions with BESS absorbing/injecting power from/to the grid, as well as large active power commands beyond the capability of the battery. Simulations are aimed to investigate the steady-state and transient performances of BESS responses while displaying minimum overshoot.