Bidirectional power flow control of grid to battery and battery to grid systems for Energy Storage application of Microgrids

Solar and wind energy are highly intermittent and difficult to match with user’s demands. Within this context, energy storage, especially the battery energy storage system, has been recognized as a key technology to address such intermittency and to facilitate the future penetration of renewables sustainably. Due to light-weight and high energy density, the lithium-ion battery is taking a large portion of the actual storage device’s role in grid and electric vehicle application. This work develops a bidirectional power flow control for the single-phase grid to lithium-ion battery and vice versa. The proposed system is initially developed in MATLAB Simulink and a laboratory prototype is constructed to verify the results experimentally. A full bridge converter system based on SiC-MOSFET switches is utilized. Quadrature transport delay and phase synchronization technique are used to transform the single-phase time varying stationary signal into the time invariant dq rotating signal. The charging and discharging current controller of grid connected battery is developed in dq frame. The current controller results in smaller overshoot, almost zero steady-state error, and rapid tracking. The experimental and simulation results are found to be in good agreement.