Controlling Bidirectional Power Flow Of BESSs In DC Microgrids using Sliding Mode Controller

A sliding mode controller (SMC) is designed to control the bi-directional power flow (charging/discharging) of the battery energy storage system in a DC microgrid and its output is compared with a PID controller using MATLAB/Simulink. The controller is designed so that after meeting the load demand, the excess energy from renewable energy sources (RESs) can be stored by BESS and fulfil the need of load by feeding stored energy in case of insufficient RESs. The BESS is modelled with a DC-DC bi-directional converter where all battery parameters are constant. The controller is designed so that it uses the VMC of DC-DC bidirectional converter. Algorithms of sliding mode control (SMC) for buck and boost power converters are discussed in the paper. In both such cases, voltage control is shown. The proposed controller regulates the battery voltage in charging mode and output voltage in discharging mode. Sliding surface which is the function of error variable is assigned to the SMC and by using the sign function we created a correct control law. In addition, this proposed control technique is implemented based on PWM. At the end of paper simulations results are demonstrated and the results of the simulation obtained show the efficiency and robustness of the proposed control method.