Second order harmonics reduction technique using model predictive control for household energy storage systems

This paper proposes an output current ripple reduction algorithm using model-based predictive control (MPC) for an energy storage system (ESS). In single-phase systems, the DC/AC inverter has a second-order harmonic at twice the grid frequency of a DC-link voltage caused by pulsation of the DC-link voltage. The output current of a DC/DC converter has a ripple component because of the ripple of the DC-link voltage. The second-order harmonic adversely affects the battery lifetime. The MPC predicts the output current of next state from a converter model. The optimal duty is determined by minimizing the error between the reference and the predicted current. Due to the calculated optimal duty, the dynamic response is fast. The proposed algorithm has an advantage of reducing the second-order harmonic of the output current in the variable frequency system. The proposed algorithm is verified from the PSIM simulation with the 3 kW ESS model.