Ripple Power Mitigation in Single-phase PV Systems: An Innovative Active Power Decoupling Approach Using BESS

Existing methods for active power decoupling in a single-phase photovoltaic (PV) system with battery storage (PSBS) often rely on large electrolytic capacitors to handle the inherent power difference at twice the grid frequency. However, the use of such capacitors inevitably reduces device reliability and power density. A novel active power decoupling (APD) method is introduced based on a shared battery energy storage system (BESS) for a single-phase PSBS without additional power switches or passive storage components. A feedforward control strategy is proposed to ensure that the BESS fully absorbs the inherent ripple power, which significantly reduces the capacitance of the DC link while maintaining sufficiently low ripple in the DC bus voltage. Using the BESS for APD and power regulation leads to a notable decrease in the size of the electrolytic capacitors required at the DC link. Simulation results align closely with the theoretical analysis results and are experimentally verified using a 1-kW single-phase PSBS prototype. The results demonstrate the successful mitigation of second-order ripple power with the proposed APD method.