A Cascaded Multi-Port Converter with Energy Storage Units for Large-scale Photovoltaic Systems

The integration of photovoltaic (PV) power into the grid by inverting after DC boosting has become the main method for large-scale PV power plants. However, increasing the capacity, efficiency, and conversion ratios of grid-connected PV converters present major challenges. To tackle these challenges, this paper proposes a new converter topology consisting of an arm multiplexing multiport inverter (AMMI), an input-paralleled and out-isolated (IPOI) DC-DC converter, and distributed energy storage units (ESU). In this proposed topology, The AMMI improves sub-module utilization from 50% to 66.7%, while the medium-frequency DC/DC converter isolates and steps up the voltage, and the ESU balance the power flow of the system. The proposed converter can transmit PV power to the grid in two ways. Moreover, the control scheme of the converter is proposed in detail. Based on the simulation results, it is evident that the converter performs well in both steady-state and transient conditions.