Design and Simulation of a Grid-Connected Two-Stage Bidirectional Converter for a Combined PV-Stationary Energy Storage System

This paper investigates the use of a single-phase, two-stage power converter for interfacing the grid with a lithium-ion battery storage system for building-integrated PV (BIPV) applications. It can be used to mitigate the main power quality issues associated with grid integration of renewables: voltage harmonics across the local load and harmonics in current injected into the grid by the distributed generation inverter. In the system, the bidirectional grid-tied AC/DC and DC/DC converters sharing a common DC-link are used to charge and discharge the battery storage system while meeting the power quality requirements from the IEC Standard 61727 and as well as IEEE Standard 1547-2003. Firstly, the power converters’ mathematical models are described. The feedforward decoupling scheme is applied to control the DC-link voltage for the AC/DC converter. The proportional-integral (PI) and proportional resonant (PR) controllers are designed for voltage and current control stages, respectively. Additionally, the cascaded PI controller is applied to control the voltage and current of the battery pack. The system simulation model for a 10kW converter is implemented in MATLAB/Simulink for a grid-interfaced 50kWh Li-ion battery storage system. The simulation results are analysed and reported to evaluate the performance of the model and the performance of the applied control method. Moreover, the results are compared with the state-of-the-art research work to validate the improvement in similar applications.