Battery energy storage system for PV output leveling based on bidirectional isolated DC-DC converter

A photovoltaic (PV) system has a variable power output that depends on solar irradiance level and ambient temperature. This will be an issue when there is a massive penetration of PV in the future. Therefore, an energy storage system is indispensable to compensate the problem of PV output fluctuations. Battery energy storage system (BESS) employing power electronic converters can be used for compensating the fluctuating PV power. This paper proposes a 2-kW full-bridge bidirectional isolated dc-dc converter that is employed in a BESS with PWM converter for PV output power leveling. This paper also presents a current controller using the DQ synchronous reference frame for regulating voltage at the high-voltage dc side, and a bidirectional power flow control for controlling the output power of the BESS to ensure that the power that is injected to the point of common coupling (PCC) is leveled at 2 kW. The performance of the system is confirmed with PSCAD simulation.