Hybrid energy storage for large PV systems using bidirectional high-gain converters

The increasing installation capacity of large-scale photovoltaic (PV) systems requires higher power-rated converters and connection at a higher voltage level at the point of common coupling (PCC). Additionally, the inherent intermittency of the solar irradiation affects both transient- and steady-state operation of these PV systems. This paper proposes a large-scale PV system based on high-gain interleaved (HGI) converters and a hybrid energy storage system (HESS). The HESS consists of batteries and supercapacitors: the supercapacitors are used to smooth the high-frequency fluctuations of the PV output power, and the batteries are employed to balance the power difference between the PV array and the load demand. Bidirectional high-gain (BHG) converters are used as chargers for the HESS. Thus the relatively low voltage of the energy storage systems can be boosted to higher values required by the inverter DC bus. High-gain interleaved converters are used to connect the PV arrays to the inverters. The power and voltage ratings of the high-gain converters can be increased by using interleaved configurations. Simulation results are presented to validate the performance of the proposed PV system configuration.