Research on charging/discharging control strategy of battery-super capacitor hybrid energy storage system in photovoltaic system

The power of photovoltaic (PV) system is greatly influenced by the natural environment factors, contributing to poor power supply reliability and voltage quality, while energy storage system can solve this problem effectively. Hybrid energy storage system combines the characteristics of the battery with larger capacity, medium power and fewer charge/ discharge times and the super capacitor with the characteristics of larger power density, smaller capacity and long cycling life, realizing complementary advantages of battery and super capacitor in operation. The storage system is controlled by power electrical converters to charge or discharge in harmony, which guarantees the quality of the PV energy, improves the overall performance of the energy storage system, extends the operation life of the energy storage system and reduces the costs of PV power. The paper adopts double BUCK- BOOST DC/DC converters to form a power bi-directional power transmission control circuit of hybrid energy storage system. The circuit controls the charging and discharging operation of battery and super capacitor orderly, and realizes the high-quality control of DC bus voltage of PV system.