A VSG-based Grid-Connected Photovoltaic Generation System with Hybrid Energy Storage

Photovoltaic (PV) generation stands out as a particularly auspicious renewable energy source, experiencing rapid expansion in scale. Nevertheless, PV generation is exceptionally susceptible to environmental conditions. To maintain the dependable functioning of the system, achieve power equilibrium among different generation units, and ensure high-quality output power, a hybrid energy storage system is utilized to alleviate fluctuations in the DC bus voltage. This article presents control techniques for the hybrid energy storage system and DC bus voltage in a PV system when operating in grid-connected mode. Battery and supercapacitor units, due to their complementary energy characteristics, are utilized to suppress the impact of PV power fluctuations on the DC bus when PV power undergoes sudden changes. Additionally, the use of virtual synchronous generators is employed to synchronize the system during grid connection, increasing the system's inertia. Simulation results demonstrate that the proposed strategies effectively and rapidly suppress DC bus voltage fluctuations, thereby enhancing the reliability and stability of the system.