An energy storage system using secondary batteries combined with advanced power control schemes is considered the key technology for the sustainable development of renewable energy-based power generation and smart micro-grids. The performance of energy storage systems in practical application mainly depends on their power conditioning systems. This paper proposes a silicon carbide-based multifunctional power conditioning system for the vanadium redox flow battery. The proposed system is a two-stage circuit topology, including a three-phase grid-tie inverter that can perform four-quadrant control of active and reactive power and a bi-directional multi-channel direct current converter that is responsible for the fast charging and discharging control of the battery. To achieve the design objectives, i.e., high reliability, high efficiency, and high operational flexibility, silicon carbide-based switching devices, and advanced digital control schemes are used in the construction of a power conditioning system for the vanadium redox flow battery. This paper first describes the proposed system topologies and controller configurations and the design methods of controllers for each converter in detail, and then results from both simulation analyses and experimental tests on a 5 kVA hardware prototype are presented to verify the feasibility and effectiveness of the proposed system and the designed controllers.
Keywords: energy storage system; power conditioning system; silicon carbide; vanadium redox flow batteries.