A Power Conversion System For Large-Scale Reversible SOFC Energy Storage System

As the penetration rate of renewable energy in the utility grid increases, large-scale energy storage system (ESS) will become an essential infrastructure in the grid. Reversible solid oxide fuel cell (RSOFC) technology is a promising solution for large-scale ESS. However, the wide voltage range and low power of single RSOFC stack electrical characteristics have complicated the interface converter design. It is necessary to connect multiple stacks through a power conversion system to integrate the power because a single stack of RSOFC is small. This paper proposes a power conversion system for large-scale RSOFC ESS. The system consists of a cascaded H-bridge (CHB) converter and multiple multiport converters, and they are connected to a common dc bus. Because of the electrical characteristics of RSOFC, a two-stage CLLC based multiport converter topology is employed to achieve high voltage gain and operate at a wide voltage range. The control strategy of the proposed power conversion system is presented. Simulation tests verify the feasibility and effectiveness of the proposed conversion system