Control structure design of a solid oxide fuel cell and molten carbonate fuel cell integrated system: Bottom-up analysis

A solid oxide fuel cell and molten carbonate fuel cell integrated system is a power generation system with enhanced fuel and carbon dioxide utilization. Due to its complex structure, designing a control system is important for its smooth and efficient operation. This study is a continuation from the previous study focusing on a top-down, steady-state economic analysis for synthesizing the control structure of the solid oxide fuel cell and molten carbonate fuel cell integrated system to maximize power generation and carbon dioxide utilization. In this study, a bottom-up analysis is performed to design a control layer and validate the proposed control structure via dynamic simulation. The control configuration uses a decentralized approach with proportional integral-derivative control to maintain the fuel cell system at its optimum target. The control performance with the proposed control structure and configurations are evaluated and analyzed. Four control loops involving gas concentrations are considered, based on different time scales between the regulatory control and supervisory layers. The results of the proposed control system confirm that the integrated fuel cell system is controllable despite the deviation of the fuel cell voltages from their nominal values.