A unified standard thermal resistance-impedance-circuit approach for dynamic characteristic analysis of grid-connected solid oxide fuel cell system

The dynamic integration of Solid Oxide Fuel Cell (SOFC) systems with power electronics presents significant challenges due to the disparate time scales of thermo-electrochemical processes and electronic control systems. This manuscript develops a unified standard thermal resistance-impedance-circuit approach for grid- connected SOFC systems. This approach provides a comprehensive cross-scale dynamic model, coupling the standard thermal impedance (STI) method for SOFC modeling with power regulation circuit for converter and inverter, which constructs the overall system topology and characterizes the transmission and coupling characteristics of various physical parameters within different components, integrating the multi-physical processes, cross-timescale dynamics and inter-disciplined areas to facilitate real-time simulation and control. On this basis, we analyze the dynamic response processes of power electronics equipment, and SOFC systems under varying load conditions. The results show that the power electronics respond in sub-second time frames (0.15–0.5 s), Balance of Plant (BOP) components have intermediate response times (7–9 minutes), and SOFC stack exhibit slow response times (25–39 minutes) when the load changes. This unified model visualizes the transfer and coupling properties of physical parameters within different components, highlights the interactions between the slow thermal-electrochemical dynamics and the fast-switching power electronics, then emphasizes the topology’s capacity to handle transient states and ensure robust performance. The proposed framework provides a pathway for enhancing computational efficiency, improving power quality, and ensuring operational stability in distributed energy systems.