Dynamic Modeling and Validation of a Fuel Cell-Based Hybrid Power System for Zero-Emission Marine Propulsion: An Equivalent Circuit Model Approach

This article proposes a dynamic modeling approach for fuel cell (FC)-based hybrid power systems based on equivalent circuit models. The proposed model framework represents the electrical and electrochemical properties of the FC, batteries, power electronics, and associated controllers. Power- and fuel management in FCs are inherently coupled, constituting dynamics of mass balance, energy balance, and electric loading. Such interactive dynamic behaviors are addressed by introducing active circuit models with inputs from loads, controllers, and operational conditions. The resulting model can then describe the multiphysics properties of the hybrid energy system via an integrated and unified entity so-called an electric twin model. It is composed of only electrical variables, which reduces the need for multidomain analysis in system design and control. Moreover, it presents modularity, making it applicable to the design of real systems in multi-MW and various power configurations. The model's integrity and controllers are tested by a hybrid power system model, where stable load sharing, fuel management, and voltage regulation are proven. The developed model is then validated by the real operation data of a 500 kW FC designed for marine propulsion. The model verification includes both steady-state polarization curves and dynamic load profiles in all possible loading conditions. Consistency with simulations has been observed during both steady-state and dynamic loading.