System-Level Dynamic Modeling and Cross-Domain Disturbance Propagation of an Electricity–Hydrogen–Heat Coupling Subsystem for Integrated Transportation Hubs

Integrated transportation hubs are characterized by fast-varying and strongly coupled electricity, hydrogen-refueling, and thermal demands driven by traffic activities. To characterize their short-term dynamic interactions, this paper develops a compact system-level model of a core electricity–hydrogen–heat coupling subsystem comprising a PEM electrolyzer, a hydrogen storage tank, a fuel cell, and a thermal side. Power- and temperature-dependent off-design models are established for the PEM electrolyzer and fuel cell, while a lumped-parameter thermodynamic model with real-gas correction is developed for the hydrogen storage tank. The electrolyzer and fuel-cell models achieve calibration MAPEs of 0.39% and approximately 0.81%, respectively, against published reference data. Two typical disturbance scenarios are then investigated. Under a 30 kW electrical-load step, the grid-power deviation is reduced from a peak of approximately 29.4 kW to about 9.1 kW, while the hydrogen-refueling-demand disturbance produces only a minor thermal-side temperature variation. The results reveal distinct propagation magnitudes and time-scale characteristics across the electrical, hydrogen, and thermal domains. The proposed framework provides a compact and physically interpretable tool for short-term cross-domain dynamic analysis of integrated transportation hubs.