Solid oxide fuel cells (SOFCs) with enhanced fast ramping power capability and overload tolerance can find important applications in grid frequency regulation and data center overload protection. Recently, we have demonstrated a new SOFC configuration featuring a built-in chemical Fe-bed in the anode chamber of a tubular SOFC and exceptional fast power ramping and overload tolerance. In this presentation, we showed our theoretical understanding of the enhanced dynamic performance through a two-dimensional axial symmetrical numerical model. The model couples the charge and mass transport in the tubular SOFC with chemical reaction kinetics in the Fe-bed, producing axial distributions of Nernst potential, H₂O/H₂ molar ratio, local current density and fuel utilization under different operating conditions. The crucial role of Fe-bed in providing instant fuel to support fast ramping and overload currents has been explicitly explained by this computational model.