A novel prediction framework for large-disturbance stability in marine hybrid SOFC/battery microgrids using mixed potential theory

SOFC-powered marine DC microgrids offer a promising path for maritime decarbonization but face large-signal instability risks due to low system inertia and slow fuel cell dynamics during abrupt load changes. Traditional small-signal methods fail to predict stability under such large disturbances. This paper overcomes this limitation by introducing a mixed potential theory-based stability analysis framework, tailored for SOFC-battery hybrid shipboard systems. We derive explicit analytical criteria that directly link controller parameters to large-signal stability boundaries, enabling prior robustness assessment without local linearization. Simulations and hardware-in-the-loop experiments confirm the criterion’s accuracy in predicting instability thresholds under severe transients and provide actionable insights for co-designing SOFC operating limits, storage sizing, and controller gains. This work delivers both a novel theoretical tool and practical guidance for stable, high-performance operation of next-generation SOFC-based marine power systems.