Power-Deficit-Constrained Hierarchical Energy Management for Hydrogen–Electric Ships

To address power supply–demand mismatch in hydrogen–electric hybrid ships under load fluctuations, variations in energy states, and limited power-supply capability, this paper develops a power-deficit-constrained hierarchical energy-management strategy. Rather than directly determining the power commands of individual energy units, the upper-level PPO-Lagrangian controller adaptively regulates the ECMS equivalent factor according to system states and explicit power-deficit constraint feedback, while the lower-level ECMS performs instantaneous power allocation among the fuel cell, battery, and diesel generator. The resulting allocation determines the realized constraint cost, which is fed back to update the Lagrange multiplier and subsequent equivalent-factor regulation, thereby forming a closed-loop cross-layer coordination mechanism. Simulations were conducted using navigation data from a nearshore bulk carrier and compared with representative energy-management strategies. The results show that the proposed strategy can achieve favorable performance in power-deficit suppression, constraint feasibility, diesel-generator dependence, and operational economy under load disturbances and component degradation, providing a methodological basis for further real-time implementation and experimental validation of constrained energy management in hydrogen–electric ships.