A load disturbance-based energy management strategy in fuel cell‑lithium battery hybrid systems for marine applications

The fuel cell/lithium-ion battery hybrid systems offer a promising solution for energy-efficient power supply. However, fuel economy, power distribution quality, and system lifetime critically depend on the performance of the energy management strategy (EMS). To address the challenges posed by frequent start-stop operations and severe load fluctuations under marine conditions—where existing strategies often struggle to balance computational complexity, operational adaptability, and durability—this paper proposes a real-time load-disturbance-based EMS (LD-EMS). The strategy innovatively adopts real-time load fluctuation intensity as the core decision variable. Through lightweight online evaluation, it dynamically identifies power variation trends, intelligently allocates transient and high-frequency fluctuating power to the lithium battery, and thereby maintains the fuel cell operation within a high-efficiency and stable region. Experimental results based on a fully-physical hybrid power system test platform demonstrate that, compared with conventional state-machine EMS (SM-EMS) and power-following EMS (PF-EMS), the proposed LD-EMS shows significant advantages under both standard and stochastic load profiles. In a 30 kW fully-physical test system, LD-EMS reduces overall hydrogen consumption by 18.6% and 15.3% relative to SM-EMS and PF-EMS, respectively, while exhibiting only a 2.6% gap compared to the dynamic programming-based EMS (DP-EMS). Moreover, it reduces the load-variation frequency by 87.5% and 94.4% versus SM-EMS and PF-EMS. These improvements stem from the effective suppression of frequent load changes on the fuel cell, which not only meets system power demands but also significantly extends the fuel cell's service life.