Energy management of marine multi-energy hybrid propulsion systems using an improved equivalent consumption minimization strategy

Marine multi-energy hybrid propulsion systems (MEHPS) can improve ship energy efficiency and reduce emissions, but their coupled propulsion devices and energy sources make coordinated energy management challenging. This study proposes an improved equivalent consumption minimization strategy (iECMS) for steady-state MEHPS energy management. The method retains the equivalent consumption framework but removes the explicit calibrated battery equivalence factor from the instantaneous objective. Battery discharge is evaluated through equivalent fuel cell power and the experimentally obtained fuel cell power–hydrogen consumption relationship, thereby avoiding battery equivalence factor calibration. An inland bulk carrier was selected as the prototype vessel, and an integrated simulation model including a natural gas (NG) engine, motor, lithium-ion battery, fuel cell, photovoltaic (PV) system, and equivalent propulsion load was used. Under the baseline inland waterway sailing condition, the total equivalent NG consumptions of the two-level static logic threshold-based strategy (SLTBS), the calibrated two-stage adaptive ECMS (A-ECMS), and iECMS were approximately 31.2, 29.5, and 29.2 kg, respectively, corresponding to reductions of approximately 5.33% and 6.42% for A-ECMS and iECMS relative to SLTBS. iECMS also achieved the lowest control smoothness index and the lowest tank-to-wake NO x and CO 2 emissions, with an average computation time of 2.834 ms per control interval.