Hierarchical Power Management of Shipboard Hybrid Energy Storage System Under Multiple Pulse Loads

All-electric ships face multiple onboard pulse loads, including propulsion fluctuations resulting from uncertain navigation conditions, and the power demands of radar or weapon systems. In this paper, a large-scale hybrid energy storage system (HESS) is utilized to provide multi-timescale flexibility to coordinate the main engines to mitigate the impacts of those pulse loads, and a hierarchical power management method is proposed by two steps: the first is to quantify multiple pulse loads and propose a “rolling charging/discharging” strategy to mitigate the pulses; the second considers the power characterization of the battery and proposes a model-free adaptive learning control to reduce unnecessary charging/discharging cycles of HESS and adaptively deal with the impact of navigation uncertainties on the battery. The proposed method is proved by three case studies, and the results show: 1) compared with the case of the single main engine power supply, the proposed “rolling charging/discharging” strategy can reduce the deviation of DC voltage by 84.5%; 2) compared with conventional four methods, the proposed strategy can reduce the internal energy flow and the power tracking error in HESS and the power fluctuation of battery by 75.65%, 95.38%, and 22.9% at most, respectively; and 3) adaptively ensure that the safety operation of the battery under uncertain conditions.