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

All-electric ships face multiple onboard pulse loads, including the propulsion fluctuations resulted by 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 mitigate the impacts of those pulse loads, and a hierarchical power management method is proposed by two steps: the first is to quantity multiple pulse load demands and propose a ‘‘rolling charging/discharging’’ strategy for HESS to mitigate the pulses; the second coordinates the main engine and HESS to address the resulted direct current (DC) voltage sags meanwhile reducing unnecessary charging/ discharging cycles of HESS. The proposed method is proved by two case studies, and the results show: 1) compared with the case of single main engine power supply, the proposed ‘‘rolling charging / discharging’’ strategy can reduce the deviation of DC voltage by 89.3%, and 2) compared with conventional methods, the proposed strategy reduce 63.29% internal energy flow in HESS.