An improved energy management strategy for a hybrid fuel cell/battery passenger vessel

Abstract

The combination of a fuel cell and an energy storage system for the reduction of fuel consumption and improving the dynamics of hybrid power systems has successfully been used in transportation applications. In order to realise the benefits of hybrid fuel cell power systems, an energy management strategy is essential for distributing the required power properly between the fuel cell and the energy storage system. For a hybrid fuel cell/battery passenger vessel, an improvement to the classical proportional-integral (PI) controller based energy management strategy is presented. This takes fuel cell efficiency into consideration as an input to maintain higher efficiency of fuel cell and reduce stresses on it and hence reduce its fuel consumption.A 25.5 m long passenger vessel is used and its propulsion system is modelled in MATLAB/Simulink environment using the SimPowerSystems toolbox. The performance of the proposed PI energy management strategy is compared to original PI, equivalent fuel consumption minimization strategy (ECMS), and state-based energy management strategies in terms of consumed energy, battery state of charge, fuel cell efficiency, hydrogen consumption, and the stresses seen by each power source of the hybrid system taking into consideration a daily operation of 8 h. Results indicate that a daily hydrogen saving of 3.5%, 1.7%, and 1.4% compared to the ECMS, state-based, and the original PI strategies respectively can be achieved by adopting the proposed PI strategy in addition to lower stress on the fuel cell.