Designing a Hierarchical Energy Management Strategy for a Hybrid Multi-Stack Fuel Cell System

This paper proposes a hierarchical energy management strategy (EMS) for a hybrid multi-stack fuel cell (FC) system. This system requires 2 kW of power from the FC side and the rest should be supplied by a lithium-ion battery pack. In the first step, several stack allocation schemes (dualstack, triple-stack, and quadruple-stack) are compared in terms of total system efficiency to provide the required power by the FCs and one of them is selected to be used in the hybrid system. Subsequently, the hierarchical EMS with two operating layers is deployed to perform the power allocation. In the first layer, the proposed EMS utilizes sequential quadratic programming to determine the portion of power that should be supplied by the multi-stack FC system while maintaining the battery state of charge within the accepted boundary limits. In the second layer, genetic algorithm is utilized to distribute the power among different FCs in the multi-stack system by maximizing an objective function based on efficiency of the whole system. The obtained results indicate that the proposed hierarchical EMS is able to decrease the hydrogen consumption up to 4.19% and 12.5% in comparison with other commonly used EMSs in the literature under the same driving cycle.