Two-level Energy Management Strategy for a Fuel Cell-Battery-Ultracapacitor Hybrid System

This paper provides a two-level energy management strategy for a fuel cell-battery-ultracapacitor (UC) hybrid system. In the proposed strategy, the battery and UC packs are seen as an energy storage system (ESS) at the first level and the equivalent consumption minimization strategy is used to distribute load power between this ESS and the fuel cell system. The penalty factor is tuned based on estimated average load power and SOC of the ESS. At the second level, the power distribution between the battery and UC packs is determined using the equivalent series resistance-based control strategy to minimize the energy loss. Then, the performance of the proposed two-level energy management strategy is analyzed in simulation under a realistic load profile. Finally, detailed comparison results show that the two-level energy management strategy can achieve lower hydrogen consumption, compared with the rule-based method.