HIERARCHICAL ENERGY MANAGEMENT STRATEGY BASED ON THE MAXIMUM EFFICIENCY RANGE FOR A MULTI-STACK FUEL CELL HYBRID POWER SYSTEM

Abstract

A multi-stack fuel cell hybrid power system (MFCHS) consists of multiple sources with various characteristics. The power distribution between different sources influences the performance of the system, which involves many factors. To distribute the power effectively and enhance the efficiency and fuel economy of a single-stack fuel cell system, this study proposed a hierarchical energy management strategy (EMS) for MFCHS. An MFCHS configuration that included three fuel cell systems and a battery was presented. An MFCHS model that incorporated the effect of altitude was constructed, and an efficiency analysis of the multi-stack fuel cell system (MFCS) was performed. The hierarchical EMS of MFCHS was composed of a bottom control layer and a top management layer. The bottom control layer utilized a coordinated optimal distribution strategy based on the maximum efficiency range of MFCS to realize optimal power allocation between the different fuel cells in MFCS. The top management layer used EMS under multiple operating conditions to realize the effective distribution of the demand power between MFCS and the battery. Results demonstrate that the proposed strategy improves the average efficiency of MFCS by up to 5.2% and 8.9% compared with those of the equal distribution and daisy chain strategies, respectively. The proposed strategy also displays good performance in terms of the hydrogen consumption of MFCS, which saved 1% and 3% hydrogen compared with the equal distribution and daisy chain strategies, respectively. The proposed strategy results in promising improvements in the overall performance of the system. This study provides a good reference for developing EMS for MFCHS. Keywords: Fuel cell, Multi-stack fuel cell hybrid power system, Energy management strategy, Coordinated optimal distribution, Maximum efficiency range