Experimental validation of power distribution control and energy management strategies for hydrogen-electric hybrid power ship

To investigate the actual performance of ship energy management strategies in practical hybrid power systems under complex operating conditions, three energy management strategies were tested based on a scaled experimental platform. A hydrogen-electric hybrid ship was selected as the research object, and existing characteristics of onboard energy management systems were utilized to design strategy Ⅰ. Additionally, by establishing eight operational rules for the start-stop cycles of fuel cell stacks, strategy Ⅱ and a state machine strategy were developed. A scaling method for the experimental platform was proposed to simulate both fuel cell systems and battery systems. Based on the optimal efficiency point of the fuel cell and the characteristics of the experimental platform, a scaling factor of 342.857 was designed. In both steady-state and transient conditions, the performance of power distribution control, efficiency, energy consumption, operating pressure, as well as application characteristics and limitations, were analyzed based on experimental data. Experimental results indicate that the average deviation of power distribution control on the experimental platform is within 1%, demonstrating a strong capability to track the reference power of the fuel cell optimized by energy management strategies. Specifically, under steady-state and transient conditions, the state machine strategy achieves average absolute deviations between actual current and reference current of 0.120% and 0.029%, respectively. Among the three proposed rule-based energy management strategies, the state machine strategy shows superior overall performance in terms of energy savings and reduction of operational pressure on the fuel cell. In both steady-state and transient conditions, compared to the existing strategy Ⅰ, the state machine strategy reduces hydrogen consumption by 2.84% and 7.23%, respectively, in comparison to the existing strategy Ⅱ, it reduces the frequency of fuel cell stack start-stop cycles by 83.00% and 84.23%, respectively. The state machine strategy maintains the average efficiency of the fuel cell stack above 52%. However, during its application, this strategy faces challenges such as frequent start-stop operations of the fuel cells, conflicts in decision-making authority, and performance degradation of the fuel cells. Additionally, the proposed experimental method has certain limitations; specifically, the response time of the fuel cell simulation equipment is 1 s with a power loss of 300 W, which is also influenced by testing environments as well as scaling and simplification processes. The proposed experimental method and energy management strategy can serve as a guide for the research and application of efficient energy management strategies in actual vessels.