Capacity configuration and optimization of an off-grid wind-solar-hydrogen integrated system considering hybrid hydrogen production with alkaline electrolyzers and proton exchange membrane electrolyzers

Hydrogen energy storage is a promising solution to mitigate the intermittency of renewable power. Current capacity configuration methods for hybrid electrolyzer systems (HES) often neglect the operational differences between alkaline (AEL) and proton exchange membrane (PEM) electrolyzers as well as the impact of power distribution strategies across multiple units. To address this research gap, this study proposes a novel control strategy that incorporates electrochemical, hydrogen production, state transition, and voltage degradation models for both AEL and PEM. On this basis, a multi-electrolyzer power allocation strategy is developed, integrating efficiency improvement with a rotational scheduling rule. Case studies confirm that the proposed strategy delivers superior performance compared to conventional dispatch methods. Specifically, system energy utilization efficiency is enhanced to 66.2 %, while the annual start–stop frequencies of AEL and PEM electrolyzers are reduced to 375 and 209, respectively. Moreover, the strategy alleviates voltage degradation imbalance, thereby ensuring consistent and equitable electrolyzer usage. The results demonstrate both the technical feasibility and practical benefits of this strategy, offering new insights for renewable energy-driven hydrogen production with HES.