Two-stage optimization for hybrid renewable hydrogen production systems: Capacity configuration and electrolyzer array operation strategy

With the acceleration of the low-carbon transformation of global energy, green hydrogen technology has become a development focus. Aiming at the contradiction between the volatility of wind-solar power generation and the stability of the electrolytic hydrogen production system, this paper constructs the refined models of alkaline (ALK) and proton exchange membrane (PEM) electrolyzers and proposes a two-phase optimization strategy, achieving global optimization. In the design stage, the power allocation strategy of hybrid hydrogen production system aimed at capacity optimization considering the volatility of wind and solar power is proposed, and multi-objective optimization is carried out using the improved NSGA-II algorithm. In the operation stage after capacity optimization, a three-stage operation strategy and a modular rotation control strategy are proposed. Simulation data show that the wind-solar hybrid system reduces output power fluctuation. Its hydrogen generation after capacity optimization is 30% higher than that of single ALK electrolyzer system, and the system cost is 40% lower than that of single PEM electrolyzer system. The three-stage operation strategy and rotation control strategy reduces the start-stop frequency of the electrolyzers by 76.5%, extends their high-efficiency operation time, and increases overall hydrogen yield by 2.4%. Meanwhile, it reduces the dispersion of operational state time by more than 70%, achieving load balancing and working time balancing under different weather conditions. When wind and solar resources are abundant, the system with 20 MW wind power and 10 MW photovoltaic capacity produced 61,300 Nm3 of hydrogen daily with a curtailment rate as low as 0.5%.