Exploration of the configuration and operation rule of the multi-electrolyzers hybrid system of large-scale alkaline water hydrogen production system

•A multi-electrolyzers flexible hybrid system is developed.•The different configurations of electrolyzer are compared and analyzed.•The proposed system could achieve the minimum load of the ALK’s system to be 6.25%.•Doctor triage strategy can solve the problem of disbalance between multi-electrolyzers. This study presents a multi-electrolyzers hybrid system for wind-hydrogen system, and two control strategies are proposed. And two different configurations that could achieve the target value of the lower load limit are compared and analyzed. Different switch strategies between multi-electrolyzer are also proposed and simulated. In terms of the configuration of the electrolyzer, the results show that four 0.5 MW electrolyzer could achieve the 99% energy absorptivity and the absorption is 96.54% when the 0.5 MW electrolyzer and 1.5 MW electrolyzer are configured, however, the hydrogen production of the latter is higher. Then the switching strategies between four electrolyzers are proposed. The first strategy (“Equal force strategy”) will lead to a disbalance in the working time of electrolyzers, it’s dangerous for the ALK system. The improved strategy (“Doctor triage strategy”) is proposed and simulated, the results show that the disbalance between electrolyzers is slight compared with the first strategy. And the disbalance will be enlarged when the cycle period becomes longer in the improved strategy. If the period is extended to 6017 h, the value even reaches 75 times of 6.42 h. In a word, the developed general procedure is well feasible for the improvement of energy efficiency and scale of the industry’s commercial alkaline water electrolyzers.