Active pressure and flow rate control of alkaline water electrolyzer based on wind power prediction and 100% energy utilization in off-grid wind-hydrogen coupling system

•The voltage and HTO model are developed and calibrated, its relative error is within 5%.•Under the condition of pressure control, the minimum load is 11.78%.•Couples with pressure and lye flow rate controlling methods, minimum load decreased to 8.95%.•100% absorption of energy is realized by multi-electrolyzers. To increase the energy-conversion efficiency while maintaining safety in commercial alkaline water electrolyzer (AWE) systems. In this paper, (1) a 4 kW AWE system test is conducted to study the effect of pressure, temperature and lye flow rate on the hydrogen in oxygen (HTO) and voltage. (2) The mechanism of HTO is analyzed, and this paper first presents the steady-state and dynamic HTO model in AWE system with physical porous separator. Meantime, the voltage and HTO model are developed and calibrated by the steady-state and transient operation conditions, and relative errors are within 5 %. (3) Based on the analysis of the pressure and lye flow rate on HTO, it is important to obtain the optimal pressure-current density change trends, with an extension of the AWE system’s minimum load from 20 % by the traditional constant pressure controller to 11.78 % by the pressure controller and 8.95 % by the pressure and lye flow rate control, and its corresponding current density is 0.0264 A/cm2 and 0.0196 A/cm2, respectively. (4) Both the multi-AWE configuration and alkaline water electrolyzer couples with battery could complete 100 % utilization of wind power. Therefore, the controlling methods is a great way of lowering load limit of AWE and cutting the start-stop times under renewable energy conditions, besides, the controlling methods and multi slot hybrid mode can achieve 100 % energy utilization in hydrogen production scenario of wind power network.