Power Management for Off-Grid Hydrogen-Electric Coupling System Considering Electrolyzer Temperature-Varying Characteristics

Off-grid hydrogen production by alkaline water electrolyzers (AWEs) is a promising way to consume renewable energy sources (RESs). However, restricted by the slow electrolyzer temperature-rising process, the AWEs cannot start in a short time. The utilization of RESs is greatly curtailed during the temperature-rising period of AWEs. In this article, a power management method for an off-grid hydrogen-electric coupling system is proposed to solve this problem. First, the thermal-electric model of AWEs is established. The model depicts the relationship between the electrolyzer temperature and electrolyzer maximum power. Second, a power management method is developed. The core of the method is that the AWE will be preheated in advance by the battery (BAT). When the power of RESs rises, the AWEs can start in a short time and consume more power. Finally, the proposed method is verified on a photovoltaic-AWE-BAT experimental platform. The experimental results indicate that the proposed method can achieve power sharing among different units. For the 2.5-kW AWE, the maximum power that the electrolyzer can consume is raised from 59.12% to 96.56% rated power before the RES power rises. Thus, the power regulation flexibility of AWEs can be improved greatly.