Dynamic Modeling of Multi-Energy/Mass Flows in Alkaline Water Electrolysis Systems

The alkaline water electrolysis hydrogen production system involves cross-coupling of gas–liquid multicomponent flows, which poses challenges for developing high-accuracy and fast-solving dynamic models suitable for power system simulation. This paper proposes a dynamic mechanistic modeling method for alkaline water electrolysis that balances accuracy with computational efficiency. Firstly, a zero-dimensional mechanistic voltage model of the alkaline electrolyzer is established, incorporating the electric double-layer capacitance effect. Secondly, based on mass and energy conservation principles, a coupled dynamic mechanistic model is developed, which integrates the alkaline electrolyzer, hydrogen–oxygen separator, and electrolyte circulation. Finally, the accuracy and solving speed of the proposed model are validated using the RTLAB real-time simulation platform and a 5 kW (1 Nm3/h) physical prototype of an alkaline water electrolysis system. The overall mean absolute percentage error of the model is 1.94%.