Objective The study aims to establish a dynamic simulation model for coordinated operation of multiple proton exchange membrane(PEM) electrolyzers under photovoltaic power fluctuations, providing theoretical foundations for optimizing large-scale hydrogen production systems.

Method In accordance with electrochemical principles, the Aspen Custom Modeler software was employed to develop a model for the PEM electrolysis cell. Subsequently, this model was integrated as a sub-routine into the Aspen Plus software environment. In Aspen Plus, ELECNRTL physical property calculation method and appropriate module were used to build a combination of multiple 20 m³/h level PEM electrolytic hydrogen production processes. In the calculation, the system's current density was set to change with the light intensity, and the step change of current density was used to simulate the fluctuation of renewable energy. The hydrogen production process of combining two, three, and four 20 m³/h PEM electrolysis cells.

Result It was resulted in an average hydrogen production rate of 41.03 m³/h, 61.55 m³/h, and 82.07 m³/h, respectively. The hydrogen loss during separation and refining was around 3.9%, and the energy consumption of the PEM electrolysis cell was 4.504 kW·h/m³. Compared with the on-site data of 4.509 kW·h/m³ from a demonstration project of China Power Engineering Consulting Group, the relative error was controlled at 0.1%.

Conclusion In actual operation, utilizing the mechanism of combining multiple electrolytic cells can make it possible to selectively disable some PEM electrolysis cells when the input power of the system decreases due to weak light, effectively deal with the uncertainty of renewable energy output, and improve the system energy conversion rate. The research results can provide a theoretical reference for the actual photovoltaic water electrolysis process for hydrogen production.