Introduction  This study proposes a photovoltaic coupling electrolysis water hydrogen production system modelling method with the purpose of solving the problem of inconsistency and mismatching of the simulation signals between electrolyser and others modules. The electrolyser is the key equipment in the photovoltaic-coupled water electrolysis hydrogen production system. The common simulation model of the electrolyser is mostly based on the electrochemical theory and established by using the signal model, which could cause signal transmission mismatching and increase system complexity.

  Method  In order to solve the problems, it was proposing a method of simulating the electrical characteristics of the electrolytic cell by using the equivalent resistance. By fitting the working characteristic curve of the known electrolyser, the relationship between the working current and the impedance of the electrolyser was obtained. The information of the equivalent resistance of the electrolyser was inherited from the fitting curve and connected to the system as a load. When the system power supply fluctuated, the electrolyser simulation module could adjust the load according to the system working conditions, to achieve linkage with the system power supply.

  Result  The simulation results show that the built photovoltaic-coupled water electrolysis hydrogen production system can accurately predict the hydrogen production according to the input light condition and enable load adjustment with the fluctuation of photovoltaic power supply, additionally have a residual value of the fitting result of ≤±0.2.

  Conclusion  This method simplifies the photovoltaic coupling electrolysis water hydrogen production simulation system, unifies the simulation signal, and forms system blocks to facilitate system expansion. The simulation output results are in line with the actual operation of the electrolyser and have achieved the expected goal, which proves the feasibility of the simulation method.