Modelling and capacity allocation optimization of a combined pumped storage/wind/photovoltaic/hydrogen production system based on the consumption of surplus wind and photovoltaics and reduction of hydrogen production cost

To achieve "carbon neutrality", clean energy such as wind and solar energy is being developed, but due to the random and intermittent characteristics of wind energy and photovoltaics, the instability of grid connections and the abandoning wind and photovoltaics need to be addressed urgently. This paper proposes a method to solve the problems of grid connection and abandonment in wind and photovoltaic generation systems, that is, to establish a combined pumped storage/wind/photovoltaic/hydrogen production system through the pumped storage and hydrogen production system. The system consists of a pumped storage/wind/photovoltaic complementary subsystem and a hydrogen production subsystem. First, different models in the system are modelled using Simulink and the characteristics of the models are analysed. Subsequently, the wind turbine model and the PV model are simulated to derive the wind-PV complementary characteristic curves, and it is found that the load demand cannot be met by relying on wind-PV complementary power generation alone. To achieve system stability and economy, pumped storage is configured to smooth the output of wind power and PV. After comprehensive consideration, the optimal pumped storage capacity is determined to be 1000 MW. Then, through the simulation of the pumped storage/wind/photovoltaic system, it is found that even though pumped storage can absorb the wind and photovoltaic outputs, there is still a surplus when the wind and photovoltaic outputs are in excess. Therefore, this surplus energy is used for hydrogen production and the configuration of the hydrogen production system is optimized using a particle swarm algorithm to minimize the cost per unit of hydrogen production. After particle swarm optimization, it was determined that the unit cost of hydrogen production was minimized to 3.54 CNY/Nm3 for the configuration of 55 electrolysis tanks of 4 MW and 219 lead-acid tanks of 1 MW/2 MWh. Meanwhile, the electrolysis tank simulation model and the lead-acid battery simulation model were used to obtain maps of their operating conditions, hydrogen production and hydrogen storage tank pressure. In view of the addition of an energy storage system to the wind and photovoltaic generation system, this paper comprehensively considers the two energy storage modes of pumped storage and hydrogen production, and proposes a corresponding capacity optimization configuration scheme, which has reference value for improving the consumption and stability of wind and photovoltaics and realizing the sustainable utilization of clean energy.