Research On The Performance Of Direct Coupling PEM Electrolytic Water Hydrogen Production System For Photovoltaic Power Generation

With the increasing demand for energy supply for social and economic development,traditional fossil energy sources are gradually being replaced by green energy sources due to the limited amount and environmental pollution problems.Solar energy as the most widespread and abundant green energy has become the world’s largest development and utilization of energy sources in the first.In recent years,with the rapid increase in the installed capacity of photovoltaic power generation,the utilization rate of power generation has also been gradually attached importance.Renewable energy is not stable due to its own volatility and intermittent generation of current,making it more difficult to couple with the grid.Hydrogen,as the most promising secondary energy source,is growing rapidly as a percentage of global energy demand Renewable energy generation is often combined with electrolytic water hydrogen production system to build a new energy system,which converts electricity that cannot be consumed by the grid into hydrogen energy storage.Compared with the traditional construction of new energy systems,the direct-coupled connection method eliminates multiple middleware,reduces energy loss and saves the maintenance cost of middleware.In recent years,there has been an increasing number of studies related to the structural performance of direct-coupled connections.In this paper,we study the performance of direct-coupled PEM electrolytic water hydrogen production system for photovoltaic power generation,focusing on the degradation model of the proton exchange membrane electrolyzer and analyzing the structural optimization of the direct-coupled system,as follows:(1)The mathematical models of photovoltaic power generation system and electrolytic water hydrogen production system are analyzed in detail,and the simulation modeling and characteristic curve analysis of the two subsystems are carried out separately to study the effects of ambient temperature and irradiance on photovoltaic power generation;the effects of temperature,pressure and current density on the characteristic curve of electrolyzer are studied.At the same time,the simulation models are used as a basis to verify the results of subsequent structural optimization search.(2)The lightweight industrial hydrogen production system is analyzed,the functional module of the proton exchange membrane electrolytic water hydrogen production system is designed,the hardware experimental platform is built,and the functions of PEM electrolytic water hydrogen production and hydrogen production data monitoring are realized,which provides data support for establishing the degradation model of the proton exchange membrane electrolyzer.Secondly,the working conditions of the electrolyzer,the core component of the hydrogen production system,were analyzed,and the SVDD algorithm based on the nearest neighbor density was used to improve the classification accuracy of the mixing area considering the existence of the mixing area in the working condition data.(3)To characterize the degradation performance of the PEM electrolytic cell,a degradation model building method based on least squares polynomial fitting is adopted;a degradation model building method based on the infectious disease model is proposed for the PEM electrolytic cell and the model parameters are solved by combining with the particle swarm optimization algorithm.The polynomial fitting is mainly used to build a simple model to describe the degradation from the data.Based on the infectious disease model,three degradation models are proposed based on the degradation mechanism of the proton exchange membrane,and the particle swarm optimization algorithm is used to solve the parameters of the three degradation models to characterize the degradation of the electrolytic cell.(4)The multi-objective particle swarm optimization algorithm is used to optimize the structure of the direct coupled system by combining the annual irradiance and temperature data,taking into account the two objectives of minimizing the annual energy transfer loss and maximizing the hydrogen production.The Pareto optimal solution set is analyzed to find the optimal solution in the three-dimensional solution space by considering the variables of the number of series and parallel connections of electrolytic cells and the variables of water activity operability.A direct coupled system is designed and demonstrated,and the optimal structure of direct coupling is verified by simulation experiments,and the energy transfer efficiency of the system is calculated up to 95.1%by inputting typical weather data.