Capacity Optimization Of Integrated Systems Of Electric Vehicle Battery Swapping Stations And Photovoltaic Power Generation

With energy crisis and environmental problems become increasingly apparent, countries in the world are all committed to the development of renewable energy and electric vehicles. According to the existing energy structure of our country, the carbon emissions generated by charging electric vehicles through the grid is not lower than that of conventional fuel vehicles, making it difficult to achieve the effect of energy conservation and emission reduction. It will help solve the problem to establish the integrated systems of electric vehicle charging infrastructure and renewable energy power generation since electric vehicles could take advantage of renewable energy locally. Among various types of renewable energy, photovoltaic power generation can be used well in urban environment, having an inherent advantage to integrate with electric vehicle charging facilities. Therefore, this paper takes the integrated systems of electric vehicle battery swapping stations and photovoltaic power generation as the study object and focuses on capacity optimization of the integrated systems. The specific work is as follows.1. The typical structures of integrated systems are analyzed. Two system structures are chosen respectively from independent photovoltaic power system structures and grid connected system structures for establishing the capacity optimization models of integrated systems. According to different characteristics of the two typical system structures, the corresponding energy exchange strategies are proposed respectively.2. Two basic calculation models are established based on Monte Carlo simulation method for solving the capacity optimization model of integrated systems. The annual second-use capacity of electric vehicle batteries during system lifetime could be obtained by the calculation model of second-use capacity of electric vehicle batteries. The energy demand of battery swapping of24hours in one day could be obtained by the calculation model of energy demand of battery swapping.3. According to the independent photovoltaic power system structure, the capacity optimization model of integrated systems considering second-use of electric vehicle batteries is established. The maximum annual system profit is taken as the objective function. The constraints are established from the variation scope of decision variables, the charging power of electric vehicle batteries, the charging and discharging power of storage batteries, the system power balance and the energy of electric vehicle batteries in the station and storage batteries. The optimization model is solved by differential evolution algorithm and the optimal capacity configuration scheme could be obtained. The reasonability of the capacity of electric vehicle batteries, storage batteries, photovoltaic power generation system and the corresponding converters is analyzed. The application effect and system income are also explored.4. According to the grid connected system structure, the multi-objective capacity optimization model of integrated systems comprehensively considering the economic and environmental benefits is established. The minimum annual system cost and the proportion of the utilization energy of photovoltaic power generation in the total energy consumption are taken as the objective functions. The constraints are established from the external environment, construction scale, system operation and battery swapping service. The optimization model is solved by NSGA-II algorithm and the Pareto solution set could be obtained. The optimization results are analyzed in detail from the capacity variation of the main system components, the system power balance, the energy of electric vehicle batteries and the critical electricity price. The sensitivity analyses are conducted on some uncertain factors. All of the analyses verify the reasonability of the optimization model.