Research On The Influence Of Electric Vehicle Charging On Power Grid Load And Optimal Charging Strategy

With the development of technology,the demand of environmental protection and the shortage of fossil fuels in the future,the electric vehicle industry is gradually rising.Although the appropriate number of electric vehicles’ charging will not cause large fluctuations,but with a wide range of popularization of electric vehicles,more and more widely using in transportation,large numbers of electric vehicles join the distribution network will cause various effects on operation and management of power system.Electric vehicles can be viewed as an uncontrollable load with strong mobility.Electric vehicle accessing to the network for large-scale will generate new high power load,and easily coinciding with the peak of household electric load.There will be overload problem in part of existing heavy network;low voltage problem will appear in main line;in low-voltage power distributing network the line loss will increase,pressure drop will become larger,and the inter-phase load will become imbalance.With the development of technology,vehicle to grid(V2G)technology will be widely used,electric vehicles can be used as distributed generations to supply power for power grid,this behavior will change the direction of power flow,the setting of relay protection will become complex.The year 2030 is chosen as the target year in this paper,and Zhengzhou as the target city,according to the current development of China’s electric vehicle industry,I predict the holdings of various types of electric vehicles in 2030;then build the mathematical models of charging process depending on the driving habits of different types of vehicles.Then,combining the results of the prediction with the mathematical model I draw the charging load characteristic curve of electric vehicle without considering other factors.Analyzing the influence of large scale electric vehicles’ charging based on the daily load curve.On the basis of the analysis and research,this paper establishes the optimal charging strategy of electric vehicles,and analyzes the change of the charging load curve.The implementation of the optimal chargingstrategy can improve the quality of daily load characteristic curve,reduce the peak valley difference,avoid the overlap between the charging load and the peak load and reduce the surge load.V2 G is mentioned in the conclusion and prospect,this technology will be the ultimate way to solve the problem of large-scale of electric vehicles combining to network of in the future.