Analysis Of Harmonic Characteristic And Measurement Data For Electric Vehicle Charging Pile

With the development of the future auto industry because of advantages of low-carbon economy and energy saving.The market of electric vehicles and their supporting charging facilities also has a broad development prospect in the future.Under the support of relevant national policies and the high attention of local governments at all levels,State Grid Shandong electric power company and its affiliated city and county companies are helping the promotion and application of new energy vehicles in our province.In recent years,the number of new electric vehicles has increased explosively.However,as a non-linear random load,the electric vehicle charging pile will cause a series of power quality problems in the distribution network,in particular,a large number of random,time-varying harmonics are generated.It is of great practical significance to analysis and study the harmonic of charging the electric vehicle charging pile.Through the field tests of electric vehicle charging in Wenshang County,Jining City,Shandong Province,the paper focuses on the harmonic characteristics of the electric vehicle charging station.Based on the measured data of electric vehicle charging,theoretical principle,simulation modeling and practical measurement data analysis are studied in the paper.The main contents are listed as follows:(1)The principle of harmonic generation in the process of electric vehicle charging is the theoretical basis of modeling the harmonic source of electric vehicle charging pile.Based on the conventional AC charging and DC fast charging methods,the paper introduces the working principle of electric vehicle charging station by combining with the constant current charging,constant voltage charging and two-stage charging methods.On this basis,the equivalent time-varying resistance model of electric vehicle based on battery charging characteristics is proposed,which simplifies the DC/DC power converter.(2)Based on the simplified DC/DC power converter model,the harmonic generation mechanism of electric vehicle charging pile under AC charging and DC charging is analyzed.The models of AC charging pile and DC charging pile are built in Matlab/Simulink.By comparing the simulation results with the measured data,the influencing factors of harmonic current in EV charging station are studied,which provides a reference for the construction of EV charging station and the selection of charger configuration.(3)Through the actual measurement of the operating voltage and current of the electric vehicle charging station,the measured data of different electric vehicles are obtained.Then the harmonic characteristics of electric vehicle charging station are obtained by analyzing the data of harmonic voltage,harmonic current,harmonic current phase angle change,harmonic voltage total distortion rate,harmonic current total distortion rate,etc.during the charging process.The harmonic control method of electric vehicle charging station is given according to harmonic characteristics of charging station.By analyzing the harmonic suppression methods such as installing active filter,pulse width modulation rectifier technology,fast dynamic filter compensation,the harmonic suppression measures suitable for large-scale electric vehicle charging station in Shandong Province are proposed.