Research On Harmonic Effect Of Electric Vehicle On Distribution Network Under Disordered Charging Mode

For the unparalleled advantages in environmental protection,energy saving and so on,electric vehicles have been widely used currently.There are a lot of nonlinear power electronic components in the electric vehicle on-board charger,harmonic pollution will be brought to the power network when electric vehicles are connected to the power grid on a large scale.In order to avoid centralized charging during the peak period,it is necessary to control the charging behavior of electric vehicles.At present,disordered charging is the main charging mode for electric vehicles before the orderly charging control strategy will be applied widely.In the disordered charging mode,a large number of electric vehicles will not only increase the power load,but also produce a large amount of harmonic current to affect the power quality.Therefore,to study the law of harmonic distribution in the disordered charging mode is of great significance to take reasonable measures to eliminate harmonic pollution.In order to study the time distribution of harmonic current in electric vehicle charging and reduce the harmonic pollution caused by electric vehicles in the disordered charging mode,charging load modeling and on-board charger modeling have been research in this thesis.Firstly,the common control methods of APFC are compared each other,single-period control technique is selected as the control method for APFC.The on-board charger model based on rectification + APFC technology + DC/DC structure is established,which the parameters of the main components of on-board charger are calculated.The model and the simulation process are simplified via using nonlinear equivalent resistance.The harmonic characteristics of the input current of on-board charger are analyzed by FFT and wavelet transform.Then,Monte Carlo method is used to model the charging load of electric vehicle.The charging load curve and daily load curve are simulated and compared to analyze the impact of electric vehicle charging load on distribution network in residential area.Based on the Simulink platform,the charging station model of the residential area is built,according to the load distribution of the electric vehicle in the disordered charging mode and the vehicle model of the electric vehicle,the charging situation of electric vehicle is simulated at different time,and the current is analyzed by FFT.The simulation results show that when the electric vehicle charge load reaches the maximum,the total harmonic distortion rate of the current is the biggest,the content of the third harmonics is higher than the others,and the content of the third harmonics increases with the increase of the charging load.The APFC technology based on single-period control can effectively restrain harmonic currents and reduce the harmonic pollution caused by electric vehicles when charging.