Research On The Power Quality Of Large-Scale Electric Vehicle Connecting To Distribution Network In Xining

In recent years,with the development of electric vehicles and related technologies,the number of vehicles is gradually increasing.While meeting the requirements of the era of green travel,it also brings new challenges to the distribution network in Xining city.Uncertain charging behavior is one of the important characteristics of electric vehicles,which directly leads to the randomness of charging load.The large-scale grid connected charging behavior of electric vehicles will have a serious adverse impact on the voltage quality and harmonic problems in power quality.In view of the above problems,it is necessary to do a good job in risk factors,impact degree,charging guidance mode,impact analysis on power quality after the distribution network is connected to large-scale electric vehicles,so as to meet the challenges in the future development.The research contents of this paper are as followsFirstly,based on the comprehensive consideration of the driving law,travel time,charging mode,battery characteristics,the type and quantity of electric vehicle load,the load model of large-scale electric vehicle grid charging is studied.Around the establishment of the model,the historical driving and travel data of electric vehicle users are fully considered,and the load characteristics of electric vehicles including charging mode and duration are deeply studied,which provides the simulation model basis for the research of voltage quality and harmonic pollution.In addition,analyze and study the voltage quality problems caused by the large-scale access of electric vehicles.When the slow charging of large-scale electric vehicles is carried out,it will cause more serious three-phase load imbalance.The line selection device for electric vehicle chargers is used to conduct a comparative simulation analysis of three-phase load balance and unbalance based on an actual 10KV distribution network in central Xining,which verifies that the charging method of the distribution network considering the three-phase load balance can be more improved.Reduce system network loss and improve voltage quality.Finally,a comparative study of the specific effects of different types of chargers on the harmonic pollution caused by electric vehicle charging and the analysis of harmonic control measures.At the same time,combined with the simulation of an actual distribution network in a certain district of Xining,it is concluded that the large-scale electric vehicle charging behavior caused the harmonics.The law of change of wave pollution problem and the analysis,research and simulation verification of harmonic control measures.The simulation results show that the uncontrollable rectifier charging station is equipped with a source filter and the harmonic control effect is significant.For the PWM rectifier charger,only better results can be obtained by using passive filters with lower cost for harmonic control.