Impacts And Countermeasures Of The Transient Voltage Stability Of Electric Vehicles Accessing Tothe Distribution Network

clean electric vehicles can bothreplace Part of the role of fossil energy, greatlyreducing the use of fossil energy, efficient solving energy structure adjustment problems,and can eliminate the problem of vehicle emissions and protect the environment. Thus,less pollution and pollution-free electric vehicles has become a global focus of attention,the world have enacted incentives to promote the development of the electric vehicleindustry. As the scale of the future of electric vehicles direct access to the distributionnetwork, will have a significant impact on the planning and operation of power gridsecurity and stability. Therefore, studying the impact on the transient voltage stable ofdistribution network which the electric vehicles access to, is not only an important way toanalysis the security and stability situationof large-scale electric vehicle accessing to thedistribution network, but also canprovide some guidance about the distribution networkplanning.Based on the transient characteristics of the electric vehicle car batteries, weestablisha model of electric vehicle charging stations. consideringthe slip-torque characteristics ofinduction motor loads, we proposed a transient voltage stability margin index ofconsidering an induction motor load. on this basis, we analyzequantitative influence of thetransient voltage stable when the large-scale electric vehicle access to distribution network.considering the reverse discharging V2G mode, we study the distribution networkimprovement measures of transient voltage instability.Firstly, comparative analysis of three commonly used-car electric vehicle lithium-ionbattery, lead-acid batteries, nickel-metal hydride batteries transient characteristics,consider transient characteristics of lithium rechargeable constant changes in the largerstage, the establishment of a two-stage bi-directional AC-DC, model electric car chargingstations DC-DC converter unit in the matlab/simulink simulation verifies the proposedcharging stations charging and discharging characteristics meet the requirements. Application Circuit fundamental theorem on the distribution network equivalent circuitwas assembled, the introduction of the generalized induction motor load model, adetailed analysis of its transient slip-torque characteristics, proposed to consider aninduction motor load transient distribution network voltage stability margin indicators andcomparative analysis with traditional transient Voltage indicator-similarities anddifferences between critical clearing time, based on two simple power system simulationnode to verify the indicators mentioned in this article has a better advantage. Based on theabove, combined with IEEE14node examples in matlab/simpowersystem analyzed theelectric vehicle load is concentrated and dispersed modes to quantify the impact on thedistribution network were transient voltage stability and considering V2G technology,distribution network transient voltage instability were feasible improvements.