Study On Electric Field Distribution And Discharge Characteristics Of Additional Conductor Of Lanzhou-Xinjiang High-Speed Railway Catenary Under Dust Environment

Gansu and Xinjiang are connected by the Lanzhou-Xinjiang high-speed railway.As one of the main channels of the "eight vertical and eight horizontal" high-speed railway,Lanzhou-Xinjiang high-speed railway passes through an important source of sandstorms and sandstorm prone areas,and passes through the world’s longest wind zone.Strong winds and dust seriously threaten the safety of Lanzhou-Xinjiang high-speed railway;in order to make the train turn around and disappear in the wind zone,a wind barrier was slowly built along Lanzhou-Xinjiang high-speed railway to withstand the impact of strong wind on the train.However,the existence of the wind barrier intensifies the galloping of the additional conductor of the overhead contact system,and the increase of sand particles will cause the distortion of the space electric field around the live conductor,reduce the electrical insulation strength of the air gap,and in serious cases,may cause air breakdown between the additional conductor and other adjacent conductors or additional conductors,This situation has caused tripping accidents in many traction substations in Xinjiang.Therefore,this thesis focuses on the study of the additional conductor of the contact network of Lanzhou-Xinjiang high-speed railway,focusing on the electric field distribution characteristics and corona discharge characteristics of the positive feeder under different parameters of the aluminum conductor steel reinforced(ACSR).The main work and results are as follows:(1)Construct an equal scale model of additional conductors of the span catenary,import it into COMSOL,and achieve coupling between flow field and particle field.Use finite element simulation calculation to calculate the distribution of sand and dust λ as a characterization parameter,analyze the distribution characteristics of sand and dust under different wind speeds and directions.Due to the presence of wind barriers,the wind speed at the additional conductor increases.As the wind speed increases,the distribution of sand and dust at the additional conductor increases λ reducing and gradually approaching the distribution of sand and dust at the entrance,negative angle winds can increase the distribution of sand particles compared to positive angle winds.(2)For a clean air environment without sand and dust,the electric field distribution characteristics of the positive feeder line are analyzed.Using the maximum value of the surface electric field intensity of ACSR as a characterization parameter,and the maximum surface electric field intensity of the ACSR appears at the midpoint of the outer arc of the aluminum wire.When operating with traction load,the generation of various harmonics causes voltage fluctuations,and the change in electric field intensity of the ACSR is consistent with the proportion of voltage changes.(3)By analyzing the maximum electric field intensity on the surface of ACSR under different working conditions,it is found that an increase in sand particle size,concentration,and charge to mass ratio will cause the maximum electric field intensity on the surface of ACSR to increase exponentially.For each time the sand particle concentration increases by 1time,the maximum electric field intensity on the surface of ACSR will increase by about 1.20 times,and the charge to mass ratio will increase by 1 time.Among the five common surface defects of ACSR,burrs severe changes in the distribution of electric fields caused by scratches and single line protrusions.(4)Based on the ACSR used for the additional conductor of the existing Lanzhou-Xinjiang high-speed railway contact network,a reasonable increase in the number of outermost aluminum strands will reduce the maximum surface electric field strength of the ACSR.Compared with the maximum surface electric field strength of the ACSR with the outermost aluminum strands of 27,the maximum surface electric field strength of the ACSR with the outermost aluminum strands of 22 can be reduced by 0.626 times,effectively improving the distribution of the electric field around the stranded wire.(5)Analyze the corona discharge characteristics of the positive feeder surface under different parameters of sand particles,and take the space charge density value as the characterization parameter.The maximum value of the space charge density appears at the midpoint of the outer arc on the surface of the stranded wire.With the increase of the sand particle diameter,the maximum value of the space charge density presents an overall trend of increasing.The sand particle concentration increases by one time,the maximum value of the space charge density increases by about 1.11 times,and the charge mass ratio increases by100μC/kg,the space charge density of the steel core aluminum strand increases by about 1.07 times.