Research On Model Characteristics And EMI Of Pantograph-catenary Arc Of The High Speed Train

With the rapid development of the high-speed electrified railway,China has successfully become the largest country with the high-speed railway system in the world.However,the improvement of train speed brings convenience to people’s travel and produces a series of electromagnetic(EM)compatibility(EMC)problems.When the train is running,the pantograph on the train roof and the catenary wires will inevitably be separated for a short time.Then,the pantograph-catenary arc(PAC)will be generated.The EM interference(EMI)of the PCA might lead to the failure of some on-board sensitive electronic equipment,such as speed sensor,temperature sensor,encoder and electronic display screen.Moreover,the strong EM radiation generated by the PCA will also affect the EM environment around the train,thus causing interference to the EM signals of the surrounding electronic and electrical equipment.Therefore,it is important to study the characteristics and EMI suppression method of the PCA to ensure the safe operation of trains and maintain the balance of EM environment around the high-speed railway system.In this thesis,based on the distributed parameter models of the high-speed train passing through common and neutral sections and the PCA model,the transient current and voltage characteristics and radiation characteristics of the PCA are studied.In addition,the fault problem caused by the PCA EMI on the on-board speed sensor of the high-speed train and the EMI suppression method are analyzed and studied.The main work of this thesis can be summarized as follows:(1)The distributed parameter models of the high-speed train passing through common and neutral sections are established.Firstly,the train-catenary system of the high-speed electrified railway is summarized.Secondly,based on the actual parameters and field measurement results of high-speed electrified trains in China,the relevant electrical parameters of the train-catenary system are analyzed and calculated.Finally,the distributed parameter models of high-speed train passing through common and neutral sections are established respectively.The the Bergeron equivalent calculation circuit is used to solve the distributed parameter models.The research results provide the model basis for the follow-up study of the transient characteristics of the PCA.(2)The model of the PCA is improved.Because the states of the PCA produced at common and neutral sections are different,and the high-speed airflow field will change the dissipation power of the arc.It is necessary to modify the PCA model.Different solutions to the power dissipation of the PCA generated by the train passing through the common and neutral sections are proposed,and the PCA models generated at the two sections are established respectively.Combined with the distributed parameter model of the high-speed train,the transient voltage and current of the PCA when the train passes through the common and neutral sections at different speeds are obtained by ATP-EMTP software.(3)Based on the improved arc model and the field-measured data,the radiation characteristics of the PCA are studied.This paper focuses on the frequency band(108MHz～336MHz)of arc energy concentration,which covers the signal frequencies of Omnidirectional Beacon System(OBS)(108MHz～117.975MHz),VHF Communication System(VHFCS)(118MHz～136.975MHz)and Glide Beacon System(GBS)(328.6MHz～335.4MHz)in airport communication and navigation equipment.Taking the electrified railway in operation as the research object(the train speed limit is 250km/h),firstly,the electric field strength of the PCA is measured when the train passes through the common and neutral sections at different speeds.Secondly,the Least Square Method is improved,and the correctness of the improved model is verified by correlation coefficient and residual diagram.Thirdly,the amplitude-frequency characteristic curves of the PCA under different train speeds are fitted.In addition,comparing the measurement data and theoretical calculation results,the influence of train speed on the EM radiation of the PCA is analyzed.Finally,the EMI limits of OBS,VHFCS,and GBS are calculated,and the speed limits of the train passing through the airport EMI sensitive area are proposed to avoid the influence of arc radiation on the airport communication and navigation signal.(4)The EMI of the PCA is studied.Firstly,the working principle of the on-board speed sensor and door control system of the high-speed train are analyzed.Then,the variation of the space magnetic field around the train is measured when the pantograph is lowered.The results show that the PCA generated during pantograph lowering will cause EMI to the speed sensor.Secondly,the EMI coupling mechanism and value of the speed sensor is analyzed and calculated.Thirdly,the EMI caused by the PCA on TCU speed sensor cable is tested,and the theoretical calculation results are verified by measurement data.Finally,the EMI suppression method by nesting ferrite magnetic rings on the outer cable-shielding layer of TCU speed sensor is proposed.Besides,the type,number,length and suppression effect of the magnetic rings are verified by experiments,which proves that the method is effective and feasible in suppressing EMI of the PCA.