Study On Induced Electricity Characteristics Of Catenary And Its Emergency Blackout Safety Protection Technology

The rapid development of high-speed railways puts forward higher requirements for electrical safety protection technology in the construction,maintenance and emergency rescue of the catenary.How to improve the efficiency of work and ensure the power supply reliability of the traction power supply system under the premise of ensuring safety has become a problem of widespread concern.During V-shape skylight of emergency blackout,due to the electromagnetic and electrostatic coupling between the up and down catenaries,there will be induced electricity on the maintenance catenary.If the protection measures are inadequate,it will cause induced electric shock accidents.Therefore,research on the induced electricity characteristics and its emergency blackout safety protection technology systematically are very important.Obtaining the impedance and admittance parameters of the traction network accurately is the basis of the analysis of the induced electricity characteristics.This article first discusses the parameters and mathematical models of all-parallel autotransformer traction network,then uses the existing conductor impedance parameters and admittance parameters calculations and their combined algorithms to calculate the traction network parameters of ordinary sections,tunnel sections,and viaduct sections.The characteristics of common locomotive load models are also introduced.To grasp induced electricity coupling principle,combined with the existing power system multiconductor transmission lines theory,a general multiconductor transmission lines induced electricity model is proposed.According to the difference of induced electricity coupling mechanism and the different grounding method,the capacitive induced voltage,inductive induced voltage,capacitive induced current,and inductive induced current are calculated.when the catenary is parallel to the high-voltage transmission lines,the multiconductor transmission lines induced electricity model can be directly used for calculation.However,when the catenary crosses the high-voltage transmission lines,the catenary needs to be divided into small segments,because the magnitude and phase of the space potential generated are different from point to point in different paths of the transmission lines passing through the catenary.When there are enough segments,it can be approximately regarded as each segment is parallel to the high-voltage transmission lines.The induced voltage and induced current of each segment are superimposed and calculated,and finally the total induced voltage and induced current are obtained.When calculating the induced electricity under the coupling action of the adjacent working catenary,the corresponding induced voltage and induced current calculation formulas are derived on maintenance catenary according to the location of the train.Quantitative calculation on induced electricity characteristics of the catenary is the key to develop safety protection technology for emergency blackout.Induced voltage and induced current on the maintenance catenary of the external power grid was calculated using MATLAB programming under different transmission power,cross-span distance and cross-span angle,then conclusion similar to the existing literature was obtained,which proves the correctness of the theoretical derivation.The simulation model of all-parallel autotransformer traction network was built with actual parameters in the Simulink platform.Analyzing the output steady-state electrical quantity and conclusions consistent with the existing literature proves the reliability of the model,then induced voltage and current were calculated under different parallel length of up and down catenaries,traction load current in working catenary,variable location of locomotive,different grounding resistance of maintenance catenary,et al,verifying the theoretical derivation and the distribution of induced electricity characteristics was obtained finally.Safety protection technology for emergency blackout needs to be based on on-site test data,therefore induced voltage test plan for V-stop,vertical stop,and V-stop with single-ended grounding of catenary were designed and typical lines were selected to test to obtain induced voltage under various working conditions.Research on two typical emergency blackout scenes for train fire rescue and climbing operations were carried out.First,a human body voltage divide model during train fire rescue was established,then the minimum safe length of the fire water column was calculated using the maximum induced voltage measured under various working conditions,finally safety protection measures for train fire rescue were developed combined with the characteristics of induced electricity.Induced voltage was calculated by simulating the train climbing operation under different location of grounding line and various operation conditions of locomotive,then safety protection measures for train climbing operations were developed and on-site tests were conducted to verify the validity of the protection measures.