Research On Short Circuit Fault Identification And Location Of DC Traction Power Supply System Of Urban Rail Transit

In recent years,the rapid development of urban rail transit,and gradually become the People’s Daily is the most important means of transportation,ensuring safe and reliable operation of dc traction power supply system is the foundation of urban rail traffic safety stability prevail,DC to DC traction power supply system structure analysis,identification of short circuit fault timely and efficient and reliable,and rapid positioning problem after the short circuit fault in become our important research subject.In this paper,an effective identification method of short circuit fault current is proposed in the case of metallic short circuit in dc traction power supply system.Dc traction power supply system for urban rail transit,the difficulty of positioning,respectively,puts forward a way to use failure after transient data for fault location algorithm and considering the practical engineering,the DC traction power supply system in rail reflux system,put forward a kind of track circuit with double side steady-state algorithm of distributed parameters.This paper introduces the DC traction power supply system,including 24 pulse rectifier,rail and catenary,electric locomotive and ac transmission module.The simulation model of dc traction power supply system of urban rail transit was built by using MATLAB/Simulink module.The starting current of the locomotive and the fault current waveform when the traction network and rail are short-circuited are obtained.Based on the singularity detection of signal by wavelet identification and the characteristics of two kinds of current,the wavelet analysis is proposed to distinguish the locomotive starting current and short-circuit fault current.The 6-layer resolution analysis of db4 wavelet is used to verify the multi-group simulation data and the measured short-circuit data,and the results prove the effectiveness of the proposed identification method.Aiming at the problem of fast location after the occurrence of short-circuit fault,this paper proposes to use the berryon model in the distributed parameter model to make the equivalent of the catenary in the dc traction power supply system,and use the principle of the lowest voltage at the short-circuit point to conduct fault location.Considering that the parameters of catenary may change in the actual line of operation,the method of parameter estimation is proposed to avoid the influence of the inaccurate parameters of traction network on the ranging results.A large number of simulation results show that the accuracy of the proposed time-domain fault location algorithm based on berryon model is higher than that of several traditional location algorithms,and is not affected by the location of the fault.The traditional fault location method makes use of the transient electrical capacity after the fault occurs,but the skin effect of the rail and the delay of the sampling device will have a great impact on the positioning accuracy of the fault location method using transient data.Therefore,this paper proposes that after the occurrence of a short circuit fault,the dc traction network voltage is applied between the catenary and the rail by using the circuit test circuit of feeder switchboard of traction substation adjacent to the fault area,and the traction network port resistance measured twice is used for fault location.In this paper,the fault of dc traction power supply system is simulated by CDEGS simulation software,and the influence of different contact resistance,fault location and transition resistance on the location accuracy is discussed.A bare wire was used to simulate the conditions of complete insulation and low transition resistance on the low-power platform in the laboratory,which verified the effectiveness and practicability of the two-terminal steady-state ranging algorithm.