Research On Fault Location Of High Speed Railway Contact Network

High-speed railway has become an important trend in the development of electrified railways in China.Therefore,the power supply system of high-speed railways is required to deliver electric energy more stably and reliably.At this stage,the main power supply mode of China's high-speed railway contact network is AT power supply.Combined with the actual situation in China,it generally adopts Double line full parallel AT power supply mode,which has large transmission power and long power supply interval.The power supply mode has the advantages of large transmission power,long power supply interval and high reliability,and can be well adapted to high-speed electrified railways with high speed and high density.However,it is more complicated in structure than the original traction network power supply system,and therefore requires higher precision and sensitivity for the fault location of the high-speed railway contact network to ensure safe and reliable operation of the high-speed railway.Firstly,this thesis introduces the chain network model of multi-conductor transmission line to elaborate the structure and mathematical model of the full-parallel AT power supply mode.The MATLAB program for calculating the electrical parameters of the contact network is used to calculate the impedance parameters and admittance parameter matrix of the entire fully parallel AT-powered contact network after multi-conductor equivalence.Then,the simulation model of each part of the contact network is built in Simulink software in combination with the contact line parameters.Secondly,the fault transient traveling wave propagation process of multi-conductor transmission line is analyzed deeply,and compared the advantages and disadvantages of several modern traveling wave ranging methods,D-type traveling wave ranging is selected as the basic ranging method;to calculate the phase-mode transformation matrix and each the propagation characteristics of the current modulus,combined with the simulation example,select the current mode 3 component as the amount of the fault to be analyzed.Then the properties and classification of wavelet transform are systematically studied.The relationship between wavelet transform and signal singularity is expounded and several expressions of wavelet basis functions and time domain waveforms for singularity detection are given.The construction method of wavelet base-multi-resolution analysis and fast decomposition algorithm in practical application-Mallat algorithm is introduced.According to the selection principle of wavelet base and decomposition scale,cubic B-spline wavelet is selected as wavelet base.The definition and detailed construction method of B-spline wavelet are given.Finally,the D-type ranging method in double-ended traveling wave ranging and the improved D-type traveling wave ranging method without the influence of wave velocity are used to simulate and analyze the permanent short-circuit fault of the high-speed railway traction network,and the traction and transformation are obtained.The uplink and downlink fault transient traveling wave waveforms of the and the partitions are programmed,and the M file of the corresponding ranging procedure is written to obtain the fault point position,and the simulated vehicle load,fault position,transition resistance,voltage phase angle of the fault time,etc.The influence of several influencing factors on the fault location results.In order to make the fault transient waveform and the ranging result more intuitive and easy to operate,a GUI interface of a high-speed railway contact network fault location system is designed based on MATLAB.The simulation results show that the D-type traveling wave method and the improved D-type traveling wave ranging method are not affected by the position and number of inorganic vehicles,locomotives,fault point position,transition resistance and voltage phase angle at fault time.The improved D-type traveling wave ranging method has higher anti-interference ability,and both can accurately locate the short-circuit fault of the high-speed railway contact network,and have high reliability and applicability.