Research On Traveling Wave Propagation Characteristics And Fault Location Of Fully Parallel AT Traction Network

The fully parallel AT traction power supply system is widely used in China’s high-speed railways due to its strong power supply performance and low interference to communication lines.The line topology is complex,and the probability of failure is the highest compared to other power supply modes,especially the short-circuit fault type.There is no backup line in the traction network.Once a fault occurs,it will affect the production safety of the railway department.The measurement accuracy of the existing fault location device is affected by many factors.The traveling wave method is maturely used in the power grid,and there is no such device in the traction network,so it is a very important research topic to use the traveling wave method to locate the fault of the traction network.First,this article introduces the fully parallel AT traction power supply system and various other power supply methods,calculates the impedance and admittance parameter matrix of the traction network,the matrix dimension is 14 × 14,and adopts the gradual merging rule to convert the electrical parameter matrix of the traction network It is merged into a matrix with a dimension of 6×6,which provides theoretical and data support for the subsequent research on the traveling wave propagation characteristics of the fully parallel AT traction network.Secondly,based on the electrical parameter matrix in Chapter 2,the current phase-mode transformation matrix of the traction network is calculated,and the traveling wave propagation characteristics of the traction network are analyzed,including the influence of the frequency variation characteristic curve of the traction network and the earth resistivity on the traveling wave propagation coefficient.The mode speed at a frequency of 5k Hz is used as the distance measurement data in the following text.Analyze the influence of AT autotransformer on traveling wave propagation through ATP-EMTP simulation.Third,use ATP-EMTP to establish a complete simulation model of the traction power supply system,and verify the propagation path and law of the fault current traveling wave through theoretical analysis of the traveling wave propagation path and simulation waveforms at multiple measurement points of the line.After a fault occurs,the power supply arm must have the characteristics of low singularity of the current signal at the end and end of the power supply arm,and it is difficult to detect.A traveling wave ranging method based on the time-frequency spectrum similarity fully parallel AT traction network is proposed.This method first measures the double-ended current data,and then calculates the time-frequency spectrum similarity matrix of the upstream and downstream current traveling waves at the traction substation to identify the fault point section,and finally selects the current traveling wave at the measurement end of the same section as the fault point using A Type ranging formula ranging can solve the problem of identifying the second reflected wave by using the same polarity of the reflected wave at the fault point as the initial traveling wave,and the polarity of the reflected wave at the end of the AT and the opposite polarity of the initial traveling wave.Through the simulation verification of no-load and locomotive load,the wavelet arrival time is calibrated with the wavelet modulus maximum value,and the fault distance is calculated.The simulation results show that the traveling wave ranging method proposed in this paper can effectively identify the reflected wave and accurately locate it.Finally,the traveling wave distance measurement method based on time-frequency spectrum similarity is integrated and visualized.Based on the GUI graphical user interface in MATLAB,a set of fully parallel AT traction network traveling wave fault location system is developed.Interface design Concise and friendly,it can accurately and quickly find the distance under various short-circuit fault conditions,and the results are accurate.