Single-ended Traveling Wave Fault Location For Transmission Lines Based On Wavefront Information

The rapid and accurate location of the fault after a power transmission line failure can not only repair the faulty line in time and ensure the user’s power supply,but also has important significance for the safety,stability and economic operation of the power system.The traveling wave fault location method is accurate and has a wide range of applications.It is currently widely used on power lines.The traveling wave fault location system of transmission lines generally adopts the double-ended method as the main method,and the single-ended method is the supplementary method.When the traveling wave distance measuring device at one end of the line fails to capture the initial traveling wave of the fault,the double-ended method will fail the distance measurement;some lines are not configured according to the double-ended method.In the above case,the single-ended method is an effective complement to the double-ended method.The single-ended method is affected by the foldback at the impedance mismatch point of adjacent lines,and it is difficult to identify the reflected wave head at the fault point.In response to this problem,existing research proposes a combination of power frequency ranging and traveling wave fault location.This method is generally implemented through the cooperation of a fault recorder and a traveling wave fault location device,which has poor reliability.The wavefront steepness of the initial traveling wave of the fault is related to the distance to the fault.The paper analyzes the relationship between the steepness of the wavefront and the distance to the fault.Wave fault location method.The specific research content is as follows:(1)The influencing factors of the wavefront distortion of the initial traveling wave of the fault are analyzed.Distortion occurs when the fault traveling wave propagates on the line,and the degree of distortion of the fault traveling wave is related to the distance to the fault.On this basis,this paper analyzes the influence of fault type,modulus,initial phase angle of fault,transition resistance at fault point,and earth resistivity on traveling wave distortion.(2)Fit the wavefront of the zero-mode component of the initial traveling wave of the fault,and use the wavefront steepness obtained by the fitting to characterize the degree of wavefront distortion,and obtain the relationship between the initial traveling wave wavefront steepness of the fault,the distance to the fault,and the resistivity of the earth.formula.(3)Based on the foregoing analysis,a single-ended traveling wave positioning method combining wavefront steepness and wavelet modulus maximum is proposed.First,obtain the wavelet transform modulus maximum value of the single-ended traveling wave waveform recorded after the line fault,obtain the initial wave head and the starting point of each reflected wave head,and then calculate the initial fault distance through the initial wave front steepness,and filter the closest The maximum value of the wavelet modulus of this distance is used to determine the reflection wave head of the fault point and carry out accurate ranging.(4)PSCAD was used for simulation verification,and the simulation results verified the effectiveness and accuracy of the method.It is difficult to identify the reflected wave head of the fault point in the single-ended traveling wave fault location method of the transmission line.Based on the relationship between the initial wave front steepness of the fault and the distance to the fault,the paper conducts the preliminary fault location,and combines the wavelet transform modulus maximum value of the fault waveform to accurately confirm the reflected wave head of the fault point,and realizes the automation of single-ended ranging.At the same time,the method only uses the fault traveling wave signal,does not require other information assistance,and is easy to implement.In addition,the proposed method has better adaptability in scenarios such as different initial phase angles of faults,different fault transition resistances,and different earth resistivities.