Research On Fault Location For Transmission Line Based On Distributed Monitoring

The transmission line is the most widely distributed component of the power grid,which bears the responsibility of transmitting electric energy.Accurate fault location of transmission line can reduce the labor and material costs of post-fault patrol and improve the reliability of power supply.Aiming at the problems of low accuracy and many influencing factors of traditional traveling wave fault location methods,this paper relies on distributed traveling wave monitoring points arranged on transmission lines to study the methods to improve the accuracy of traveling wave fault location of transmission lines.In order to solve the problem that the location accuracy of traditional traveling wave fault location method is greatly affected by the uncertainties of traveling wave velocity and overhead line length,the necessity and the advantages of setting up distributed monitoring points is analyzed in this paper.The on-line real-time measurement of traveling wave velocity by distributed monitoring points can greatly eliminate the fault location error caused by the error of overhead line length and improve the accuracy of traveling wave fault location method for transmission lines.Aiming at the problem of fault location and phase selection after fault happens,this paper uses the principle of phase-separated current phase differential based on fault component to judge the fault zone and phase in transmission line,and combines this principle with the above-mentioned traveling wave fault location method,proposes a fault location process based on distributed monitoring.In order to solve the problem of low accuracy and non-adaptability of traditional traveling wave head detection algorithm,this paper uses variational mode decomposition and energy operator to detect traveling wave head,and combines this algorithm with fault location method based on distributed monitoring.The simulation results show that the location accuracy is quiet good.At the same time,this paper quantitatively analyses the wave head detection error caused by the discrete sampling process of traveling wave,and studies the relationship between the fault location accuracy and the sampling frequency of traveling wave signal.Aiming at the problem that the results of traditional traveling wave head detection algorithms are greatly affected by noise,this paper proposes a traveling wave head detection algorithm with noise based on multiple variational mode decomposition.The simulation results show that the algorithm can detect the time when the fault traveling wave arrives at the monitoring point more accurately even in the case of serious noise interference,and the fault location effect is better.At the same time,this paper analyses many factors that may affect the traveling waveamplitude,and studies the influence of noise on the location accuracy of fault traveling wave signals with different amplitudes.Aiming at lightning faults which often cause tripping accidents,this paper discusses the possible types of lightning faults caused by overvoltage of direct lightning,analyses the traveling wave propagation law of various types of lightning faults,and puts forward the judgment method of the relative positions of flashover points and shielding points when shielding flashover faults occur.The fault location method based on distributed monitoring is used to locate various lightning stroke faults.The simulation results show that the fault location method based on distributed monitoring can accurately locate the fault points regardless of the type of lightning stroke fault.