Research And Application Of Fault Diagnosis Methods For Overhead Transmission Lines

With the rapid development of my country’s economy and the further advancement of modernization and digitization,the development of all walks of life is inseparable from a reliable power system.Power systems are increasingly complex,in the power system,overhead transmission lines are the part of the system that have the most contact with the external environment.They are easily affected by harsh environments,weather,and attacked by birds and beasts.If the failure of the transmission line is not dealt with in time,it may cause a large-scale power outage.When the transmission line fails,a transient zero-sequence current will be generated in the line,which contains a large amount of fault information when the fault occurs.According to the transient zero-sequence current collected by the wave recording device when the fault occurs,the fault line is selected and the fault type is identified,it is of great significance to quickly diagnose faults and ensure the safety and reliability of the power system.This paper analyzes and studies the fault transient zero-sequence current collected by the wave recording device in the actual power system when a single-phase ground fault occurs,and compares and analyzes various fault line selection and type identification methods at home and abroad,and proposes an overhead transmission line.The fault diagnosis method has good practical significance.1)This paper studies the fault line selection method of transmission line based on time series characteristic distance.Firstly,the transient zero-sequence current generated by the actual fault is analyzed,and the moving average method is used to denoise it,so as to facilitate the extraction of the first wave of the transient zero-sequence current by the proposed algorithm;then,by extracting the first wave of the transient zero-sequence current The amplitude characteristics of the wave are calculated,and the characteristic Euclidean distance of different lines is calculated to complete the line selection.Finally,the feasibility of the method is verified by real fault data and Matlab/Simulink simulation data of single-phase grounding of power system.2)This paper studies the fault classification method of transmission line based on model fusion.For the transient zero-sequence current of the fault line,the characteristics of different types of faults in the time domain are not obvious,so it is transformed into the frequency domain by Fourier transform.Since the actual fault samples are few,the deep belief network and support vector machine,which have better effect under small sample size,are used to construct the classification model,and the results of the classification model are fused at the decision-making layer through the D-S evidence fusion theory.Experiments on real data sets show that the proposed method is feasible,and the classification accuracy and fault tolerance can be improved through decision level fusion.3)Design and implement a transmission line fault diagnosis system.The method proposed in this paper is integrated into the overhead transmission line fault diagnosis system,the files input by the user are analyzed,and the transmission line fault line selection and classification are carried out.Finally,the diagnosis results are fed back to the user through the visual interface.Provide technical support for technicians and realize rapid fault diagnosis,which has practical application significance.