Study On Method Of Fault Location Of Transmission Lines Based On Current Traveling Waves

Fast and accurate fault location of transmission line is of great significance to improve the reliability of power supply and to ensure the stability and economy of the power grid.Compared with the method of fault analysis,the method of traveling wave is not affected by the transition resistance,the operation mode and the fault type,Especially with the development of modern electronic technology and signal processing technology,the positioning accuracy,reliability and adaptability of the method of traveling wave are further improved.This paper takes the transient current traveling wave for the research object,and focus on recognition of traveling wave head and the method of fault location to do some associated work.In this paper,I propose a matrix of the phase mode transformation which can correctly reflect the different fault characteristics,the matrix is not only to solve that electromagnetic coupling has impact on the extraction of fault wave head,but also can judge the fault phase by single module.In addition,in order to reduce the impact on cumulant caused by the vertical arc and to ensure the validity of the singular point wave head detection of the traveling wave,this paper proposes a three-point positioning method based on multi-point data and phase comparison,Firstly,this method utilizes multi-point current phase comparison to judge the fault area,then,selecting current measurement points in the fault area and the adjacent fault area to make up the three-point positioning method to obtain the fault location.Aiming at the problem of local mean decomposition,this paper put forward an improved algorithm which uses a method of waveform matching extension reflecting the signal endpoints and their internal law to solve the problem of endpoint effect,and which obtains the local mean function and the envelope function to solve the problem of excessive smoothing by linear interpolation.Afterwards the method of the improved local meandecomposition is applied to the wave head extraction of the traveling wave,and combines with the method of multi-point data location to calculate the fault distance.In order to further reduce the quantization error caused by the sampling rate of positioning device,this paper puts forward a method which is applied in wave head detection of traveling wave based on the combination with sampling rate conversion and variational mode decomposition.Firstly,the method of variational mode decomposition is used to decompose the components of linear modulus after the sampling rate conversion,and is combined with the teager energy operator to accurately calibrate the time that the initial traveling wave arrives,then,this method of the wave head detection is proved effectively under different fault conditions.