Research Of Double Terminal Traveling Wave Fault Location Based On The Exact Model Of The Line

With the development of high voltage power transmission technology,high voltage and long distance transmission lines have increased rapidly in recent years.Due to the long distance transmission line across the region,the line running environment is complex and changeable climate.Therefore,the line fault occurs frequently.In addition,high speed circuit breakers are widely used in electric power systems.It makes the line insulation failure generally no obvious traces.Line inspector can not identify the location of the fault point with the naked eye.These factors have brought great difficulties to the fault finding.Accurately and quickly locate the fault point,which is conducive to timely troubleshooting and ensure the reliability of power supply.Because the precision of the traditional double ended fault location algorithm is greatly influenced by the length of the line.Based on such a point,this paper focuses the feature extraction of fault traveling wave based on improved line model.This paper mainly researches three aspects:(1)Span between two adjacent tower was chosed as line length model in the traditional fault location algorithm.There is a big error in the actual project between span and wire length because of the existence of the line sag.In view of the above problems,the transmission line length of the catenary equation was introduced here at first.Then the wire length model of the parabolic equation was deduced based on the high degree of similarity between catenary equation and parabolic equation.In this paper,the double terminal fault location model of single circuit transmission line is established.Simulation analysis of real example is carried out on the fault of single phase to earth.The parabolic model is proved to have good accuracy and applicability.It can solve the problem of fault location accuracy of long distance transmission line affected by wire length.This line model was used as fault location algorithm.(2)In order to decoupling fault current,a new phase mode transformation matrix was introduced here.The accuracy of the new phase mode transformation matrix was verified by the simulation results and error analysis.By selecting proper linear mode component as the fault location signal,the single module can be used to characterize all fault types.According to the selection principle of the wavelet basis.The performance of the first type,second type of B spline and DB4 wavelet were compared under different fault types and fault conditions.Finally,the second type of B spline wavelets were selected as the signal processing tools because of the excellent comprehensive performance.(3)The denoising method of the traveling wave signal was studied.Due to the different decomposition scales,the wavelet transform modulus maxima of transient traveling wave and the noise are different.This characteristic can be used to achieve denoising of original signal.Compared with the traditional full wave Fourier filter,the filter does not need to set up a special filter unit.By adding white noise to the traveling wave signal to simulate the actual situation.By the analysis,the full denoising of transient traveling wave signal can be realized under the decomposition scale 4.