Research On Fault Location Methods Of Power Transmission Lines Based On Traveling Waves

Fast and accurate fault location of transmission lines is of great significance for fault isolation and repair,improving power supply reliability and ensuring economic operation of power grid.Compared with traditional fault analysis method,fault location of transmission line with traveling wave has obvious advantages,and it is almost not affected by transition resistance,system operation mode and other factors.But the accuracy of location in practical application is not high,there are still some key problems need to be studied in depth.The main research work of this paper is to further improve the accuracy and applicability of traveling wave location in transmission lines.Firstly,the generation and propagation characteristics of fault transient traveling wave and the principle of single and double terminal location based on traveling wave are analyzed in detail.In order to solve the problem of traveling wave coupling among phases,the characteristics of several common phase-mode transform decoupling methods are compared and analyzed,and then a new phase-mode transformation method is adopted to realize the use of a single mode component to characterize the fault information when different types of short circuit occur.The rationality of choosing traveling wave line mode component as characteristic quantity for fault location is proved through the analysis of traveling wave mode component and dispersion effect.Secondly,the wave head detection methods of fault traveling wave signal are studied in depth.Based on the fault data obtained by simulation,the wavelet modulus maximum,mathematical morphology and cosine modulation filter are used to compare and analyze the wave head calibration effect.For the strong fault signals obtained by simulation,the above methods can effectively calibrate the signal mutation points and have good consistency,but there are many limitations in dealing with weak fault signals,especially in real-time recording fault transient waveforms.Therefore,this paper adopts a Hough Transformation wave head detection method based on straight line detection.The comparative analysis results show that the method has better adaptability to the measured fault data,which lays a foundation for further improving the accuracy of traveling wave fault location.Then,a method based on the natural frequency of traveling wave is adopted to eliminate the disadvantage of inaccurate calibration of wave head in traditional traveling wave location.VMD algorithm is introduced when MUSIC algorithm is used to extract traveling wave natural frequencies,which improves the reliability of natural frequencies extraction.After a detailed analysis of the principle and feasibility of this method,it can be applied to fault location of three-terminal and multi-terminal teed transmission,which are widely used in practice,thus improving the applicability of fault location.Finally,the simulation model was built in the MATLAB/SIMULINK simulation platform.Keeping other simulation conditions unchanged,the position of fault point,fault type and transition resistance value of fault point are changed successively to study how these factors affect the location results of traveling wave natural frequency method.The comparative analysis and simulation results show that the relative errors of the fault location results are basically within 1%,which meet the actual requirements of the project,and the accuracy and adaptability of fault location are also improved.