Research On Distributed Fault Location Method For Transmission Line Based On Wavelet Transform

As the very important part of power system to deliver the energy, transmission lines are prone to be disturbined by fault. The fault on the transmission line not only can cause failure of supply, but also can result in the loss of stability of the whole system. To detect the fault quickly and accurately can not only improve the reliability but also reduce the recovered time. It can be helpful to deal with the fault. Fault detecting is an urgent research topic. It is necessary to be as a part of smart grid, and is valuable to earn the economic benefits.At first, this article elaborated traveling wave process on transmission line, analyzed the function of phase-mode transformation in three-phase line's decoupling, and also introduced the basic principles, advantages and disadvantages of the existing traveling wave fault location methods. Then the basic concept of wavelet analysis was described with emphasis on the multi-resolution analysis, Mallat algorithm and wavelet transform modulus maxima principles. The denoising processing to the traveling wave signals in singularity detection was also studied.At present, based on the principle of traveling wave fault location of transmission line methods have been widely used, including single-ended and double-ended method. The device which uses these methods is mainly installed in the substation, and at the same time these methods are the use of traditional voltage and current transformers to measure the traveling wave signals, but the traditional transformer exists narrow band, easy-to-saturation, and poor high frequency response, what is made the first detected wave slow down the line, leading to large error in head wave positioning. In this paper, in view of traveling wave propagation characteristics along transmission line, transmission line fault detection uses a multi-point distributed method. Rogowski coil current sensor uses the principle of good features with broadband and linear. Based on this, two distributed fault location algorithms, model time delay locating method and two-point symmetric locating method, were studied and proposed under detailed deduction and analysis. The single-line simulation model was set up by ATP-EMTP, and the distributed fault location system was tested in simulation experiments with data processing function of MATLAB. The results show that all of the two algorithms can meet the demands of high precision and reliability in accident scene.The simulations in this paper are all based on the practical program ATP-EMTP, programmed in MATLAB with new modeling, so the studies are important for theory research and practical applications.