Transmission Line Traveling Wave Fault Location Based On Wavelet Analysis

With the development of electrical networks, the function of the fault location is attracting more and more attentions from the system operators. So it is the goal for the researcher concerned to improve the accuracy and reliability of the fault location in this area. At present the fault location method based on travelling wave is relatively accurate, and there are many such fault locators operating in internal and external power systems. But there are still some aspects waiting for being further improved, such as the location precision, reliability, and so on. Therefore, the majority of my work in this thesis is listed as follows:It is difficult to construct directional travelling waves due to the difficulty in obtaining voltage transient travelling waves. Using three phase current measured at the bus of fault lines we get the mode 2 component of the current travelling wave by phase-mode transformation. And then we demarcated the saltation time and starting time of this travelling wave respectively by the first kind of cubic B-spline wavelet and the second kind of cubic B-spline wavelet. Excellent location results were obtained in double terminals simulation of travelling wave fault location.The propagation velocities of different frequency components in the travelling wave are also different, but the detection of highest frequency component of the travelling wave is difficult, so the appropriate propagation velocity should be selected. The average propagation velocity of travelling waves was calculated in this thesis, and the location errors were kept within 300m using this average velocity.If the travelling wave signal is polluted by noises, adopting denoise methods is not always beneficial to identify the singularity points of travelling waves. Because any denoise method is unable to eliminate the noise completely, while the travelling wave signal may be distorted. Based on the correlation of wavelet components in different scales, we enhanced signals and eliminated noises using wavelet component product of 2~3～2~5 scales, and then identified the travelling wave successfully. So the reliability of travelling wave location is improved obviously in noise environment.Based on travelling wave theory, travelling waves are not generated in transmission lines if the single-phase-to-ground fault occurs when the phase voltage...