Research On Fault Location Of Transmission Line Based On Transient Travelling Waves

With the rapid development of economics, more and more HV transmission lines are used to transfer power . Once a fault occurred on transmission line, whether the fault transmission line could be returned to its normal states as soon as possible is related to the fault location. The existing methods of fault location based on travelling waves, both of single-terminal or double-terminal, were not accurate enough. This shortage is caused by the uncertain of travelling wave speed and the overhang of transmission line.The main research work is focused on how to improve the accuracy of fault location, which is concerned about the following aspects:1. Based on the introduction of the wave course of transmission line, the effect of coupling among three phase lines can be solved by phase-mode transform. Then the echo and refraction of travelling waves at the discontiguous spot of impedance, such as the fault point or busbar, are analysed.2. As a new tool of mathematics, wavelet transform has the ability of analysis both in time-domain and frequency-domain. So it can be used to analyse transient travelling waves. After introduce the theory of wavelet transform, the application of wavelet transform on power system is discussed.3. After analyse the spread rule of transient travelling waves on transmission line, new methods of single-terminal fault location and double-terminal fault location are presented. These methods can avoid the effect of wave speed and overhang of transmission line. So the accuracy of result can be improved to a new step.4. The proposed new methods of fault location are implemented by using the model which is composed of the Simulink blocksets running in MATLAB development environment. Several simulation tests involving all kinds of fault situation are carried out on the model. The result shows that the new methods are more accurate than the traditional method.In the last chapter, not only all of the research work accomplished in this thesis is summarized, but future improvement work is pointed out as well.