Research On Fault Location Of Transmission Line Under Lighting Stroke Based On Singular Value Decomposition

With the rapid development of power industry in our country, the extra high voltage transmission lines are increasing, high precision and reliability of the fault location is very important to ensure it work safely and reliable. Fault location device based on the traveling wave principle has been widely used in power system, but at the same time, there still remain problems such as lightning interference and other factors that will negatively impact its reliability. Therefore, an in-depth research on the traveling wave fault location is still of great significance to improve the safety, reliability and economical operation of the line. The main study in this paper is as follows:1) Based on traveling wave singularity detection problem, a new singularity point detection method based on multi resolution singular value decomposition (singular value decomposition, SVD) is studyed, the SVD detail signals has the bility to detection the singularity and polarity of traveling wave when Hankel matrix is used, and discussed the linear relationship between the modulus maxima of the pulse in the detail component and the mutation or slope in the singular point. The difference spectrum of singular value combined with iterative SVD noise reduction method is proposed, singularity point of traveling wave under strong noised background can be detected more accurately and reliably.2) The transient characteristics difference between the lightning shielding failure of transmission line fault current and common single-phase short circuit current are studied. studyed the gradient, frequency and waveform characteristics of fault current, and analysed from the three aspects:using the SVD pulse modulus maxima representation of the fault current gradient, the content of fault current frequency is judged by the singular values which are obtained from the fault current singular value decomposition of time-frequency matrix, using the transient current subsection integral representation the characteristic changes of waveform, and studied the corresponding criterion for recognition, the recognition method of lightning fault are got.3) For conditions that lightning point and flashover point are different, analyzed the selection of lightning side. The fault location method is studied by the time of lightning initial traveling wave and the reflection wave from fault point which got from the lightning side, and analyzed the factors affecting the location of the fault point, simulation results of EMTDC show that the fault location method is effective.