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

With the rapid development of the national economy,the society's demand for electricity is increasing day by day.The long-distance and extra-high voltage transmission lines have been widely used.As the transmission lines become increasingly complex,inevitably a variety of failures will occur.Once the line failure,may cause a large area blackout,resulting in adverse social impact.Therefore,when the line failure,quickly and accurately find the fault point,not only for the maintenance of lines and fast recovery power supply,but also for the entire power system security and stability and economic operation are of great significance.Transmission line fault location includes fault line selection,fault phase selection and fault location.At present,most of the literatures are considered one of the three,However,in the transmission line fault location,people sometimes care about two or even all three of them,and the uncertainty of the traveling wave velocity also increases.The fault location error.In view of the above problems,this thesis mainly completed the following aspects:(1)In order to improve the accuracy and sensitivity of fault location and fault-phase selection for transmission lines,a method resolving this problem is proposed in this paper.Firstly,the traveling wave in transient fault signals is analyzed by wavelet transform.The modulus maxima of wavelet transform are applied to initial fault traveling waves detection,thereby achieving fault location and fault-phase selection.And then,by extracting the transient DC component among the transient fault signals,a fault-phase selection method based on transient DC component for transmission lines is presented.(2)The uncertainty of traveling wave speed always causes big deviations to the fault location.In order to conquer the influence of traveling wave speed on transmission line fault location,a new method of fault location by using three measurement points was presented in this paper.The method contains two main parts:the establishment of the identification matrix for the faulty section and fault point location.Firstly,the arrival times of the initial fault traveling waves are used to form the identification matrix for the faulty section,and the faulty section can be identified according to characteristics of element in the formed identification matrix,and the matrix avoids the influence of wave speed;Secondly,a new locating algorithm without influence of wave speed was derived based on the principle of double-end traveling wave fault location.(3)The Matlab simulation software is used to simulate the various fault types of the transmission line.The simulation program is compiled and the method based on the wavelet transform is verified to prove the correctness and sensitivity.At the same time,compared with the method based on Hilbert transform,the method proposed in this paper presents the superiority.