| The fault location for transmission lines is of great significance to help power line maintenance crews search for fault point and restore the lines'transmission service without too much delay. Being compared with traditional fault location methods based on fundamental frequency components, the traveling wave methods have higher accuracy. However, some problems existed in the traveling wave methods are still not well solved in practice and they may seriously affect the fault location accuracy and reliability sometimes. The development of transmission line on-line monitoring technology and communication technology may provide conditions for solving these problems. On this basis, starting with the main factors that influence the fault location accuracy of traveling wave methods, the traveling wave detection method, the wave velocity determination method and the fault location method based on traveling waves of multiple measurements are studied in this paper. At the same time, the accurate fault location for multi-terminal transmission lines which have a special network structure and the fault phase selection are also studied.A traveling wave detection method based on Fast Intrinsic Mode Decomposition (FIMD) and Teager Energy Operator (TEO) is proposed in this paper. The aerial mode component of each measured current wave is decomposed by FIMD, and then the instantaneous teager energy of the obtained first intrinsic mode function is calculated by TEO. According to the first sudden arising of the calculated teager energy, the arrival time of the initial fault traveling wave is determined. The problems of Hilbert-Huang Transform for traveling wave detection can be solved by the proposed method.A novel fault location scheme for transmission lines based on traveling waves of three current measurements is proposed in this paper. A rogowski coil current transformer is used to measure the fault current in the midway of a transmission line and the faulted line section is identified through comparing the phase angles of the measured currents at two ends of a line section. The wave velocity is calculated by the ratio of the length of the non-faulted line section to the time that the wave travels through this line section, and then the fault point is located accurately.A novel fault location scheme for transmission lines based on traveling waves of multiple current measurements is proposed in this paper. The faulted line section is identified through comparing the phase angles of multiple current measurements. Then the current measurements used for fault location are selected according to the identified faulted line section and the principle is to make the faulted line section be in the middle of the selected current measurements as far as possible. The wave velocity of the fault current wave is calculated by the aforementioned wave velocity determination method, and finally the fault point is located according to the two-ended traveling wave method.A novel fault location scheme for multi-terminal transmission lines based on the two-ended traveling wave method is proposed in this paper. According to the two-ended traveling wave fault location method and the time that the initial fault traveling wave arrives at each terminal, the proposed fault section identification matrix is formed. Then, the fault section identification rules are proposed respectively for different fault conditions. The terminal that can form the most two-ended lines through the fault point is selected as the local terminal, and then the fault point is located by averaging the fault distances calculated with all the two-ended lines.A fault phase selection method based on high order muti-resolution singular entropy is proposed in this paper. The high-order cumulant calculated with wavelet coefficients of the fault current components are used to form state matrix, and then the fault types of a transmission line are determined by the entropy of the obtained singular values from the state matrix.
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