Ultra-high-speed protection of transmission lines using traveling wave theory

A new traveling-wave-based algorithm is proposed in this paper for the protection of transmission lines. In the proposed algorithm, Teager energy operator is used to extract traveling waves. Teager energy operator has a high computational efficiency and extracts traveling waves with high resolution. The amplitude of the first detected traveling wave as well as that of the traveling waves which are detected in 2L/v and 2(L - x)/v seconds ("L" is the line length, xis an initial guess about the fault location, and "v" is the traveling wave propagation speed) after the first one are used to discriminate internal and external faults. Then the traveling wave propagation speed and the time difference between the first and the second traveling waves are used to find the fault location. This process can also be used for the internal fault identification. Finally, two decision trees and the amplitude of initial current traveling waves in different modes are used for the fault type classification and faulted phase selection. The feasibility of the proposed algorithm is investigated by test signals which are simulated in PSCAD/EMTDC, and the algorithm is implemented in MATLAB. (C) 2015 Elsevier B.V. All rights reserved.