Accelerated trip of power transmission line based on biorthogonal wavelet analysis

This paper presents a novel approach to accelerated trip of power transmission lines using biorthogonal wavelet transform to improve the performance of protection relays. The existing principle derived from the second abrupt changes of the sequence currents to accelerate trip has been widely applied, while a fault occurs in the second zone of the distance protection. However, a lower sensitivity has been observed for some specific system parameters and fault types for which the second abrupt changes of sequence currents are particularly faint. The wavelet analysis has an outstanding characteristics to extract signal components, by contrast to the conventional Fourier analysis which is inefficient to detect the faint abrupt signal. A fourth-order biorthogonal wavelet decomposition algorithm is proposed in this paper, which possesses the capability of fast calculation, partitioning the higher frequency band and linear phase. This algorithm, provided as an accelerated trip scheme, can efficiently extract the faint second abrupt changes of the sequence currents and is able to deal with the dead-zone problem of conventional protection techniques. The simulation result obtained using MATLAB/SIMULINK shows the feasibility and efficiency of the proposed approach.