Optimization of accelerated trip scheme based on wavelet analysis

This paper presents a novel approach to accelerated trip of power transmission lines by using biorthogonal wavelet transform to improve the performance of protection relays. The existing accelerated trip principle has been widely applied. However, a lower sensitivity has been observed for some special system parameters and fault types to which the second abrupt changes of sequence currents are especially faint. A wavelet decomposition algorithm is proposed in this paper, which possesses capabilities of fast calculation, partitioning the higher frequency band and linear phase. This algorithm provides an accelerated trip scheme, which can efficiently extract the faint second abrupt changes of currents and is able to deal with the dead-zone problem of conventional scheme. The simulation results of MATLAB/SIMULINK show its feasibility and efficiency.