Wavelet-DFT based Hybrid Adaptive Algorithm to Fast Distance elaying in Series Compensated Transmission Lines

Abstract

The work reported in this paper presents the design and performance evaluation of a new Hybrid adaptive algorithm deployed in fast Distance protection of a series compensated transmission system. The proposed algorithm is a hybrid scheme which incorporates multi resolution analysis (MRA) of wavelet transform along with adaptive window Discrete Fourier Transform (DFT). The phasor estimation technique possesses the advantage of recursive computing and adaptive compensation method for removal of decaying dc offset in the fault transient signal. The fault detection index is embedded along with variable data window such that the proposed scheme provides fast tripping decision with high accuracy. A dynamic model of a transmission system equipped with series compensation capacitor along with MOV (Metal Oxide Varistor) is simulated using Power System Block Set of MATLAB/SIMULINK Software. Extensive simulation considering different percentage of series compensation has been carried out to obtain large set of fault transients signal samples. The evaluation results based on the criteria of speed and accuracy of line fault detection is presented, which demonstrates the efficacy of the proposed scheme.