Development of 𝒅�˗𝒒� WPT-based digital protection for symmetrical faults occurring during power swings [articol]

Abstract

This paper presents the performance evaluation of a new digital protection for symmetrical faults occurred during the occurrence of power swing. The proposed digital protection is based on extracting the first level low frequency and high frequency sub-band contents present in the 𝑑 ̶ 𝑞 -axis three phase instantaneous current components. This characterization helps to provide enough information to efficiently detect and discriminate power swing and symmetrical faults during power swing in two machine system. The utilized Wavelet Packet Transform (WPT) is realized by a half-band digital low and high pass filter, whose coefficients are determined by the Daubechies 𝑑𝑏4 wavelet basis functions. The WPT coefficients contain information that offer accurate, fast, and reliable detection in discriminating power swing and symmetrical fault. This detection method is immune to the power swing slip frequency, fault inception time and fault location. To test the proposed method, several power swings and faults are numerically simulated in MATLAB/SIMULINK.