Algorithm for transformer differential protection based on wavelet correlation modes

Identifying internal fault from magnetizing conditions in power transformer using the cascaded implementation of wavelet transform and empirical mode decomposition

“…Plenty of literatures have suggested methods to detect internal fault from inrush currents. As shown in Figure 1, these methods are classified into 7 groups based on the input signals and the procedure of their algorithm as follows: (a) methods that use harmonic components of the differential current, [1][2][3][4] (b) methods based on utilizing the wave shapes of differential current, [5][6][7][8][9][10][11][12] (c) methods based on the flux signals, 13,14 (d) methods based on power calculating, [15][16][17] (e) methods based on voltage and current signals, 18,19 (f) methods based on transformer inductance, 20,21 and (g) methods based on artificial intelligence techniques. [22][23][24][25][26] Abbreviations: Current transformer, (CT); Discrete wavelet transform, (DWT); Empirical mode decomposition, (EMD); Intrinsic mode functions, (IMFs); Fast Fourier transform, (FFT); Low-pass filters, (LPF); High-pass filters, (HPF) Symbols: D n , n'th level detail coefficient; r n , EMD residue signal; IMF n , IMF of level n; X(t), Input signal of EMD method; i diff , Differential current; E IMF;rn , Energy of the IMFs and the residue; E D2 , Energy of D 2 ; i No (n), Normalized differential current in sample n; є 1 , Threshold of criterion 1; є 2 , Threshold of criterion 2…”

“…Plenty of literatures have suggested methods to detect internal fault from inrush currents. As shown in Figure , these methods are classified into 7 groups based on the input signals and the procedure of their algorithm as follows: (a) methods that use harmonic components of the differential current, (b) methods based on utilizing the wave shapes of differential current, (c) methods based on the flux signals, (d) methods based on power calculating, (e) methods based on voltage and current signals, (f) methods based on transformer inductance, and (g) methods based on artificial intelligence techniques …”

Comparison of Various Mother Wavelets for Fault Classification in Electrical Systems

“…In addition, wavelets are used to detect faults or abnormalities in transformers [13][14][15][16][17][18][19][20][21][22]. They are used to detect vibrations or electrical signals.…”

“…Most papers use wavelets to classify inrush and internal and external faults. The differential current is used as input for the wavelet transform to analyze faults [14][15][16][17][18][19][20][21]. The boundary wavelet transform is implemented in the differential protection of power transformers to distinguish internal faults from other disturbances.…”

“…However, many studies only focus on transmission lines or transformers, and few have combined the two components when analyzing systems. Most of the references use wavelets to detect and identify fault types in electrical systems, but they do not analyze the mother wavelet [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]20,21]. Additionally, there are research articles that compare mother wavelets [18,19,22,23].…”