Application of Discrete S-Transform for Differential Protection of Power Transformers

Abstract

Abstract-In this paper, a novel scheme based on Hyperbolic S-Transform (HST) is proposed for digital differential protection of power transformers. Hyperbolic S-transform is a powerful tool for non-stationary signal analysis in noisy conditions. Decision logic has been devised using extracted feature from differential currents due to transient phenomena in transformers. The HST of the differential current is calculated. Then, a Decision Index (DI) is calculated according to the spectral energy and standard deviation of the S-matrix. It is seen that DI values are different in the cases of internal faults and inrush currents. The scheme has been implemented in MATLAB environment and the inputs are differential currents derived from EMTP software. In order to simulate the internal turn to turn and turn to earth faults, the power transformer is modeled using 8×8 RL matrices obtained from the subroutine BCTRAN of EMTP software. The differential current signals are infected by noise and the robustness of the algorithm under noisy conditions is investigated.

Funções de Proteção de Sistemas Elétricos Baseadas na Transformada de Stockwell: Revisão Bibliográfica e Implementação

“…As proteções de transformador e barramento apresentaram tempos de atuação de ≈ 1, 5 e ≈ 0, 75 ciclo fundamental, respectivamente. Ashrafian et al (2012) também propuseram uma protecão de transformador, porém, os autores utilizaram um fator dado pelo produto da energia e do desvio padrão do espectro calculado com a TS. Ainda sobre proteção de transformador, Shah et al (2016) propuseram o uso do valor máximo da amplitude do espectro dado pela TS e o desvio padrão doângulo, associado ao uso de Support Vector Machine.…”

Optimal selection of analyzing window of arbitrary shape for S-transform using PSO algorithm

“…The method is applicable in a wide range of areas such as seismic signal analysis [2], [6]- [7], transformer internal fault [3]- [5], [17] and internal incipient fault [8], [18]- [20] detection and pattern recognition [21].…”