Aplicação da transformada wavelet na classificação do estado operacional de câmaras de disjuntores.

Abstract

A method for analysis of Dynamic Contact Resistance (DCR) curves using the wavelet transform is proposed. The method consists in applying the wavelet transform to the DCR curve and detail coefficient energy calculation. Haar, Daubechies 4, Daubechies 6, Daubechies 8, Coiflet 6, Coiflet 12 and Symlet 8 orthogonal wavelets were used. The analyses were made until the third level of decomposition. The degradation level classification of the high voltage circuit breakers extinction chambers is carried out through the detail coefficient energy associated to the curve at each level. All tests for this dissertation used synthetic DCR curves (computationally generated). Initially, two DCR curves were used to generate other curves. The first curve represents the DCR of a circuit breaker in good condition. The second represented the DCR circuit breaker with arcing contact in an advanced deterioration state. The generated curves show intermediate degradation states between the first and second curves, totaling nine curves. A set composed of 809 curves were created by adding random noise to the nine curves. The added noise had a normal distribution. Researchers use the value of area under the curve for classifying the degradation degree of the arcing extinction chamber. A classification process was done using wavelet transform in this work. The results obtained using the wavelet transform have been compared with those using as criterion the value of area under the curve. Analyzing the results, the wavelet Coiflet 12 highlights as the most suitable for the classification of the extinction chambers degradation state of high voltage circuit breakers. The third level of wavelet decomposition showed better results.