Aplicação da transformada wavelet à filtragem de sinais de descargas parciais.

Abstract

The electrical insulation is one of the most important parts of electrical equipment, which objective is to keep separate the different potential parts to guarantee the correct operation of the equipment. Thus, the integrity of those electrical insulations is essential for the correct operation of the equipment, and, in the case of failure, damage is caused to the equipment, to the others that compose the electrical system, people close to the installation and damage to the company’s image. Failures in the electrical systems can cause the interruption of the electrical energy supply, generating very high fines applied by regulatory agencies. The electric companies have interest on the correct operation of their equipment, and a way to verify that can be the verification of the integrity of the electrical insulation by measuring its partial discharge level. However, those measurements are very hard to be made in the great part of electrical equipment due to the low intensity level of the discharges, in addition to the from various sources such as electromagnetic emissions, system switching among others. In this work, a digital filtering method based on Wavelet Transform is used to perform the attenuation of noise in real partial discharge signals measured in laboratory. From the experimental results, it’s verified by visualizing the resultant waveforms a considerably attenuation of noise present in partial discharges. The noise filtering allows a future partial discharge quantification, making possible to know the integrity of the equipment insulation and also to make decisions about the operation of the equipment such as maintenances for the correct and more trustable operation of the equipment.