Extração de atributos de fáculas de imagens ultravioletas de isoladores poliméricos.

Abstract

On inspection with ultraviolet sensitive camera, it is only supplied information on where the corona discharges are concentrated and an estimative of intensity of these discharges in high voltage equipment. For this purpose, it was developed a methodology of faculae attribute extraction of ultraviolet images from 230 kV polymeric insulators. In order to do this, videos captured by the ultraviolet detection camera were used as work material. The methodology of the work consists of the development of several digital image processing routines, initially, to adapt images and, later, to quantify the attributes of interest extracted. The image adaptation routines seek to segment the shape of the insulator from the background, to segment in an image the faculae that represent discharges caused by corona effect, to integrate faculae from multiple frames in only one image, to eliminate what is to be considered noise and to segment the shape of the insulator into parts of interest. The attribute quantification routines are destined for faculae area, perimeter, form factor and persistence, in addition to their distances of the 230 kV polymeric insulator parts of interest. As a result of the development of these routines an algorithm for attribute extraction is presented. Finally, a sensitivity analysis of the parameters used in the algorithm is made, with the intention to delimit its use conditions. Two case studies of the application of the algorithm were performed, for each of them 64 combinations of number of frames and noise limit were processed. Presenting the surfaces of area, perimeter, shape factor and persistence of the faculae attributes in function of the two cited parameters. In order to determine which number of frames and noise limit would be suitable, it was adopted as metric to look for the lowest gradient value of the attributes surfaces. In conclusion the methodology for extracting attributes from the UV image faculae of insulators to improve the classification of insulators was successfully developed and the contribution of the work is presented in extracting attributes and determining suitable number of frames and noise limits for UV videos.