Caracterização das condições operacionais de isoladores poliméricos usando atributos das descargas corona.

Abstract

This work presents a method for evaluating the operational conditions of polymeric insulators, focusing on the characterization of corona discharges using attributes extracted from ultraviolet (UV) images. For this purpose, measurement campaigns and UV images capturing were carried out in laboratory, in various arrangements, using the Daycor II UV detection camera, and, simultaneously, the partial discharges signals were measured and captured using the IEC 60270 classical method. In order to comply with inspection methodological criteria, the UV camera’s capture parameters were established based on approximations. In addition, the sensitivity of the main attributes of UV images to the linear variation of the camera's capture parameters was evaluated in order to compare which attributes are more or less sensitive to capture conditions. During the digital UV image processing, the following attributes were evaluated as reference: the area of the faculae integrated in the capture interval, the mean pixels/frame distribution of the image, the persistence of the faculae, the number of objects/frame and the persistence map. In addition to these attributes, the photon counting rate presented by the camera was also evaluated. The image attributes were correlated with the statistical attributes of corona discharge pulses and these correlations were addressed in order to characterize the behavior of polymeric insulators under various conditions of pollution, humidity and defects. It was possible to obtain safe correlations between the attributes of corona discharge, both of the image and pulses, and the operational conditions of the insulators, so that the quantification of corona discharges can be performed using the parameterization of UV images.