Classification of the polymeric insulators degradation conditions by UV radiation levels (corona) and Fuzzy Logic

Summary

The insulation of electric power transmission systems is made predominantly using electrical insulators. Electrical insulator failures have undesirable consequences, being the main cause of transmission line outages. In its operational environment, high voltage outdoor insulators are submitted to severe conditions. The increase in electric field strength causes surface discharges (corona) or partial discharges, internal to the insulators; and atmospheric conditions, such as air-density and humidity, affect corona generation. Corona produces ultraviolet light, heat and a gaseous by products (ozone, NO2). Corona in the presence of water generates nitric acid which may cause surface deterioration. Electrical utility companies are constantly seeking predictive techniques that indicate the appropriate moment for maintenance intervention, while aiming toward a continuous increase in service indexes. So, in order to identify the degenerative process of polymeric insulators, technical inspection using UV radiation emitted by corona discharge was applied in the laboratory. During the tests, 230 kV polymeric insulators in different degradation conditions were used. The obtained ultraviolet images were subjected to image processing in order to obtain the concentration of pixels. Discharge levels of corona (points / min and concentration of pixels) were used as parameter in a Fuzzy Logic system to classify the insulator degradation conditions.

Additional informations

Authors

Yingyan Liu, Kurrat Michael, Weining Bao, RAJA NAYAK