Energy eigenvector analysis of surface discharges for evaluating the performance of polymer insulator in presence of water droplets

Due to hydrophobic properties of polymer insulator, formation of discrete water droplets and the induced surface discharges on the insulator are typical phenomena during the insulator operation. To investigate the performance of polymer insulator in presence of discrete water droplets, maximum value, cumulative charge and energy eigenvector of discharge current were investigated. Effects of droplet numbers, droplet location, volume and contamination on surface discharges were analyzed. Obtained results reveal that with the development of surface discharges from initiation of corona discharge to arcing discharge and surface flashover, the dominate components in discharge current are the low frequency (0-78 Hz) components. For the condition of both single droplet and double droplets, flashover voltage and maximum value, cumulative charge and energy eigenvector of discharge current show the increasing tendency with increasing the droplet volume from 10 to 30 μL, but show the decreasing tendency under the condition of increasing the droplet volume from 30 to 40 μL and increasing the droplet contamination from 1.0 to 3.0 mS/cm. However, for triple droplets, the flashover voltage and investigated characteristics of discharge current show the decreasing tendency under the condition of increasing the droplet volume from 10 to 40 μL and increasing the droplet contamination from 1.0 to 3.0 mS/cm. Meanwhile, based on the comparison of droplet effects, it can be found that both droplet numbers and droplet location have significant influence on surface discharges.