Generation of Reproducible Reference Insulation Defects in Experimental Tests Cells for Controlled PD monitoring

Abstract

Partial discharge (PD) monitoring applications enable the performance of appropriate diagnosis regarding the insulation condition of high-voltage (HV) electrical grids. During the last decade on-line PD monitoring systems have been increasingly implemented by utilities and large electricity consumers in HV installations. Therefore, the evaluation of their performance is interesting in order to check whether they are generally effective with respect to their functionalities. For the characterisation of the PD monitoring instruments and of the requirements of acquisition time (number of cycles per second), the performance of laboratory tests with real insulation defects is required. As these are monitoring tests, they entail a long time (at least one day), and during this time the monitored insulation defects must behave in a stable manner. The main scope of the study presented is to design, manufacture and characterise the behaviour of three test cells, each integrating a characteristic insulation defect, with the aim of using them in laboratory monitoring tests lasting at least one day. The considered insulation defects are as follows: an internal cavity in a solid dielectric, corona effect and a surface defect. The measurements carried out with the designed test cells have shown that they are suitable for their implementation in PD monitoring tests of long duration.