Diagnostics analysis of partial discharge events of the power cables at various voltage levels using ramping behavior analysis method

Abstract

Partial discharge events can occur in high-voltage cables. It can be caused by defects in the cable insulation, contamination, or a combination of both. Partial discharge in cables can lead to insulation failure and cable failure. This investigation aims to identify the trends and patterns in the internal partial discharge (PD) occurrences in the power cables when exposed to different voltage levels - 6.4, 7.4, 9.4, and 11.3 kV. For pattern extraction, a well-established method, ramping behavior analysis, is implemented to extract and classify PD occurrences into sets of significant and stationary events. In this investigation, significant events correspond to an absolute peak (the discharge pulse) and subsequent oscillations from the measurement sensor. The stationary events represent a collection of noise that is recorded during the measurement. These noise signals are essentially small variations within a pre-determined threshold range. Furthermore, a comparative analysis is performed for each voltage level and for the voltage levels.This investigation brings new knowledge on how internal partial discharge pulses occur at various voltage stress levels. Specifically, the emerging patterns and trends of internal partial discharge events. The results indicate that there is a positive correlation between the number of PD events and the increase in stress levels. Furthermore, negative PD peaks are more frequent at lower stress levels.