Partial discharge

About: Partial discharge is a research topic. Over the lifetime, 13997 publications have been published within this topic receiving 102058 citations. The topic is also known as: PD.

Wavelet packet denoising for online partial discharge detection in cables and its application to experimental field results

Abstract: Partial discharge measurements taken online are severely corrupted by noise due to external disturbances. In this paper a powerful noise reduction technique, based on a wavelet packet denoising algorithm, is employed to isolate the signals from the noise. This methodology enables the denoising of partial discharges that are heavily corrupted by noise without assuming any a priori knowledge about the partial discharge features. A brief description of the wavelet packet theory as an extension of the multi-resolution analysis is given. Results of the application of this algorithm to simulated data of low signal-to-noise ratio are presented, demonstrating substantial improvement in signal recovery with minimum shape distortion. Finally, the capability of this technique is highlighted by applying it to experimental field data taken from three-phase 11 kV cables.

Notes on theoretical and practical aspects of polymeric insulation aging

Abstract: This article starts from the same points that generated the John Tanaka review, as an homage to his unforgettable contribution to the science of dielectrics and electrical insulation.

Electromagnetic (EM) wave characteristics in GIS and measuring the EM wave leakage at the spacer aperture for partial discharge diagnosis

Abstract: For the insulation diagnosis of gas-insulated switchgears, the UHF method, which detects electromagnetic wave (EM-wave) in the UHF band (300 MHz to several GHz) with little noise influence, has rapidly developed in recent years. The study in this paper has proposed the evaluation of the location of adhering metallic particles based on the theory of EM-wave propagation by only using the time-waveform information of the EM-wave emitted due to partial discharge, and also analyzed and studied the validity using the FD-TD method. As a result, the duration of the time-waveform differed with respect to the location of the adhering metallic particle, and this difference was caused by the difference in the relative electric field intensity at the tip of the metallic particle among EM-wave modes and the difference was more when the tank diameter was larger. Based on this result, the method for evaluating the location of metallic particle according the time-waveform was studied. In addition, the characteristics of the leakage EM-wave at the spacer aperture were analyzed, and based on the result obtained, two types of antennas, patch and waveguide slot antennas, achieving compactness and a high sensitivity were proposed

A clustering technique for partial discharge and noise sources identification in power cables by means of waveform parameters

Abstract: On-line partial discharge (PD) measurements have become a common technique for assessing the insulation condition of installed high voltage (HV) insulated cables. When on-line tests are performed in noisy environments, or when more than one source of pulse-shaped signals are present in a cable system, it is difficult to perform accurate diagnoses. In these cases, an adequate selection of the non-conventional measuring technique and the implementation of effective signal processing tools are essential for a correct evaluation of the insulation degradation. Once a specific noise rejection filter is applied, many signals can be identified as potential PD pulses, therefore, a classification tool to discriminate the PD sources involved is required. This paper proposes an efficient method for the classification of PD signals and pulse-type noise interferences measured in power cables with HFCT sensors. By using a signal feature generation algorithm, representative parameters associated to the waveform of each pulse acquired are calculated so that they can be separated in different clusters. The efficiency of the clustering technique proposed is demonstrated through an example with three different PD sources and several pulse-shaped interferences measured simultaneously in a cable system with a high frequency current transformer (HFCT).

Electrical treeing behavior at high temperature in XLPE cable insulation samples

Abstract: This paper reports on investigations aiming to understand the behavior of electrical trees formed in XLPE cable insulation at elevated temperatures. Samples cut from a real high voltage cable equipped with an embedded electrode system and composed of a needle separated by 2 mm from counter electrode were used. The temperature was varied between 50 and 90 °C and the range of voltage changed between 9 and 18 kV. The electrical treeing process was followed by means of microscopic observation from the moment of initiation until the leading branches connected the counter electrode and partial discharge (PD) activity was monitored simultaneously. The shape and fractal dimension of the resulting trees were analyzed. It was found that temperature and voltage level had pronounced effect on the process of electrical tree formation. At lower voltages different type of trees could be formed, whereas at higher voltages branch trees dominated. Increase of test temperature reduced the time for tree initiation, whereas the tree growth time was less affected, except for the lowest voltage level at which the slowest tree development was observed at the highest test temperature. It is postulated that the impeding effect of elevated temperature on tree growth is due to a change of tree channel sidewall conductivity, whereas the observed reduction of tree initiation time with the increase of temperature and voltage level is attributed to lowering of the threshold energy for damage at higher temperature as well as increasing of the injection current at higher voltage level.