scholarly journals Frequency Resolved Partial Discharges Based on Spectral Pulse Counting

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6864
Author(s):  
Anderson J. C. Sena ◽  
Rodrigo M. S. de de Oliveira ◽  
Júlio A. S. do do Nascimento
Keyword(s):  
Partial Discharges ◽  
Mapping Technique ◽  
Laboratory Measurements ◽  
Pulse Counting ◽  
Spectral Bands ◽  
Spectral Analyzer ◽  
Counting Data ◽  
Electromagnetic Signals ◽  
Similar Phase ◽  
Generator Stator

A partial discharge (PD) classification methodology based counting PD pulses in the spectral domain is proposed and presented in this paper. The spectral counting data are processed using the proposed PD Spectral Pulse Counting Mapping technique (PD-SPCM), which leads to a Frequency-Resolved Partial Discharges (FRPD) map. The proposed map is then used for PD detection and classification. In this work, corona and slot FRPDs are presented in frequency bands up to 500 MHz, obtained from laboratory measurements performed using two hydro-generator stator bars. The electromagnetic signals from the PDs were captured using a patch antenna designed for this purpose and a spectral analyzer. The corona and slot PDs were chosen because one can be mistakenly classified as the other because they may present similar Phase Resolved PD (PRPD) maps and may occupy shared spectral bands. Furthermore, corona and slot PDs can occur concurrently. The obtained results show that the corona and slot PDs can be properly identified using the developed methodology, even when they occur simultaneously. This is possible because, as it is experimentally demonstrated, corona and slot PDs have appreciable levels of spectral pulse counting in particular bands of the frequency spectrum.

Eclipse mapping and related techniques

1996 ◽  
Vol 176 ◽  
pp. 69-84
Author(s):  
René G. M. Rutten
Keyword(s):  
Spatial Structure ◽  
Accretion Disks ◽  
Variable Stars ◽  
Uv Spectra ◽  
Resolving Power ◽  
Mapping Technique ◽  
Cataclysmic Variable ◽  
Optical Telescope ◽  
Spectral Bands ◽  
Accretion Process

Eclipse mapping is a technique to deduce spatial structure on very small angular scales in eclipsing cataclysmic variable stars (CVs). By analysing the eclipse light curve, information is obtained on the brightness structure of the accretion disk and of the compact mass-accreting object in these systems. This information would otherwise be well beyond the resolving power of any optical telescope. Since the development of the eclipse mapping technique by K. Horne, about one decade ago, it has now become an important tool in the study of CVs. Originally eclipse mapping was employed to construct brightness maps of accretion disks in broad spectral bands. Recently, maps of much higher spectral resolution have become available from which optical and UV spectra have been reconstructed in spatial detail across accretion disks. Such information is very important for our understanding of the physics of the accretion process.In this paper I will describe the eclipse mapping technique and review recent results. In conjunction, I will briefly highlight other techniques related to the mapping of surface structure in CVs.

scholarly journals Automatic PRPD Image Recognition of Multiple Simultaneous Partial Discharge Sources in On-Line Hydro-Generator Stator Bars

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 326
Author(s):  
Ramon C. F. Araújo ◽  
Rodrigo M. S. de Oliveira ◽  
Fabrício J. B. Barros
Keyword(s):  
Partial Discharge ◽  
Classification Problem ◽  
Input Pattern ◽  
Partial Discharges ◽  
Data Set ◽  
Stator Windings ◽  
Unknown Sample ◽  
On Line ◽  
A New Technique ◽  
Generator Stator

In this study, a methodology for automatic recognition of multiple simultaneous types of partial discharges (PDs) in hydro-generator stator windings was proposed. All the seven PD sources typical in rotating machines were considered, and up to three simultaneous sources could be identified. The functionality of identifying samples with no valid PDs was also incorporated using a new technique. The data set was composed of phase-resolved partial discharge (PRPD) patterns obtained from on-line measurements of hydro-generators. From an input PRPD, noise and interference were removed with an improved version of an image-based denoising algorithm previously proposed by the authors. Then, a novel image-based algorithm that separates partially superposed PD clouds was proposed, by decomposing the input pattern into two sub-PRPDs containing discharges of different natures. From the sub-PRPDs, one extracts features quantifying the PD distribution over amplitudes and the contour of PD clouds. Those features are fed as inputs to several artificial neural networks (ANNs), each of which solves a part of the classification problem and acts as a block of a larger system. Once trained, ANNs work collaboratively to identify an unknown sample. Good results were obtained, with overall accuracies ranging from 88% to 94.8% for all the considered PD sources.

Partial Discharges Measurements for Power Cable Insulation System

2016 ◽  
pp. 334-350
Keyword(s):  
Computer Simulations ◽  
High Voltage ◽  
Partial Discharges ◽  
Simple Solution ◽  
Power Cable ◽  
Laboratory Measurements ◽  
Coupling Behavior ◽  
Additional Costs ◽  
Cable Systems ◽  
Detection Unit

On-site PD measurements on high voltage cables have to concentrate on the cable accessories because there is a remaining risk for assembling faults on site. PD sensors with an appropriate coupling behavior to accessory-internal PD give sensitivities of a few pC or even better. Unfortunately, two main reasons prevent the general use of PD sensors in cable accessories. First of all, the costs for PD sensors have to be balanced with the costs of the accessories, importance of the cable link, consequential costs for outage etc. This is the reason why PD sensors were mainly used EHV cable systems. The second reason is limited accessibility: the PD sensor cable at the accessory has to be connected to a PD detection unit. Accessibility is much more difficult for direct buried cable systems than for cable terminations and tunnel-laid cable systems: the senor cable must pass the ground and the end up in a box on the surface to provide access. This solution causes additional costs and new problems like sealing the sensor cable against humidity, capability to withstand sheath testing etc. By looking for alternative access to PD signals from cable joints of long cable systems, a very simple solution proved suitable: detecting PD at cross-bonding links. To investigate the high frequency propagation of PD pulses in cross-bonding links, computer simulations and laboratory measurements were done.

scholarly journals A System Based on Artificial Neural Networks for Automatic Classification of Hydro-generator Stator Windings Partial Discharges

2017 ◽  
Vol 16 (3) ◽  
pp. 628-645 ◽  
Author(s):  
Rodrigo M. S. de Oliveira ◽  
Ramon C. F. Araújo ◽  
Fabrício J. B. Barros ◽  
Adriano Paranhos Segundo ◽  
Ronaldo F. Zampolo ◽  
...  
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Automatic Classification ◽  
Partial Discharges ◽  
Stator Windings ◽  
Artificial Neural ◽  
Generator Stator
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