Journal ArticleDOI
PD characteristics of oil-pressboard insulation under AC and DC mixed voltage
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TLDR
In this paper, the partial discharge (PD) occurring in oilpressboard insulation is the one of the main causes of insulation breakdown, and it is the main factor of electrical aging of materials.Abstract:Â
The insulation problem of converter transformers has become one of the core issues in HVDC system, which is receiving more and more attention. A converter transformer has complex structures and requires high insulation level. The voltage waveform which the converter transformer insulation withstands is different from AC transformers. In the valve side of the converter transformer, the insulation endures a mixed voltage of AC voltage, DC voltage, harmonics and the pulsating component etc. Partial discharge (PD) occurring in oil-pressboard insulation is the one of the main causes of insulation breakdown, and it is the main factor of electrical aging of materials. Even though PD characteristics under pure AC or DC voltage waveform have been studied by many researchers, little research has been done with the mixed voltage. In this paper, the AC + DC mixed voltage experiment system is set up to study the PD characteristics under mixed voltage waveforms. The study results indicate that the pressboard withstands most of the DC component and void withstands most of the AC component when applied mixed voltage. For PD inception voltage, it is decided by both the AC component and DC component. For PD development, AC component has more significant influence than DC component. However, the DC component is found to promote PD activity under AC half cycle with the same DC polarity and inhibit PD activity under AC half cycle with the opposite DC polarity. The results in this paper provide an experimental foundation for the converter transformer insulation breakdown mechanism and analysis.read more
Citations
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Journal ArticleDOI
Improving RF-Based Partial Discharge Localization via Machine Learning Ensemble Method
Ephraim Iorkyase,Christos Tachtatzis,Ian Glover,Pavlos I. Lazaridis,D Upton,Bakhtiar I. Saeed,Robert Atkinson +6 more
TL;DR: A low cost, autonomous partial discharge radiolocation mechanism to improve PD localization precision that uses the wavelet packet transform (WPT) and machine learning ensemble methods to locate PDs.
Journal ArticleDOI
Partition and recognition of partial discharge development stages in oil-pressboard insulation with needle-plate electrodes under combined AC-DC voltage stress
Simeng Li,Wen Si,Qingquan Li +2 more
TL;DR: In this article, behavior of different characteristic parameters of the PD activity recorded in the oil-pressboard insulation with needle-plate electrodes is investigated, including amplitude of apparent charge in pC, frequency of occurrence of PD pulse, PD pattern (PRPD-pattern), additional parameters are defined to describe the PD development processes under AC-DC combined voltage stress.
Journal ArticleDOI
3D modeling of an HVDC converter transformer and its application on the electrical field of windings subject to voltage harmonics
TL;DR: In this paper, the effects of voltage harmonics on the main insulation of converter transformers have been analyzed using a full-scaled 3D converter transformer model, and the electric field of the proposed model is calculated under AC, DC, and polarity reversal voltages.
Journal ArticleDOI
Hyperspectral imaging of high voltage insulating materials subjected to partial discharges
TL;DR: In this article, hyperspectral imaging was used to assess the dielectric surface aging of high voltage insulation materials, and the results revealed the effects of insulation erosion and deterioration.
Journal ArticleDOI
PD detection and analysis of oil-pressboard insulation under pulsed DC voltage
TL;DR: In this paper, a 6-pulse DC voltage generator and PD detection and analysis of oil-pressboard insulation under pulsating DC voltage waveform is analyzed through computer simulation.
References
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Journal ArticleDOI
Partial discharges at DC voltage: their mechanism, detection and analysis
Peter Morshuis,Johan J. Smit +1 more
TL;DR: In this paper, a concise review is given of the progress made in the field of partial discharges (PD) at DC voltage, focusing on the progress that was made at Delft University of Technology over a period of 14 years in three PhD projects.
Journal ArticleDOI
Aging phenomenology and modeling
Gian Carlo Montanari,L. Simoni +1 more
TL;DR: In this article, the authors present the fundamentals of phenomenological aging theory and life modeling and give electrical and combined-stress life data for different materials, showing either linear or curvilinear behavior.
Journal ArticleDOI
Models for insulation aging under electrical and thermal multistress
P. Cygan,J.R. Laghari +1 more
TL;DR: A review of the methods and models used in lifetime studies of solid insulators under single and multiple stress conditions is presented in this paper, where several models under combined electrical and thermal stresses are presented and their applicability is analyzed.
Journal ArticleDOI
A new methodology for the identification of PD in electrical apparatus: properties and applications
TL;DR: In this article, the identification of basic PD source typologies (i.e., internal, corona and surface discharges) is then achieved, resorting to fuzzy algorithms.
Journal ArticleDOI
Evaluation of dc insulation performance based on space-charge measurements and accelerated life tests
TL;DR: In this paper, the authors proposed test methods and parameters, based on the pulsed electroacoustic technique, which can be used for the evaluation of the electrical performance of polymeric insulation under dc fields.