Electrical-Based Diagnostic Techniques for Assessing Insulation Condition in Aged Transformers

Fofana, I.; Hadjadj, Yazid

doi:10.3390/en9090679

Cited by 78 publications

(53 citation statements)

References 91 publications

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“…According to the measurement results of on-site oil sample at test temperature T, the complex relative permittivity of insulation oil can be obtained by the direct current conductivity in terms of Equation (8). Then, the correlation of complex relative permittivity spectroscopy among the whole transformer insulation, insulation oil and insulation paper can be derived by Equation (7). The master curve technique was used to correct the temperature effect on FDS curves.…”

Section: A Power Transformer In Servicementioning

confidence: 99%

“…Unfortunately, it is a fact that the electrical and mechanical properties of the transformer oil-paper insulation system become aging gradually due to the combination stresses of the mechanical vibration, thermal, electrical, oxygen, water and other factors, in the long-term service process [4][5][6][7][8]. Historically, the applications of oil sample analysis (OSA) in terms of equilibrium relationships between insulating oil and cellulose insulation, dissolved gas analysis (DGA), dielectric loss factor (DLF) and insulation resistance (IR) have been commonly used for performing non-destructive condition monitoring of transformer insulation [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

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Grey Relational Analysis for Insulation Condition Assessment of Power Transformers Based Upon Conventional Dielectric Response Measurement

et al. 2017

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Abstract:Conventional dielectric response measurement techniques, for instance, recovery voltage measurement (RVM), frequency domain spectroscopy (FDS) and polarization-depolarization current (PDC) are effective nondestructive insulation monitoring techniques for oil-impregnated power transformers. Previous studies have focused mainly on some single type of dielectric measurement method. However, the condition of oil paper insulation in transformer is affected by many factors, so it is difficult to predict the insulation status by means of a single method. In this paper, the insulation condition assessment is performed by grey relational analysis (GRA) technique after carefully investigating different dielectric response measurement data. The insulation condition sensitive parameters of samples with unknown insulation status are extracted from different dielectric response measurement data and then these are used to contrast with the standard insulation state vector models established in controlled laboratory conditions by using GRA technique for predicting insulation condition. The performance of the proposed approach is tested using both the laboratory samples and a power transformer to demonstrate that it can provide reliable and effective insulation diagnosis.

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Section: A Power Transformer In Servicementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Grey Relational Analysis for Insulation Condition Assessment of Power Transformers Based Upon Conventional Dielectric Response Measurement

et al. 2017

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“…One of the currently used methods of online measurement of PDs is a method of detection and localisation of acoustic emission (AE) signal sources and the ultra-high frequency (UHF) signal, both of which belong to a group called unconventional methods [2][3][4]. In these methods, the recorded measuring signal, based on different physical phenomena, is associated with the effect of PD generation in a way that prevents its calibration, e.g., correlation with the apparent charge, which is a widely accepted parameter describing the phenomenon of PD generation.…”

Section: Introductionmentioning

confidence: 99%

Moisture Migration in an Oil-Paper Insulation System in Relation to Online Partial Discharge Monitoring of Power Transformers

2016

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Most power transformers operating in a power system possess oil-paper insulation. A serious defect of this type of insulation, which is associated with long operation time, is an increase in the moisture content. Moisture introduces a number of threats to proper operation of the transformer, e.g., ignition of partial discharges (PDs). Due to the varying temperature of the insulation system during the unit's normal operation, a dynamic change (migration of water) takes place, precipitating the oil-paper system from a state of hydrodynamic equilibrium. This causes the PDs to be variable in time, and they may intensify or extinguish. Studies on model objects have been conducted to determine the conditions (temperature, humidity, time) that will have an impact on the ignition and intensity of the observed phenomenon of PDs. The conclusions of this study will have a practical application in the evaluation of measurements conducted in the field, especially in relation to the registration of an online PD monitoring system.

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“…However, it must be emphasized that moisture and aging separation still constitute a challenging point in this domain [6,34,35].…”

Section: Moisture In Oil Determinationmentioning

confidence: 99%

Review of Physicochemical-Based Diagnostic Techniques for Assessing Insulation Condition in Aged Transformers

et al. 2016

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Abstract:A power transformer outage has a dramatic financial consequence not only for electric power systems utilities but also for interconnected customers. The service reliability of this important asset largely depends upon the condition of the oil-paper insulation. Therefore, by keeping the qualities of oil-paper insulation system in pristine condition, the maintenance planners can reduce the decline rate of internal faults. Accurate diagnostic methods for analyzing the condition of transformers are therefore essential. Currently, there are various electrical and physicochemical diagnostic techniques available for insulation condition monitoring of power transformers. This paper is aimed at the description, analysis and interpretation of modern physicochemical diagnostics techniques for assessing insulation condition in aged transformers. Since fields and laboratory experiences have shown that transformer oil contains about 70% of diagnostic information, the physicochemical analyses of oil samples can therefore be extremely useful in monitoring the condition of power transformers.

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Electrical-Based Diagnostic Techniques for Assessing Insulation Condition in Aged Transformers

Cited by 78 publications

References 91 publications

Grey Relational Analysis for Insulation Condition Assessment of Power Transformers Based Upon Conventional Dielectric Response Measurement

Grey Relational Analysis for Insulation Condition Assessment of Power Transformers Based Upon Conventional Dielectric Response Measurement

Moisture Migration in an Oil-Paper Insulation System in Relation to Online Partial Discharge Monitoring of Power Transformers

Review of Physicochemical-Based Diagnostic Techniques for Assessing Insulation Condition in Aged Transformers

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