Power transformer disruptions- a case study

Marques, André P.; Ribeiro, Cacilda de Jesus; Azevedo, Cláudio Henrique Bezerra; Santos, Jose Lopes dos; Sousa, Felipe de; Brito, Leonardo da Cunha

doi:10.1109/mei.2014.6749569

Cited by 15 publications

(8 citation statements)

References 4 publications

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“…Such ageing processes are unnoticeable for the standard methods what may cause misdiagnosis in the technical condition of the insulators and, as a result, it may lead to disastrous consequences such as explosions. The statistics, which present that from 12 to 40% of the catastrophic failures of the power transformers resulted from bushing malfunctions, can be found in the literature [3][4][5][6]. Due to inefficiency of tg 50Hz there is the need to search for new measurement solutions that increase predictability of defects in HV (high voltage) bushings insulation [6,7].…”

Section: Introductionmentioning

confidence: 99%

“…It is mainly used to test HV motor insulation, and the measurement conditions and the interpretation of the results are included in the IEEE number 4, 1978 standard ("Standard Techniques for High-Voltage Testing"), standard number 43, November 1974 ("Recommended Practice for Testing Insulation Resistance of Rotating Machinery"), and in [14]. The method of calculating the absorption coefficient Ka defined in these standards is Ka = 30 30 (4) where i30M and i30C are, respectively, the measured and calculated leakage currents after 30 min of the SVM test. The absorption coefficient Ka for the new insulation based on epoxy resins should be less than 2, while in the case of degraded insulation, its value should be 5-7.…”

Section: Introductionmentioning

confidence: 99%

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Condition Assessment of HV Bushings with Solid Insulation based on the SVM and the FDS Methods

et al. 2020

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This paper presents the dielectric response of the insulation of bushings as an effect of the simulated long-term aging process. The experiment was conducted under a condition of a high temperature difference between the current circuit and the cover. The dielectric response was measured with the FDS (Frequency Dielectric Spectroscopy) and the SVM (Step Voltage Measurement) methods. The research has shown the correlation between the aging time and some parameters obtained with the FDS and SVM analysis.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Condition Assessment of HV Bushings with Solid Insulation based on the SVM and the FDS Methods

et al. 2020

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“…Failures in power transformers’ windings are responsible for 35% of transformer faults [1]. If not identified prior to their occurrence, such failures can cause several disorders, such as interruption of electricity supply, financial losses and accidents.…”

Section: Introductionmentioning

confidence: 99%

Localisation of inter-layer partial discharges in transformer windings by logistic regression and different features extracted from current signals

Júnior¹,

Paula

Boaventura³

et al. 2020

IET Science, Measurement &Amp; Technology

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Partial discharge (PD) investigations can identify and localise incipient failures in power transformers early, thus avoiding considerable financial losses. The feature extraction of PD signals is a fundamental step for the development of such location techniques since it directly influences the performance of a location method. This study presents a detailed comparative analysis of four traditional approaches for the obtaining of attributes towards a better set of signal features for the location of PDs. The approaches were critically compared regarding their ability to locate experimentally generated discharges between adjacent layers of a prototype winding. In order to perform such analysis, a localisation structure based on logistic regression models was elaborated, capable of determining both layers and sections of the winding affected by PDs and easily applicable in practice. The results show energy features of wavelet coefficients, obtained through the decomposition of high-frequency current signals acquired at the winding endings, achieve better performance in the PD localisation, accurately indicating discharge occurrence points among layers and sections of the winding.

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“…Among the different types of faults that affect transformers, studies show that internal faults in the windings are the most common, around 30% (Marques et al, 2014). In general, this type of fault is governed by the degradation of the solid insulation system, usually consisting of paper impregnated with oil and/or insulating varnish (Mondal and Kumbhar, 2017).…”

Section: Introductionmentioning

confidence: 99%

Multiple Linear Regression Models for Partial Discharge Location Along Transformer Windings

Júnior

Paula

Boaventura

2019

Anais Do 14º Simpósio Brasileiro De Automação Inteligente

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More recently, it has been noted an increase in the incidence of failures in power transformers, mainly due to degradation of the solid insulation system. The identification of current pulses related to Partial Discharges (P Ds) has enabled the early detection and location of the solid insulation deteriorated regions, which is very useful to optimize the planning of the maintenance interventions, preventing unexpected power interruptions and reducing downtime. Even though several techniques for P Ds location have been proposed in recent years, limitations can still be noted, such as the inability to specify the discharge location in narrower regions and unproved applicability in windings of different configurations. In view of these, in this work, a P D location method is analysed, based on multiple linear regression models developed in conjunction with stepwise variable selection and analysis of variance methods. The technique is applied from P Ds simulation data, obtained through accurate transformer high frequency modelling, using statistical and principal components features of the terminal windings current signals. The results show that the P Ds can be effectively located, with high accuracy and success rate, for both layer-type and disk-type windings of transformers.

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Power transformer disruptions- a case study

Cited by 15 publications

References 4 publications

Condition Assessment of HV Bushings with Solid Insulation based on the SVM and the FDS Methods

Condition Assessment of HV Bushings with Solid Insulation based on the SVM and the FDS Methods

Localisation of inter-layer partial discharges in transformer windings by logistic regression and different features extracted from current signals

Multiple Linear Regression Models for Partial Discharge Location Along Transformer Windings

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