Effect of Core Magnetization on Frequency Response Analysis (FRA) of Power Transformers

Abeywickrama, Nilanga; Serdyuk, Yuriy V.; Gubanski, Stanislaw

doi:10.1109/tpwrd.2007.909032

Cited by 90 publications

(38 citation statements)

References 11 publications

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“…This agrees well with the fact that in a rapid transient condition, the flux lines tend to center around the conductors rather than penetrating the iron core and for high-frequency components of surges, the iron core acts effectively as an earthed boundary [9]. Some studies [10], [11] have neglected the effect of distributed shunt conductance which is considered a valid assumption for impulse voltage distribution analysis in the case of a faultless transformer, but may not be adequate in the case of fault diagnosis. Neglecting shunt conductance in the equivalent circuit will eliminate the study of leakage fault inside a transformer which could have been caused by several reasons, such as insulation damage, ground shield, or hot spots.…”

Section: Transformer Modelsupporting

confidence: 80%

A Novel Online Technique to Detect Power Transformer Winding Faults

Abu-Siada

Islam

2012

IEEE Trans. Power Delivery

169

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Frequency-response analysis (FRA) has been growing in popularity in recent times as a tool to detect mechanical deformation within power transformers. To conduct the test, the transformer has to be taken out of service which may cause interruption to the electricity grid. Moreover, because FRA relies on graphical analysis, it calls for an expert to analyze the results. As so far, there is no standard code for FRA interpretation worldwide. In this paper, a novel online technique is introduced to detect the internal faults within a power transformer by constructing the voltage-current ( ) locus diagram to provide a current state of the transformer. The technique does not call for any special equipment as it uses the existing metering devices attached to any power transformer to monitor the input voltage, output voltage, and the input current at the power frequency and, hence, online monitoring can be realized. Various types of faults have been simulated to assess its impact on the proposed locus. A Matlab code based on digital image processing is developed to calculate any deviation of the locus with respect to the reference one and to identify the type of fault. The proposed technique is easy to be implemented and automated so that the requirement for expert personnel can be eliminated.

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Section: Transformer Modelsupporting

confidence: 80%

A Novel Online Technique to Detect Power Transformer Winding Faults

Abu-Siada

Islam

2012

IEEE Trans. Power Delivery

169

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“…The governing factor in this phenomenon is magnetic viscosity, which is defined as the time dependence of magnetization under a constant magnetic field. The impedance measurement, mainly below 10 kHz, is observed to be significantly dependant on DC magnetization, instances when power supply switches off, and demagnetization [19].…”

Section: Frequency Response Analysis (Fra)mentioning

confidence: 99%

Analysis of winding inter-turn fault in transformer: A review and transformer models

Bhide¹,

Srinivas²,

Banerjee³

et al. 2010

2010 IEEE International Conference on Sustainable Energy Technologies (ICSET)

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Transformers have emerged as an integrated part of a power system. Any fault in the transformer can cause a severe outage, which therefore necessitates continuous monitoring and diagnostics of its operation. The renewed thrust in smart power system networks along with the development of advanced methods in the monitoring and diagnostics has resulted in major impetus to research in the related domain. Among the detection of various faults in the transformer (or in any electrical machine in general), detection of winding inter-turn fault is critical since its effect is not easily comprehendible at lower magnitude in the signatures of terminal voltages and currents. Several techniques have been reported in the literature for detecting this fault. This paper reviews and compares the diagnostics methods based on their advantages and limitations. This highlights a further scope in the monitoring and diagnostic of the winding inter-turn fault. Finally, simple analytical models of three-and five-legged transformers are developed based on their electrical and magnetic equivalent circuits, which can be easily implemented in the analysis of winding inter-turn fault. Various results obtained from the analytical models are validated with the help of Finite Element (FE) modeling using ANSYS Parametric Design Language (APDL).

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“…This is mainly shown in consistent magnitude deviations with possible slight shifts of low frequency resonances. In contrast, the overall response shape remains consistent compared with the reference ones [2,24]. RM does not normally affect responses above 20 kHz, which can be easily eliminated using core demagnetisation techniques.…”

Section: Residual Magnetisation (Rm)mentioning

confidence: 67%

Winding Frequency Response Analysis for Power Transformers

Tang

2011

Condition Monitoring and Assessment of Power Transformers Using Computational Intelligence

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Nowadays, FRA has received great attention for transformer winding condition assessment, which has gradually replaced the conventional LVI method. It provides higher sensitivity to changes occurring in a transformer winding compared with the LVI method and can be performed relatively easily on-site. In this chapter, first the origin of FRA and the definition of FRA transfer functions are introduced. Two FRA methods, i.e. the impulse response method and the SFRA method, are presented alongside a typical experimental test setup for FRA. Then a brief literature review of winding models is given, which can be used for analytical calculations and circuit simulations for windings. The rest of this chapter focusses on FRA comparison techniques and the interpretation of frequency response measurements regarding various types of winding faults.

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Effect of Core Magnetization on Frequency Response Analysis (FRA) of Power Transformers

Cited by 90 publications

References 11 publications

A Novel Online Technique to Detect Power Transformer Winding Faults

A Novel Online Technique to Detect Power Transformer Winding Faults

Analysis of winding inter-turn fault in transformer: A review and transformer models

Winding Frequency Response Analysis for Power Transformers

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