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Journal ArticleDOI

Nonlinear Interpretation Technique for Lightning Impulse Test

24 Mar 2015-IEEE Transactions on Power Delivery (IEEE)-Vol. 30, Iss: 3, pp 1623-1625
TL;DR: In this paper, a nonlinear interpretation technique was proposed to detect the fault in transformer windings during the impulse test, which was applied to 90-MVA 220/110-kV, 250-mVA 500/275/33kV transformers and a 22kV interleaved winding.
Abstract: The nonlinear interpretation technique is proposed to detect the fault in transformer windings during the impulse test. To prove feasibility of the proposed technique, 90-MVA 220/110-kV, 250-MVA 500/275/33-kV transformers, and a 22-kV interleaved winding are used.
Citations
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Journal ArticleDOI
TL;DR: In this article, the principles of vector space representation of signals are effectively adopted in the measured transient signals during the impulse testing of transformers and shunt reactor, and the mutual effective coefficient makes a best mutual matches through appropriate mathematical formulation to provide the occurrence or non-occurrence of faults.

7 citations

Journal ArticleDOI
TL;DR: In this paper, the bivariate dependent rate analyses are proposed to identify the failure in transformer windings, which enable the calculation of winding response due to any impulse voltage excitation of full wave (FW) and chopped wave impulse (CW) for typical transformers.
Abstract: Identification of winding insulation failure during lightning impulse testing of transformer has been an important issue over a long period of time. It requires a significant human expertise and knowledge for proper judgment of transformer insulation. In this paper, the bivariate dependent rate analyses are proposed to identify the failure in transformer windings. The proposed analyses enable the calculation of winding response due to any impulse voltage excitation of full wave (FW) and chopped wave impulse (CW) for typical transformers. Initially, the line of best-fit on the scatter diagram is utilized to visualize the similarities between the measured winding responses and also to identify the type of relationship with potential outliers. Further, ellipse analysis is utilized to calculate the diversification (size, shape and orientation) between the responses. The actual interdependency between winding responses is established through nonlinear interpretation coefficients. To prove the feasibility of the analyses, 66.7 MVA, 90 MVA, 150 MVA, 250 MVA transformers, 80 MVAr reactor and 22 kV interleaved winding are used.

4 citations


Cites background from "Nonlinear Interpretation Technique ..."

  • ...The measures of nonlinear correlation coefficients are asymmetric, because the bounded value of ψA may be different from ψB [12]....

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Journal ArticleDOI
TL;DR: In this article, a single-phase transformer with a voltage specification of 345kV (high voltage)/115kV(low voltage) and a capacity of 200 MVA was proposed.

3 citations

Proceedings ArticleDOI
01 Dec 2014
TL;DR: To remove noise and achieve better SNR, interval dependent wavelet de-noising technique is utilized against multivariate de- noising technique to identify the winding fault in transformer.
Abstract: In transient phenomena of transformer, one of the important research areas of interest is removing the noise in the measured signals during impulse test and to find if there exists a relation between the high frequency transient signals to declare about pass criterion or fail criterion of the transformer at manufacturing location. In this paper, to remove noise and achieve better SNR, interval dependent wavelet de-noising technique is utilized against multivariate de-noising technique. After proper selection of de-noising technique to identify the winding fault in transformer, nonlinear interpretation technique is employed. To prove the usefulness of the proposed technique, impulse testing data of 66.7 MVA and 250 MVA transformers are used.

2 citations

Journal ArticleDOI
TL;DR: In this article , a single-phase transformer with a voltage specification of 345 kV (high voltage)/115kV (low voltage) and a capacity of 200 MVA was proposed, which can withstand high electrical signals, such as lightning impulses and insulation damage.

1 citations

References
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Journal ArticleDOI
TL;DR: It is demonstrated that from phase shifts the authors may estimate transmission delays between at least certain classes of EEG signals, and can asses, unambiguously, how the transmission of information between different brain sites develops.
Abstract: To investigate the degree of interdependence of EEG signals, we have to use signal analysis methods. Three of these are described and their performance is compared: the cross-correlation (coherence and phase), the average amount of mutual information (AAMI) or the normalized AAMI, also called transmission coefficient T, and the correlation ratio h2 that is a general measure of nonlinear fit between any two signals. The three methods were applied to simulated and real signals in order to put in evidence how nonlinear relationships may affect differently these three measures of association. The nature of the interdependence between EEG signals is not characterized only by the degree of association, but also by the corresponding phase relationship. A basic question is whether such a phase shift can be interpreted as a transmission delay. However, a fundamental problem is that a phase shift may be difficult to interpret in terms of a biophysical model. A procedure is described in order to solve this problem. This involves computing the phase spectrum between the pair of signals, estimating the gain of the corresponding linear transfer function and the associated minimum phase. By subtracting the minimum phase from the phase spectrum, a corrected phase function can be obtained. From the slope of this phase function, a transmission delay can be estimated. This procedure is illustrated by applications to simulated and real EEG signals. It is demonstrated that from phase shifts we may estimate transmission delays between at least certain classes of EEG signals. In this way we can asses, unambiguously, how the transmission of information between different brain sites develops.

199 citations

Journal ArticleDOI
TL;DR: In this article, three different methods of acquiring the time differences of arrival (TDOA) from the PD waveforms are discussed, including the first peak of the signal as the arrival instant, or from the cross-correlation of the PD signal waveforms, or by applying the similarity function to the plots of PD signals cumulative energy.
Abstract: The location of a partial discharge (PD) source inside a transformer can be determined from the time differences of arrival (TDOA) between signals that are captured by an array of UHF sensors. The TDOA can be acquired from the received PD waveforms. In this paper, three different methods of acquiring the TDOA from the PD waveforms are discussed. The time difference can be calculated either by taking the first peak of the signal as the arrival instant, or from the cross-correlation of the PD waveforms, or by applying the similarity function to the plots of the PD signals cumulative energy. Computation algorithms for determining the TDOA automatically are introduced so that possible bias from human interpretation is avoided. The presence of noise and its effect on the accuracy of the PD localization will also be presented. Experimental results show the first-peak method has higher accuracy than the two other methods. The application of signal denoising further improves the localization accuracy.

133 citations


"Nonlinear Interpretation Technique ..." refers methods in this paper

  • ...The measured responses are passed through the multivariate denoising technique [2] to remove the noise (Figs....

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Journal ArticleDOI
01 Mar 1998
TL;DR: In this paper, a novel approach using the short-time Fourier transform and wavelet transform (time-frequency analysis tools) for fault detection during impulse testing of power transformers is described.
Abstract: A novel approach using the short-time. Fourier transform and wavelet transform (time-frequency analysis tools) for fault detection during impulse testing of power transformers is described. The neutral and/or capacitively transferred currents which are recorded during an impulse test can be directly analysed with this approach. These currents are considered to be evolving in time, i.e. as nonstationary signals, especially when there is a fault. Results from simulation studies are presented wherein the fault condition is modelled as a fast decaying transient superposed on the neutral current. A comparison of the two transforms is made to assess their ability to detect as small a fault as possible and other implemenational issues. Advantages of these methods over the conventional transfer function method are demonstrated, and it appears that the wavelet transform is better suited for this task.

102 citations


"Nonlinear Interpretation Technique ..." refers background in this paper

  • ...The identification of fault during impulse excitation is a nontrivial task and, to some extent, remains subjective [1]....

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Journal ArticleDOI
V. Jeyabalan1, S. Usa1
TL;DR: In this article, the limitation of time domain correlation method in locating partial discharge (PD) in transformer windings is found out, and frequency domain correlation with Gram Schmidt orthogonalization is proposed.
Abstract: Partial discharge (PD) is one of the sources of insulation failures in Power transformers. Knowledge of the PD source locations are important for transformer maintenance and repair. Due to the complex structure of the transformer, it is very difficult to locate the PD accurately in transformer winding. Correlation methods are applied to locate the PD source across the winding. The PD across parts of the winding are simulated by applying voltage pulse across the sections. The winding response for a reference PD impulse across transformer sections are taken as base for correlation and correlated with winding response of PD impulse across any section with different PD pulse widths. In this paper the limitation of time domain correlation method in locating PD in transformer windings is found out. To overcome the limitation of time domain correlation method, frequency domain correlation with Gram Schmidt orthogonalization is proposed. Simulation and experiments are performed on layer, continuous disc and interleaved windings to prove the feasibility of the proposed method.

39 citations


"Nonlinear Interpretation Technique ..." refers methods in this paper

  • ...To analyze the sensitivity of the proposed technique for identification of partial discharge (PD) in the transformer winding during impulse excitation, a 22-kV interleaved winding is considered [4]....

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  • ...Further, to analyze the usefulness of the proposed technique for PD detection, the normal winding response and one with the PD response is utilized [4], and the results are shown in Table I....

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  • ...The experimental details and impulse PD response measurements are given in [4]....

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Journal ArticleDOI
30 Jan 2004
TL;DR: In this article, an objective classification of faults that can occur during impulse tests on power transformers is proposed, including nonlinear elements, breakdown, and partial discharge events, and an analysis of a layer winding, in the time and frequency domains, with these faults shows that current assessment methods must be used with caution.
Abstract: An objective classification of faults that can occur during impulse tests on power transformers is proposed. It includes nonlinear elements, breakdown, and partial discharge events. An analysis of a layer winding, in the time and frequency domains, with these faults shows that current assessment methods must be used with caution. A model reference approach is proposed to distinctly improve recognition in such cases. The method is immune to changes of wave shape and the instant of fault is available by observation.

35 citations


"Nonlinear Interpretation Technique ..." refers methods in this paper

  • ...Hence, the differences between and form the basis for failure recognized by the model reference approach [5], and are extended numerically using the Euclidean distance method (unbounded measure) [6]....

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