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Proceedings ArticleDOI

Online assessment of winding deformation based on optimised excitation

25 Oct 2010-pp 84-89

TL;DR: On line assessment of winding deformation in a power transformer can be performed via a bushing tap excitation with optimized high frequency excitation through a benchmark layer winding to validate the suitability of the technique.

AbstractOn line assessment of winding deformation in a power transformer can be performed via a bushing tap excitation with optimized high frequency excitation. A benchmark layer winding is used to validate the use of the specific high frequency excitation. Axial displacement, compression and buckling of the winding are simulated and the changes identified. Measurements are performed on a voltage transformer to verify the suitability of the technique. The procedure will result in a considerably shorter time for measurement.

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Citations
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Journal ArticleDOI
Abstract: This paper presents the current status and future trends in the application of the frequency-response analysis (FRA) technique with the transformer in service (online) through bibliographic review and analysis. As a result, three basic stages of the online FRA test have been identified and defined: injection and excitation signal measurement; recording, filtering and processing of measured signals; and curve analysis and interpretation. This work presents an overview of the online FRA technique, useful for subsequent research in this area.

96 citations


Cites methods from "Online assessment of winding deform..."

  • ...The second reference presents an online assessment of winding deformation by using optimized multi-sine excitation compared to a chirp signal [42]....

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Proceedings ArticleDOI
01 Sep 2016
Abstract: Frequency response analysis (FRA) is a technique used to diagnose the mechanical integrity of a transformer winding; such diagnostic tools can be of enormous value since power transformers are a critical asset within any electrical network. To minimize the probability of an unexpected outage, or prevent a catastrophic failure, maintenance and monitoring of power transformers is essential for utilities. Over the past couple of decades, FRA has been utilized as an off-line diagnosis method. However, with the recent development in smart grid systems, there is now a growing interest in the development of on-line FRA techniques. This paper proposes a technique for in-service monitoring of power transformer winding deformation, which uses a broad frequency sine wave voltage excitation signal and high frequency Current Transformers (CT) in conjunction with the bushings test taps. Experiments using this system were conducted and then validated on a single-phase 22kV/110V voltage transformer.

10 citations


Cites methods from "Online assessment of winding deform..."

  • ...Methodology Bushing tap injection techniques utilizing voltage sensors and current probes were considered by Setayeshmehr [10] and other researchers [11]-[13]....

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Proceedings ArticleDOI
01 May 2017
Abstract: With the recent development in smart grid systems, there is now a growing interest in the development of on-line monitoring techniques. This is to reduce the maintenance costs as well as minimizing the probability of unexpected outages, or potentially to prevent catastrophic failures in the electrical network.

6 citations

Proceedings ArticleDOI
01 May 2014
Abstract: Winding deformation in power transformers affects its mechanical integrity. Diagnosis of winding deformation is a necessary step towards preventing its permanent failure. Sweep Frequency Response Analysis (SFRA) is widely used to analyze the nature and extent of deformation. However, the location of deformation needs the signature from the deformed transformer at various locations, which is practically not feasible. In this paper, Finite Element Method (FEM) and SFRA are used to model deformations on a benchmark winding and obtain corresponding signatures. Different parameters derived from SFRA are used as indices to distinguish type and location of deformations.

4 citations


Cites methods from "Online assessment of winding deform..."

  • ...An improved method is proposed in [8] that gives faster response by the use of optimized multi-sine signal....

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Proceedings ArticleDOI
11 Jun 2019
TL;DR: It is revealed that the winding inter-disk and inter-turn faults lead to FRA anti-resonance frequency shift and response magnitude alteration in online FRA.
Abstract: Transformers are considered as the key components in power system network as they are employed in generation, transmission and distribution sectors. Hence electricity providers are highly concerned about proper operation of these valuable assets and specifically normal performance of the transformer active parts. One of the most reliable techniques to monitor the active part of the transformer is the Frequency Response Analysis (FRA). Given the fact that FRA technique has been successfully utilized in offline application for transformer diagnosis; it has been recently studied to apply the FRA once the transformer is in service, called online FRA. In this study, the transformer winding inter-disk and inter-turn faults are studied along with the effect of the bushing on frequency response signature in online FRA setup. Transformer winding physical model is created, simulated and numerically analyzed. It is revealed that the winding inter-disk and inter-turn faults lead to FRA anti-resonance frequency shift and response magnitude alteration in online FRA. Emulation of transformer bushing in the form of two paralleled capacitors unveils the significant influence of this component over the low frequency band of FRA spectrum. Destructive effect of the bushing reactive impedance should be taken into consideration during online FRA test measurements.

2 citations


Cites background from "Online assessment of winding deform..."

  • ...Active part mechanical faults can be expressed as the winding inter-disk or inter-turn shortcircuit, displacement or deformation, buckling, bending, spiraling, rupture, tilting, or the faults related to the transformer core, or the faults in diverter- or selector switch of tap-changer [6]-[11]....

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References
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Journal ArticleDOI
J. Christian1, K. Feser
Abstract: The paper investigates three different ways of using the transfer function method for detecting mechanical winding displacements in power transformers. The most reliable approach is time-based comparison , which requires finger print data from a previous measurement. Such information is, however, usually not available. For multilegged transformers without zigzag-connected windings the results of separately tested legs can be used as mutual references (construction-based comparison ). A third approach is to compare the transfer functions with those obtained from an identically constructed transformer ( type-based comparison). However, for a transformer with given nominal specification data, the winding design may over time undergo changes which causes changes to the transfer function. It is proposed to solve this problem by calculating tolerance bands using transfer functions from a big group of the same-type transformers. A novel statistical algorithm for this purpose is presented. The approach is demonstrated for a set of 28 specified identically 200-MVA power transformers.

158 citations


"Online assessment of winding deform..." refers background in this paper

  • ...INTRODUCTION Methods for assessing winding deformation in power transformers have received sufficient attention in the recent years [1], [2]....

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Journal ArticleDOI
TL;DR: The properties of ten different excitation signals are studied to analyze their suitability as excitation signal for fast Fourier transform (FFT)-based signal and network analyzers and the flexibility to create a customized amplitude spectrum is investigated.
Abstract: The properties of ten different excitation signals are studied to analyze their suitability as excitation signals for fast Fourier transform (FFT)-based signal and network analyzers. Their influence on the measurement time, accuracy, and sensitivity to nonlinear distortions is described. The flexibility to create a customized amplitude spectrum is investigated. With this information it becomes possible to select the best excitation signal for many applications. >

151 citations

Journal ArticleDOI
R.C. Degeneff1
Abstract: This paper presents a method for calculating terminal and internal impedance versus frequency for a lumped parameter model of a transformer The transformer's total frequency response can be accurately determined from this impedance data directly, ie, the terminal resonance and anti-resonance and internal amplification factor characteristic can be calculated for a single or three-phase transformer model Since most equipment associated with power system operation can be accurately modeled with lumped parameter networks, this method also provides an accurate, straightforward method for determining the resonance characteristic of those systems An additional significance of this method is that the accuracy of the calculation is limited only by the user's ability to represent the equipment or system Heretofore, the accuracy of this calculation was limited by the simplifying assumptions required of the network model by each solution method This paper presents the definitions and mathematical theory underlying the method Two examples are presented in which comparisons are made between measured and calculated values for a helical air core coil and a 200 MVA single-phase autotransformer The agreement is excellent

149 citations

Journal ArticleDOI
Abstract: Frequency response analysis (FRA) is an emerging, powerful non-intrusive condition monitoring and diagnostic tool for verifying the mechanical integrity of power transformers. FRA results are graphical in nature and require trained experts to interpret test results. The work reported discusses numerical-criteria-based evaluation techniques. Persons not familiar with interpreting the FRA results can apply the evaluation criteria. The various criteria help in deriving proper conclusions. By evaluating correlation coefficient (CC), standard deviation and absolute sum of logarithmic error (ASLE) techniques, it is possible to discriminate between defective and non-defective windings. Experimental studies were conducted on two test transformers for axial and radial displacements, and additionally two sets of identical substation transformers. The techniques mentioned above are useful for interpreting frequency responses even in situations when a reference fingerprint was not available. However, it was concluded that if original fingerprints are available, the method gives very reliable indication for diagnosing the faulty winding. In addition, the severity of displacement/deformation can also be concluded from the amount of variation of the parameters from the suggested critical values.

96 citations


"Online assessment of winding deform..." refers background in this paper

  • ...Similarly, a case study is conducted in [12] on a 31....

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Journal ArticleDOI
Abstract: Online transformer condition monitoring techniques based on transfer function methods, such as transmission-line diagnostics and swept frequency-response analysis, require the injection of a known test signal into the transformer On larger power transformers, a practical method is to use the available bushing tap connection In this paper, we will discuss a custom high-power signal generator that injects high-frequency signals on the bushing tap of the transformer under investigation, as well as a circuit to replace the bushing tap short and allow online operation of the system Finally, the system is demonstrated on a 650 kV transformer

90 citations


"Online assessment of winding deform..." refers background or methods in this paper

  • ...The excitation voltage is applied across the bushing tap [2] as shown in Fig 18....

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  • ...An online method was also proposed for measurement of deformation based on excitation from a bushing tap [2]....

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  • ...INTRODUCTION Methods for assessing winding deformation in power transformers have received sufficient attention in the recent years [1], [2]....

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