Winding movement in power transformers: a comparison of FRA measurement connection methods

Jayasinghe, J.A.S.B.; Wang, Z.D.; Jarman, Paul; Darwin, A.W.

doi:10.1109/tdei.2006.258206

Cited by 97 publications

(53 citation statements)

References 8 publications

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“…Each connection can be used for measuring the frequency response. However, some studies [21,22] showed that the inter-winding connections are more sensitive to common mechanical changes. …”

Section: Influencing Factorsmentioning

confidence: 99%

Diagnostic Measurements for Power Transformers

et al. 2016

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Abstract:With the increasing age of the primary equipment of the electrical grids there exists also an increasing need to know its internal condition. For this purpose, off-and online diagnostic methods and systems for power transformers have been developed in recent years. Online monitoring is used continuously during operation and offers possibilities to record the relevant stresses which can affect the lifetime. The evaluation of these data offers the possibility of detecting oncoming faults early. In comparison to this, offline methods require disconnecting the transformer from the electrical grid and are used during planned inspections or when the transformer is already failure suspicious. This contribution presents the status and current trends of different diagnostic techniques of power transformers. It provides significant tutorial elements, backed up by case studies, results and some analysis. The broadness and improvements of the presented diagnostic techniques show that the power transformer is not anymore a black box that does not allow a view into its internal condition. Reliable and accurate condition assessment is possible leading to more efficient maintenance strategies.

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“…Each connection can be used for measuring the frequency response. However, some studies [21,22] showed that the inter-winding connections are more sensitive to common mechanical changes. …”

Section: Influencing Factorsmentioning

confidence: 99%

Diagnostic Measurements for Power Transformers

et al. 2016

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Section: Effects Of Test Configuration On Frequency Response Analysismentioning

confidence: 99%

“…Investigations were carried out to determine the sensitivity of these connections to three types of winding displacements or deformations. Considering a typical two-winding transformer, the FRA measurements can be expressed using terminal voltages and currents as shown in Figure 7 [20]. To determine the relative sensitivity of the three FRA connection methods to the detection of different types of winding movement, simulations of two-winding transformer model were carried out.…”

Section: Effects Of Test Configuration On Frequency Response Analysismentioning

confidence: 99%

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A Review of Frequency Response Analysis Methods for Power Transformer Diagnostics

et al. 2016

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Abstract:Power transformers play a critical role in electric power networks. Such transformers can suffer failures due to multiple stresses and aging. Thus, assessment of condition and diagnostic techniques are of great importance for improving power network reliability and service continuity. Several techniques are available to diagnose the faults within the power transformer. Frequency response analysis (FRA) method is a powerful technique for diagnosing transformer winding deformation and several other types of problems that are caused during manufacture, transportation, installation and/or service life. This paper provides a comprehensive review on FRA methods and their applications in diagnostics and fault identification for power transformers. The paper discusses theory and applications of FRA methods as well as various issues and challenges faced in the application of this method.

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“…This form of winding deformation was presented by Jayasinghe et al [48] to investigate the sensitivity of three FRA measurement schemes. These are end to end voltage (V 1out /V 1in ), input admittance (I 1in /V 1in ) and transfer voltage (V 2 /V 1in ).…”

Section: Axial Bendingmentioning

confidence: 99%

Frequency response analysis for transformer winding condition monitoring

Yousof¹,

Fairouz²

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The large power transformer is one of the most expensive assets in a power system network.Special attention needs to be taken to monitor this expensive asset. Among the most critical aspect of a transformer that needs to be monitored is the mechanical condition of the windings and core.One of the best approaches to achieve this is by performing the Frequency Response Analysis (FRA) test on the transformer. The test measures the transfer function response of the transformer winding. If any physical changes occur, it will affect the original response, which can be used to detect any abnormality. However, the critical challenge in this technique is to correctly interpret the measured response in determining the transformer status. Although various investigations have focussed on this issue, the interpretation aspect of FRA is still not fully established.In order to contribute to the improvement of a FRA interpretation scheme, this thesis investigates the sensitivity of FRA measurement on several common winding deformations and explores a new potential diagnostic scheme of FRA. A wide range of power transformers have been used throughout this study ranging from a small sized prototype laboratory transformer to a 30 MVA power transformer installed at a substation.Initially, a mathematical model is established to simulate the frequency response of a power transformer. This is achieved by comparing three models, which are available in the literature.These models are compared in terms of their accuracies to simulate the response and their applicability to studying winding deformation. The comparison shows that the multi-conductor transmission line model is the best approach due to its ability to model each turn of a winding.With the developed model, the sensitivity of the winding response is investigated. This study shows that a minor change to the winding geometrical parameters could cause a considerable change on the response. On a different issue, it is found that a similar winding failure mode may cause a different response variation depending on the winding type. A study based on measurement is also conducted to investigate the influence of windings from other phases to the tested winding. It reveals that the end to end open circuit response is susceptible to the condition of an adjacent winding. Additionally, investigation on the winding response sensitivity due to the tap changer setting is also carried out.This thesis studies several winding deformations, which includes tilting and bending of conductors and inter-disc fault. These three faults are examined in terms of their severity of damage and location of the fault. Statistical analysis is applied to determine the overall condition of the winding. On the other hand, transfer function based analysis is proposed to extract further iii information if the winding is found to be faulty. This includes using the pole plot and Nyquist plot, in which the latter proved to be useful for all winding failure modes. The transfer function is achieved by applying vec...

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Winding movement in power transformers: a comparison of FRA measurement connection methods

Cited by 97 publications

References 8 publications

Diagnostic Measurements for Power Transformers

Diagnostic Measurements for Power Transformers

A Review of Frequency Response Analysis Methods for Power Transformer Diagnostics

Frequency response analysis for transformer winding condition monitoring

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