Understanding power transformer frequency response analysis signatures

Abu-Siada, A.; Hashemnia, Naser; Islam, Syed; Masoum, Mohammad A. S.

doi:10.1109/mei.2013.6507414

Cited by 148 publications

(62 citation statements)

References 29 publications

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“…[33]. The lower frequency bands FB1 and FB2 are dominated by the core magnetizing inductance and winding series capacitance, while FB3 and FB4 are related to the leakage inductances of the windings and the capacitances of adjacent windings [36,37]. The high frequency part of FB4 up to 2 MHz represents smaller details of the active part geometry together with the winding leads.…”

Section: Interpretation Of Frequency Response Measurementmentioning

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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Section: Interpretation Of Frequency Response Measurementmentioning

confidence: 99%

Diagnostic Measurements for Power Transformers

et al. 2016

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“…In FRA applications, the frequency ranges are divided into bands as shown in Table 1 where the detection of sensitivity of associated fault types are also indicated [11]. Typical transformer distributed model component values are Rs (Ω): 0.5, Ls (μH): 65, Csh (nF): 0.026, Cg (nF): 6, CHL (nF): 5, 1/G (MΩ): 7 [18]. In FRA applications, the frequency ranges are divided into bands as shown in Table 1 where the detection of sensitivity of associated fault types are also indicated [11].…”

Section: Transformer Modelsmentioning

confidence: 99%

“…This can help in establishing a standard code for FRA signature interpretation. The effects of ±10% variation in various electrical parameters on FRA resonance frequency and magnitude (compared to healthy FRA signature) are summarized in Table 3 [18]. Table 4 shows the effect on FRA when changes were made in different parameters of the transformer model shown in Figure 4 [19].…”

Section: Transformer Modelsmentioning

confidence: 99%

“…After removing the transformer from service, there are several methods to diagnose the fault and one of these methods is FRA as noted earlier. Authors of [18] presented investigations done on a 0.4/10 kV, 100 kVA, oil-immersed transformer after a failure occurred. FRA measurements were performed on the transformer with respect to HV winding (i.e., V-U and V-W) and between HV and LV windings (i.e., U-u, V-v, and W-w).…”

Section: Case Study Of In-service Failure Diagnosticsmentioning

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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“…Apart of the described methods to model the frequency response based on numerical calculation of R, L, C, G and M, it is also possible to employ finite element method. This method offers analysis from electric field perspective such as work presented in [60].…”

Section: Modelling the Transformer Winding Frequency Responsementioning

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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Understanding power transformer frequency response analysis signatures

Abstract: Data obtained using a distributed parameter model to simulate a power transformer are presented. These data could be used in the formulation of standard codes for interpretation of the frequency response analysis signatures of power transformers.

Cited by 148 publications

References 29 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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