Contribution of inrush current to mechanical failure of power transformers windings

Barros, Rafael Mendonça Rocha; Costa, Edson G. da; Araújo, Jalberth Fernandes de; Andrade, Fábia Letícia Martins de; Ferreira, Tarso Vilela

doi:10.1049/hve.2018.5019

Cited by 11 publications

(3 citation statements)

References 11 publications

(16 reference statements)

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“…When the transformer suffers from a short-circuit fault, a strong short-circuit electromagnetic force is produced due to the mutual effect of huge short-circuit current and the leakage magnetic field. This can lead to defects such as displacements, shift of laminations, or deformation of windings, connections or supporting structures, which seriously affects the safe and stable operation of the power system [5][6][7]. In 2010, EDF conducted short-circuit tests on eight amorphous alloy distribution transformers with capacities of 250, 400, and 630 kVA.…”

Section: Introductionmentioning

confidence: 99%

Novel power distribution short‐circuit testing technique based on supercapacitor and modular multi‐ports AC/DC conversion

Zhang,

Pei,

et al. 2023

IET Power Electronics

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With the growing capacity of the distribution network, the probability of short circuit accidents gradually increases. Accidents such as deformation of distribution transformer windings, shift of laminations, fracture and even explosion of mechanical and insulation components caused by insufficient short‐circuit withstand ability seriously affect the safe and stable operation of the distribution network. The short‐circuit test proved to be an effective way to detect the performance of equipment under fault impact. A power source with supercapacitor is proposed here for short‐circuit test of 10 kV distribution transformers, which can realize the short‐circuit test application economically and flexibly with expandable capacity. First, the advantages and disadvantages of test power source by short‐circuit test generators, special power line, and the proposed method are compared. Second, the structure, working principle, design scheme, and control strategy of the novel short‐circuit testing device are introduced. Furthermore, a 14 MVA/5 MJ energy storage short‐circuit test power source is designed for the testing requirements of 10 kV/630 kVA distribution transformers. Finally, the simulations and experiments are used to verify its feasibility.

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Section: Introductionmentioning

confidence: 99%

Novel power distribution short‐circuit testing technique based on supercapacitor and modular multi‐ports AC/DC conversion

Zhang,

Pei,

et al. 2023

IET Power Electronics

View full text Add to dashboard Cite

show abstract

“…In addition to the above mentioned topics, the mechanical and thermal design of the coils is also important in terms of service life and efficiency. Typically, high electromechanical stresses caused by large currents will lead to the occurrence of mechanical failure in the coils [26]. To prevent coil damage during the EMF process, additional high‐strength materials are required to improve the mechanical strength of the coil.…”

Section: Introductionmentioning

confidence: 99%

The importance of coil conductivity and eddy current effects in the analysis of electromagnetic forming process

et al. 2021

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Coil design and performance analysis are critical for the electromagnetic forming (EMF) process. However, previous studies have paid little attention to the coil conductivity, and the influence of eddy current effects in coil conductors on the forming process has not been well understood. This work aims to address these problems through numerical and experimental investigations. It is found that, due to the eddy current effects, the uneven current distribution appears in the coil conductors that should be considered when analysing the forming process, especially for the cases with large heights of coil conductors. Meanwhile, an important and interesting discovery is that the eddy current effects can greatly reduce the sensitivity of the coil conductivity with respect to the workpiece deformation, the Joule heating and the temperature rise in the coil. For instance, compared to a forming system with a copper coil, the forming height of the workpiece in the forming system with an AA5083-O coil is reduced by less than 5 % under the same discharge energy, while the copper conductivity is 3.3 times that of the latter. These results are helpful to understand the EMF process and achieve the optimal design of coils.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

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“…An FRA measurement is normally carried out by the transformer manufacturer in factory, as the ‘reference’ for the future diagnostic FRA measurements which are either conducted after the transformer's transportation and installation or after a system short circuit fault current passing through the transformer. The short circuit current could induce an electromagnetic force, several hundred time larger, and lead to the mechanical deformation/displacement/damage of a winding [4]. When measuring the frequency response of a winding, a sinusoidal low‐voltage signal is injected at one end and the response signal is received at the other end of the winding.…”

Section: Introductionmentioning

confidence: 99%

Transformer winding type recognition based on FRA data and a support vector machine model

et al. 2020

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Frequency response analysis (FRA) is regarded as the most effective technique to detect mechanical faults of transformers. Over the years, FRA measurement data have been collected by utilities into transformer asset databases. The characteristic of FRA data is fundamentally determined by the transformer's equivalent electrical circuit, which consists of inductance and capacitance parameters that are windings' design and structure dependent. Different winding types tend to have different FRA characteristics, and a transformer's design information such as winding type, dimension etc. is often not known to the utility but critically important for asset management. This study reviews the state‐of‐the‐art transformer FRA databases and application of machine learning techniques in this field, and proposes to apply a support vector machine (SVM) model onto the FRA data to identify the winding type. The SVM model is first trained by FRA traces of transformers with known winding types, and after testing, the SVM model is then applied to FRA traces with unknown winding information. A set of data from the UK's National Grid FRA database, was used to demonstrate and verify the SVM model. All transformers used in this study are 400/275/13 kV transmission transformers, which were designed using four different winding types, namely multiple layer, plain disc, interleaved disc and single helical windings. The proposed method can successfully identify the correct winding type.

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Contribution of inrush current to mechanical failure of power transformers windings

Cited by 11 publications

References 11 publications

Novel power distribution short‐circuit testing technique based on supercapacitor and modular multi‐ports AC/DC conversion

Novel power distribution short‐circuit testing technique based on supercapacitor and modular multi‐ports AC/DC conversion

The importance of coil conductivity and eddy current effects in the analysis of electromagnetic forming process

Transformer winding type recognition based on FRA data and a support vector machine model

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