FRA vs. short circuit impedance measurement in detection of mechanical defects within large power transformer

Abstract In this paper, the axial nonlinear vibrations of the transformer winding under steady state operation case and short circuit case are studied in single degree and multi-degree models. In the case of having ampere-turn balance, the steady state response of the former model is obtained by using multi-scale method and periodic shooting method, analytically and numerically. At the same time, the computing method of Jacobi matrix in the periodic shooting method has been modified, so that the computing CPU time is saved. For multi-degree mechanical model of a single phase transformer windings, the time domain response and relation between the response and various parameters are obtained by Runge-Kutta method. For ampere-turn unbalance case, an electric-mechanical coupled problem, that the electric force depends the displacement of the winding are foomed, and the nonlinear forced Mathieu equation is established for this problem; and then the nonlinear dynamical response and global dynamical behaviors are analyzed. Finally, for a 20 MVA single phase three windings transformer, a series of short circuit experiments have been performed and the axial dynamical response force, magnetic field, strain etc. have been measured. The theoretical results well agree with the experimental results.

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Calculation of Leakage Magnetic Field and Short-Circuit Impedance of Power Transformer

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.986-987.1767 ◽

2014 ◽

Vol 986-987 ◽

pp. 1767-1770

Author(s):

Fang Xu Han ◽

Yan Li ◽

Xin Sun ◽

Longnv Li

Keyword(s):

Magnetic Field ◽

Power Transformer ◽

Short Circuit ◽

Equivalent Circuit Model ◽

Simulation Software ◽

Secondary Development ◽

Element Analysis ◽

Leakage Magnetic Field ◽

Basic Language ◽

Circuit Impedance

The leakage magnetic field and equivalent circuit model of OLTC double-winding power transformer has been established by electromagnetic field Finite Element analysis software. The method of field-circuit coupled method has been used to calculate its magnetic field leakage, the short circuit impedance obtained by the calculation of formula and compared with the experimental data. At the same time, based on the calculation method for the Visual Basic language as a tool for MAGNET software for secondary development, obtain the software to calculate the short-circuit impedance of power transformer simulation software, and is verified by using the typical products, proves the validity of this software.

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Frequency response analysis and short-circuit impedance measurement in detection of winding deformation within power transformers

IEEE Electrical Insulation Magazine ◽

10.1109/mei.2013.6507412 ◽

2013 ◽

Vol 29 (3) ◽

pp. 33-40 ◽

Cited By ~ 98

Author(s):

Mehdi Bagheri ◽

Mohammad Naderi ◽

Trevor Blackburn ◽

Toan Phung

Keyword(s):

Frequency Response ◽

Short Circuit ◽

Impedance Measurement ◽

Power Transformers ◽

Response Analysis ◽

Frequency Response Analysis ◽

Winding Deformation ◽

Circuit Impedance

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Non-linear Impact of the Short Circuit Impedance Selection on the Cost Optimized Power Transformer Design

Periodica Polytechnica Electrical Engineering and Computer Science ◽

10.3311/ppee.15331 ◽

2020 ◽

Vol 64 (3) ◽

pp. 221-228

Author(s):

Tamás Orosz ◽

Zoltán Ádám Tamus

Keyword(s):

Design Process ◽

Power Transformer ◽

Short Circuit ◽

Design Rule ◽

Design Parameters ◽

Electrical Machine ◽

Preliminary Design ◽

Large Power ◽

Final Design ◽

The Cost

Since the electrical machine design is a complex task it can be divided into sub-problems, e.g. preliminary and final design processes and checking of the final design. This paper deals with the preliminary design process, which provides the key-design parameters of the electrical machine. Traditionally, these electrical machine models in preliminary design phase neglect or use oversimplified insulation system models and the tap changing selection is not involved during the calculation of key-design parameters. The aim of this study is to assess the effect of the insulation distance minimization and tap-changing on the key design parameters of a cost-optimized large power transformer. For this purpose, the paper shows some examples, where the cost optimal design — in contrast to the classical insulation design rule — contains larger insulation distances than the possible minimum values. The effect of tap-changing methods are also investigated. These cost optimization made by a verified, metaheuristic method-based transformer optimization algorithm. The results show involving the insulation design and tap-changing selection into the preliminary design process can provide more economical designs.

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Fault diagnosis of actual large-power high-voltage windings using transfer function method

Archives of Electrical Engineering ◽

10.2478/v10171-011-0025-4 ◽

2011 ◽

Vol 60 (3) ◽

pp. 269-281 ◽

Cited By ~ 2

Author(s):

Ebrahim Rahimpour ◽

Stefan Tenbohlen

Keyword(s):

Fault Diagnosis ◽

Transfer Function ◽

High Voltage ◽

Function Method ◽

Power Transformer ◽

Short Circuit ◽

Large Power ◽

Transfer Function Method ◽

Comparison Algorithms ◽

Test Objects

Fault diagnosis of actual large-power high-voltage windings using transfer function method The transfer function (TF) method is presently a well-known method used to detect various types of winding damage in power transformers. Although abundant research has been done on this subject using laboratory windings as test objects, it is hard to find one, whose test objects are actual large-power transformer windings. Hence, a 400 kV disc winding consisting of 86 discs is used in this paper to study turn-to-turn short circuit with the help of the TF method. To evaluate the effects of this type of fault on TF curves, some mathematical comparison algorithms are used in this research.

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