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Analysis of Current Higher Harmonics Impact on Losses in Transformer Foil Winding
Žďárský, Jan ; Klíma, Petr (referee) ; Mrajca, Miroslav (advisor)
This paper deals with the analysis of the effects of non-sinusoidal current on the foil windings of power transformers. This issue is important in transformer design since losses are measured only when sinusoidal current is passed through. In some applications, these losses need to be recalculated to account for the effect of higher harmonics of the current in actual operation, as these losses are related to transformer heating. A literature search of available sources that have already described this issue is performed in this work. In this paper, a model for simulation in Ansys Maxwell environment is presented, using which the losses due to higher harmonics will be calculated.
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Analysis of Electrical Steel Additional Losses Caused by Stacking Holes
Kozlíček, Jiří ; Bílek, Vladimír (referee) ; Mrajca, Miroslav (advisor)
This bachelor's thesis deals with the analysis of losses in the electrical steel sheets of a distribution transformer, particularly the losses around stacking holes, which are used for stacking individual sheets during production. The thesis also includes standardized methods according to IEC 60404-2, 60404-3, and 60404-10, which can be used to determine the magnetic properties of materials used in transformers. Part of the thesis is the evaluation of the given issue using the finite element method, with the help of the Ansys program. Simulation models of 3 different types of sheets, which are commonly used in practice are designed in this program. The conclusion then focuses on quantifying the additional losses due to stacking holes, which is further discussed.
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Comparison of Additional Losses Calculation Methods in Transformer Multilayer Winding
Dohnal, Stanislav ; Světlík, Martin (referee) ; Mrajca, Miroslav (advisor)
This bachelor thesis deals with the problem of magnetic field dissipation and multilayer windings in distribution transformers. The thesis also focuses on the analysis of additional losses, for which it is necessary to mathematically describe the relationship between the dissipative magnetic field and the induced eddy currents. The output of the work is a comparison of methods for calculating additional losses in multilayer windings of transformers with different rated powers, which is done using the finite element method in 2D, the semi-analytical method in 2D and 3D and the analytical method.
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Loss and Heat Calculation of Oil Transformer Top Cover Near Bushings
Trombik, Šimon ; Toman, Marek (referee) ; Mrajca, Miroslav (advisor)
This bachelor's thesis deals with the calculation of losses on the cover of an oil transformer in the vicinity of LV bushings. This is because there is thermal stress and aging of the seal under the grommet and, subsequently, oil leakage. The production of oil transformer sub-parts is briefly described here, and the chapter is devoted to transformer grommets. Another part is also a literature search of eddy losses in the cover and container of the oil transformer. Subsequently, the preparation of the electromagnetic and thermal simulation is described here, where a lot of attention was paid to heat in particular.
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Production Comparison of High Voltage Winding of Dry Transformers
Mrajca, Miroslav ; Bulín, Tomáš (referee) ; Ondrůšek, Čestmír (advisor)
This bachelor thesis deals with the history, importance, usage, construction and principle of the operation of transformers. The thesis also focuses on the detailed description of the parts which the dry power transformer is composed from, as well as the description of their manufactory and following assembly into one unit. The thesis contains the comparison of different technologies of manufactory of higher voltage winding and magnetic circuit. The thesis contains a process of design of the dry transformer with an example of calculation. The output is a comparison of different high voltage winding technologies in terms of production costs and winding factor.
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Design of oil distribution transformer
Mrajca, Miroslav ; Mach, Martin (referee) ; Ondrůšek, Čestmír (advisor)
This master thesis deals with the manufacturing process of oil distribution transformers. Firstly, the thesis devotes to the design arrangement of the magnetic circuit and its manufacturing technology. The procedure of cutting laminations for core and their building into the core. Subsequently, the thesis describes technologies used for manufacturing primary and secondary windings including procedures on winding machines. Then it deals with the production of the tank and the final assembly of the transformer into one unit. The next part of the thesis discusses the design procedure of the assigned distribution oil transformer with a numerical calculation while respecting the requirements of the standards. Finally, the costs of the material of the designed transformer are determined.
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Axial Channel Effect on Leakage Reactance in Split-Winding Transformer.
Mrajca, M. ; Cipín, R.
Transformer short-circuit impedance is one of the most important output parameters in the design process. Its value depends mainly on leakage inductance, which is different for one or both shorted output windings during short-circuit test of split-winding transformer with input windings working in parallel. In this paper, an analysis of split-winding transformer with changing axial channel between winding pairs and its effect on leakage reactance has been performed for both shorted outputs. The effect is evaluated with analytical calculations, 3D and 2D finite element method simulations on a typical 5300 kVA three-phase oil transformer. The results show that the channel can’t be neglected in short-circuit calculation and the geometry of the transformer can be simplified to 2D with minimal influence on results.
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Design of oil distribution transformer
Mrajca, Miroslav ; Mach, Martin (referee) ; Ondrůšek, Čestmír (advisor)
This master thesis deals with the manufacturing process of oil distribution transformers. Firstly, the thesis devotes to the design arrangement of the magnetic circuit and its manufacturing technology. The procedure of cutting laminations for core and their building into the core. Subsequently, the thesis describes technologies used for manufacturing primary and secondary windings including procedures on winding machines. Then it deals with the production of the tank and the final assembly of the transformer into one unit. The next part of the thesis discusses the design procedure of the assigned distribution oil transformer with a numerical calculation while respecting the requirements of the standards. Finally, the costs of the material of the designed transformer are determined.
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Production Comparison of High Voltage Winding of Dry Transformers
Mrajca, Miroslav ; Bulín, Tomáš (referee) ; Ondrůšek, Čestmír (advisor)
This bachelor thesis deals with the history, importance, usage, construction and principle of the operation of transformers. The thesis also focuses on the detailed description of the parts which the dry power transformer is composed from, as well as the description of their manufactory and following assembly into one unit. The thesis contains the comparison of different technologies of manufactory of higher voltage winding and magnetic circuit. The thesis contains a process of design of the dry transformer with an example of calculation. The output is a comparison of different high voltage winding technologies in terms of production costs and winding factor.
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Global Satellite Navigation System Galileo
Šunkevič, Martin ; Pokorný, Pavel (advisor) ; Mrajca, Michal (referee)
In the introductory part, the diploma thesis deals with Global Navigation Satellite Systems in general. The American system GPS, Russian GLONASS and Chinese Compass are briefly introduced. Consequently, the main focus will be on European system Galileo, which is currently being developed. The first part describes basic principles behind the system, technical aspects of ground and space segment -- e.g. Galileo satellites or atomic clocks -- and more importantly services, which will be available to the users. Some GNSS applications, combined use of GNSS systems are other themes touched upon in the thesis. The next part is devoted to the history of development of the Galileo system, the primary (Public Private Partnership) and current way of financing (EU funding), evaluation of costs of the system and revenues generated after the completion. The arguments supporting the implementation of the system are specified at the very end.
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