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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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Design of a transformer station for power output from a PV power plant and a diesel generator
Marák, Jiří ; Procházka, Aleš (referee) ; Orságová, Jaroslava (advisor)
This thesis is about design of a transformation station for power output from both a photovoltaic power plant and a diesel generator, serving as grid support. The primary objective is to devise a comprehensive solution including conceptualization, grid connection point, and transformer specifications capable of handling the 5 MW power output from the PV plant and the 1000 kW output from the diesel generator, including the calculation of short-circuit conditions. Furthermore, the thesis delves into the design of network breakpoints and protective measures.Lastly, it proposes dispatch control and billing metering in accordance with the operational requirements stipulated by the distribution system operator.
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Dynamic modelling of active railway traction feeders for power quality assessment
Bureš, Jan ; Doleček, Radovan (referee) ; Klusáček, Jan (advisor)
The thesis is focused on modelling of traction feeders for 25 kV 50 Hz traction system in order to assess the influence on voltage quality at point of the connection in 110 kV distribution grid. With respect to various technology of traction feeders, the feeder models, including conventional feeding system and modern converter stations, emphasize operating principle, detailed power circuit structure and description of influence on voltage quality in the distribution grid. The selected technologies of traction feeders are modeled in simulation software PSCAD and influence on voltage quality at the point of connection is assessed via an example, which reflects a realistic operation of traction vehicles in the typical traction system. The models are parametrizable and thus can be used for the connectivity assessment for the distribution system according to national distribution system operators’ standard PNE 33 3430-0. Moreover, the thesis also deals with the use of modern converter feeders for auxiliary frequency services. The operation principle is demonstrated on examples where the basic algorithm and requirements for control layer of converters is described. Finally, an algorithm for synchronization of the feeders supplying adjacent 25 kV 50 Hz railway traction system sections is designed and presented by means of simulation. In general, the thesis shows the use of dynamic models for connectivity assessment to the distribution grid in pre-project phase and for definition and development of converter feeders use cases upon feeding of the railway traction system.
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An effect of natural phenomena on electrical devices
Müller, Michal ; Aubrecht, Vladimír (referee) ; Bušov, Bohuslav (advisor)
The Thesis deals with the impact of natural effects on electrical equipment. It describes the various natural effects and shows how it impacts, what it impacts on and what the source of its impact is. The main point of this Thesis is the issue of atmospheric charge (storm and lightning) and the issue of coronal mass ejection (CME). The Thesis shows causally consequences string of geomagnetical field disturbances and resultant power system impacts. There are mentioned historic storm events and power system impacts and description of events in Hydro-Quebec – the most important event. Of this species. At the end there are shows possible way of mitigation power system impacts.
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MV netwok design for 75 new houses in Damborice
Makuta, Peter ; Novák, Vojtěch (referee) ; Ptáček, Michal (advisor)
Content of this thesis is medium voltage network design for seventy five houses in Damborice. At the beginning author discuss about history of transmission network and distribution network. Next topic is about steady state of network. In theoretic part are different solving methods of linear and non-linear simultaneous equations discussed. Author describes four methods – method of node voltages, elimination of balance node, Gauss-Seidel and Newton method. The electric properties of both the overhead transmission lines and cable lines and their variety are part of this work too. There is purpose, forms and parameters of transformers described. Simplicity of author’s design should reduce the usage of many electrical elements visible to residents.
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Power Converter for the electric DC arc welding
Vranák, Daniel ; Vorel, Pavel (referee) ; Patočka, Miroslav (advisor)
The main aim of thesis was produce a draft power converters for DC arc welding, which would be suitable for use in regular service. For the purpose of the proposal, first must be acquainted with the possible methods used converters whose distribution and explain the principle place in beginning thesis. Next it was transferred detailed design of individual components, which was used for the construction of the power part of the welder.
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Hybrid Microphone Preamplifier
Valach, Ondřej ; Hanák, Pavel (referee) ; Koton, Jaroslav (advisor)
The diploma thesis deals with the design of hybrid microphone preamplifier with stepless choice of amplification technology between active part using tube or semiconductor elements. Before the design, the basic physical relations of electroacoustics were described. Problems of connection of audio devices, their voltage and noise conditions. At last technical properties of microphones and tubes were described. In the practical part, the overall structure of the hybrid preamplifier is designed and the goals of the thesis are set. This is followed by a detailed design of the preamplifiers. From input circuits through individual amplifier stages of the semiconductor and tube sections to the output of the device. Much of the circuit was tested by software simulations. Based on the results obtained in the design of the signal part of the preamplifier, the power circuits were designed. Finaly the preamplifier functionality was verified by measurement on the Audio Analyzer.
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Simulink transformer models based on equivalent circuits
Petrič, Peter ; Huták, Petr (referee) ; Pazdera, Ivo (advisor)
The aim of the bachelor‘s thesis is to project and then realize models of transformer in Matlab/Simulink program. These proposed procedures show the relation between original transformer and its spare connections. The first part of bachelor‘s thesis is oriented to theory of transformers which defines basic parametres and relations between them in transformer. Later in this part we try to describe cross-over from basic transformer model to the spare connection which is needed in realization of model in Simulink. The second part of bachelor‘;s thesis is oriented to theoretical description of vector transformation. It describes some basic relations of general transformation, currents transformation and voltage in certain connections. The third part of bachelor‘s thesis shows some practical realization of spare connection models of basic transformer in Simulink program. In this part we modeled some current transformer models and voltage for single-phase and three-phase system. As to compare we have created process of currents and voltages in transformer as well as power and load of each model.
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Conceptual design of the reconstruction of an E.ON 22 kV distribution network installed at a specic area
Vepřek, Tomáš ; Nepevná, Vlastimila (referee) ; Blažek, Vladimír (advisor)
The aim of this thesis is a modification of the distribution network (DS) of the city of Brno to ensure power supply in the required quantity and quality for end consumers. Calculation of steady - state operation of distribution network (DS) of Brno is performed in the programme PAS DAISY Off-Line v.4.00 Bison. On the basis of available data (dispatching scheme, load current of stem lines and reserved power of wholesale customers) we will analyze the steady-state of network. We will find out which of the 110/22 kV transformer stations, cable and overhead lines are overloaded and perform network adjustments to ensure safe and reliable operation by 2015. We will identify in which year we will need to build a new power node in the northern part of Brno. The conclusion is focused on technical and economic evaluation of proposed alternative network arrangements.
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