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Change of voltage at LV terminals of a MV/LV power distribution transformer caused by changes in its load
Jandora, Jiří ; Bátora, Branislav (referee) ; Blažek, Vladimír (advisor)
The thesis deals with the use of distribution transformers, their integration into the electrical network, their properties, and principles and means of regulation according to changes in load. The introductory chapter is devoted mainly to the theoretical background concerning the functioning of the transformers. Even though it is not the focus of this thesis, a brief summary of their structure will be provided because it is presumed that not all the readers are familiar with this particular electrical network block and thus they should be explained how the transformer works. Then the ways of transformer regulation will be outlined. In the theoretical part, the important point for the reader is the substitution of the transformer by two-port network i.e. the equivalent circuit. The two-port network is a substitution of the connection properties by simple electric elements, which are not so problematic for further use. When dealing with the two-port networks in the chosen equivalent circuit, Blondel’s constants will be used. Blondel’s constants facilitate working with the basic network invariables of the circuit such as amperage, voltage and power. The second part of the thesis is devoted to solving a problem that involves the use of distribution transformers. The problem is as follows: there is a manufacturing plant with three transformers, each of them having rated power and nominal transformation ratio. The manufacturing plant is supplied by HV three-phase line with rated voltage and parameters given by the distribution point, where constant voltage is maintained. The task is to determine in what ways the voltage of the low voltage terminals of the transformers will change when changing the power from idling circuit to the rated load. The power factor should be constant. The method for solving this task has already been outlined in the theoretical part. The results are summed up in a simple chart completed with diagrams, which concisely describe the result of the research.
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Optimization of magnetic circuit of induction motor for frequency up to 210 Hz
Binek, Martin ; Cipín, Radoslav (referee) ; Vítek, Ondřej (advisor)
This master’s thesis first deals with the theory concerning induction motor. It briefly desbribes the construction of three-phase induction motors, the generation of tractive force, power flow with loss distribution and also torque characteristic. In the next part an analytical calculation of the parameters of equivalent circuit for an existing induction motor with known dimensions is performed. After the calculation it is possible to find out the rated parameters of the motor, which makes it possible to further compare results with the values obtained by other methods. The next step was to create a model of the motor in RMxprt program, which is later also translated to ANSYS Maxwell 2D model. Simulations were carried out in both interfaces. As the next step the results obtained by the three methods are compared with measured values and also evaluated. The final part of the thesis focuses on the optimization of the magnetic circuit for higher frequencies. Efficiency of the modified induction motor is examined for higher frequencies using RMxprt Optimetrics and this procedure is performed for both default and alternative electrical steel materials.
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Measurement and analysis of single-phase transformer
Princ, Pavel ; Huzlík, Rostislav (referee) ; Vítek, Ondřej (advisor)
The aim of that diploma thesis is low power transformer simulation via its substitutitional circuitry.As Instrument for matematical description of model and simulation of various operating situations with different amplitude and types of load was used Labview software. The software was simultaneously used for real transformer measurement and to compare these results with calculated values. The created program is also applied for measuring excercise for students. In The thesis is described measured transformer in terms of final elements method in FEMM software and there is showed the procedure of its design.
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Calculation of parameters of induction motor using FEM
Pešek, Michal ; Skalka, Miroslav (referee) ; Vítek, Ondřej (advisor)
This project is focused on finite element method, for purposes of asynchronous motor modeling. Program FEMM is used here, which works with two-dimensional models. The model is based on an existing motor. Then was conducted a series of simulations that are used to calculate the parameters of the circuit model. Then was measured the existing asynchronous motor and performed the calculation of the circuit model parameters of the motor. Compared with data obtained from motor and models Then was compared their torque characteristics. Moments was identified at certain slip frequencies and voltage or current in circuit model.
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Instrument voltage transformers of outdoor type
Velešík, Petr ; Bušov, Bohuslav (referee) ; Vaněk, Jaromír (advisor)
The function analysis of instrument voltage transformer with the aid of his equivalent diagram and his phasor diagrams is main part of my masters thesis. I solve the influence and errors of his equivalent diagram’s elements on this instrument voltage transformer. Than I talk about suitable magnetic materials using for instrument voltage transformers. There are 3D pictures which show lay-out of instrument voltage transformers’s windings and his magnetic circuit.
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Mechanical Torque Analysis of Induction Machine Based on Magnetic Circuit Saturation
Skalka, Miroslav ; Bendl,, Jiří (referee) ; Voženílek, Petr (referee) ; Ondrůšek, Čestmír (advisor)
e main goal of this thesis is mechanical torque analysis of induction machine based on magnetic circuit saturation, oversaturated areas classification and the possibility of oversaturated areas reduction of their influence on machine properties. Whole problem is solved by finite element method in ANSYS program. Work is divided into the description and creating of electromagnetic model, a method of the induction machine equivalent circuit parameters determination, the electromagnetic field calculation by finite element method, experimental measurement using LabVIEW program with measurement accessories (PCIe card National Instruments), data processing program in DIAdem, results analysis of calculations in terms of magnetic circuit saturation, the influence of magnetic circuit material based on electromagnetic field distribution and the magnetic flux density along the air gap including spectral analysis using MATLAB and the electromagnetic torque and its parasitic torque components calculation.
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Coupled model of transformer
Adamec, Lukáš ; Huzlík, Rostislav (referee) ; Vlach, Radek (advisor)
The bachelor's thesis deals with the creation of a coupled model of transformer in the Matlab system. The coupled model connects two basic physical domains - electricity and heat transfer. It all starts with the selection of suitable equivalent circuit diagrams that represent the electrical and thermal properties. Their connection is then called as coupled model, which captures their mutual influence. An important part of the thesis is the identification of elements (thermal resistances and capacities, stray inductance, etc.) of equivalent circuit. Open-circuit and short-circuit tests are used to identify electrical elements, thermal elements are then determined from the temperature curves of the sub-parts of the transformer – core and winding. The goal of the thesis is that the output of the coupled model corresponds as closely as possible to the behavior of a real transformer. Compliance is verified by the final simulation.
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Optimization of magnetic circuit of induction motor for frequency up to 210 Hz
Binek, Martin ; Cipín, Radoslav (referee) ; Vítek, Ondřej (advisor)
This master’s thesis first deals with the theory concerning induction motor. It briefly desbribes the construction of three-phase induction motors, the generation of tractive force, power flow with loss distribution and also torque characteristic. In the next part an analytical calculation of the parameters of equivalent circuit for an existing induction motor with known dimensions is performed. After the calculation it is possible to find out the rated parameters of the motor, which makes it possible to further compare results with the values obtained by other methods. The next step was to create a model of the motor in RMxprt program, which is later also translated to ANSYS Maxwell 2D model. Simulations were carried out in both interfaces. As the next step the results obtained by the three methods are compared with measured values and also evaluated. The final part of the thesis focuses on the optimization of the magnetic circuit for higher frequencies. Efficiency of the modified induction motor is examined for higher frequencies using RMxprt Optimetrics and this procedure is performed for both default and alternative electrical steel materials.
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Analysis of damage to the rotor bars of induction machines
Henzel, Roman ; Michailidis, Petr (referee) ; Skalka, Miroslav (advisor)
This bachelor thesis deals with disorders of induction machines with focus on the failure or damage to the rotor bars or end rings. The work includes a literature research of the low resistance measurement, which can be used to determine the rotor bar resistance of the squirrel cage induction machine. The experimental measurement of the analyzed motor with the following conditions (short-circuit, no-load and load) is also includes. The magnetic model of the machine was described and created in MAXWELL and results were compared with the LabVIEW software (in order to verify the accuracy of the particular simulation). Analysis results evaluation of three phase squirrel cage induction machine with broken rotor bars was done.
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Mechanical Torque Analysis of Induction Machine Based on Magnetic Circuit Saturation
Skalka, Miroslav ; Bendl,, Jiří (referee) ; Voženílek, Petr (referee) ; Ondrůšek, Čestmír (advisor)
e main goal of this thesis is mechanical torque analysis of induction machine based on magnetic circuit saturation, oversaturated areas classification and the possibility of oversaturated areas reduction of their influence on machine properties. Whole problem is solved by finite element method in ANSYS program. Work is divided into the description and creating of electromagnetic model, a method of the induction machine equivalent circuit parameters determination, the electromagnetic field calculation by finite element method, experimental measurement using LabVIEW program with measurement accessories (PCIe card National Instruments), data processing program in DIAdem, results analysis of calculations in terms of magnetic circuit saturation, the influence of magnetic circuit material based on electromagnetic field distribution and the magnetic flux density along the air gap including spectral analysis using MATLAB and the electromagnetic torque and its parasitic torque components calculation.
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