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Development of the tool for application of the method for localization of unsymmetrical faults
Pospíšil, Tomáš ; Vyčítal, Václav (referee) ; Topolánek, David (advisor)
In resonant earthed distribution systems, the capacitive current of the system is compensated by grounding via a arc suppression coil. The level of fault current is then very small and independent on the fault location which greatly complicates the rapid finding of the fault site. At this moment there is no method to be used to directly locate the site of a single-phase fault in the distribution network, new methods and solutions are being constantly sought to address the shortcomings of the existent localization methods. The diploma thesis deals with the design of a universal software tool that allows to apply a new method of locating an asymmetric fault in the distribution network. The tool is created in a MATLAB environment and utilizes the negative sequence voltage measured on the low-voltage sides of the distribution transformers and the negative sequence current measured behind the power transformer. By using the proposed tool, it is possible to read the parameters of any part of the distribution system that the user enters together with the measured values of the voltage and current into the initialization file. After the specified network parameters are loaded, a numerical model is created, which is then used for the method. In the work is described in detail the way of entering the parameters of the network into the initialization file, the method of automatic assembling of the numerical model based on the entered data and the possibility of customizing the calculation parameters. At the end of the thesis, the functionality of the proposed software tool is verified on data from simulation of the test network.
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Testing of the admitance principle of the fault indicator
Musil, Milan ; Vyčítal, Václav (referee) ; Topolánek, David (advisor)
The thesis deals with the proposal, implementation and evaluation of test for fault condition indicators. Thesis focusing on earth fault indicators based on admittance principles. These indicators must be able to evaluate earth faults in compensated, compensated with auxiliary resistor, unearthed and high-resistance earthed networks. The proposed tests verify the current and voltage measurement errors in inputs including monitored characteristic variables such as conductance and susceptance. The proposed test are applied to a selected ample of the fault indicator. As part of the tests, the indicator is subjected to secondary test using the Omicron CMC256plus tester as well as test on fault records that have been converted to COMTRADE for this purpose. The last series of tests carried out uses the physical model of the medium voltage system, where the tested equipment is subjected to fault states in the compensated whit auxiliary resistor system and isolated system. Furthermore, part of the thesis is research of new methods of earth fault detection, including their principles and function description. Also included in the thesis is an overview of manufacturers of indicators, or protection, who are involved in the production of earth fault protection.
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The framework for application of phase allocation of consumers
Franěk, Vít ; Koudelka, Jan (referee) ; Vyčítal, Václav (advisor)
The aim of this work is to introduce the issue of the smart grids concept, as well as the issue of phase identification sorting from implementation smart grids. The issue of phase identification sorting is described by several possible methods. The work continues by calculating the theoretical network and processing the values measured from the low voltage network and applying the phase identification method based on voltage events. Based on the results, a laboratory task proposal is prepared.
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Probabilistic approach for evaluation of the safety of earthing systems
Klíč, Tomáš ; Vyčítal, Václav (referee) ; Topolánek, David (advisor)
This thesis deals with the grounding systems, namely their evaluation in terms of safety. The introduction describes the grounding theory, the principle reason for their use, and the difference between the current evaluation method of grounding systems in terms of security against electric shock and a new approach. Another part is devoted to describing the assessment of grounding systems in terms of safety, respectively. permissible touch and step voltages using currently based ČSN and PNE. Another essential part of the theoretical description of how to assess safety of grounding systems in terms of probabilities, consisting in determining the probability of death of a person, including the probability of failure and the probability of a man close to the rated grounding system during the disturbances, and classify the probability tolerable, moderately tolerable or intolerable and if necessary, assign the risk group appropriate solutions to mitigate the risks. The work, of course, the practical part. Designed for probabilistic approach will be processed illustrative example of evaluation chosen grounding system, which would be the basis for the negotiation of an international group CIRED / CIGRE focused on this issue.
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Design and optimization of laboratory HV models
Kočí, Zbyněk ; Vyčítal, Václav (referee) ; Varmuža, Jan (advisor)
Bachelor's thesis is focuses on the operation of the distribution system in the Czech Republic and the use of new types of cables in the world. It describes the characteristics, division and use of overhead lines and cable lines. This work also deals the division and control DC networks, their advantages and disadvantages. In superconducting cables is engaged in their development, advantages and disadvantages. Describes their application and use in the future. It also describes the parameters affecting the properties of the ropes and the cables of the AC and DC wiring and ways to mitigate the negative effects on the ropes and on the surrounding environment. Work deals with measurement and counting of the laboratory models for their optimization. Finally, the work describes a proposal of new laboratory model for the measurement and stating components, which are needed for optimization models and the production of a new model
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Unsymmetrical power flow calculation with the help of software applications
Ermolenko, Ilya ; Koudelka, Jan (referee) ; Vyčítal, Václav (advisor)
This work consists of four parts. The first part of the thesis provides a theoretical introduction to the power flow calculation problem. Furthermore, the analysis of power flow calculation as a linear and as a nonlinear problem is performed. In this thesis, Newton’s iteration method is used in the calculation of the nonlinear problem. The following describes possibilities for improving the power flow calculation by improving the Newton's iteration method and using non-standard methods. The second part describes the possibilities of power flow calculation using various software applications, such as Pandapower, Matpower, OpenDSS and PSS Sincal. In the third part of the thesis the selected software applications tool is used to test the possibility of unsymmetrical power flow calculation in the LV network for the state with and without the PEN conductor, and the calculation of the ground fault in the compensated network. In the fourth part of the work, the unsymmetrical power flow calculation is tested for a larger LV network, further is performed the evaluation of the influence of PEN conductor modeling on the calculation results compared to the calculations of a network without this conductor.
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Measurement of electrical soil resistivity
Matyska, Stanislav ; Topolánek, David (referee) ; Vyčítal, Václav (advisor)
This master’s thesis deals with the measurement of the electrical soil resistivity. In the theoretical part there are described the methods by which the soil resistivity is measured – especially the Wenner’s method, which was used for the practical measurements. Then there is also described the one-layered and the two-layered model of this method. Furthermore, there is described the procedure for the measurement of soil resistivity using the OMICRON CPC 100 and PU 193 instruments used in the measurement. To verify the modeling of a two-layered soil model, the theoretical part of the thesis describes the soil modeling process using the program Ansys. As for the practical part of the thesis, the measurements were carried out in three localities: Brno – Královo Pole; Hrušovany nad Jevišovkou – Pravice; Hustopeče nad Bečvou – Vysoká. The measured values were processed using the Matlab’s graphical user interface (GUI) that was developed within this thesis. From these values, at least one two-layered soil model was created for each location and both meters – a total of 12 models were created. For these models, measurements were simulated in Ansys. The results of the simulations were then compared with the measured values. The aim of this thesis is to compare the measured data with the data obtained by the simulations and subsequently to describe the suitability / unsuitability of the substitution of the one-layered soil model for the two-layered one for given measurements.
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Touch voltages and earth surface potentials of selected earthing systems designs
Novodomec, Radim ; Topolánek, David (referee) ; Vyčítal, Václav (advisor)
The aim of the bachelor’s thesis was to investigate the influence of the shape, size, placement of earthing systems designes as well as the influence of the soil model on the size of the resulting potential and touch voltage during the passage of ground current. For the construction and subsuquent simulation of these phenomena, the Ansys Maxwell Desktop program was used, which is suitable for using the finite element method, as the use of analytical methods is demanding. The results were further processed in Excel into graphs. The resulting touch voltage was determined as the difference between the maximum potential of the earthing system and the potential at distance of 1 meter.
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Magnetic field measurement with gaussmeter FW BELL 4090
Urbánek, Pavel ; Krčál, Vít (referee) ; Vyčítal, Václav (advisor)
This thesis focuses on the basics of magnetic field and its measurement. The field will be measured with the FW Bell 4090 instrument and depending on the success and accuracy of the measurements, the bachelor thesis should include a possible integration into teaching. The measurement of the magnetic field will be adjusted to verify whether the device parameters in accordance to the manual. The most important attributes are the accuracy of single field or multi-field measurements, the accuracy of measurements in all axes of the instrument, and measurements over a given frequency range.
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