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Modelling Of Electrical Installations
Earthing Systems In Ansoft Maxwell
Vycital, Vaclav
This paper discusses the possibilities of modelling of ES in Ansoft Maxwell software. The possible way of definition of the problem with possible modelling difficulties were discussed. The possible error in obtained results by choosing a value of radius of the earth model as well as choosing a value of target percent error in the software by the user is also discussed. The discussion is supplemented with a simplified sensitivity analysis of these input variables and the results are validated by comparing the results with results obtained from simplified analytical formulas.
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Electricity Load Forecasting Using Auto-Regressive and Artificial Neural Network Model
Vyčítal, Václav
In this paper a short review of two forecasting models Autoregressive and Artificial neural network is presented. Both models were used to demonstrate its superior performance in load forecasting issues. In the third section the results of load forecasting experiment are given. For obtained forecasted results mean absolute percentage error for autoregressive model was 0.644 % and for artificial neural network model 2.31 %. In this paper error distribution for both models is also shown.
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Determination of electromagnetic field distribution around underground power cable
Gromotovič, Ivan ; Paar, Martin (referee) ; Vyčítal, Václav (advisor)
The thesis deals with the distribution of the electromagnetic field around the conductor in the way of laying the conductors. The paper describes the structure of the cables and their lettering. More detailed is described the underground cable and various ways of protecting the conductor against mechanical damage are shown. The functions of the locator of underground lines on the electromagnetic field principle are briefly described . In the practical part, in simulation software Ansys Maxwell has been designed models to simulate the layout of the underground line. The output of the thesis is the comparison of the results created by the simulations.
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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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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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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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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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The calculation of the short-circuit currents and voltages of given distribution network
Vyčítal, Václav ; Vaculík, Petr (referee) ; Toman, Petr (advisor)
This thesis deals with the transient phenomena in electric power systems especially short circuits. Than short circuit is classified to other types of faults in electric power system. The study also describes short circuit current as a function of time. However to complete a basic theory of short circuits, separate chapters are devoted to the causes of short circuits and to hazards connected with short circuit currents. The main part of this paper is devoted to the derivation of the formulas for calculation of short circuit currents using symetrical components and to calculation method presented in IEC 60909. In the end of this part there is a example of a simple network with calculation of symetrical and asymetrical short circuit current. In the last part of this thesis there is an example of 110 kV network with calculation of short circuits currents on busbars. The topology of the network and elekctrical equipment data are based on real part of a distribution network situated in the Czech Republic.
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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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Creation of a laboratory model of the earth system
Moliš, Martin ; Vyčítal, Václav (referee) ; Topolánek, David (advisor)
This work deals with designing of grounding system model. This model might be used for potential distribution, step and touch voltage measuring, depending on particular grounding system. Moreover measuring transferred potential into another grounding system and the influence of foreign grounding system’s presence on the overall earth resistance. The aim of this work is to create a simulation on the model of whole system’s behavior during a fault on the power line. This model also might be used for laboratory classes.
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