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Design of instrument transformers for digital protection relays
Souček, Jan ; Matuška, Marcel (referee) ; Toman, Petr (advisor)
Master’s thesis is concerned with instrument transformers, which are used in conjunction with numerical protection relays. Therefore mainly with protective transformers of class P and transformers dimensioned for transient effects, which are important e.g. for fast differential or distance protections. The introduction includes fundamental notions, quantities and equations, which refers to instrumental current and voltage transformers. Below are mentioned connection diagrams of these transformers applied to specific electrical network types and faults, of which identification is required. These diagrams and faults are supplied with math equations and eventually with phasor diagrams. Noted informations corresponds to the present standards. Task of the next part is to compile requirements for dimensioning of current transformers, which imposes digital protections from ABB, AREVA and Siemens companies. These requirements, which mostly defines the minimal accuracy limit factor or the knee-point voltage of current transformer, are specified for individual protection terminals, eventually for specific protective functions. Part of the thesis is computer program developed as macro in the Microsoft Office Excel program via Visual Basic for Applications programming language. Program uses equations noted in this work and it can be used for quick dimensioning of current transformers for protective terminals from manufactures mentioned above.
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SAIDI and SAIFI Calculation for a Low Voltage Distribution Networks in Mesh Configuration
Dohnal, Josef ; Souček, Jan (referee) ; Paar, Martin (advisor)
This diploma thesis aims to briefly interpret problems relating to continuity of distribution of electrical energy in a distribution network of low voltage. It also mentions methods of calculation of a distribution system´s reliability which are the most used in practice. Next, there is a chapter dedicated to how distribution networks are projected and operated in the Czech Republic and in the United Kingdom. Based on experiences with meshed networks operation this thesis designs protection of meshed distribution network of low voltage. In the end, a non-sequential method of Monte Carlo is used to calculate System Average Interruption Index (SAIDI) and System Average Interruption Frequency index (SAIFI).
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Power Losses Calculation Depending on Distribution Network Configuration
Domes, František ; Souček, Jan (referee) ; Paar, Martin (advisor)
This master‘s thesis deals with the calculation of losses depending on the configuration of the distribution network. The first part focuses on the general theory regarding some used calculation methods of steady operation. The next part is theoreticly dedicated to the technical losses, possibilities of their influencing and their calculation. In the practical part is carried out the choice of calculation method of steady operation. This method is implicated into the proposed program in programming environment MATLAB.Furthermore, on the basis of a partial measurement in the distribution network and using the proposed program are determined the sizes of offtakes of mesh network. For the existing mesh network is designed its radial operation. In the last part are calculated the losses of this network for both of these mentioned operations.
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Analysis of propagation of "lion roar" emissions using the data of the Cluster spacecraft
Krupař, Vratislav ; Santolík, Ondřej (advisor) ; Souček, Jan (referee)
The main task of this thesis was a statistical study of lion roar wave emissions in the Earth's magnetosheath. Large data set obtained from the Cluster spacecraft has been used. We have studied a frequency distribution, a wave power distribution and a spatial distribution. We have investigated propagation characteristics using advanced methods applied on multi-components measurement. We have confirmed the narrow-band structure of lion roars. We have compared observed and estimated (from the cold plasma theory) time lags between spacecraft during short separations.
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Solar Wind Modification in the Earth Foreshock
Urbář, Jaroslav ; Němeček, Zdeněk (advisor) ; Souček, Jan (referee) ; Vandas, Marek (referee)
Title: Solar Wind Modification in the Earth Foreshock Author: Jaroslav Urbář Department: Department of Surface and Plasma Science Supervisor: Prof. Zdeněk Němeček, Department of Surface and Plasma Science Abstract: The thesis presents statistical studies of the solar wind deceleration and deflection in the foreshock and its potential causes. The multi-point observa- tions from the THEMIS mission in the foreshock are compared with a Wind solar wind monitor with motivation to estimate different factors influencing evolution of solar wind speed and its deflection. We have found a systematic deceleration of the solar wind mainly due to its proton component with a decreasing distance to the bow shock that is controlled by the compressibility and the level of magnetic field fluctuations in the ULF wave range associated with the flux of reflected and accelerated particles. We can conclude that the reflected particles excite waves of large amplitudes that decelerate the solar wind protons throughout the foreshock as well as in front of the Moon. Keywords: Earth foreshock; reflected protons; solar wind proton velocity recon- struction; deceleration; ULF waves 1
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Analysis of wave-particle interactions in space plasmas
Černý, Miroslav ; Santolík, Ondřej (advisor) ; Souček, Jan (referee)
This work deals with the linear analysis of plasma waves, especially with the methods of solution of a hot plasma dispersion relation. There are cited some results achieved in the space plasma research and mapped current numerical methods of their analysis. Besides, this work introduces a new numeric procedure, computer code PDRS (Plasma Dispersion Relation Solver), which allows finding solution of a dispersion function of a cold or hot plasma with general distribution function. It also demonstrates the usage of the PDRS methods on real examples of waves in space plasma based on the spacecraft Cluster measurement.
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Laboratory investigation of dust charging and impact ionization
Nouzák, Libor ; Pavlů, Jiří (advisor) ; Jeřáb, Martin (referee) ; Souček, Jan (referee)
Dust is an almost ubiquitous component of the cosmic plasma (e.g., planetary and cometary magnetospheres, the heliosphere, the interstellar medium, supernova shells). However, it can be also frequently encountered in industrial applications as a principal agent in material treatments, or as an undesirable ingredient in a production of microelectronic components, or in fusion devices. Since dust particles are one of the main elements of interest in the solar system (e.g., Earth, Jovian and Saturnian systems) and in the interstellar medium, there is a number of missions (e.g., ROSETTA, Cassini) that provided investigations of the properties and global dynamics of charged dust grains. In these environments, the relevant charging processes are interactions with electrons and ions of the solar wind and photoemission by solar UV radiation that often dominates. However, in-site investigations of such processes are difficult because several processes act in accord. The present thesis studies charging processes in laboratory settings where these processes can be investigated separately. In the first series of experiments focused on applications in the lunar or planetary surroundings, a single (charged) dust grain is stored in an electrodynamic trap and expose to electron and/or ion beams with variable energies and...
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Lysias' Speech against Eratosthenes. Translation, Commentary, and Introductory Study.
Nývlt, Pavel ; Souček, Jan (advisor) ; Marek, Václav (referee)
Lysias' speech Against Eratosthenes is the most famous speech of Lysias, Athen's most prolific author of lawcourt speeches. It deals with a murder of Lysias' brother Polemarchus, who was arrested and executed under the rule of so-called "Thirty Tyrants" in 404 B. C. And yet the topics covered are much wider, the speech thereby becoming a portrayal of the darkest times athenian democracy ever witnessed and a valuable document of democratic point of view on the events. The speech is commented from a historical point of view, focusing in the first place on political history and history of law.
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