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Simulation of temperature-rise in MV switchgear assemblies
Kapalla, Alexej ; Bušov, Bohuslav (referee) ; Valenta, Jiří (advisor)
This thesis focuses on the issue of heating of medium-voltage switchgears. The paper contains descriptions of the individual devices which the switchgear consists of. Furthermore, the paper examine the theoretical relations which describe the heating of the conductor. It also present the normative regulations regarding the heading of MV switchgears as well as specific impacts which influence the final temperature-rise. This is followed by chapters that describe the refining of a 3D model of specific switchgear for purposes of simulating temperature-rise, further followed by chapters that look at the actual simulation environment. The thesis further focuses on the actual simulation of MV switchgear temperature-rise and it will compare the results of the simulation with measurements taken under real conditions. The thesis also includes results of simulated temperature-rise while taking into consideration the forced cooling of the switchgear. In the last part, it focuses on the creation of an excel file, which enables the prediction of final results for the temperature-rise of disconnector based on its contact resistance.
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Design of Protection Relays for MV Distribution Grid
Sochor, Tomáš ; Bukvišová, Zuzana (referee) ; Toman, Petr (advisor)
The master´s thesis deals with the design of medium voltage power line protection and the calculation of reliability indicators. First, it deals with the possibilities of power system operation. Subsequently, it divides the networks according to the grounding of the transformer node and the switching elements and devices occurring in the MV distribution network are mentioned. It presents the basic classification of power line protection and its use, especially it focuses on overhead and cable MV power lines. It also discusses the reliability of the power supply and lists the basic reliability indicators and their possible calculation. The practical part describes the changes in the considered area of the distribution network, where the reconstruction of the power line VN872 and a new way of powering the village Drnholec will take place. The impact of this change on the reliability of the supplied energy is also calculated. Furthermore, the protection of the power line is designed and the correctness of its setting is then verified on the model in the PSS Sincal software.
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Autonomous and dispatching control of distributed power generating plants operated in the HV distribution system
Dvořáček, Jiří ; Jurík, Michal (referee) ; Drápela, Jiří (advisor)
Theses focuses on the evaluation of the possible means of active and reactive power control of generating units connected to medium voltage. First part summarizes analysis of Czech Republic medium voltage distribution grid. It summarizes means of autonomous and dispatcher control of generating units with respect to European Comission directive RfG, standard ČSN EN 50549-2 and national implementation PPDS. Following parts provide description of generating unit and distribution grid models used for simulation in PSCAD. Last part focuses on evaluation of results obtained via simulating steady-state scenarios as well as continuous simulation.
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Proposal of design and configuration of 22 kV network after installation of 110/22 kV transformation in Brno-Sever switching substation
Mišinger, Ondřej ; Beneš, Jan (referee) ; Blažek, Vladimír (advisor)
The theoretical part of this thesis deals with distribution networks in terms of distribution according to different criteria, describes the main elements of electric distribution networks and their qualities. The following describes the methods of calculating the steady state of electrical networks. These methods are nowadays used as basics for computer programs. In the penultimate chapter of the theoretical part are summarized the principles for the development of present networks and construction of new electrical networks. The aim of practical part of the thesis is to assess the current condition of the network 22 kV in the city of Brno and assess the condition after installation of 110/22 kV transformation in Brno-Sever switching substation. After evaluating the results of steady state electrical network and identifying certain problems is the following aim a proposal of solving problems that emerged in the network. The result should be operational, functional and reliable electric distribution network. This thesis used to calculate the steady state electrical networks by software PAS DAISY Off-Line Bizon V4.
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Deficiencies and inaccuracies in measurement of MV distribution network laboratory model
Němec, Jiří ; Vyčítal, Václav (referee) ; Ptáček, Michal (advisor)
The paper analyzes the deficiencies and inaccuracies in measurement of medium voltage distribution network laboratory model. The aim is to propose solution to these problems. In the second chapter, basics of the theory of medium voltage network and the operating parameters of distribution grids are described. The theoretical part is mainly based on the Czech technical standards. The third chapter focuses on description of the laboratory model and it contains its label values. The fourth chapter deals with executed measurements and mathematical models created in the program PSCad. Comparison of the measurements and the computer simulations is included. Description of the measurements contains its purpose, the measured parameters and results of the measurements. Input parameters for creating computer simulations are listed and their results are processed. In response to measurements, yet unknown parameters of the laboratory model and its behavior in various operational states are clarified. On the basis of the findings, which this paper brings, it is possible to modify the laboratory exercise and thus reach more accurate results.
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Diagnostics of medium voltage and high voltage circuit breakers
Kapalla, Alexej ; Šimek, David (referee) ; Dostál, Lukáš (advisor)
This bachelor work is focused on medium-voltage and high-voltage circuit breakers and their diagnostics. The thesis presents the history of HV circuit breakers and their main division. Subsequently, the relevant standards are listed in the work and diagnostics of the MV circuit breaker VD4 and the HV circuit breaker S1-245 from AEG is performed. In case of the VD4 circuit breaker, a new and used circuit breaker was diagnosed. The measured values are then compared and the impact of usage is shown. The work describes the measurement of main contact resistance, insulation resistance, closing and opening times and vacuum quality.
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Monitoring in Middle- and Low-Voltage distribution systems penetrated by distributed generation
Kolacia, Tomáš ; Kolář, Vladimír (referee) ; Drápela, Jiří (advisor)
This thesis concerns monitoring in Middle- and Low-Voltage distribution systems penetrated by distributed generation. Monitoring itself means measuring voltages and power flows and sending relevant data to the supervisory system. The first part of the thesis describes distribution systems with differences between individual voltage levels. The following chapter is focused on consequences of high share of renewable energy sources in distribution systems. Most of the problems are partially resolved by technical conditions for connection of the new power sources. However, difficulties with voltage regulation and uncontrolled power flows to higher voltage levels remain. These are the reasons for measuring voltages and currents in medium voltage networks. Second to last subhead of this chapter is dedicated to possible benefits of monitoring. The fourth part of the thesis deals with voltage and current sensors with their advantages and disadvantages. The best suitable devices are chosen in the end of the chapter. It is crucial to mention that sensors are only part of measuring system. Analog outputs from current or voltage transformers need to be converted to digital signal and further processed. After that required quantities are finally sent. Properties of these circuit cards are described in the sixth chapter. Following part aims to define a certain key that will determine the suitable locations for installation of the measurement. The final part of the thesis compares measured voltages and power flows from real 22 kV network with calculated values from computer program PAS DAISY Bizon.
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Calculation of temperature field of the busbar bridge
Měrka, Ivan ; Maxa, Jiří (referee) ; Vyroubal, Petr (advisor)
This term project’s aim is to theoreticaly analyze thermal phenomena and losses in electrical power devices, describe the design and application of UniGear ZS1 type switchgear, put together a computer simulation model for thermal calculations of current and optimized solution and finally to discuss obtained results and compare them with experimentally acquired values. The main objective of this project is to determine, whether simulation is a viable and reliable enough method, that it could replace the costly real life physical testing. Modelling of the progress of thermal processes in different parts of the examined busbar will be done in computer aided design program Solidworks and its simulation plugin Flow Simulation.
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Application of Sensors and Digitalization Based on IEC 61850 in Medium Voltage Networks and Switchgears
Štefanka, Martin ; Braciník, Peter (referee) ; Müller,, Zdeněk (referee) ; Toman, Petr (advisor)
Vzduchem izolované vysokonapěťové rozváděče jsou nedílnou součástí energetického distribučního řetězce a to jak v průmyslovém, tak ve veřejném sektoru. Hlavní funkcí rozváděče je ochrana pracovního personálu, rozpojování/odpojování a spínání, izolování, měření proudů a napětí, chránění a ovládání zatížení a komunikace dat do řídících systémů. V každé z výše zmíněných funkcí probíhal technologický vývoj v průběhu posledních 40 let. Dnešní rozváděče jsou spolehlivé a elektrickému oblouku odolné zařízení, zoptimalizované téměř k fyzikálním limitům dielektrických, elektromagnetických a termodynamických polí. Vakuové vypínače zajišťují stálou a spolehlivou vypínací funkci. Taktéž v oblasti chránění, řízení a komunikace došlo k mnoha technologickým proměnám. Od elektromechanických relé přes zařízení založená na tranzistorech, později na jednoúčelových mikroprocesorech, až po dnešní multifunkční vysoce výkonná mikroprocesorová inteligentní elektronická zařízení. Pouze oblast měření proudů a napětí setrvala z technologického hlediska posledních 40 let beze změny. K dominujícím měřícím technologiím dneška stále ještě patří indukčně založené transformátory proudu a napětí. Byly sice provedeny některé pokusy k obměně technologie měření jako takové, nicméně bez dosažení úspěchu. Tato dizertační práce je zaměřena na poskytnutí nového náhledu na alternativní technologii měření v elektrických sítích a ve vzduchem izolovaných vysokonapěťových rozváděčích, kterou lze využít jak pro měření proudu, tak i napětí. Tato práce vysvětluje, proč Rogowského cívky, odporové a kapacitní děliče jsou tou správnou volbou a měly by být použity ve vysokonapěťových rozváděčích a podrobně analyzuje přesnost měření a jejich příslušné meze. Dále tato práce popisuje, že pro nasazování nových měřících technologií musí být postupováno systematicky. Senzory připojené k inteligentním elektronickým přístrojům a schopností komunikace založené na IEC 61850 spolu s vysokorychlostní komunikační sběrnicí Ethernetu vytvoří systém, který zjednoduší a sjednotí konstrukci rozváděčů a umožní oddělit aspekty projektování měření od studie zkratových selektivit. V práci je také uveden příklad, jak tento nový systém může přinést změny a zjednodušení do oblastí projektování a řízení. V této práci jsou popsány výsledky několikaletého úsilí při stanovení nových měřících a digitalizovaných přístupů ve vysokonapěťových rozváděčích pod autorovým vedením. Toto úsilí také vedlo k uvedení nového produktu – UniGear Digital - konceptu od ABB. Závěrečná část práce demonstruje praktické nasazení všech výsledků v této práci při skutečných aplikacích.
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Dimensioning of Anchor Sections of MV Overhead Lines
Křepela, Pavel ; Jáhn, Vítězslav (referee) ; Orságová, Jaroslava (advisor)
Overhead lines are using in the vast majority for distribution of electricity in medium voltage level in the Czech republic. This Master’s Thesis deals with theoretical and practical knowledges to design and construction of these lines. Particularly, the mechanical properties of overheads lines and solving their calculation in accordance with applicable standards. The main task is to acquaint potentional designers in this sphere with this issue, which is recently ignored. An important benefit is the practical calculation of the actual overhead 22kV.
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