Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-06-09T12:11:11Z No. of bitstreams: 1 pedrodacruzloureiro.pdf: 1767688 bytes, checksum: 1fa1e4fbfaa6feaf5a5c88ea70df09d6 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-13T13:31:22Z (GMT) No. of bitstreams: 1 pedrodacruzloureiro.pdf: 1767688 bytes, checksum: 1fa1e4fbfaa6feaf5a5c88ea70df09d6 (MD5) / Made available in DSpace on 2016-07-13T13:31:22Z (GMT). No. of bitstreams: 1 pedrodacruzloureiro.pdf: 1767688 bytes, checksum: 1fa1e4fbfaa6feaf5a5c88ea70df09d6 (MD5) Previous issue date: 2012-04-16 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho é proposta a aplicação de redes neurais artificiais para ajuste de parâmetros de um compensador estático de reativos, para controle de tensão e harmônicos. Devido à intensa produção de correntes harmônicas e possíveis afundamentos de tensão em instalações industriais como o forno a arco, é necessário um sistema de controle eficiente e robusto. Além disso, os sistemas elétricos de potência se encontram em um cenário com a presença cada vez maior de geração distribuída, cargas não-lineares e forte tendência à operação no contexto das smartgrids e microgrids. Sendo assim, o suporte de reativos deve ser adequado a esses sistemas, podendo atuar de forma rápida, precisa e confiável. Uma possível solução é a utilização de um compensador estático de reativos (CER) com função adicional de filtragem no ponto onde se deseja controlar a tensão e a distorção harmônica. Entretanto, para o correto funcionamento, é necessário um sistema preciso para o ajuste dos parâmetros do CER, ou seja, determinar os ângulos de disparo dos tiristores e o número de bancos de capacitores a serem ligados. Neste trabalho é proposta uma estratégia de controle via redes neurais artificiais, treinadas para o reconhecimento de padrões de operação em regime permanente e definição da configuração do CER, conferindo inteligência ao equipamento. Os desenvolvimentos propostos foram implementados no ambiente MatLab®. A validação do método é feita através de simulações em sistemas-teste, presentes na literatura técnica, utilizando o fluxo de potência pelo método de injeção de correntes trifásico harmônico. Os resultados obtidos mostram as vantagens da utilização da estratégia proposta. / In this work, an artificial neural network-based static var compensator tuning is proposed for voltage and harmonic distortion control. Due to intense harmonic current injection and possible voltage sags produced by industrial facilities such as arc furnaces, an efficient robust control system is needed. Besides, electrical power systems face a new scenario with high penetration of distributed generation and non-linear loads and increased smart grid and microgrid trends. Therefore, the available reactive power sources must be able to provide system control in order to operate the system in a fast, accurate and reliable way. The application of a static var compensator (SVC) with additional filtering function at the controlled node is a possible solution. However, a precise SVC parameters tuning is needed, in order to make the system to work properly. In this work, a control strategy based on artificial neural networks is proposed. The neural networks are trained to recognize steadystate operating patterns and give the SVC adjustment. The proposed technique was implemented in the MatLab® environment. The methodology is validated by simulations in test-systems available in technical literature, using the three-phase harmonic current injection method power flow. Results show the advantages of the proposed methodology.

stainless steel, duplex steel, vakuum metallurgy, decarburization

Stålindustrierna Sandvik, Sandviken och SSAB, Borlänge tillverkar billets (kvadratiska ochlångsmala stålämnen). Vid tillverkningen av billets förflyttas stålämnena stegvis i ugnensamtidigt som de hettas upp. När stålämnena når slutet av ugnen lyfts de ur av en externmaskin. För att tids- och energieffektivisera den sista etappen krävs positionsbestämning avämnena då de når slutet av ugnen. Dessa aspekter är viktiga ur en ekonomisk såväl sommiljövänlig synpunkt då induktiva ugnar använder en stor mängd energi. Tillämpningen ärtänkt att användas av stålindustrin. UWB-radarns bredbandiga karakteristisk gör den till en lämplig ersättare till dagens sensorersom kräver håltagning i ugnens valv. Det breda frekvensspektrat hos en UWB-radarmöjliggör ytmonterade enheter i kontrast till de konventionella sensorer som används idag.Underhållsstopp för rengöring av sensorhålen kan då undvikas. Arbetet började med teoretisk studie rörande UWB-teknik och radar i allmänhet. Därefterutformades testscenarion för att studera radarvågen under varierande förhållanden. Denradaruppställning som användes under testscenariorna var framåtspridande radar. Deresulterande mätningarna signalbehandlades i Matlab. Resultatet visar att det är möjligt att detektera objekt av olika dimensioner och former på olikaavstånd, med hjälp av UWB-radar. Denna metod fungerar även som ett passagelarm, vilkenkan användas inom fler områden. / The steel industries Sandvik, Sandviken and SSAB, Borlänge, produces billets (quadratic,long steel units). Billets travelling through the furnace will heat up. At the end of the furnace,the billets will require precision measurements regarding its position, due to the extractingdevice. Sensors that are used today require an unobstructed view, which is achieved by holesin the furnace walls. Maintenance is needed in order to ensure that no impurities are cloggingthe holes. The goal with this thesis is to investigate whether it is possible to detect rectangular billets byusing an UWB-radar system. The broadband characteristics of an UWB-unit makes it asuitable successor, as free sight is not a requirement. This will decrease downtown due tomaintenance and optimize the time required for billets extraction.This involves economic and environmental aspects as well, due to lower energy consumption. This will be tested by collecting radar measurements for further signal processing. The usedradar system is forward scattering radar. The work started with a theoretical study aboutUWB-technique and basics about radar. Thereafter test scenarios were designed to study howthe radar wave is affected by changing environments. The resulting measurements were latersignal processed in Matlab. This work shows that it is possible to detect billets with various dimensions, using UWBradar.The algorithm can also be used as a passage alarm, which can be used in other areasthan furnaces.

The task of the diploma thesis named VBA and Maple Application on Process Engineering Problems is to show the possibilities of using these programming languages for various engineering tasks. Particularly the programming language Visual Basic for Application (VBA), which is a part of MS Office package, is very little used in practise. That´s why this thesis solves the complex task of a furnaces design process; the topic was reccomended by the supervisor prof. Ing. Josef Kohoutek, CSc. Specifically, the thesis deals with calculations of heat transfer and optimization of the height of extended surfaces of tubes in the convection section of process furnaces. The entire task is elaborated in VBA and runs in Excel. After entering the input information, the created program first calculates the size and heat output of the convection section, but it can also optimize the height of extended surfaces in different parts of the convection section and thus minimize investment costs.