Este trabalho apresenta o desenvolvimento e a implementação computacional de um algoritmo para a localização de faltas em linhas de transmissão. O algoritmo proposto é baseado em métodos heurísticos, isto é, Algoritmos Genéticos (AG) e Pattern Search (PS), sendo capaz de identificar o ponto de ocorrência da falta utilizando fasores de tensão e corrente de pré e pós-falta, estimados a partir de medições disponíveis apenas no terminal local da linha de tranmsissão. Nesta abordagem, ambas as ferramentas de otimização possuem natureza heurísticas sendo menos propensas a cair em valores mínimos locais, o que implica uma maior eficiência e precisão na determinação da localização da falta. Além disso, o método utiliza potências de curto-circuito monofásicas e trifásicas de ambos os terminais da linha (local e remoto), a fim de obter seus equivalentes de Thévenin, e os parâmetros elétricos da linha de transmissão. Com o objetivo de avaliar o desempenho do algoritmo proposto, consideram-se nas simulações quatro sistemas de transmissão diferentes, que representam sistemas reais de transmissão brasileiros. O primeiro está constituído por uma típica linha de transmissão de 138 [kV] com circuito duplo, e os outros três sistemas são constituídos por linhas de transmissão típicas de 230, 500 e 765 [kV] com circuito simples. A partir dos quatro sistemas de transmissão simulados no software Alterative Transients Program (ATP/EMTP), foram gerados um total de 928 situações de falta. A versão do algoritmo desenvolvido para localização de faltas foram descritas e implementadas, através do software científico MATrix LABoratory (MATLAB), apresentando resultados com altos níveis de precisão. / This paper presents the development and implementation of a computational algorithm for location faults in transmission line. The proposed algorithm is based on heuristic methods, namely AG and PS, being able to identify the occurrence of the fault point using phasor voltage and current pre and post-fault, estimated from measurements available only on the local terminal of the transmission line. In this approach, both optimization tools have heuristic nature being less prone to falling into local minimum values, which implies grater efficiency and accuracy in the determination of fault location. Moreover, the method use singles-phase and three-phase short-circuit powers of both the line terminals (Local and remote), to obtain the Thévenin equivalent and the electrical parameters of the transmission line. In order to evaluate the performance of the proposed algorithm were considered four different transmission systems; these systems represent real systems of Brazilian transmission. The first this made up of a transmission line typical of 138 [kV] with double circuit, the other three systems are made up of transmission line typical of 230, 500 and 765 [kV] of single circuit. Whereas the four simulated transmission systems in the softwareATP/ EMTP, generated a total of 928 situations fault. The version of the algorithm designed to locate faults, have been described and implemented through scientific software MATLAB, presenting results high levels of accuracy.

A utilização de energia solar fotovoltaica é amplamente difundida no mundo e possui caráter promissor no Brasil atualmente. Apesar do grande potencial brasileiro, esta fonte de energia ainda apresenta baixos níveis de utilização. A competitividade da geração fotovoltaica de grande porte em usinas solares fotovoltaicas ainda não atingiu patamares admissíveis com taxas de retorno financeiro atrativas ao mercado nacional. Por se tratar de uma fonte de energia renovável, sua utilização no cenário mundial tem apresentado crescimento nos últimos anos. Mesmo em países que apresentam potenciais solares inferiores aos do Brasil, esta fonte de energia tem se mostrado competitiva devido aos incentivos oferecidos. Tendo em vista este prisma, o presente trabalho busca apresentar possibilidades de inserção de usinas solares fotovoltaicas no Estado do Rio Grande do Sul. A usina proposta possui capacidade de geração de 30 MWp. Este estudo visa apresentar uma proposta de diversificar a geração de energia elétrica no estado do Rio Grande do Sul, apresentando uma nova alternativa de geração de energia renovável. Para tal realização, foram estudadas as linhas de transmissão e subestações existentes no estado do Rio Grande do Sul como forma de avaliar a possibilidade de conexão direta da nova usina, tendo como objetivo a redução do custo de instalação. Foi realizado o cálculo da produtividade fotovoltaica para o estado do Rio Grande do Sul e a análise dos custos de instalação desta fonte no Estado, bem como a relação de preço da geração centralizada no estado. / The use of photovoltaic solar energy is widespread in the world and has promising character in Brazil today. Despite the large Brazilian potential, this energy source still shows low levels of utilization. The competitiveness of photovoltaic generation in large solar photovoltaic power plants has not yet reached acceptable levels with attractive rates of financial return to the national market. Because it is a renewable source of energy, its use in the world has been increasing in recent years. Even in countries that have lower solar potential than Brazil, this source of energy has been competitive due to the incentives offered. Given this perspective, this paper seeks to show the possibilities for integration of photovoltaic solar plants in the state of Rio Grande do Sul. The proposed plant has a generation capacity of 30 MWp . This study aims to present a proposal to diversify the electricity generation in the state of Rio Grande do Sul, presenting a new alternative source of renewable energy . For this achievement, the existing transmission lines and substations were studied in the state of Rio Grande do Sul as a way to evaluate the possibility of direct connection of the new plant, with the objective of reducing the cost of installation. The calculation of photovoltaic productivity for the state of Rio Grande do Sul and cost analysis of installing this source was held as well the price ratio of centralized generation.

Na sociedade atual as estruturas de linhas de transmissão são consideradas componentes essenciais do sistema de infraestrutura urbana. Sua função é a de transmitir a eletricidade gerada nas fontes de produção até o consumidor através de uma rede de distribuição. Este tipo de estruturas por sua extensão, exposição e variações topográficas, se mostram vulneráveis ao carregamento dinâmico de ventos originados a partir tormentas elétricas, tais como downbursts e tornados. No Brasil tem-se observado nos últimos tempos um aumento de acidentes neste tipo de estrutura, principalmente devido à incidência de fortes ventos. No presente trabalho estuda-se o comportamento dinâmico de um trecho de linha de transmissão da empresa Eletrobrás FURNAS quando submetido à ação de ventos provenientes de downburst. Na pesquisa foram identificados os principais modelos analíticos disponíveis na literatura que oferecem o campo de velocidades horizontais e verticais médias e a componente flutuante. Com base e alguns dos modelos identificados na revisão bibliográfica, implementou-se um programa computacional capaz de simular todas as componentes do campo de velocidades de um downburst em movimento. A partir do programa implementado foi realizado um estudo paramétrico onde identificou-se a combinação de variáveis do evento que provoca a maior energia cinética armazenada. Finalmente é apresentada uma revisão estrutural dos montantes da torre central da linha modelada, através da análise da relação demanda/capacidade na altura da coluna. Dos resultados obtidos, pode-se concluir que a combinação de variáveis que provoca os resultados de forças internas mais críticos varia em relação a cada componente da linha considerado. O estudo de sensibilidade das variáveis envolvidas nos modelos implementados revelou que existe um incremento monotônico crescente da energia cinética armazenada com o aumento dos parâmetros e para a maioria dos casos, exceto quando =500 . Da flutuação e sua influência no comportamento dinâmico na linha analisada, conclui-se que a consideração das flutuações na resposta dinâmica dos cabos condutores e para-raios pode ser desprezada, fato que foi comprovado através dos valores obtidos na inclinação das linhas de tendência realizadas. / Transmission Lines (TL) are considered one of the essential components of the urban infrastructure. Their role is to transmit electricity from sources of production to the distribution system and then to consumers. This type of structure for its length, exposure and topographical variations, show themselves vulnerable to dynamic loading winds originated from electrical storms such as tornadoes and downbursts. In Brazil, it has been observed recently, an increase in the accidents of this type of structure, primarily due to incidence of strong winds. In the present research, is analyzed the dynamic behavior of a transmission line system of Eletrobras Furnas Company when subjected to downburst. In the investigation, the main analytical models available in the literature that offer the wind field of horizontal and vertical speeds and the fluctuating component were identified. Based on some of the models identified in the literature review, was implemented a computer program capable of simulating all components of the velocity of a moving downburst. Based on the implemented program was conducted a parametric study in order to identify the combination of variables that causes the greatest kinetic stored energy. Finally is presented a structural review of the columns of the central tower of the system, by examining the demand/capacity relationship. Regarding to the parametric study, it was found that the combination of variables which causes the most critical internal forces varies for each component of the line considered. The sensibility study of the variables involved the models used in this study revealed that there is a growing monotonic increase in the stored energy with the accretion of and 1.parameters for most of the cases, except when 0=500 . Analyses conducted using the fluctuations in the mean wind field reveal that the resonant response of the conductor and ground wire cables can be neglected, a fact that was confirmed by the values obtained from the slope of the trend lines held.

Orientador: Sérgio Kurokawa / Banca: Luiz Fernando Bovolato / Banca: Afonso José do Prado / Resumo: Esta dissertação descreve um processo alternativo para decompor uma linha de transmissão trifásica, simétrica e não transposta nos seus modos exatos por meio da utilização de duas matrizes de transformação. A primeira é a matriz de Clarke que desacopla a linha em suas componentes a, ß e zero. A componente ß é um modo exato enquanto que as componentes a e zero são acopladas. Em seguida, as componentes a e zero são representadas por uma linha bifásica que pode ser decomposta em seus modos exatos por meio de uma matriz de transformação adequada, cujos elementos podem ser sintetizados, no domínio do tempo, por técnicas de aproximações por curvas. O método pretende unir as vantagens da matriz de transformação exata (que produz modos exatos) com as vantagens da matriz de Clarke, que é real, independente da freqüência e facilmente representável em programas que realizam simulações de transitórios, como é o caso do EMTP. Assim, o método pode ser utilizado em situações em que o acoplamento entre as componentes a e zero não possa ser desconsiderado. O processo foi utilizado para simular a energização de uma linha trifásica, sem transposição, com um plano de simetria vertical, 440 kV e comprimento de 500 km que foi representada no domínio modal por meio do método proposto e também por meio do uso da matriz de autovetores (como sendo a matriz de decomposição modal). O método é coerente, pois foram obtidos resultados semelhantes com os dois métodos de decomposição modal, enquanto que com o uso somente da matriz de Clarke, verificou- se certa diferença em relação aos valores esperados. / Abstract: This dissertation describes an alternative procedure to decompose a non-transposed threephase transmission line into exact modes, by using two transformation matrices. The first one is Clarke's matrix, which separates the line into quasi-modes a, ß e zero. The ß component is an exact mode while a and zero are coupled. After that, the coupled components are represented by using a two-phase transmission line without a vertical symmetry plane that can be decomposed with a modal transformation matrix whose elements can be achieved, in timedomain, through standard curve-fitting techniques. The method intends to join the Clarke's matrix advantages which crucial aspect is being real, frequency-independent and easily represented in computational transient programs (EMTP) with eigenvector's matrix used in situations where the coupling between a and zero components cannot be disconsidered. The process was used to energize a three-phase transmission line with a vertical symmetry plane, which nominal voltage is 440kV and its length, 500km. It was represented in the modal domain by considered method and, on the other hand, by using eigenvector's matrix (as being the decomposition matrix). In fact, the obtained results had shown that the method is coherent, because it is obtained similar results with the application of the two mentioned modal decomposition methods, whereas with the use of Clarke's matrix, a perceptible difference in relation to the expected values was verified. / Mestre

abstract: Switching surges are a common type of phenomenon that occur on any sort of power system network. These are more pronounced on long transmission lines and in high voltage substations. The problem with switching surges is encountered when a lot of power is transmitted across a transmission line/network, typically from a concentrated generation node to a concentrated load. The problem becomes significantly worse when the transmission line is long and when the voltage levels are high, typically above 400 kV. These overvoltage transients occur following any type of switching action such as breaker operation, fault occurrence/clearance and energization, and they pose a very real danger to weakly interconnected systems. At EHV levels, the insulation coordination of such lines is mainly dictated by the peak level of switching surges, the most dangerous of which include three phase line energization and single-phase reclosing. Switching surges can depend on a number of independent and inter-dependent factors like voltage level, line length, tower construction, location along the line, and presence of other equipment like shunt/series reactors and capacitors. This project discusses the approaches taken and methods applied to observe and tackle the problems associated with switching surges on a long transmission line. A detailed discussion pertaining to different aspects of switching surges and their effects is presented with results from various studies published in IEEE journals and conference papers. Then a series of simulations are presented to determine an arrangement of substation equipment with respect to incoming transmission lines; that correspond to the lowest surge levels at that substation. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2018

Este trabalho apresenta o desenvolvimento e a implementação computacional de um algoritmo para a localização de faltas em linhas de transmissão. O algoritmo proposto é baseado em métodos heurísticos, isto é, Algoritmos Genéticos (AG) e Pattern Search (PS), sendo capaz de identificar o ponto de ocorrência da falta utilizando fasores de tensão e corrente de pré e pós-falta, estimados a partir de medições disponíveis apenas no terminal local da linha de tranmsissão. Nesta abordagem, ambas as ferramentas de otimização possuem natureza heurísticas sendo menos propensas a cair em valores mínimos locais, o que implica uma maior eficiência e precisão na determinação da localização da falta. Além disso, o método utiliza potências de curto-circuito monofásicas e trifásicas de ambos os terminais da linha (local e remoto), a fim de obter seus equivalentes de Thévenin, e os parâmetros elétricos da linha de transmissão. Com o objetivo de avaliar o desempenho do algoritmo proposto, consideram-se nas simulações quatro sistemas de transmissão diferentes, que representam sistemas reais de transmissão brasileiros. O primeiro está constituído por uma típica linha de transmissão de 138 [kV] com circuito duplo, e os outros três sistemas são constituídos por linhas de transmissão típicas de 230, 500 e 765 [kV] com circuito simples. A partir dos quatro sistemas de transmissão simulados no software Alterative Transients Program (ATP/EMTP), foram gerados um total de 928 situações de falta. A versão do algoritmo desenvolvido para localização de faltas foram descritas e implementadas, através do software científico MATrix LABoratory (MATLAB), apresentando resultados com altos níveis de precisão. / This paper presents the development and implementation of a computational algorithm for location faults in transmission line. The proposed algorithm is based on heuristic methods, namely AG and PS, being able to identify the occurrence of the fault point using phasor voltage and current pre and post-fault, estimated from measurements available only on the local terminal of the transmission line. In this approach, both optimization tools have heuristic nature being less prone to falling into local minimum values, which implies grater efficiency and accuracy in the determination of fault location. Moreover, the method use singles-phase and three-phase short-circuit powers of both the line terminals (Local and remote), to obtain the Thévenin equivalent and the electrical parameters of the transmission line. In order to evaluate the performance of the proposed algorithm were considered four different transmission systems; these systems represent real systems of Brazilian transmission. The first this made up of a transmission line typical of 138 [kV] with double circuit, the other three systems are made up of transmission line typical of 230, 500 and 765 [kV] of single circuit. Whereas the four simulated transmission systems in the softwareATP/ EMTP, generated a total of 928 situations fault. The version of the algorithm designed to locate faults, have been described and implemented through scientific software MATLAB, presenting results high levels of accuracy.

Thin-film solar cells are widely recognised to have the potential to compete with fossil fuels in the electricity market due to their low cost per peak Watt. The Thin-Film Group at the University of New South Wales (UNSW) is engaged in developing polycrystalline silicon (poly-Si) thin-film solar cells on glass using e-beam evaporation technology. We believe our solar cells have the potential of significantly lowering the manufacturing cost compared to conventional, PECVD-fabricated thin-film solar cells. After years of materials research, the focus of the Group??s work is now moving to the metallisation of evaporated solar cells. Minimising various kinds of losses is the main challenge of the cell metallisation procedure, within which the contact resistance is always a big issue. In this thesis, the contact resistance of aluminium contacts on poly-Si thin-film solar cells on glass is investigated. To the best of the author??s knowledge, this is the first ever contact resistance investigation of Al contacts on evaporated poly-Si material for photovoltaic applications. Various transmission line models (TLM) are employed to measure the contact resistance. An improved TLM model is developed to increase the measurement precision and, simultaneously, to simplify the TLM pattern fabrication process. In order to accommodate the particular requirements of poly-Si coated glass substrates, a TLM pattern fabrication process using photolithography is established. Furthermore, a Kelvin sense tester is set up to ensure an accurate measurement of the contact resistance. After establishment of the TLM technique at UNSW, it is successfully tested on singlecrystalline silicon wafer samples. The thermal annealing process of the contacts is also optimised. Then, the general behaviour of Al contacts on uniformly doped poly-Si films (i.e., no p-n junction) is investigated using the verified TLM technique. The long-term stability of the contacts is also studied. This is followed by an investigation of the contact resistance of the back surface field and emitter layers of different types of poly-Si thin-film solar cells. Finally, a novel contact resistance measurement model is proposed that is believed to be able to overcome the measurement bottleneck of the transmission line models.

<p>This report is the result of a Master Thesis work that has been performed between October 2003 and March 2004. The purpose of the work was to evaluate a part of the signal chain in a product of Micronic Laser Systems AB. The evaluation was performed to obtain the characterisation for the signal chain, such as impedances and crosstalk. </p><p>The work started with a literature study in order to refresh and increase the knowledge that was needed before the practical work. Then measurements, computer aided simulations and comparisons between these were performed. </p><p>Measurements were performed using TDR (Time Domain Reflectometry). The results showed the impedance levels along the signal chain. This was interesting since it showed how well the different parts in the system are matched. Unmatched parts result in reflections that disturb the transmitted signal and contribute to crosstalk, which also was measured. </p><p>Simulations were done using ADS (Advance Design System), a tool from Agilent Technologies Inc. A substantial part of the simulation work was to build models of the real system. These models have been used for simulation. The simulation results were then compared to the measurement results. </p><p>The results show that the system can be better matched concerning the channel impedance. There are large variations in impedance levels along the signal chain, resulting in signal reflections. Another effect studied is crosstalk between channels. Measurements and simulations showed the presence of crosstalk but it seems to be a minor problem in the current machine.</p>

This report is the result of a Master Thesis work that has been performed between October 2003 and March 2004. The purpose of the work was to evaluate a part of the signal chain in a product of Micronic Laser Systems AB. The evaluation was performed to obtain the characterisation for the signal chain, such as impedances and crosstalk. The work started with a literature study in order to refresh and increase the knowledge that was needed before the practical work. Then measurements, computer aided simulations and comparisons between these were performed. Measurements were performed using TDR (Time Domain Reflectometry). The results showed the impedance levels along the signal chain. This was interesting since it showed how well the different parts in the system are matched. Unmatched parts result in reflections that disturb the transmitted signal and contribute to crosstalk, which also was measured. Simulations were done using ADS (Advance Design System), a tool from Agilent Technologies Inc. A substantial part of the simulation work was to build models of the real system. These models have been used for simulation. The simulation results were then compared to the measurement results. The results show that the system can be better matched concerning the channel impedance. There are large variations in impedance levels along the signal chain, resulting in signal reflections. Another effect studied is crosstalk between channels. Measurements and simulations showed the presence of crosstalk but it seems to be a minor problem in the current machine.

In recent years, passive radio frequency (RF) tags that communicate using modulated backscatter radiation have shown great potential for use in inventory management, parcel and postal tracking, for use as remote sensors, and in a host of other Radio Frequency Identification (RFID) applications. However, for the widespread use of these tags to become reality, much basic research is needed to reduce the cost, increase the range, and increase the reliability of the RF tag. This research seeks to enhance the performance of passive RF tags by developing a series of tests, or radio assay, to measure the following: the performance of RF tag antennas as a function of antenna material and manufacturing technique and the antenna performance when attached to various materials. The radio assay experiments are designed for RF tag antennas that operate in the far field of the tag reader and communicate using modulated backscatter radiation at 915 MHz. Three flexible, folded dipoles, printed on plastic substrates, were measured in the radio assay experiments. The results of the experiments include the following: the antenna gain penalty (relative to a baseline antenna) for each antenna material and manufacturing technique, the antenna gain penalty (relative to the free space antenna gain) due to material losses when the tag antenna is attached to an object, and the benefits (in terms of antenna gain) of tuning each tag antenna to the material to which it is attached. The results are presented in a form to aid RF engineers in the design of RF tag system link budgets.