Thesis: Elec. E., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 1980 / Bibliography: leaf 96. / by Jeffrey Clay McHarg. / Elec. E. / Elec. E. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006. / This thesis relates to the design and characterization of a 10 kW L-band power combiner consisting of 8 input ports. The design is implemented in a non-radial planar transmission line architecture and operates between 1.2 and 1.4 GHz. Because of the ultra high power requirements for the combiner, special attention is given to the power handling capabilities of the transmission lines and the other components involved. Simulated S-parameter models of connector to stripline transitions and a one to four-way junction, as well as measured S-parameter models of high power terminations are incorporated in the final design. A 10 kW combiner was built and measured at low power only due to time constraints and the limited availability of high power sources. Satisfactory results were obtained in terms of the graceful degradation of unit amplifiers, port mismatches and power combining efficiency.

Multi band technology helps in getting multiple operating frequencies using a single microwave device. This thesis presents the design of dual and tri band microwave devices using coupled transmission line structures. Chapter 2 presents the design of a novel dual band transmission line structure using coupled lines. In chapter 3, Design of a dual band branch line coupler and a dual band Wilkinson power divider are proposed using the novel dual band transmission line structure presented in the previous chapter. In chapter 4, Design of a tri band transmission line structure by extending the dual band structure is presented. The Conclusion and future work are presented in chapter 5.

Thesis (D. Tech. Electrical engineering) --Vaal University of Technology / A comprehensive study upon "Non-conventional methods for energy extraction from the high voltage transmission lines" was addressed in this thesis. As defined in this study, a non-conventional method to extract energy is one that does not touch the conductors of the line. The theoretical framework which originated in the Maxwell's equations was presented as a base for discussion of all the methods and the conditions for the extraction to be possible. This study presents various methods such as capacitive and inductive to extract energy from high voltage alternating current transmission lines (HVAC). Although in theory, for high voltage direct current transmission lines (HVDC), the conditions for extraction are not matched, there remain some methods that could still attract interest. The centre point of this thesis is the new power application of the Rogowski coil. This method is analysed in full extent starting from theoretical modelling, computer simulations, design of the actual Rogowski coil and power electronics associated with it, and experimental results on a reduced scale model. In doing this, strong mathematical tools and computer software such as Matlab 6, Quick Field and MathCAD were used. At the end of this thesis, some conclusions are presented together with new ideas for further research in the field.

Localizadores de faltas são dispositivos designados para determinar a localização do ponto de incidência de faltas em linhas de transmissão dos sistemas elétricos de potência. Esta localização possibilita uma restauração mais rápida da operação de um sistema elétrico, contribuindo assim para um alto grau de continuidade no fornecimento de energia. Este trabalho apresenta um estudo comparativo entre duas abordagens distintas para localização digital de faltas. Os métodos se distinguem quanto à natureza dos dados de entrada. Um dos métodos utiliza dados disponíveis apenas em um único terminal, enquanto que o outro, utiliza dados provenientes dos dois terminais da linha de transmissão. As teorias fundamentais de ambas as técnicas são estudadas e simulações computacionais das mesmas são extensivamente testadas utilizando-se dados provenientes de uma simulação das linhas de transmissão sob falta. / Fault locators are devices designed to pinpoint the location of the fault on transmission lines of electric power systems. This location allows a fast restoration of the power system operation, contributing to a high level of continuity on power delivery. This work shows a comparative study between two digital fault locator approaches. The methods differ on the nature of input data. One of the methods uses data available from only one end, while the other uses data from the both ends of the transmission line. The fundamental theories of the two techniques will be studied, and computacional simulations are extensively tested with data obtained from simulation of faulted transmission lines.

Este trabalho tem por objetivo apresentar o desenvolvimento e a implementacao em uma rotina computacional, de algoritmos para a localizacao de faltas em linhas de transmissao com subestacoes conectadas em derivacao. Os algoritmos propostos neste trabalho integram uma metodologia para localizacao de faltas, que e capaz de identificar corretamente o ponto de ocorrencia do defeito utilizando as componentes de fase dos fasores de tensoes e correntes, calculadas atraves dos registros desses sinais, efetuados por oscilografos digitais e/ou reles de protecao instalados nos terminais da linha de transmissao. Alem disso, a metodologia para localizacao de faltas tem acesso aos parametros eletricos da linha e informacoes sobre o tipo de ligacao e o carregamento dos transformadores conectados aos terminais das derivacoes. Este trabalho apresenta tambem o desenvolvimento dos modelos para os elementos do sistema de transmissao, em componentes de fase. Estes modelos sao utilizados pelos algoritmos que integram a metodologia para localizacao de faltas. / This research presents the development and implementation in a computational routine, of algorithms for fault location in multi-terminal transmission lines. The algorithms proposed in this work are part of a fault location methodology, which is capable of correctly identifying the fault point based on voltage and current phase components. The voltage and current phasors are calculated using measurements of voltage and current signals from intelligent electronic devices, located on the transmission line terminals. The algorithms have access to the electrical parameters of the transmission lines and to information about the transformers loading and their connection type. This work also presents the development of phase component models for the transmission system elements used by the fault location algorithms, that are part of the fault location methodology.

Estruturas alteadas são fortemente afetadas pelas ações naturais, que são por sinal, as ações de maior complexidade na engenharia estrutural em função do grande número de variáveis envolvidas. O vento é uma destas ações e também uma das mais importantes em condições gerais. Em projeto, a ação do vento é normalmente considerada através das indicações normativas de cada país, que são, em função de sua complexidade, descritas na forma de métodos estático equivalentes, suficientes para maioria dos casos. Este critério não difere ao se tratar de linhas de transmissão, no entanto, grande parte das normas do mundo basearam-se no comportamento das torres autoportantes, mas que vêm sendo igualmente utilizadas em projetos de torres estaiadas. Por este motivo, se propõe a análise estatística de esforços de uma torre estaiada, modelada em conjunto com os demais componentes de uma linha de transmissão, de modo a compará-los aos resultados obtidos pelo método estático equivalente da IEC 60826 (IEC 2003). A hipótese de carregamento estudada é a ação transversal do vento na linha. Na simulação numérica, diversos campos aleatórios de velocidades são gerados, sendo as ações também calculadas pela formulação da norma IEC 60826. Os campos foram gerados por dois diferentes métodos, o método de Deodatis (1996) e método de Riera e Ambrosini (1992), ambos baseados no método de superposição de ondas. O espectro de velocidades utilizado neste trabalho é o espectro de Davenport. Apesar de saber da importância de outras fontes de não linearidades, foram consideradas neste trabalho: a não linearidade geométrica dos componentes, computada automaticamente com o uso do método de integração explícito por diferenças finitas centrais, e a não linearidade física dos cabos suspensos. Diferentes parâmetros de amortecimento foram testados para os componentes estruturais. Nos resultados é possível observar que a IEC 60826 mostrou-se suficiente na estimativa de esforços da maioria dos elementos analisados, no entanto, nas barras pertencentes ao mastro da torre verificaram-se valores normativos inferiores aos calculados pelo método numérico. Nestas barras, a diferença chegou a aproximadamente 22% pelo método de Deodatis (1996) e a 12% pelo método de Riera e Ambrosini (1992), ambos na configuração de menor amortecimento testada e para o intervalo de confiança de 98%. / High structures are strongly affected by natural loads, which are the most complexity loads in the structural engineering due the large number of variables involved. The wind is one of these actions and one of the most important in general conditions. In design, the action of wind is normally accounted through the country‟s standards indications which, due to its complexity, are usually descripted by equivalent static methods, enough in the most cases. This criterion does not differ for transmission lines, however, the most of standards in the world were based on the self-support towers behavior, but they are also being used for guyed towers design. Therefore, in this study is proposed a statistic analysis of internal forces in the guyed tower elements, modeled together with the other transmission lines components, in order to compare them with the results obtained by equivalent static method of IEC 60826 (IEC 2003). The load hypothesis is the across wind action. In the numerical simulation, several random velocity fields were generated, the actions being calculated by the formulation of IEC 60826 standard. The fields were generated by two different methods, the method of Deodatis (1996) and the method of Riera and Ambrosini (1992), both of them are based in the wave superimposition method. The power wind spectrum (PSD) used in this work is the Davenport‟s spectrum. Although knowing the importance of other nonlinearities, were considered in this work: the geometric non-linearity of all elements, which are automatically computed by explicitly integration method by central finite differences used, and the physic non-linearity of suspended cables. Different damping rates were considered for the structural components. In the results, it is possible to observe that the IEC 60826 was enough in the estimation of internal forces on the majority of elements analyzed, however, on the tower mast bars were verified normative values smaller than those obtained by numerical method. In these bars, the difference among analyses reached 22% by Deodatis (1996) method and 12% by Riera e Ambrosini (1992) method, both of them considering the lower tested damping configuration and the 98% confidence interval.

Este trabalho apresenta o desenvolvimento de algoritmos para determinação da estimativa da distância de ocorrência de falta em uma linha de transmissão de alta tensão, em relação a um terminal local, e também a classificação do tipo de falta, utilizando técnicas baseadas em redes neurais artificiais. Os testes e a validação dos algoritmos propostos são feitos a partir de dados simulados para os fasores de tensão e corrente, em regime permanente, com uso da linguagem MATLAB. Os fasores são obtidos com uso de cálculo tradicional de curto e parâmetros reais de uma linha de transmissão conhecida. Em casos reais os fasores seriam obtidos de amostras de tensões e correntes detectadas por dispositivos de proteção localizados nos terminais local e remoto da linha de transmissão em análise. As simulações das redes neurais para a classificação do tipo de falta e para a obtenção da estimativa da distância de falta foram feitas com duas rotinas escritas em MATLAB levando em consideração erros de medição dos fasores. Os resultados obtidos permitem avaliar a eficiência e a precisão dos algoritmos propostos em relação aos já existentes e conhecidos na literatura, e que usam somente equacionamento elétrico. / This work presents the development of algorithms for determination of the estimate of the distance of occurrence of fault in a high voltage transmission line, in relation to a local terminal, and also the classification of the fault type, using techniques based on artificial neural networks. The tests and the validation of the proposed algorithms are made using simulated data for the voltage and current phasors, in steady state, with use of the MATLAB language. The phasors are obtained with use of traditional calculation of short-circuit and real parameters of a known transmission line. In real cases the phasors would be obtained with samples of voltages and currents detected by protection devices located in the local and remote terminals of the transmission line in analysis. The simulations of the neural networks for the classification of the fault type and for the obtaining the estimate of the fault distance were done with two routines written in MATLAB taking into account measurement errors of the phasors. The obtained results allow to evaluate the efficiency and the accuracy of the proposed algorithms in relation to the already existent and known in the literature, and that use only electric equations.

There is a general consensus worldwide for a need to increase the capacities of transmission lines by not physically altering the transmission structures. Amidst this challenge, dynamic thermal rating (DTR) system appears as an appropriate option. Besides that, many countries have also pledged to integrate wind energy sources into their power networks. Taking these as motivations, the purpose of this thesis is to carry out the reliability analysis of DTR system for transmission lines. The two main standards - IEEE 738 and CIGRE, use for calculating the line rating of overhead lines has been analysed and compared. It was demonstrated that the two standards yield insignificant differences in their calculated line ratings. A new methodology that can systematically assess the reliability and risk of any DTR system designs was proposed in this thesis. In the reliability assessment part, methods such as the event tree analysis (ETA), risk reduction worth (RRW) and wide range method (WRM) were used. The risks of DTR systems were evaluated by implementing them in the IEEE 24-bus reliability test network (RTN). The network's loss of load and the percentages of the conductor loss of tensile strength constitute the risks of DTR systems. In the risk assessment part, a multiple-linear regression (MLR) model was proposed to estimate missing weather values during the failure of DTR sensors. Results in this thesis show that the MLR model is accurate and has only estimation error of less than 6%. It avoids overestimating the risk of DTR systems. An optimum DTR system design was also selected. The strategic placement of DTR sensors along a transmission line is an important reliability issue too. Hence, a new DTR sensor placement algorithm that considers the effects of DTR system ratings on the amount of line sagging, conductor annealing and the correlation between DTR system ratings and actual line ratings was proposed. Results in this thesis show that the newly proposed algorithm outperforms the currently published algorithm in terms of causing no spans to sag beyond their ground clearance limits and all spans experience lesser annealing effects. The 2-dimensional movement of line spans in their longitude and latitude directions, which the currently published algorithm also lacks, are considered in the proposed algorithm. This thesis also investigates the reliability behaviours of a power network that has DTR systems and wind farms. The proposed methodology for achieving that considers the reliability of transmission lines, DTR systems, conventional generators and wind turbines. The chronological behaviour of DTR ratings and wind farm power outputs was modelled using the auto-regressive and moving-average (ARMA) model. The correlations between the ARMA models were also considered. Results in this thesis show that by considering the correlation effects, the network's reliability indices are not over and under estimated. A new reliability index for describing the amount of wind power integration named as Expected Wind Power Delivered (EWPD) was proposed as well.

Este trabalho apresenta o desenvolvimento de algoritmos para determinação da estimativa da distância de ocorrência de falta em uma linha de transmissão de alta tensão, em relação a um terminal local, e também a classificação do tipo de falta, utilizando técnicas baseadas em redes neurais artificiais. Os testes e a validação dos algoritmos propostos são feitos a partir de dados simulados para os fasores de tensão e corrente, em regime permanente, com uso da linguagem MATLAB. Os fasores são obtidos com uso de cálculo tradicional de curto e parâmetros reais de uma linha de transmissão conhecida. Em casos reais os fasores seriam obtidos de amostras de tensões e correntes detectadas por dispositivos de proteção localizados nos terminais local e remoto da linha de transmissão em análise. As simulações das redes neurais para a classificação do tipo de falta e para a obtenção da estimativa da distância de falta foram feitas com duas rotinas escritas em MATLAB levando em consideração erros de medição dos fasores. Os resultados obtidos permitem avaliar a eficiência e a precisão dos algoritmos propostos em relação aos já existentes e conhecidos na literatura, e que usam somente equacionamento elétrico. / This work presents the development of algorithms for determination of the estimate of the distance of occurrence of fault in a high voltage transmission line, in relation to a local terminal, and also the classification of the fault type, using techniques based on artificial neural networks. The tests and the validation of the proposed algorithms are made using simulated data for the voltage and current phasors, in steady state, with use of the MATLAB language. The phasors are obtained with use of traditional calculation of short-circuit and real parameters of a known transmission line. In real cases the phasors would be obtained with samples of voltages and currents detected by protection devices located in the local and remote terminals of the transmission line in analysis. The simulations of the neural networks for the classification of the fault type and for the obtaining the estimate of the fault distance were done with two routines written in MATLAB taking into account measurement errors of the phasors. The obtained results allow to evaluate the efficiency and the accuracy of the proposed algorithms in relation to the already existent and known in the literature, and that use only electric equations.