Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Begovic, Miroslav; Committee Member: Divan, Deepakraj; Committee Member: Dorsey, John; Committee Member: Ferri, Bonnie; Committee Member: Lambert, Frank.

Thesis (Ph. D.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references (p. 131-136). Also available via the World Wide Web.

No description available.

No description available.

Made available in DSpace on 2014-06-11T19:22:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-10-05Bitstream added on 2014-06-13T19:48:54Z : No. of bitstreams: 1 lima_aa_me_ilha.pdf: 1365201 bytes, checksum: 5bed2a52c8671bde5572016fadf55dc7 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O Problema de Planejamento da Expansão do Sistemas de Transmissão de Energia Elétrica tem por objetivo escolher, entre um conjunto predefinido de circuitos candidatos, aqueles que devem ser incorporados ao sistema de forma a minimizar os custos de investimento e operação e atender a demanda de energia futura ao longo de um horizonte de planejamento com confiabilidade, assumindo como conhecido o plano de geração. É considerado um problema muito complexo e difícil de resolver por se tratar de um problema não linear inteiro misto, não convexo, multimodal e altamente combinatório. Este problema tem sido resolvido usando técnicas clássicas como Decomposição de Benders e Branch and Bound, assim como também algoritmos heurísticos e metaheurísticas obtendo diversos resultados, porém com uma série de problemas, por exemplo, alto tempo de processamento pelos computadores e problemas de convergência. Neste trabalho se apresenta a metaheurística Busca Dispersa que é um método que combina sistematicamente conjuntos de soluções para se obter soluções melhores. O algoritmo é apresentado sistematicamente, explicando sua estrutura básica e a forma como é adaptado para resolver o problema do planejamento da expansão de sistemas de transmissão, considerando a modelagem matemática conhecida como modelo de transporte e o modelo DC. São realizados testes com o sistema Garver de 6 barras, o sistema IEEE de 24 barras e o Sul Brasileiro de 46 barras e os resultados obtidos são comparados com os obtidos com outras metaheurísticas, mostrando um bom desempenho tanto em velocidade de processamento como em esforço computacional / In the Transmission Expansion Planning problem of power systems a predefined set of candidate circuits are selected, in order to minimize investment and operation costs and meet the future energy demand over a planning horizon while reliability is considered and the generations plans are known. It is considered a very complex problem and difficult to solve because it is a mixed integer nonlinear problem, not convex, multimodal and highly combinatorial. This problem has been solved using classical techniques such as Benders Decomposition and Branch and Bound, as well as heuristic and metaheuristics algorithms achieving different results, but with some difficulties, such as high demand for processing by computers and convergence problems. This paper presents the scatter search metaheuristic which is a method that combines systematically sets of solutions to obtain better solutions. The algorithm is presented systematically, explaining its basic structure and how it is adapted to solve the Transmission Expansion Planning problem, considering the mathematical model known as transportation model and DC model. Tests are performed with Garver 6 bus system, IEEE 24 bus system and the South Brazilian 46 bus system, and the results obtained are compared with those obtained with other metaheuristics, showing a good performance both in processing speed as in computational effort

Orientador: Rubén Augusto Romero Lázaro / Banca: José Roberto Sanches Mantovani / Banca: Carlos Roberto Mendonça Rocha / Resumo: O Problema de Planejamento da Expansão do Sistemas de Transmissão de Energia Elétrica tem por objetivo escolher, entre um conjunto predefinido de circuitos candidatos, aqueles que devem ser incorporados ao sistema de forma a minimizar os custos de investimento e operação e atender a demanda de energia futura ao longo de um horizonte de planejamento com confiabilidade, assumindo como conhecido o plano de geração. É considerado um problema muito complexo e difícil de resolver por se tratar de um problema não linear inteiro misto, não convexo, multimodal e altamente combinatório. Este problema tem sido resolvido usando técnicas clássicas como Decomposição de Benders e Branch and Bound, assim como também algoritmos heurísticos e metaheurísticas obtendo diversos resultados, porém com uma série de problemas, por exemplo, alto tempo de processamento pelos computadores e problemas de convergência. Neste trabalho se apresenta a metaheurística Busca Dispersa que é um método que combina sistematicamente conjuntos de soluções para se obter soluções melhores. O algoritmo é apresentado sistematicamente, explicando sua estrutura básica e a forma como é adaptado para resolver o problema do planejamento da expansão de sistemas de transmissão, considerando a modelagem matemática conhecida como modelo de transporte e o modelo DC. São realizados testes com o sistema Garver de 6 barras, o sistema IEEE de 24 barras e o Sul Brasileiro de 46 barras e os resultados obtidos são comparados com os obtidos com outras metaheurísticas, mostrando um bom desempenho tanto em velocidade de processamento como em esforço computacional / Abstract: In the Transmission Expansion Planning problem of power systems a predefined set of candidate circuits are selected, in order to minimize investment and operation costs and meet the future energy demand over a planning horizon while reliability is considered and the generations plans are known. It is considered a very complex problem and difficult to solve because it is a mixed integer nonlinear problem, not convex, multimodal and highly combinatorial. This problem has been solved using classical techniques such as Benders Decomposition and Branch and Bound, as well as heuristic and metaheuristics algorithms achieving different results, but with some difficulties, such as high demand for processing by computers and convergence problems. This paper presents the scatter search metaheuristic which is a method that combines systematically sets of solutions to obtain better solutions. The algorithm is presented systematically, explaining its basic structure and how it is adapted to solve the Transmission Expansion Planning problem, considering the mathematical model known as transportation model and DC model. Tests are performed with Garver 6 bus system, IEEE 24 bus system and the South Brazilian 46 bus system, and the results obtained are compared with those obtained with other metaheuristics, showing a good performance both in processing speed as in computational effort / Mestre

The main objective of this study is to develop a methodology to assist in the reconfiguration and expansion of an electrical sub-transmission network within the framework of Value-based planning. This methodology applies to typical municipal networks found in South Africa. A literature study indicates that most of the fundamental concepts for power system reliability is well established with extensive research done in North America, and other parts of the world. Reliability worth assessment of sub-transmission networks in South Africa, which include composite networks and substation reliability, is however not well developed. From a Value-¬based point of view the literature further does not provide much linkage to the evaluation of alternative long-term network options. This is especially true in terms of the life cycle cost assessment of network alternatives, which include the prediction of customer damages as a function of network performance. In this dissertation a methodology is proposed which utilises the basic network reliability concepts to assess the performance of existing and future alternative network options. The load point Expected Unserved Energy is used to quantify network performance and is obtained through a contingency enumeration process. An existing Geographical Load Forecasting technique defines all customers connected to a load point, on a homogeneous level. This information along with Sector Customer Damage Functions is used to predict existing and future Composite Customer Damage Functions at the associated load point in the sub-transmission network. To arrive at the total minimum cost, which is the objective of Value-based planning, the present worth for each alternative is obtained from the annual utility and customer cost over the life cycle of the alternative. The alternative that result in the lowest present worth is identified as the preferred alternative. A case study is conducted on the sub-transmission network of the Greater Pretoria Metropolitan Council (GPMC) in order to prove the methodology. The entire network is analysed in order to identify the sub-system with the worst performance from a reliability point of view. Alternative network options are identified and the methodology is used for the evaluation of these alternatives. The application of this methodology provides the network planner with the ability to make better decisions with regard to the allocation of reliability. Through the calculation of reliability indices, tangible guidelines can be provided to quantitatively assess the impact of different network alternatives. These guidelines assess contingency probabilities explicitly and along with reliability worth evaluation provide a fundamental tool to conduct Value-based planning. The application of this methodology can lead to significant savings in capital investment while maintaining an acceptable level of reliability. / Dissertation (M Eng (Electrical Engineering))--University of Pretoria, 2006. / Electrical, Electronic and Computer Engineering / unrestricted

This research is aimed at analyzing the performance of the restricted earth fault relay used on a 400kV capacitor bank scheme used on the Eskom Transmission network. After the commissioning of two Capacitor Banks using the above mentioned scheme design the plant was energized. As a result of the energization the Shunt Capacitor Bank (SCB) then experienced spurious trips. The cause of the trips was found to be the operation of the restricted earth fault relay. In this research project, restricted earth fault protection on SCBs in the Eskom Transmission environment will be the area of interest. The proposed research will analyze the current SCB protection scheme in service specifically looking at the restricted earth fault circuit design and relay performance. An equivalent model of the SCB from primary plant perspective based on theory will be derived. Recording and analyzing of Comtrade transient waveforms respectively, when the bank is nergized, will be done in order to provide a reference base to work from. Manual alculations of various parameters from the derived model including transient inrush currents and fault currents will be performed to access applicable scheme parameters. Further calculations will include the voltage setting for the restricted earth fault relay. As a result of the analysis a recommendation will be made on a viable solution or a revised design will be put forward, based on the results, to improve the scheme’s performance. The protection scheme is used on the two 400kV 100MVAR capacitor banks 11 and 12 at Hydra Substation.

Several methods for calculating the electrical phase and modal parameters of overhead transmission lines are described in this thesis; then, a graphical method for evaluating communication frequency response of delta transmission lines -based on the guidelines given by W. H. Senn [12,13,14]- is developed. The graphical method, combined with the parameters calculation methods, obviates the need of large mainframe computers for the analysis of power line carrier (PLC) systems. A new technique for assessing coupling alternatives, based on Senn's method, is developed. The technique is applied to generate coupling recommendations; it is found that many of the current recommendations given elsewhere [21] are not reliable. Finally, future work to be done in this field is proposed. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

D.Ing. / The technique of using a live power cable to simultaneously transport a communication signal, has been practiced since the early 1900’s. In most cases, power-line communications has been implemented as a retrofit technology, with its main benefit being the utilization of a ‘free’ existing network. This driving force of power-line communications is typical for high-, medium-, and low-voltage distribution networks, as well as intra-building networks currently targeted for home automation and home networking. Researchers have thus focused on the optimum use of these existing power-line channels, often accepting the inherent drawbacks of this hostile communication channel. Apart from unpredictable noise sources, two main disadvantages of the low-voltage powerline network as a communication channel, are i) the unknown power cable characteristics and topology and ii) time-dependent fluctuation of the power-line impedance level as loads are unpredictable switched into, and out of the network. These two factors have obscured the requirements for proper coupling and impedance adaptation to the degree that most researchers and manufacturers have merely accepted this typical ≈ 20-dB coupling loss as one of the inherited disadvantages of the power-line channel. Most researchers and manufacturers have thus defaulted to a guessed power-line impedance level, and have used one fixed coupler winding ratio under all circumstances, regardless of power-line conditions. This study has shown that proper coupling and impedance adaptation can yield significant transmission gains even with limited (qualitative) knowledge of a power-line channel and its topology. After formulating design steps for an impedance-adapting coupler that facilitates bidirectional transmission, the impact of the fluctuating power-line impedance on coupler bandwidth was investigated. Next, impedance adaptation strategies were considered and the tradeoff between series cable requirements and parallel load requirements was explored. A model of sufficient simplicity was developed to facilitate qualitative description and classification of power outlets – functioning as communication nodes. Very interesting simulation results were obtained and these were verified using a laboratory setup of characterized power cables and calibrated loads. Next, these simulation results were employed to improve power-line transmission over a live, uncharacterized 220-V residential network by means of i) classifying typical residential rooms qualitatively in order to choose proper coupler winding ratios and ii) using an innovative dual coupler for dedicated on-off switching with harsh loads, thereby mitigating the fluctuating impact of said loads on low-voltage power-line communications.