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One of the most important problems involved in power system operations is stability evaluations to determine whether or not a system will remain in synchronism during transient disturbances. The mathematical expressions from which stability is determined are relatively simple in themselves; however, the direct solution of the simultaneous equations involved cannot easily be accomplished by conventional methods. Present-day techniques, using network analyzers, cut the amount of work ad time considerably. For handling problems which are too complicated for conventional computation but too small to justify time on the large network analyzer are available, miniaturized network analyzers are available. One of such analyzers is the G.E. Mlniaturised A.C. Network Analyser, which is the object of this investigation. The investigation shows that it is possible to calibrate the phase angle dials and use them in conjunction with stability evaluations. The results so obtained are fairly accurate ad where necessary, corrections can be employed. / Master of Science

Made available in DSpace on 2014-06-11T19:22:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-08-07Bitstream added on 2014-06-13T18:49:41Z : No. of bitstreams: 1 souza_ch_me_ilha.pdf: 651441 bytes, checksum: b139e90078b1de276ac99f40362c2bf7 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho apresentam-se o desenvolvimento e a implementação de um algoritmo computacional para o problema de planejamento e projeto de circuitos secundários de distribuição de energia elétrica. O problema é formulado como um modelo de Programação Não Linear Inteiro Misto (PNLIM), e para sua solução propõe-se um algoritmo de Busca Tabu (BT). Esta ferramenta permite determinar e avaliar os custos dos elementos que compõem o sistema de distribuição (reforma e/ou construção de redes secundárias), evidenciando sua robustez e precisão. Os algoritmos de cálculo mecânico e definição de estruturas são baseados em normas técnicas para se determinar os postes e estruturas do sistema sob estudo. Os condutores são especificados pelo algoritmo de fluxo de potência trifásico respeitando as condições topológicas, físicas e ambientais. Toda metodologia de cálculo e projeto utilizada neste problema está de acordo com os Procedimentos de Distribuição do Sistema Elétrico Nacional (PRODIST). Para mostrar a eficiência do modelo proposto e da metodologia de planejamento e projeto desenvolvidos, apresentam-se resultados para dois sistemas reais de distribuição com 76 e 54 barras, respectivamente. / In this work, the development and implementation of a computational algorithm for the planning and design of secondary circuits of power distribution systems problem, is presented. The problem is formulated as a Non-linear Integer Mixed Programming (NLIMP) problem; and for its solutions it is proposed a Tabu Search (TS) algorithm. This tool allows determining and evaluating the cost of elements that are part of the distribution system (upgrade and/or construction of secondary networks), showing its robustness and accuracy. Mechanic calculation algorithms and structure definitions are based on technical norms in order to determine poles and structures of the system under study. Conductors are specified by the three-phase power flow algorithm, satisfying topological, physical and environmental conditions. All the calculation and design methodology used in this problem agrees with the Distribution Procedures of the National Electric System (PRODIST). In order to show the efficiency of the proposed model and the developed planning and design methodology, results for to real-life distribution systems, with 76 and 54 buses, are presented.

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Electrical Impedance Tomography is a non-invasive, non-ionizing, non-destructive and painless imaging technology that can distinguish between cancerous and non-cancerous cells by reproducing tomographic images of the electrical impedance distribution within the body. The primary scope of this thesis is the study of hardware modules required for an EIT system. The key component in any EIT system is the excitation system. Impedance measurement can be performed by applying either a current or voltage through emitting electrodes and then measuring the resulting voltages or current on receiving electrodes. In this research, both types of excitation systems are investigated and developed for the Sussex EIM system. Firstly, a current source (CS) excitation system is investigated and developed. The performance of the excitation system degrades due to the unwanted capacitance within the system. Hence two CS circuits: Enhance Howland Source (EHS) and EHS combined with a General impedance convertor (GIC: to minimise the unwanted capacitance) are evaluated. Another technique (guard-amplifier) has also been investigated and developed to minimise the effect of stray capacitance. The accuracy of both types of CS circuits are evaluated in terms of its output impedance along with other performance parameters for different loading conditions and the results are compared to show their performance. Both CS circuits were affected by the loading voltage problem. A bootstrapping technique is investigated and integrated with both CS circuits to overcome the loading voltage problem. The research shows that both CS circuits were unable to achieve a high frequency bandwidth (i.e. ≥10MHz) and were limited to 2-3MHz. Alternatively, a discrete components current source was also investigated and developed to achieve a high frequency bandwidth and other desirable performance parameters. The research also introduces a microcontroller module to control the multiplexing involved for different CS circuit configurations via serial port interface software running on a PC. For breast cancer diagnosis, the interesting characteristics of breast tissues mostly lie above 1MHz, therefore a wideband excitation source covering high frequencies (i.e. ≥1-10MHz) is required. Hence, a second type of the excitation system is investigated. A constant voltage source (VS) circuit was developed for a wide frequency bandwidth with low output impedance. The research investigated three VS architectures and based on their initial bandwidth comparison, a differential VS system was developed to provide a wide frequency bandwidth (≥10MHz). The research presents the performance of the developed VS excitation system for different loading configurations reporting acceptable performance parameters. A voltage measurement system is also developed in this research work. Two different differential amplifier circuits were investigated and developed to measure precise differential voltage at a high frequency. The research reports a performance comparison of possible types of excitation systems. Results are compared to establish their relationship to performance parameters: frequency bandwidth, output impedance, SNR and phase difference over a wide bandwidth (i.e. up to 10MHz). The objective of this study is to investigate which design is the most appropriate for constructing a wideband excitation system for the Sussex EIM system or any other EIT based biomedical application with wide a bandwidth requirement.

Orientador: Marcos Julio Rider Flores / Banca: Ruben Augusto Romero Lazaro / Banca: Sergio Azevedo de Oliveira / Banca: Eduardo Nobuhiro Asada / Banca: Roberto Cayetano Lotero / Resumo: Neste trabalho é apresentado um modelo estocástico linear inteiro misto para o problema de planejamento da expansão da rede de transmissão multiestágio considerando restrições de segurança N −1 (PERTMRS) a longo prazo. Considerando uma amostragem de cenários para a demanda e geração (com uma probabilidade para cada cenário) é possível transformar o modelo estocástico proposto num equivalente determinístico linear inteiro misto (LIM). O uso de um modelo LIM garante a convergência para a solução ótima do PERTMRS usando métodos de otimização clássica existentes. O critério de segurança N −1 indica que o sistema de transmissão deve ser expandido de tal forma que, com a saída de operação de uma linha existente ou candidata (em um conjunto pré-definido de contingências) do sistema, o mesmo ainda deve operar adequadamente. O modelo foi implementado usando a linguagem de modelagem algébrico AMPL e solucionado usando o solver comercial CPLEX. Os sistemas de testes: Garver de 6 barras e IEEE de 24 barras; e os sistemas reais: Colombiano de 93 barras e o Boliviano de 57 barras foram usados para avaliar o modelo proposto. Para os sistemas de grande porte uma estrategia de redução do espaço de busca combinatório do problema é apresentado para facilitar a implementação do modelo. / Abstract: In this work we present a mixed integer linear stochastic model for the long term multistage transmission expansion planning problem considering N −1 security constraints (PERTMRS). Considering a sampling for each demand and generation scenario (with a predefined probability for each scenario), the proposed stochastic model can be transformed to a deterministic mixed integer linear programming problem (LIM). The use o LIM model gurantess the convergence to the optimum solution of the PERTMRS if a classical optimization techniques is employed. The N −1 safety criterion indicates that the transmission system must be expanded such that, with an outage of an existing or candidate line (from a predefined set of contingencies, the system should still operate properly. The model was implemented using the algebraic modeling language AMPL and solved using the commercial solver CPLEX. The 6-bus Garver and the IEEE-24 buses test systems and the real 93-bus Colombian and 57-bus Bolivian systems were used to evaluate the proposed model. For large systems a strategy to reduce the combinatorial search space of the problem is presented to facilitate implementation of the model. / Doutor

Michael J. Marcus. / 10255788 / Originally issued as an S.B. thesis, Dept. of Mechanical Engineering, Massachusetts Institute of Technology, 1972. / Includes bibliographical references (p. 53-54).

J.G. Linvill. / "March 14, 1950." / Bibliography: p. 28. / Army Signal Corps Contract No. W36-039 sc-32037 Project No. 102B. Dept. of the Army Project No. 3-99-10-022.

Favorable price trends and increasing demand for renewable energy sources portend accelerating integration of solar photovoltaic (PV) generation into traditional electric power system networks. Managing the variable output of massive PV resources makes system frequency regulation more complex and expensive. ISOs must procure additional regulation and load following capacity, while power plants must supply more regulation work. In contrast to costly physical storage solutions, this thesis proposes to address the issue by reconfiguring the electricity market pricing structure to translate all power imbalances into real-time market price signals. More accurately determining the instantaneous value of energy, electric power markets could reward participants who can quickly respond to frequency fluctuations. By utilizing short term forward markets to monetize the risk associated with intermittency, the true cost of reliability is determined and could reduce wasteful capacity payments. This market redesign is an ideal open platform for disparate smart grid technologies which could encourage all suppliers, loads and generator, to offer supply or reduce consumption when it is needed most and could vastly improve frequency performance metrics.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [51]-52).