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Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 92-93).

The work described in this thesis merges two traditionally unrelated engineering disciplines, high voltage dielectrics and artificial neural networks (ANN) applied as a condition-monitoring paradigm.

This thesis presents the results of analysis of the spectral shape and variability properties of the radio to X-ray continua of a sample of BL Lac objects and OVV quasars ("blazars"). These results have important implications for the unification of BL Lac objects, OVV quasars and low polarisation quasars into a single class of objects showing a smoothly continuous distribution of properties. The spectral shape of the violently variable millimetre to ultraviolet emission indicates that in this wavelength region the blazar emission is dominated by a very compact, single synchrotron component which becomes self-absorbed at wavelengths longer than 3 mm. The centimetre emission can be attributed to a separate, more slowly varying component, which can be identified with an underlying 'quiescent" component, similar to that observed in the low polarisation quasar 3C273. The OVV quasars also exhibit evidence of an optical excess, which we identify with the optical excesses which are observed in low polarisation quasars. The variability behaviour of the BL Lac objects is consistent with repeated injections or reaccelerations of electrons within in a small "flaring" synchrotron component, with subsequent radiative energy loss. In the case of the OVV quasars, however, the variability behaviour at near-infrared wavelengths is not consistent with emission from a single synchrotron component. It is shown that the behaviour of the Off quasars provides evidence for the presence of an additional non-variable, near-infrared spectral component, reminiscent of that observed in 3C273. The sizes of the regions responsible for the flaring and quiescent emission are deduced to be 10-2 and 10 parsecs, respectively. It is suggested that the flaring regions may represent regions of enhanced emission within a relativistic jet, possibly due to shock-waves within the jet.

Trading with electrical power is not the domain of few, chosen economic subjects anymore. My thesis describes in details contracts of this useful commodity. Rules of trade are determined by energy branch of an exchange. The same case is as well Power Exchange Central Europe, which determines commodity contracts and defines particular parameters and rules of trading. Part of the thesis is dealing with possible market positions and provides a product overview of energetic commodity. Final results of trading at PXE in recent years are analyzed and compared with real contracts on German exchange market. The end is focused on possible purchasing strategies of electrical power.

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Orientador: José Pissolato Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-21T11:22:49Z (GMT). No. of bitstreams: 1 Carriel_LazaroPartamian_M.pdf: 4727086 bytes, checksum: dcf745210139d03b3d6ea5af9c6db4d8 (MD5) Previous issue date: 2012 / Resumo: O transformador é o maior ativo, o mais importante e o mais caro do sistema elétrico de potência. Este estudo tem a finalidade de apresentar uma metodologia e um processo de análise do ciclo de vida útil de transformadores de potência baseada na condição, para evitar perda de vida adicional devido ao acréscimo de carga em condição de contingência no sistema. A abordagem foi feita em duas fases e abrangem tanto a metodologia da norma ABNT como a norma do IEEE. Na primeira fase é verificado o comportamento do modelo térmico devido a sobrecargas e, na segunda, a influência das condições do óleo isolante / Abstract: The transformer is the largest, most expensive, most important asset in the electric power system. This study will present a methodology to analyze the useful life of power transformers based on their condition, in order to avoid incremental loss of life caused by overload under contingent operating conditions. The approach has been performed in two phases, following both ABNT and IEEE standards. In the first phase, a thermal model evaluates the effect of overloads on transformers' useful life. In the second phase, the influence of the conditions of the insulating oil is verified / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica

There is a need for generalised definitions of electrical powers to provide a simultaneous common base for measurement, compensation, power quality and identification of source of distortion. The major problem area today is definitions of powers in the presence of harmonics and nonlinear loads in the electrical power system. In such a scenario, there is a problem to accurately measure especially reactive (nonactive) power. This is important for accurate energy billing. Another important area is the mitigation equipment used to remove unwanted polluting quantities from the power system. Definitions of powers have an important role to play in providing the correct information for the optimal design and performance of such equipment. Evaluation of the quality of the power system to enable appropriate allocation costs to those causing deterioration in the power quality also cannot be discounted. To enable this cost allocation, there is a need to identify the polluters and the definitions should indicate degradation in power quality as well as identify the source of this degradation. Finally, it would be very useful if the definitions could also be used to perform a general analysis of the power system. This thesis commenced with investigation of the problem with an in-depth study of the existing definitions, and what other researchers have indicated about this problem, from the definitions perspective. The issues identified with current definitions are that some definitions do not possess the attributes that are related to source-load properties, and others are based on mathematical consideration and lack physical meaning. One issue in measurement of nonactive power is its nature of having zero average value. Another contributing factor is that the presence of source impedance is neglected in definitions. The use of RMS quantities to determine powers, especially instantaneous powers, in the presence of multi-frequency voltages and currents also contributes to the problem. Additionally, RMS based definitions are based on heating effect while not all sourceload relationships are totally of a heating nature. The RMS based definitions also do not satisfy the energy conservation principle. Another issue is that though harmonic currents are used, current definitions still utilise the RMS value of the voltage wave thus losing harmonic information. The solution is to decompose, as accurately as possible, the total instantaneous power into active and nonactive components utilising DC, fundamental and harmonics of voltage and current as well as being based on the power system properties. To enable this, the load model must closely represent the reality. This thesis presents the new instantaneous power definitions to achieve this. In addition to the fundamental, five sub-components for each of the active and nonactive parts are defined. The definitions are based on both the voltage and current DC, fundamental and harmonic components thus retaining harmonic information. Thus these definitions are not only mathematically based but also have a direct relationship with the load. The definitions do not make the assumption of zero source impedance. With good knowledge of the time profile of active and nonactive power components, an accurate time-domain measurement of the active and nonactive power is achieved. The components of powers introduced in the proposed definitions can be utilised to gauge power quality, to identify the source of distortion and to achieve optimal compensation. Based on the new instantaneous power definitions, the definitions for average values of the powers are also proposed. The recognition of positive going and negative going parts of the nonactive power waveform in defining the average nonactive power alleviates the problem of the “zero average nature” of nonactive power. It also retains energy information and satisfies the principle of energy conservation. The new definitions are evaluated for linear and non-linear loads in the presence of harmonics using benchmark case studies. Evaluation results demonstrate good performance of the proposed definitions. The practical applications of the definitions are explored with a number of examples from the areas of measurement of power and energy, compensation, detection of source of distortion and power quality. An application example showing the capability of the definitions in general analysis of a system is also presented. Good and useful results are obtained for all these examples. The proposed definitions are implemented on prototype systems with digital signal processors to demonstrate their practical usability. The proposed definitions are shown to be consistent with the traditional definitions under the conventional sinusoidal conditions, and their relationships to the commonly used existing definitions are also revealed.

Made available in DSpace on 2014-06-11T19:22:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-17Bitstream added on 2014-06-13T20:09:45Z : No. of bitstreams: 1 paredesquinones_m_me_ilha.pdf: 1414308 bytes, checksum: 2da97bcc0006bca0f620b6c44bf8177e (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Neste trabalho foi desenvolvido um modelo baseado em programação linear inteira mista para determinar o custo mínimo da operação de um sistema hidrotérmico de longo prazo em um mercado elétrico competitivo. O modelo é capaz de encontrar os valores ótimos de operação para um período futuro nas usinas térmicas e hidroelétricas, considerando os limites normais e de emergência e as perdas de potência ativa nas linhas de transmissão, para diferentes níveis de carregamento, com múltiplos reservatórios de acumulação e de regulação. Adicionalmente, a previsão da hidrologia foi modelada mediante modelo SARIMA para o período de análise, considerando o histórico dos dados hidrológicos. O modelo foi implementado na linguagem de modelagem matemática GMPL. O problema de programação linear inteira mista foi resolvido usando o solver GLPSOL. As predições das hidrologias foram feitas na linguagem estatística R. Foi desenvolvida uma interface gráfica para gerenciar o modelo em GMPL, a previsão hidrológica em R e o solver GLPSOL na linguagem Qt. Desta forma é possível adicionar novos modelos, alterar dados do modelo e visualizar os resultados. Todas as linguagens e softwares usados são livres de distribuição e modificação. Para o modelo desenvolvido foram analisados os seguintes casos: sistema de 6 barras; sistema uninodal brasileiro e sistema interligado peruano. Os resultados obtidos foram comparados com os resultados encontrados na literatura com o objetivo de validar a proposta deste trabalho / In this work developed a model based on mixed integer linear programming to determine the minimum cost of operation of a hydrothermal system in a long-term competitive electricity market. The model is able to find the optimal values of operation for a future period in thermal and hydroelectric power plants, considering the normal and emergency limits and the active power losses in transmission lines, for different loading levels, with multiple storage reservoirs and dams. In addition, predicting the hydrology was modeled by the SARIMA model for the period of analysis, considering the hydrological historical data. The model was implemented in the language of mathematical modeling GMPL. The mixed linear integer programming problem was solved using solver GLPSOL. The predictions in the hydrology using the statistical language R. It was developed a graphical interface to manage the GMPL model, the hydrologic forecasting, and solver GLPSOL in Qt graphical language. By this way, is possible to add new models, change the data of the model and view the results. All languages and software used are free to distribute and modify. For the model developed the following cases were analyzed: 6 bar system; Brazilian uninodal system and Peruvian interconnected system. The results were compared with results in the literature in order to validate the proposal of this work