Orientador: Pedro Magalhães Sobrinho / Banca: Júlio Santana Antunes / Banca: José Rui Camargo / Resumo: Na atualidade a eficiência energética é um dos assuntos mais citados nas indústrias, pois as empresas que investem em projetos de eficiência energética conseguem economizar recursos, ganhar competitividade e ajudar a amenizar a pressão sobre o aumento da oferta de energia. Postergar parte do investimento no aumento da oferta de energia permite ao governo e ao empresário liberarem recursos para outras prioridades, sem perda de qualidade, segurança no abastecimento e com ganhos sociais e ambientais. Este estudo apresenta critérios de aplicação da metodologia da eficiência energética em uma indústria siderúrgica onde são avaliadas três áreas dentro desta usina, tais como sistemas motrizes, sistemas térmicos e sistemas de iluminação, onde pode-se obter ganhos significativos implementando a metodologia da eficiência energética / Abstract: At present energy efficiency is one of the issues most frequently cited in industries, as companies that invest in energy efficiency projects can save resources, improve competitiveness and helps ease the pressure on increasing the supply of energy. Postpone part of the investment in increasing energy supply allows the government and the business owner to release resources for other priorities, without loss of quality, security of supply and social and environmental gains. This study presents application criteria of energy efficiency methodology in a steel industry which are evaluated in three areas of a steel mill, such as drive systems, thermal systems and lighting systems, where can be made significant gains by implementing the methodology of energy efficiency / Mestre

Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Vita. / Includes bibliographical references. / Ph.D.

Thesis. 1977. B.S.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaf 84. / B.S.

Thesis. 1977. M.S.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographic references. / by Craig G. Prohazka. / M.S.

Orientador: Teófilo Miguel de Souza / Banca: Ivone Ávila / Banca: Osíris Canciglieri Júnior / Resumo: Com a crescente demanda na matriz energética global e a constante preocupação com o uso e a escassez de combustíveis fósseis,o estudo por alternativas de combustíveis mais limpos, baratos, de fácilobtenção e que conservem o meio ambiente tornou-se uma questão de interesse geral.No Brasil, o etanol à base de cana-de-açúcar é uma boa alternativa para a substituição da gasolina, visto que o país possui um território apto para ocultivo dessa cultura, mão-de-obra especializadae condições climáticas adequadas,além de ter baixas emissões de gases de efeito estufa. Para a realização deste trabalho foi utilizado um motor de ciclo Otto a gasolina, com quatro cilindros sem adaptações. Avaliou-se o desempenho do sistema, potência,tensãoe consumo específico do combustível utilizando misturas de gasolina e etanol nas seguintes proporções: E0, E5, E10, E15, E20, E30, E35, E40, E45, E50, E55, E60, E65,E70, E75, E80, E85, E90, E95 e E100. Com a crescente demanda na redução de gases nocivos ao meio ambiente, analisou-se também a quantidade de gases de exaustão expelidos pelo motor(NOx e CO2), observando uma redução na quantidade do CO2 expelido em função do aumento da concentração de etanol na mistura. Em contrapartida, a quantidade de NOx aumentou devido ao fato de a temperatura na câmera de combustão ser maior para o etanol. Como resultado observou-se que o motor-gerador fornece aproximadamente 800W de potência,o que é suficiente para permitir o funcionamento de geladeira, televisão e lâmpadas elétricas, em uma casa de pequeno porte / Abstract: Due to the growing demand in the global energy mix and the constant concern about the use andthe scarcity of fossil fuels, the study of cleaner, cheaper, easy-obtaining and environment-friendlyalternative fuels has become a matter of general interest. InBrazil, the sugar-cane-based ethanol is a good alternativefor the use of gasoline, since the country hasa land fit forcultivation of this crop, skilled labor and suitable climatic conditions, and have low emissions of greenhouse gases. In this study it wasused a four-cylinder Otto-cycle engine powered by gasoline with no adjustments. It was evaluated the system performance, power, voltage, and specific fuel consumption using mixtures of gasoline and ethanol in the following proportions: E0, E5, E10, E15, E20, E30, E35, E40, E45, E50, E55, E60, E65, E70, E75, E80,E85,E90, E95 e E100. The amount of harmful exhaust gases expelled by the engine (CO2and NOx), was also analyzed, and it was observed a reduction in the amount of CO2 expelled by the enginedue tothe increase of ethanol concentration in the mixture. In contrast, the amount of NOx increased due to thefact that the temperature in the combustion chamber ishigher for ethanol. Asa result it was observed that the motor-generator provides800W of power, which is enough to allow the operation of refrigerator, television and electric bulbs in a small home / Mestre

Brushless Doubly Fed Machines (BDFM) have potential advantages in variable speed generation and adjustable speed drive applications. The most significant of these advantages is a reduction in the power electronic converter rating, and therefore a reduction in overall system cost. Presently, efforts are being directed at optimizing the design of the BDFM and investigating areas of commercial feasibility. One possible aid in the investigation of design alternatives is finite element analysis. Finite element analysis is a numerical method for determining the field distribution in a dimensional model. Finite element techniques have been successfully used for some time in the design of induction, reluctance and permanent magnet machines. However, the characteristics of the BDFM require adjustment of the finite element design procedure used for conventional singly-fed induction machines. In this thesis, a three-dimensional finite element design procedure for modeling the BDFM has been developed. This design procedure avoids the difficulties previously associated with finite element modeling of the BDFM. The three-dimensional finite element design procedure developed in this thesis was used to model the 6/2 pole 5 horsepower BDFM laboratory machine. From the simulation results, the induced currents in the BDFM rotor bars were calculated. In the course of investigating three-dimensional finite element analysis for the BDFM, two different commercially available finite element analysis software packages were examined and tested. The first was Maxwell 3D Field Simulator produced by Ansoft Corporation, and the second was MSC/EMAS (Electromagnetic Analysis System) and MSC/XL by MacNeal-Schwendler Corporation. These two software packages are compared and their advantages and disadvantages/limitations are discussed. A tutorial for setting up and solving a three-dimensional BDFM model using MSC/XL and MSC/EMAS is presented. This goal of this tutorial is to guide a new user of MSC/XL and MSC/EMAS through the creation, setup, simulation, and analysis of a BDFM model. This tutorial contains condensed information included in the MSC/XL and MSC/EMAS program documentation provided by MacNeal-Schwendler. In addition, modeling techniques particular to the BDFM, which are not included in the program documentation, are described. This tutorial is applicable only to those individuals interested in learning how to use MSC/XL and MSC/EMAS in order to simulate a BDFM model. / Graduation date: 1995

A project funded by the Southern California Edison (SCE) Company, Research Center of Irwindale, California, has supported the development of a performance and parameter prediction software program for use during the refurbishment of large synchronous machines, turbine generators, and synchronous condensers. The computer program was developed for SCE to allow user friendly input of a machine's physical parameters such as pole/field/winding/stator dimensions, type of steel, and other related information in order to calculate the machine's reactances, time constants, and performance curves. The program also allows some degree of design calculation to be performed in order to meet certain design criteria where appropriate. The theory behind the calculations upon which the electrical calculations are built is obtained primarily from literature published in the early 1950's. Since that time, however, machine design has progressed into ever larger generators, most often in the hundreds of Megawatt range with some units exceeding one thousand Megawatts. This size increase has established the practice of winding the stator coils into parallel circuits to maintain acceptable flux and generated voltage levels. These design practices justify a re-examination of the traditional methods used to calculate a machine's reactances and time constants. Accordingly, the use of parallel circuits in the stator winding and their effect on machine parameters has not, to this author's knowledge, been addressed in public literature. These issues are exam fled and modifications to the traditional formulas have been derived for the reactances along with the process of carrying out the calculations on a per pole basis. In addition, the calculation of the parameter and performance equations of a machine are suitable for implementation on a computer due to the length and often iterative calculation procedures. The procedures used to calculate the capability and saturation curves directly from the machine's physical dimensions are developed. During development of the program a forty megawatt generator was measured in order to test and debug the program. Results of this test case are presented and compared to test values obtained at the time of the generator's installation. / Graduation date: 1994

Environmental concerns have renewed the interest in electric vehicles. To gain widespread use, electric vehicles will also have to offer good performance and be reasonably priced. AC drive systems using modern semiconductors can provide efficient operation at the required power levels, but their cost at present is still too high. This paper discusses the development of an AC induction motor drive system which potentially lowers cost by using a digital controller. The controller is shown to implement a high performance field-oriented control, while keeping a low parts count by maximizing use of interface circuits which are integrated onto the microprocessor chip. Cost is further reduced by designing the system to reuse motor control components for battery charging and eliminate the need for external circuits. Experimental results are presented for a low power prototype system. / Graduation date: 1994

Thesis (Ph.D.)--Memorial University of Newfoundland, 2000. / Bibliography: leaves 179-191.

In this dissertation, we investigate the theory and application of higher-order spectral analysis techniques to condition monitoring in shipboard electrical power systems. Monitoring and early detection of faults in rotating machines, such as induction motors, are essential for both preventive maintenance and to avoid potentially severe damage. As machines degrade, they often tend to become more nonlinear. This increased nonlinearity results in the introduction of new frequencies which satisfy particular frequency selection rules; the exact selection rule depends on the order of the nonlinearity. In addition, the phases of the newly generated frequencies satisfy a similar phase selection rule. This results in a phase coherence, or phase coupling, between the “original” interacting frequencies and the “new” frequencies. This phase coupling is a true signature of nonlinearity. Since the classical auto-power spectrum contains no phase information, the phase coupling signature associated with nonlinear interactions is not available. However, various higher-order spectra (HOS) are capable of detecting such nonlinear-induced phase coupling. The efficacy of the various proposed HOS-based methodologies is investigated using real-world vibration time-series data from a faulted induction motor driving a dc generator. The fault is controlled by varying a resistor placed in one phase of the three-phase line to the induction motor. First, we propose a novel method using a bispectral change detection (BCD) for condition monitoring. Even though the bicoherence is dominant and powerful in the detection of phase coupling of nonlinearly interacting frequencies, it has some difficulties in its application to machine condition monitoring. Basically, the bicoherence may not be able to distinguish between intrinsic nonlinearities associated with healthy machines and fault-induced nonlinearities. Therefore, the ability to discriminate the fault-only nonlinearities from the intrinsic nonlinearities is very important. The proposed BCD method can suppress the intrinsic nonlinearities of a healthy machine by nulling them out and thereby identify the fault-only nonlinearities. In addition, most machines contain rotating components, and the vibration fields they generate are periodic. These periodic impulse train signals may produce artificially high bicoherence values and can lead to ambiguous indications of faults in machine condition monitoring. The proposed BCD method can remove the artificially high bicoherence values caused by periodic impulse-train signals. With these advantages, the proposed BCD method is a new and sensitive indicator for condition monitoring. Second, we propose a novel method to estimate, from a measured single time-series data record, complex coupling coefficients in order to quantify the “strength” of nonlinear frequency interactions associated with rotating machine degradation. The estimation of the coupling coefficients is based on key concepts from higher-order spectral analysis and least mean-square-error analysis. The estimated coupling coefficients embody the physics of the nonlinear interactions associated with machine degradation and provide a quantitative measure of the “strength” of the nonlinear interactions. In addition, as an auto-quantity method utilizing a single time-series data record, the proposed method adds supplemental fault signature information to conventional tools. Such knowledge has the potential to advance the state-of-the-art of machine condition monitoring. Third, we propose a bispectral power transfer analysis methodology to quantify power transfer between nonlinearly interacting frequency modes associated with machine degradation. Our proposed method enables us to identify the relative amounts of power transferred by various nonlinear interactions, and thereby identify the predominant interactions. Such knowledge provides important new signature, or feature, information for machine condition monitoring diagnostics. / text