Orientador: Elnatan Chagas Ferreira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-24T07:37:40Z (GMT). No. of bitstreams: 1 Bacurau_RodrigoMoreira_M.pdf: 7520389 bytes, checksum: 2e88cad485dbbbdbd306a531c0ed2298 (MD5) Previous issue date: 2014 / Resumo: Neste trabalho é apresentado o desenvolvimento de um módulo medidor de energia residencial capaz de medir, além do consumo de energia total, os parâmetros elétricos necessários para a discriminação de consumo de energia por aparelho. Também é apresentado um levantamento de quais parâmetros elétricos derivados das curvas de tensão e corrente são úteis para a definição de assinatura de cargas residenciais. Os resultados dos experimentos realizados indicaram a potência ativa, a potência reativa, o fator de potência, a tensão e corrente eficazes e as cinco primeiras harmônicas ímpares do sinal de corrente como os parâmetros mais adequados para uso em sistemas não intrusivos para identificação de consumo por aparelho. Graças a técnicas de programação e decisões de projeto acertadas, foi possível desenvolver um módulo medidor de alta precisão e baixo custo, usando um microcontrolador simples e de baixo consumo. Este módulo é capaz de calcular todas as grandezas elétricas supramencionadas a frequência de 46 Hz. Os valores de tensão, corrente, fator de potência, potência ativa e potência aparente apresentaram erros inferiores a 0,3% (para cargas resistivas). O erro nas componentes harmônicas do sinal de corrente foi de 0,03% para a componente fundamental, 0,58% para a 3ª harmônica, 3,69% para a 5ª harmônica, 6,63% para a 7ª harmônica e 11,81% para a 9ª harmônica. O medidor desenvolvido será usado no projeto "Sistema Inteligente de Gestão Energética para Unidades Consumidoras de Baixa Tensão" o qual consistirá em um sistema completo de gestão de consumo de energia residencial / Abstract: We present in this project the development of a residential power meter module capable of measuring besides the total energy consumption, the electrical parameters needed for power consumption breakdown. We also present a study of which electrical features derived from current and voltage waveforms are more adequate to define signatures of residential loads. The experimental results indicated that the active power, reactive power, power factor, voltage, current and the first five odd harmonics of the current signal are good parameters to use in Non-Intrusive Load Monitoring Systems - NILM. Thanks to the use of advanced programming techniques and right design decisions, we developed, using a simple microcontroller, a high-precision, low-power and low cost smart meter. This module is capable to calculate all electrical parameters above mentioned at 46 Hz frequency. The voltage, current, power factor active and apparent power presented errors lower than 0.3% for resistive loads. The error in the harmonics of the current signal was 0.03% for the fundamental harmonic, 0.58% for the 3rd harmonic, 3.69% for the 5th harmonic, 6.63% for the 7th harmonic and 11.81% for the 9th harmonic. The smart meter presented here will be used in a larger project entitled "Intelligent Energy Management System for Consumer Units Low Voltage" which consists of a complete management system of residential energy consumption / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

Orientador: Wei-Liang Qian / Resumo: O sucesso da descrição hidrodinâmica das colisões de íons pesados relativísticos desempenha um papel vital para entender as propriedades da matéria QCD. A essência da evolução hidrodinâmica, em geral, foi atribuída à resposta dinâmica às condições iniciais flutuantes. Em particular, as características observadas nas correlações de duas partículas, referidas como ``cume'' e ``ombro'', mostraram ser reproduzidas com sucesso por simulações hidrodinâmicas com condições iniciais flutuantes evento a evento, mas não por condições iniciais médias. Posteriormente, leva ao entendimento atual, através de extensos estudos de análise hidrodinâmica/transporte baseada em eventos por eventos, que as correlações de duas partículas para o momento transversal inferior podem ser interpretadas principalmente em termos de harmônicos de fluxo $ v_n $. Notavelmente, o fluxo triangular, $ v_3 $, é atribuído principalmente à aparência da estrutura do ``ombro'' no lado externo da partícula acionadora. Além disso, entende-se que esses coeficientes harmônicos estão intimamente associados aos correspondentes $ \varepsilon_n $, as anisotropias da distribuição inicial de energia. No entanto, a linearidade entre $ v_n $ e $ \varepsilon_n $ se torna menos evidente para harmônicos maiores que $ n = 2 $. Isso sugere que as próprias flutuações de evento a evento carregam informações importantes, além da linearidade observada. Se alguém se restringe apenas à análise das relações/correlações médias de eventos entr... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

This work deals with an origin of the harmonic currents, their classification into symmetrical components and their influence on neutral conductor in distribution systems. It analyses the heat strain increase in distribution cables and distortion of supply tension in consequence of harmonic zero component flows in distribution system and it provides possibilities of neutral conductor overload and break-in protection.

Influence of transformer lamination from amorphous steel on permeability disturbance by transformer This diploma work is about difference between current materials and amorphous plates which are used as pivots of transformers. Samples are tested by frequence 50-2500 Hz. By using more suitable materials we avoid the unallowable electromagnetic interruption better and we get more positive continuance of the retroactivity on the net.

Orientador: Paulo José Amaral Serni / Resumo: Esta tese apresenta uma contribuição da área de engenharia elétrica para o gerenciamento da operação de equipamentos eletromédicos, por meio da avaliação de distorções na forma de onda da tensão em instalações elétricas hospitalares, provocadas por equipamentos utilizados pelos próprios hospitais. Após revisão bibliográfica sobre as origens, publicações normativas, e consequências dos harmônicos nas instalações elétricas, e em especial em instalações hospitalares, é apresentado o princípio das distorções na forma de onda da tensão provocado por equipamentos existentes na própria unidade consumidora, e proposto que esse fenômeno seja chamado de “autoperturbação” por harmônicos. Para comprovar a existência da autoperturbação e quantificá-la, foram realizadas medições do conteúdo harmônico da corrente em três equipamentos hospitalares de diagnóstico por imagem, e desenvolvidos um modelo analítico e um modelo computacional para a avaliação da autoperturbação. Após a apresentação detalhada dos modelos desenvolvidos, o conteúdo harmônico da corrente obtido durante as medições foi introduzido nos modelos para três cenários de cargas e para transformadores com três potências nominais diferentes. A distorção harmônica da tensão no interior da instalação foi quantificada para cada cenário e para cada transformador, confirmando a ocorrência da autoperturbação por harmônicos. Em seguida, para possibilitar uma avaliação quantitativa, preliminar à instalação dos equipamentos, é apresentado... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This thesis presents a contribution from the electrical engineering area for the management of the operation of electromedical equipment, through the evaluation of distortions in the voltage waveform inside hospital electrical installations, caused by equipment used by the hospitals themselves. After a bibliographic review on the origins, technical standards, and problems caused by harmonics in electrical installations, and especially at hospital installations, the principle of distortions in the voltage waveform caused by current drained by electromedical equipment is presented, and it is proposed that this phenomenon be called “self-disturbance” by harmonics. In order to prove the existence of self-disturbance and to quantify it, measurements were made on the harmonic spectrum of the current drained by three hospital equipment for imaging diagnostic, and an analytical model and a computational model were developed for the evaluation of self-disturbance. After the detailed presentation of the developed models, the harmonic spectrum of the currents obtained during the measurements were introduced in the models for three load scenarios and for transformers with three different rated powers. The harmonic distortion of the voltage inside the installation was quantified for each scenario and for each rated power transformer, confirming the occurrence of self-disturbance by harmonics. Then, to enable a quantitative assessment, preliminary to the installation of the equipment, a pr... (Complete abstract click electronic access below) / Doutor

The proliferation of Electric Vehicles (EVs) poses new challenges for the Distribution System Operator (DSO). For example, the rectifiers that are used for charging EV batteries could significantly influence Power Quality (PQ), in terms of harmonic distortion. The emissions from individual EV, are well regulated by current harmonic emission standards. But what the aggregation of multiple EV loads will look like is still uncertain and the research being made in this area is still in its early stage.  The DSO responsibilities include ensuring grid code compliance confirmed by PQ metering.  In general, 10 minute RMS values are sufficient. However, the large scale integration of non-linear loads, like EVs, could lead to new dynamic phenomena, possibly lost in the process of time aggregation. In this thesis PQ and, in more detail, the concept of harmonics, and how this is related to EVs, is presented. A current-harmonic load model using power exponential functions and built from actual measurement data during the individual charging of four different fully electric vehicles was constructed. The model was based on individual emitted current harmonics as a function of state of charge (SOC), and was used to deterministically simulate the simultaneous charging of six vehicles fed from the same bus. The aggregation of current harmonics up to the 11th was simulated while randomizing battery SOC, the start of charging, and the kind of vehicle. Additionally, an investigation of the impact on aggregation in time was conducted. The analysis clearly shows the importance of phase angle information, its correlation to SOC, and how the aggregation of EV loads is influenced by these factors. The analysis also shows that 10 minute RMS aggregation could lead to significant deviations from the “actual” (200ms) data.  This indicates that 10 minute value monitoring could lead to information losses.

Turbines encounter blade failures due to fatigue and creep. It has been shown in the literature that the primary cause of steam turbine blade failures worldwide can be ascribed to fatigue in low pressure (LP) turbine blades. The failure and damage to these blades can lead to catastrophic consequences. Some utilities use empirical methods to determine the forces experienced by turbine blades but desire more accurate methods. The inaccurate prediction of high-cycle fatigue (HCF), thermal durability and stage performance is introduced when one does not consider blade row interaction. Blade row interactions can, however, be accounted for by means of computational fluid dynamics (CFD). Furthermore, modern high- fidelity CFD tools would be able to contribute greatly in predicting the forces experienced by turbine blades. Numerical tools such as CFD and nite element analysis (FEA) can greatly contribute to the estimation of the remaining useful life (RUL) of turbine blades. However, in this estimation process, there are various uncertainties and aspects that affect the estimated RUL. Understanding the sensitivity of the estimated RUL to these various uncertainties and aspects is of great importance if RUL is to be estimated as accurately as possible. In this dissertation, a sensitivity analysis is performed with the purpose of establishing the sensitivity of the estimated RUL of the last stage rotor of an LP steam turbine, to the number of harmonics used in a nonlinear harmonic (NLH) CFD simulation. The sensitivity of the estimated RUL is evaluated in the HCF regime, where the cyclic stresses occur below the yield strength of the turbine blade. A CFD model, FE model, and fatigue model were therefore developed in such a manner that would suffice, regarding the purpose of the sensitivity analysis. The CFD model is validated by comparing the predicted CFD power to that of actual generated power of a dual 100MW LP steam turbine. The sensitivity analysis is performed for 3 operation conditions, and for each operational condition the aerodynamic forces were computed using 1, 2, and 3 harmonics in an NLH simulation. The estimation process considers a weak coupling between the CFD model and FE model. NLH simulations are firstly performed to calculate the unsteady static surface pressure distributions on the last stage rotor. This is followed by the mapping thereof to the FE model, for which a transient structural analysis is performed. Finally, the RUL is estimated by performing a fatigue analysis on the stress history obtained from the transient structural analysis. Based on the results of the sensitivity analysis, the following recommendations were made, from a conservative point of view. Firstly, in general, if the RUL is to be estimated with reasonable accuracy, just using 1 harmonic in an NLH simulation will not be sufficient and 2 harmonics should be used. Secondly, if the RUL has to be estimated with high accuracy, 3 harmonics should be used. / Dissertation (MEng)--University of Pretoria, 2018. / National Research Foundation (NRF) / Mechanical and Aeronautical Engineering / MEng / Unrestricted

Linear time-invariant models are widely used in the control community. They often serve as approximations of nonlinear systems. For control purposes linear approximations are often good enough since feedback control systems are inherently robust to model errors. In this thesis some of the possibilities for linear time-varying modeling are studied. In the thesis it is shown that the balanced truncation procedure can be applied to reduce the order of linear time-varying systems. Many of the attractive properties of balanced truncation for time-invariant systems can be generalized into the time-varying framework. For example, it is shown that a truncated input-output stable system will be input-output stable, and computable simple worst-case error bounds are derived. The method is illustrated with model reduction of a nonlinear diesel exhaust catalyst model. It is also shown that linear time-periodic models can be used for analysis of systems with power converters. Power converters produce harmonics in the power grids and give frequency coupling that cannot be modeled with standard time-invariant linear models. With time-periodic models we can visualize the coupling and also use all the available tools for linear time-varying systems, such as balanced truncation. The method is illustrated on inverter locomotives. / QC 20120208

We are developing a tabletop extreme-ultraviolet source using high harmonic generation at Brigham Young University. The thesis goes over the theory of high harmonic generation using the three-step model. This tabletop source was designed for probing magnetic domains of iron nanoparticles. We present optimization of the 42 eV and 52 eV harmonics through phase matching. Phase matching consists of tuning the intensity of the IR beam and pressure of the gas medium. The target gas medium used for this thesis is argon. The 42 eV harmonic was optimized to 8.2 billion photons per second. This was used with a 1500 mm focal-length lens, 15 mm medium length, laser power of 1.53 Watts, and a pressure of 12 Torr of argon gas. The 52 eV harmonic was optimized to 1.5 billion photons per second with a 1500 mm focal-length lens, 20 mm medium length, laser power of 3.29 W, and 14.9 Torr of argon gas. There are two designs for selection of harmonics: 1) a tunable design consisting of a toroidal mirror and flat diffraction grating and 2) a set of normal-incidence extreme-ultraviolet mirrors designed for 42 or 52 eV photons. Magnetic imaging uses x-ray magnetic circular dichroism to obtain magnetic contrast and use it to visualize magnetic nanosystems. Therefore, the high harmonic source also needs to generate circularly polarized light. Generating circularly polarized high harmonics is possible with a bichromatic beam. This is achieved using an apparatus called the MAZEL-TOV designed by Oren Cohen’s group at Technion University in Israel. The MAZEL-TOV consists of a BBO crystal for second harmonic generation, a pair of pulse delay compensation plates, and a quarter-wave plate. These optics are placed inline with the laser beam. We have successfully optimized the circularly polarized extreme-ultraviolet harmonics with the MAZEL-TOV. A spectrometer was made to calibrate the harmonics in the MAZEL-TOV spectrum. The tabletop source was then used to demonstrated coherent diffraction imaging of two pinholes.

Le rayonnement d'un haut-parleur monté sur une enceinte est généralement caractérisé par des mesures ou une simulation par la méthode des éléments finis. Cependant, ces méthodes de référence restent très coûteuses et ne permettent pas une interprétation physique des résultats. Dans ce manuscrit, nous proposons deux modèles analytiques pour prédire ce rayonnement, dans le cadre d'une application à une barre de son. Le premier modèle consiste à assimiler la géométrie de la barre de son à un sphéroïde. De cette manière, les variables sont séparées et on peut trouver une solution analytique sous la forme d'une somme d’harmoniques sphéroïdales. On décrira chaque étape de la méthode, ainsi que la comparaison des résultats à ceux des méthodes de référence. On développera particulièrement le calcul pour un haut-parleur circulaire sur le sphéroïde et la mise en place d'un critère de troncature des harmoniques. Ce modèle fonctionne bien en basse-fréquence, mais ne peut pas rendre compte de tous les phénomènes de diffraction par l'enceinte en haute fréquence. Pour celles-ci, la diffraction du champ sonore par les arêtes de l'enceinte devient non négligeable. Nous avons donc développé un second modèle analytique, basé sur une formulation intégrale de cette diffraction. Celle-ci est vue comme un ensemble de sources secondaires localisées sur les arêtes. On montrera comment établir ce modèle et on donnera des détails sur son implémentation. L'application de ce modèle permet d'interpréter physiquement le rayonnement d'une barre de son, et donc de conclure sur la validité du modèle sphéroïdal. On montre également comment les arêtes du baffle d'une enceinte entraînent des effets d'interférences constructives, qui peuvent induire un gain allant jusqu’à 3 dB. Ces effets entraînent également un phénomène contre-intuitif : si le haut-parleur n'est pas centré sur le baffle, la direction du maximum d'intensité du rayonnement tend à se décaler vers le côté opposé au décalage du haut-parleur sur le baffle. / The radiation from a loudspeaker mounted on a box shaped enclosure is usually characterized by measurements or simulations based on finite element method. However, these reference methods are still very expensive and do not allow for a physical interpretation of the results. In this manuscript, two analytical models are proposed to predict this radiation, within the framework of the application to a sound bar. The first model consists of assimilating the sound bar geometry to a spheroid. In this way, the variables are separated and an analytical solution can be found in the form of a sum of spheroidal harmonics. The calculation for a circular loudspeaker on the spheroid, as well as a harmonic truncation criterion, is detailed. Each step of the method will be described, as well as the comparison of the results with the reference methods. The calculation for a circular loudspeaker on the spheroid and the implementation of a harmonic truncation criterion will be developed. This model works well at low-frequency, but cannot account for the diffraction phenomena, which come from the enclosure and appear at high-frequency. Therefore, we have developed a second analytical model based on an integral formulation of the diffraction. This model is seen as a set of secondary sources located on the edges of the enclosure. It will be shown how to establish this model and how it can be implemented. This model allows us to interpret the radiation of a sound bar, and therefore allows us to conclude on the validity of the spheroidal model. It also shows how the baffle edges of a loudspeaker enclosure lead to constructive interference effects, resulting in a gain up to 3 dB. These effects also lead to a counterintuitive phenomenon: if the speaker is not centered on the baffle, the direction of maximum radiation intensity tends to shift to the opposite side of the speaker offset on the baffle.