Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-10-17T12:44:06Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissetação-Hudson-OTIMIZAÇÃO EM ESTAÇÃO ELEVATÓRIA DE SISTEM.pdf: 6157352 bytes, checksum: f068bb8afd877ced8f8d15b70cea33af (MD5) / Made available in DSpace on 2016-10-17T12:44:06Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissetação-Hudson-OTIMIZAÇÃO EM ESTAÇÃO ELEVATÓRIA DE SISTEM.pdf: 6157352 bytes, checksum: f068bb8afd877ced8f8d15b70cea33af (MD5) Previous issue date: 2016-02-29 / O crescimento da população vem demandando água em quantidades maiores, o que obriga as empresas de saneamento a encontrarem alternativas técnicas que sejam viáveis economicamente para o déficit de água das áreas urbanas. Na sua maioria essas alternativas modificam o comportamento operacional do sistema de bombeamento, geralmente aumentando o tempo de bombeamento e/ou aumentando os números de conjuntos motor-bomba em funcionamento. Os conjuntos elevatórios são responsáveis pela maior parte do consumo de energia elétrica e embora estes equipamentos sejam necessários para transportar a água através dos sistemas e garantirem a confiabilidade do abastecimento de água, o grande consumo de energia elétrica dificulta o equilíbrio financeiro das empresas de saneamento. Com esta preocupação, o presente estudo apresenta uma otimização na rotina operacional das estações elevatórias, buscando a operação ótima que minimize o custo com energia elétrica e atenda os limites físicos e operacionais envolvidos no sistema elevatório. Aplicando-se a plataforma de otimização em elevatórias reais, obteve-se uma redução na potencia utilizada de 20% se comparada à potência nominal dos conjuntos motor-bomba das estações elevatórias, originando economia de aproximadamente 7% no custo com energia elétrica das unidades. / Population growth has been demanding water in larger quantities, which requires sanitation companies to find alternative techniques that are economically viable for the water shortage in urban areas. These alternatives, in most cases, modify the operational performance of the pumping system, generally increasing the pumping time and / or increasing the number of motor-pump sets in operation. The motor-pump sets are responsible for most of the electricity consumption and although these equipment are needed to transport the water through the system and ensure the reliability of water supply, the large consumption of electricity hinders the financial stability of the sanitation company. With this in mind, this study presents an optimization routine for operating the pumping stations; seeking the optimal operation that minimizes the cost of electricity while also meeting the physical and operational limits involved in the pumping stations. Applying the optimization platform of this study on actual pumping stations, it obtained an average reduction of 20% of the nominal power of the motorpump sets of pumping stations, resulting in savings of approximately 7% in the cost of electric energy of the pumping stations.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-11-08T17:29:28Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertacao_Felipe_Correa_CD.pdf: 5991890 bytes, checksum: bf897f6d56367daee94655b05dc520e3 (MD5) / Made available in DSpace on 2016-11-08T17:29:28Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertacao_Felipe_Correa_CD.pdf: 5991890 bytes, checksum: bf897f6d56367daee94655b05dc520e3 (MD5) Previous issue date: 2015-07-31 / Capes / O conversor nove chaves (Nine-Switch Inverter - NSI) foi proposto recentemente e, desde então, um grande número de aplicações foi explorado para esta nova topologia, especialmente como um possível substituto do tradicional conversor back-to-back. A principal vantagem do NSI é o menor número de chaves (nove em vez de doze do conversor back-to-back), que, como consequência, acarreta em restrições nas amplitudes de saída do inversor. Na literatura, foram propostas diferentes técnicas de modulação por largura de pulso (Pulse Width Modulation - PWM) que respeitam estas restrições. Diante deste cenário, o presente trabalho propõe duas abordagens para a generalização da modulação no NSI: a modulação escalar quasi generalizada e a generalizada, que são baseadas no conceito de generalização para o inversor trifásico fonte de tensão (VSI) convencional e que podem ser facilmente implementadas com um reduzido esforço computacional. Este conceito propicia, através de uma abordagem sistemática e direta, a geração de qualquer técnica de PWM, seja ela contínua ou descontínua, através do ajuste de graus de liberdade específicos. Objetivando a redução de perdas, são apresentados os graus de liberdade específicos que, quando aplicados nas modulações propostas, aumentam o rendimento do inversor. Resultados de simulação confirmam a funcionalidade das modulações. / The nine-switch inverter (NSI) has been proposed recently and, since then, a large number of applications were explored for this new topology, specially as a possible substitute to the traditional back-to-back converter. The main advantage of the NSI is its lesser number of switches (nine instead of twelve of the back-to-back converter), which, as a consequence, leads to some restrictions in the total attainable amplitude at its outputs. In literature, many pulse width modulation (PWM) techniques were proposed respecting those restrictions. In this scenario, this paper proposes two generalization approaches for the modulation of the NSI: the quasi generalized scalar modulation and the generalized scalar modulation, which are based on the generalization concept for the voltage source inverter (VSI), easily implemented with a reduced computational effort. Such concept leads to a systematic and straight approach to the generation of any continuous or discontinuous PWM technique for the NSI, simply adjusting a few degrees of freedom of the modulation strategy. Aiming the reduction of the power losses, specific degrees of freedom are presented, for the proposed modulations. Simulation results confirm the validity of the proposed methods.

In this dissertation, the generalized averaging method models for inverters, reactive power control methods for photovoltaic inverters, and a noise immunity improvement for hybrid position observers for brushless dc motor drives are studied. Models of inverters and other converters based on averaging have been widely used in numerous simulation applications. Generalized averaging can be applied to model both average and switching behavior of converters while retaining the faster run times associated with average-value models. Herein, generalized average models for single- and three-phase pulse width modulation inverters are proposed. The modulation signal for the proposed model could be either a sinusoidal waveform without high order harmonics or a sinusoidal waveform with third-harmonic injection. And this generalized average models also can apply for modeling three-phase pulse width modulation inverters with varying modulation signal frequency in the reference frame. These models are based on a quasi-Fourier series representation of the switching functions that includes fundamental and switching frequency components as well as sideband components of the switching frequency. The proposed models are demonstrated both in simulation and experimentally and are found to accurately portray both the fundamental and the switching behavior of the inverter. In particular, the use of sideband components allows accurate representation of the variation in switching ripple magnitude that occurs in the steady state. The generalized average models are found to have simulation run times that are significantly faster than those associated with detailed models. Therefore, the proposed generalized average models are suitable for simulation applications in which both accuracy (including the switching behavior) and fast run times are required (e.g., long simulation times, systems with multiple converters, and repeated simulations). Variations in the output power of intermittent renewable sources can cause significant fluctuations of distribution system voltage magnitudes. Reactive power control methods that employ the reactive power capability of photovoltaic three-phase inverters to mitigate these fluctuations are proposed. These control methods cause the three-phase inverters to substitute reactive output power for real output power when fluctuations in the solar power are experienced, allowing the fluctuations to be controlled. Performance metrics for assessing the ability of these controllers to perform this mitigation are defined. The controllers are examined using the IEEE 123-bus feeder distribution system, and it is found that the controllers can effectively mitigate voltage magnitude fluctuations and that the appropriate choice of controller depends on the performance metrics of interest. Finally, a noise immunity improvement for hybrid position observers for brushless dc motor drives is proposed. A finite state machine is used to detect Hall-effect sensor transitions to determine if these transitions are true transitions or the result of momentary glitches. This filter causes a delay in the detection of the Hall-effect sensors that is compensated in the proposed observer. The proposed observer is compared in simulations with the original hybrid position observer under both non-noisy and noisy conditions for both constant and variable speed operation, and it has good performance even under high noise and variable speed conditions.

Solar energy is an abundant renewable source, which is expected to play an increasing role in the grid's future infrastructure for distributed generation. The research described in the thesis focuses on the analysis of integrating multi-megawatt photovoltaics (PV) systems with battery energy storage into the existing grid and on the theory supporting the electrical operation of components and systems. The PV system is divided into several sections, each having its own DC-DC converter for maximum power point tracking and a two-level grid connected inverter with different control strategies. The functions of the battery are explored by connecting it to the system in order to prevent possible voltage fluctuations and as a buffer storage in order to eliminate the power mismatch between PV array generation and load demand. Computer models of the system are developed and implemented using the PSCADTM/EMTDCTM software.

A unique all-optical 1x2 self-routed switch is introduced. This switch routes an optical packet from one input to one of two possible outputs. The header and payload are transmitted separately in the system, and the header bits are processed in parallel thus increasing the switching speed as well as reducing the amount of buffering required for the payload. A 1x2 switching operation is analysed and a switching ratio of up to 14dB is obtained. The objective of the research was to investigate a unique all-optical switch. The switch works by processing the optical bits in a header packet which contains the destination address for a payload packet. After the destination address is processed the optical payload packet gets switched to one of two outputs depending on the result of the optical header processing. All-optical packet switching in the optical time domain was accomplished by making use of all-optical parallel processing of an optical packet header. This was demonstrated in experiments in which a three bit parallel processing all-optical switching node was designed, simulated and used to successfully demonstrate the concept. The measure of success that was used in the simulated experiments was the output switching ratio, which is the ratio between the peak optical power of a high bit at the first output and the peak optical power of a high bit at the second output. In all experimental results the worst case scenario was looked at, which means that if there was any discrepancy in the peak value of the output power then the measurement’s minimum/maximum value was used that resulted in a minimum value for the switching ratio. The research resulted in an optical processing technique which took an optical bit sequence and delivered a single output result which was then used to switch an optical payload packet. The packet switch node had two optical fibre inputs and two optical fibre outputs. The one input fibre carried the header packet and the other input fibre carried the payload packet. The aim was to switch the payload packet to one of the two output fibres depending on the bit sequence within the header packet. Also only one unique address (header bit sequence) caused the payload packet to exit via one of the outputs and all the other possible addresses caused the payload packet to exit via the other output. The physical configuration of the all-optical switches in the parallel processing structure of the switching node determined for which unique address the payload packet would exit via a different output than when the address was any of the other possible combinations of sequences. Only three Gaussian shaped bits were used in the header packet at a data rate of 10 Gbps and three Gaussian shaped bits in the payload packet at a data rate of 40 Gbps, but in theory more bits can be used in the payload packet at a decreased bit length to increase throughput. More bits can also be used in the header packet to increase the number of addresses that can be reached. In the simulated experiments it was found that the payload packet would under most circumstances exit both outputs, and at one output it would be much larger than at the other output (where it was normally found to be suppressed when compared to the other output’s optical power). The biggest advantage of this method of packet-switching is that it occurs all-optically, meaning that there is no optical to electronic back to optical conversions taking place in order to do header processing. All of the header processing is done optically. One of the disadvantages is that the current proposed structure of the all-optical switching node uses a Cross-Gain Modulator (XGM) switch which is rather expensive because of the Semiconductor Optical Amplifier (SOA). In this method of packet-switching the length of the payload packet cannot exceed the length of one bit of the header packet. This is because the header processing output is only one header bit length long and this output is used to switch the payload packet. Thus any section of the payload packet that is outside this header processing output window will not be switched correctly / Dissertation (MEng (Electronic Engineering))--University of Pretoria, 2007. / Electrical, Electronic and Computer Engineering / unrestricted

This thesis aims to design a cabinet to house some of the required hardware to realize a 1000 A IGBT inverter controlled static excitation system. In the thesis practical design considerations are identified and solved. The suggested excitation system requires a cabinet to house the inverters. Together with inverter requirements stated by the inverter manufacturer and possible electromagnetic interference from switching of the IGBT:s, practical design considerations arise when realizing the system. Identified design considerations are heat dissipation, EMI, IP-code requirements and mechanical stresses at inverter connections. In this study, the design considerations are addressed and a cabinet design with required components inside is suggested. The suggested cabinet together with its components could fulfil the suggested system's- and the inverter's requirements. However, the IP-code allowed by the suggested EMC-seals might be lower than the IP54 required by the inverter. The cabinets EMC-properties will probably be lowered if regular rubber gaskets are used. The study suggests one possible configuration which is possible to realize. It is suggested that further consideration is dedicated to the EMI reducing properties of the cabinet if it is to be installed in an environment sensitive to EMI.

Cette thèse a pour objet l'étude de la fiabilité de modules de puissance triphasés à IGBTs 200 A - 600 V, destinés à la construction d'onduleurs de traction pour des applications automobiles hybrides ou électriques. Ces travaux visent à évaluer la tenue de ces modules de puissance en régime de cyclage thermique actif à hautes température, en mettant l'accent sur leur résistance à la fatigue thermomécanique. Deux approches complémentaires ont été mises en oeuvre dans ce but: tests de vieillissement accéléré et modélisation numérique. Une compagne d'essais de vieillissement par cyclage actif a été menée avec des profils de température variés, définis par la température ambiante et la variation de température de jonction des IGBTs, utilisés comme facteurs d'accélération des contraintes. Au cours de ces tests, les composants ont électriquement fonctionné dans des conditions semblables à une application réelle (commande MLI). L'objectif était d'identifier les modes de défaillance, d'estimer l'influence des facteurs d'accélération du vieillissement, et d'évaluer la pertinence des indicateurs de défaillance classiques dans ces conditions de stress thermiques sévères. Aussi, afin de mieux comprendre les mécanismes de défaillance responsables de la fatigue de l'assemblage des modules considérés, une modélisation thermomécanique visant à déterminer l'impact des modèles de comportement mécanique sur la durée de vie estimée des brasures, a été développée. La réponse de l'assemblage à des contraintes de cyclage actif similaires à celles appliquées durant les essais a été évaluée par analyse numérique. Les différentes lois de comportement ont été comparées en termes de contraintes, déformations plastiques, et densité d'énergie plastique dans les brasures. / This thesis is dedicated to reliability investigations led on three-phase 200~A~--~600~V IGBT power modules, designed for building drive inverters for hybrid or electric automotive traction applications. The objective was to evaluate the durability of the studied modules when they withstand power cycling in high temperature environments, and especially their resistance to thermo-mechanical fatigue. Two complementary approaches were considered: accelerated aging experiments and numerical modeling.A series of power cycling tests was carried out over a large range of temperature profiles, defined by the ambient temperature and IGBT junction temperature excursion. These quantities are used as thermal stress acceleration factors. Those experiments were led in realistic electrical conditions (PWM control scheme). They aimed at identifying the failure modes of the target devices, assessing the impact of the acceleration factors on their aging process, and evaluating the suitability of standard aging indicators as damage precursors in such harsh loading conditions. Besides, to better understand the failure mechanisms governing the fatigue life of the modules assembly, a thermo-mechanical modeling focusing on solder joints was built. Our simulation efforts concentrated on the appraisal of constitutive modeling effects on solder joints lifetime estimation. Numerical analysis of the assembly response to power cycling in similar operating conditions as practiced in experiments were performed. Behavior laws were then compared on stress, plastic strain, and strain energy density developed within the joints.

L'autonomie est, à l'heure actuelle, un des points les plus bloquants des véhicules électriques. Une optimisation du rendement de la chaîne de conversion est donc un objectif primordial. La thèse s'inscrit donc dans un contexte d'efficacité énergétique et d'intégration en électronique de puissance. Il s'agira d'améliorer les rendements de conversion et la puissance massique à la fois par le choix de technologies adaptées et par la conception de structures de conversion optimisées. Dans un premier temps, nous présentons l’impact de l’évolution de la tension de batterie HT sur le choix des technologies de composants de puissance. Différentes architectures de conversion sont également présentées et l’accent est mis sur un convertisseur en particulier : L’onduleur. Puis, nous comparons les relevés expérimentaux à ceux qui peuvent sont fournis par des fabricants pour certains composants et dans certaines conditions de fonctionnement. Ces essais permettent également d’enrichir les données des fabricants. Enfin, nous comparerons l’impact de la montée en tension des batteries HT sur les performances de différentes structures d’onduleurs (2 et 3 niveaux), pour différentes technologies de composants semi-conducteurs de puissance et pour différents points de fonctionnement de la machine associée. / Currently, autonomy of electric vehicles is one of the most blocking points for developing such mean of transport. An optimization of the efficiency of the power train is thus a primordial objective. The thesis is part of a context of energy efficiency and integration in power electronics. This will improve conversion efficiencies and mass power both by the choice of appropriate technologies and design optimized conversion structures. First, we present the impact of the evolution of the HT battery voltage on the choice of power component technologies. Different conversion architectures are also presented and the focus is on a particular converter: The inverter. Then, we compare the experimental records to those that can be supplied by manufacturers for certain components and under certain operating conditions. These tests also make it possible to enrich the data of the manufacturers. Finally, we will compare the impact of the voltage rise of the HT batteries on the performances of various inverter structures (2 and 3 levels), for different technologies of semiconductor power components and for different operating points of the machine associated.

In this diploma thesis, universal inverter was manufactured and successfully tested with DC, BLDC and AC motor. Inverter is composed of the power board for driving extralow voltage supplied electric motors (from +12V to +24V) and control board with microcontroller MC56F8257. There is also explained the principle of driving DC, BLDC and AC motor as well as description of the most frequently used peripherals and inverter. components

The accumulation of electricity as an issue is becoming more important and it’s importance is constantly growing. This is due to the fact that more renewable energy sources, mainly photovoltaic and wind power plants, are being incorporated into the electricity system, causing changes in the power grid performance. Changing in the behavior of consumers of electricity can cause further changes in the network. The ability for compensations of these changes in the power grid has just accumulation systems. This Thesis for Master’s Degree presents selected storage systems and ways in which energy can be stored. Further, in this work, a model of accumulation system with management based on general conditions will be created. This model will be tested and its behavior detected under the limit conditions.