Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 73-74). Also available via the Internet.

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

Orientador: Fernando Pinhabel Marafão / Coorientador: Marcelo Gradella Villalva / Banca: José Antenor Pomílio / Banca: Marcelo Godoy Simões / Resumo: O objetivo deste trabalho foi desenvolver um sistema de geração fotovoltaico híbrido, ou seja, capaz de funcionar tanto interligado à rede elétrica como desconectado (ilhado) desta. Quanto ilhado, este sistema fornece potência e uma tensão senoidal para a carga, desde que haja energia solar nos módulos fotovoltaicos e/ou energia armazenada no banco de baterias. Quando conectado, o sistema de geração fotovoltaico é capaz de fornecer potência ativa para a carga e/ou rede elétrica e, simultaneamente, funcionar com um Stalic Synchrnous Compensator (STATCOM), auxiliando no suporte de tensão no ponto de acoplamento comum ou, como um compensador ativo seletivo, atenuando os distúrbios elétricos causados pela carga. Para atingir o objetivo deste trabalho, o sistema de geração fotovoltaico foi estudado, projetado e analisado. O estudo passou por definições de geração distribuida e de microrede; modelagem do dispositivo fotovoltaico; escolha da técnica de rastreamento do ponto de máxima potência (MPPT); modelagem do banho de baterias; projeto, modelagem e controle dos conversores eletrônicos; projeto das malhas de controle de potência, responsáveis pelo gerenciamento do balanço de potência. Também foi realizada uma análise de três diferentes controladores aplicados ao sistema de geração fotovoltaico isolado e, análises do funcionamento do sistema híbrido com algumas multifuncionalidades agregadas, tais como: funcionamento híbrido, STATCOM e compensador ativo seletivo. Os estudos relacionados à modelagem do dispositivo fotovoltaico, escolha da técnica de MPPT, modelagem do banco de baterias e, projeto, modelagem e controle dos conversores CC-CC foram realizados por meio de simulação. Enquanto que o projeto, modelagem e controle do conversor CC-CA, os estudos do sistema fotovoltaico isolado e híbrido, assim como suas multifuncionalidades... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The goal of this work is to develop a hybrid photovoltaic generated system, which means, able to run both connected to the grid as disconnected (islanded). When it operates in the islanted mode, the system provides power and a sinusoidal voltage to the local loads, since there exist solar energy at the photovoltaic modules and/or storage energy in the battery bank. When the photovoltaic system operates in the connected mode, it is able to supply active power to the load and/or grid and, simultaneously, works as a static synchronous compensator (STATCOM), assisting in the voltage support at the point of common coupling or, as a selective active compensator, mitigating disturbance caused by the load. To reach the goal of this work, the photovoltaic system was studied designed and analyzed. The studies addressed to definition of distributed generation and microgrids; modeling of the photovoltaic device; choose of the maximum power point tracking (MPPT) technique; modeling of the battery bank; design, modeling and control of the electronic converters; design of the power control loops responsible for the power balance manager. It was also perfomed an analyze of three different controllers applied in an isolated photovoltaic generated system and analyzed a hybrid system with multifunctionalities, such as: hybrid operation, STATCOM function and selective active compensator function. The studied related to the modeling of the photovoltaic device, choose of the MPPT technique, modeling of the battery bank and, design, modeling and control of the DC-DC converters have been performed by simulation results. Whereas the design, modeling and control of the DC-AC converter, the studies the isolated and hybrid photovoltaic system, such as multifunctionalities, have been analyzed by simulation results and validated by experimental results... (Complete abstract click electronic access below) / Mestre

Thesis (M. Phil.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 81-85).

Made available in DSpace on 2015-03-03T11:52:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-08-05Bitstream added on 2015-03-03T12:06:26Z : No. of bitstreams: 1 000805979.pdf: 3252358 bytes, checksum: 2c55e4d0ec8e43d70a59a0b403ac0040 (MD5) / Esta dissertação de mestrado apresenta um estudo comparativo entre a Teoria de Potências Instantâneas (Teoria pq) e a Teoria de Potência Conservativa (CPT), das quais serão mostrados resultados de análises para circuitos trifásicos com três ou quatro condutores (3F e 3F - N), com tensões senoidais e não senoidais, equilibradas e desiquilibradas, com e sem impedância de linha para diferentes tipos de cargas (lineares e não lineares). A CPT decompõe as correntes de fase em parcelas ativas, reativas e residuais, sendo que em circuitos trifásicos estas podem ainda ser separadas em parcelas balanceadas e desbalanceadas, de forma a representar os desbalanços da carga. As não lineares da carga são representadas pela CPT através das correntes residuais. No caso da Teoria pq, as correntes de fase são decompostas em correntes ativas, reativas e de sequência zero, sendo ainda que tais parcelas podem ser decompostas em parcelas médias e oscilantes. As parcelas oscilantes representam os desbalanços e as não linearidades do circuito. Ou seja, a Teoria pq não separa tais distúrbios (desbalanços e não linearidades) em parcelas distintas de correntes. Apesar das teorias serem bastante distintas em suas formulações, a ideia central é realizar um estudo comparativo entre as parcelas de correntes e suas respectivas parcelas de potência, a fim de mostrar as similiaridades e divergências na caracterização dos fenômenos físicos dos circuitos, bem como na compensação de correntes que não contribuem para a transferência de energia útil entre fontes e cargas, as quais podem ser eliminadas ou minimizadas através de condicionadores eletrônicos em paralelo com as cargas. Neste trabalho, a avaliação das teorias para compensação de distúrbios de corrente será feita levando-se em consideração fontes de corrente ideiais, operando como filtros ativos de potência, o que elimina o feito de eventuais imperfeições de controle... / This dissertation shows a comparative study between the Conservative Power Theory (CPT) and the Instantaneous Power Theory (pq Theory). Different configurations of linear and non-linear loads and different voltage conditions will be considered, assuming three-phase circuits with 3 and 4 wires, with or without line impedance. The CPT separates the phase currents into active, reactive and void portions, and in case of three-phase circuits, the active and reactive currents can also be splited into balanced and unbalanced portions to represent the load unbalances. The circuit nonlinearities are represented by CPT through the void current term. In pq theory, the phase currents are separated into active, reactive and zero sequence currents and these portions can also be divided into constant and oscillating portions. The oscillating portions represent imbalance and harmonics on the system. In order words, the pq theory does not separate the imbalances and harmonics in individual current portions. Although these theories are quite distinct in their formulations, the central idea is to make a comparative study between the current portions and their respective portions of power, in order to show the similarities and divergences between them in terms of characterization of the physical phenomena and in terms of disturbing current compensation. In case of current compensation, ideal current sources will be applied in order to evaluate the compensation results using different current reference from CPT and pq theories. This should minimize the influences of control limitations on the analysis of the compensation efficiency under each compensation strategy. The simulation results indicate that both theories can be considered equivalents for circuit analysis or current compensation, as long as the supply voltages are not significantly distorted and/or assymetrical

Made available in DSpace on 2014-06-11T19:22:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-01-29Bitstream added on 2014-06-13T20:49:17Z : No. of bitstreams: 1 brandao_di_me_bauru.pdf: 5797211 bytes, checksum: 5821c3a27764ecbbe0c6862dce12bdde (MD5) / O objetivo deste trabalho foi desenvolver um sistema de geração fotovoltaico híbrido, ou seja, capaz de funcionar tanto interligado à rede elétrica como desconectado (ilhado) desta. Quanto ilhado, este sistema fornece potência e uma tensão senoidal para a carga, desde que haja energia solar nos módulos fotovoltaicos e/ou energia armazenada no banco de baterias. Quando conectado, o sistema de geração fotovoltaico é capaz de fornecer potência ativa para a carga e/ou rede elétrica e, simultaneamente, funcionar com um Stalic Synchrnous Compensator (STATCOM), auxiliando no suporte de tensão no ponto de acoplamento comum ou, como um compensador ativo seletivo, atenuando os distúrbios elétricos causados pela carga. Para atingir o objetivo deste trabalho, o sistema de geração fotovoltaico foi estudado, projetado e analisado. O estudo passou por definições de geração distribuida e de microrede; modelagem do dispositivo fotovoltaico; escolha da técnica de rastreamento do ponto de máxima potência (MPPT); modelagem do banho de baterias; projeto, modelagem e controle dos conversores eletrônicos; projeto das malhas de controle de potência, responsáveis pelo gerenciamento do balanço de potência. Também foi realizada uma análise de três diferentes controladores aplicados ao sistema de geração fotovoltaico isolado e, análises do funcionamento do sistema híbrido com algumas multifuncionalidades agregadas, tais como: funcionamento híbrido, STATCOM e compensador ativo seletivo. Os estudos relacionados à modelagem do dispositivo fotovoltaico, escolha da técnica de MPPT, modelagem do banco de baterias e, projeto, modelagem e controle dos conversores CC-CC foram realizados por meio de simulação. Enquanto que o projeto, modelagem e controle do conversor CC-CA, os estudos do sistema fotovoltaico isolado e híbrido, assim como suas multifuncionalidades... / The goal of this work is to develop a hybrid photovoltaic generated system, which means, able to run both connected to the grid as disconnected (islanded). When it operates in the islanted mode, the system provides power and a sinusoidal voltage to the local loads, since there exist solar energy at the photovoltaic modules and/or storage energy in the battery bank. When the photovoltaic system operates in the connected mode, it is able to supply active power to the load and/or grid and, simultaneously, works as a static synchronous compensator (STATCOM), assisting in the voltage support at the point of common coupling or, as a selective active compensator, mitigating disturbance caused by the load. To reach the goal of this work, the photovoltaic system was studied designed and analyzed. The studies addressed to definition of distributed generation and microgrids; modeling of the photovoltaic device; choose of the maximum power point tracking (MPPT) technique; modeling of the battery bank; design, modeling and control of the electronic converters; design of the power control loops responsible for the power balance manager. It was also perfomed an analyze of three different controllers applied in an isolated photovoltaic generated system and analyzed a hybrid system with multifunctionalities, such as: hybrid operation, STATCOM function and selective active compensator function. The studied related to the modeling of the photovoltaic device, choose of the MPPT technique, modeling of the battery bank and, design, modeling and control of the DC-DC converters have been performed by simulation results. Whereas the design, modeling and control of the DC-AC converter, the studies the isolated and hybrid photovoltaic system, such as multifunctionalities, have been analyzed by simulation results and validated by experimental results... (Complete abstract click electronic access below)

Orientador: Fernando Pinhabel Marafão / Co-orientador: Helmo Kelis Morales Paredes / Banca: Paulo José Amaral Serni / Banca: Claudionor Francisco do Nascimento / Resumo: Esta dissertação de mestrado apresenta um estudo comparativo entre a Teoria de Potências Instantâneas (Teoria pq) e a Teoria de Potência Conservativa (CPT), das quais serão mostrados resultados de análises para circuitos trifásicos com três ou quatro condutores (3F e 3F - N), com tensões senoidais e não senoidais, equilibradas e desiquilibradas, com e sem impedância de linha para diferentes tipos de cargas (lineares e não lineares). A CPT decompõe as correntes de fase em parcelas ativas, reativas e residuais, sendo que em circuitos trifásicos estas podem ainda ser separadas em parcelas balanceadas e desbalanceadas, de forma a representar os desbalanços da carga. As não lineares da carga são representadas pela CPT através das correntes residuais. No caso da Teoria pq, as correntes de fase são decompostas em correntes ativas, reativas e de sequência zero, sendo ainda que tais parcelas podem ser decompostas em parcelas médias e oscilantes. As parcelas oscilantes representam os desbalanços e as não linearidades do circuito. Ou seja, a Teoria pq não separa tais distúrbios (desbalanços e não linearidades) em parcelas distintas de correntes. Apesar das teorias serem bastante distintas em suas formulações, a ideia central é realizar um estudo comparativo entre as parcelas de correntes e suas respectivas parcelas de potência, a fim de mostrar as similiaridades e divergências na caracterização dos fenômenos físicos dos circuitos, bem como na compensação de correntes que não contribuem para a transferência de energia útil entre fontes e cargas, as quais podem ser eliminadas ou minimizadas através de condicionadores eletrônicos em paralelo com as cargas. Neste trabalho, a avaliação das teorias para compensação de distúrbios de corrente será feita levando-se em consideração fontes de corrente ideiais, operando como filtros ativos de potência, o que elimina o feito de eventuais imperfeições de controle... / Abstract: This dissertation shows a comparative study between the Conservative Power Theory (CPT) and the Instantaneous Power Theory (pq Theory). Different configurations of linear and non-linear loads and different voltage conditions will be considered, assuming three-phase circuits with 3 and 4 wires, with or without line impedance. The CPT separates the phase currents into active, reactive and void portions, and in case of three-phase circuits, the active and reactive currents can also be splited into balanced and unbalanced portions to represent the load unbalances. The circuit nonlinearities are represented by CPT through the void current term. In pq theory, the phase currents are separated into active, reactive and zero sequence currents and these portions can also be divided into constant and oscillating portions. The oscillating portions represent imbalance and harmonics on the system. In order words, the pq theory does not separate the imbalances and harmonics in individual current portions. Although these theories are quite distinct in their formulations, the central idea is to make a comparative study between the current portions and their respective portions of power, in order to show the similarities and divergences between them in terms of characterization of the physical phenomena and in terms of disturbing current compensation. In case of current compensation, ideal current sources will be applied in order to evaluate the compensation results using different current reference from CPT and pq theories. This should minimize the influences of control limitations on the analysis of the compensation efficiency under each compensation strategy. The simulation results indicate that both theories can be considered equivalents for circuit analysis or current compensation, as long as the supply voltages are not significantly distorted and/or assymetrical / Mestre

M.Ing. / The purpose of this study is to introduce a new three-phase AC-DC-DC converter topology with low electromagnetic interference (EMI) and unity power factor. This converter topology is obtained by merging the three-phase boost-rectifier and the full-bridge resonant-transition converter into a single, unique converter topology. This converter's boost-stage is completely soft-switched, in contrast with conventional topologies. Thus, each switch in the converter is soft-switched, and therefore the converter --is named the three-phase All Soft-Switching Unity Power Factor Converter (ASSUP). Due to the zerovoltage switching of each switch, this converter has lower switching losses as well as EMI-levels than the conventional design. In the conventional design, the boost-stage, used for power factor correction, and the actual power converter, i.e. the full-bridge DC-DC converter, are realized in two seperate stages with two separate controllers. In contrast, the converter proposed here consists of one stage only, with one controller. The first topic discussed is a theoretical background on both low-frequency power quality (power factor and THD), and high-frequency power quality (EMI). This background is necessary for comparing the proposed converter with the conventional converter. Secondly, an in-depth analysis of both the three-phase boost-rectifier and the full-bridge resonanttransition converter is done. This analysis is crucial in the analysis of the three-phase ASSUP, which is discussed thirdly. For each of the converters, a typical switching waveform is divided into unique intervals, for which the appropriate expressions are derived. The design of the practical component values is also discussed, as well as the control method for each of the converters. The three-phase ASSUP, introduced here, is lastly experimentally compared with the cascade-connection of the three-phase boost-rectifier and the full-bridge resonant-transition converter.

A novel, zero-current-transition (ZCT) topology of the single-switch three-phase boost PFC rectifier is proposed. The soft transition is achieved with a low-power auxiliary circuit employing an additional switch. The circuit can be used with an IGBT at switching frequencies up to 50. Its operation is analyzed in detail, and design guidelines are provided. The small signal model of the circuit is developed, and voltage mode control is designed. The results are verified on a 4 kW, 50 kHz, experimental ZCT rectifier with an IGBT; total harmonic distortion below 9% and efficiency above 95% were obtained. / Master of Science

Three novel power factor correction (PFC) techniques are developed for both single-phase and three-phase applications. These techniques have advantages over the conventional approaches with regard to the converter efficiency, power density, cost, and reliability for many applications. The single-phase parallel PFC (PPFC) technique was established. Different from the conventional two-cascade-stage scheme, the PPFC technique allows 68% of input power to go to the output through only one time high frequency power conversion, but still achieves both unity power factor and tight output regulation. A family of PPFC converters were proposed for different power levels, which are simpler and more efficient than the conventional two-cascade-stage systems. Since isolated boost converters are adopted as the main power stage in some of the PPFC converters, a device based soft-switching technique was proposed for using IGBTs as the main power switches, which ensures the lower cost and higher efficiency benefits of the PPFC technique. The single-ended boost converter is the most frequently used converter in the single-phase PFC applications. For high power and/or high voltage applications, the major concerns of the conventional boost converter are the inductor volume and weight, and Iosses on the power devices, which will affect converter efficiency, power density, and cost. In this dissertation, a novel three-level boost converter was developed, which can use a much smaller inductor and lower voltage devices than the conventional one, yielding higher power density, higher efficiency, and lower cost. In three-phase applications, the three-phase boost rectifier is the most popular topology for the PFC purpose. A novel high performance boost PFC rectifier was developed, which provides several superior features than the conventional one with nearly no cost increase. lt inherently provides six-step PWM operation, which is the optimal PWM scheme with no circulating energy, minimum input ripple current, and minimum . switching events. It also greatly reduces the bridge diode reverse recovery loss, which is one of the major switching Iosses in the conventional three-phase boost rectifier. Furthermore, it can adopt very simple soft-switching techniques even with three independent analog controllers to further improve the performance. Several simple soft switched three-phase boost rectifiers have been developed. Besides, the bridge shoot-through problem is virtually eliminated. As a result, these new three-phase boost rectifiers have higher efficiency, higher power density, lower cost, and higher reliability compared with the conventional one. / Ph. D.