Current Harmonics
Mostrando 13-23 de 23 artigos, teses e dissertações.
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13. Controle e integração de centrais eólicas à rede elétrica com geradores de indução duplamente alimentados. / Control and integration of wind farms to the power grid using doubly fed induction generators.
This Thesis presents the control and integration of wind farms to the interconnected power grid, using doubly fed induction generators (DFIG). The main objective of the present Thesis was to develop discrete control strategies for the wind generation system, with the goal to reduce the wind variations impacts in the grid power quality. The design technique s
Publicado em: 2006
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14. ANALYSIS, DESIGN AND DEVELOPMENT OF HYBRID MULTILEVEL SYSTEMS / ANÁLISE, PROJETO E DESENVOLVIMENTO DE SISTEMAS MULTINÍVEIS HÍBRIDOS
This Ph.D. Dissertation presents contributions to the study of hybrid multilevel systems, analyzing several issues that compose this system, such as: topological variations of the output inverter stage and input rectifier stage, design methodologies, modulation strategies and control system. This extensive analysis is carried out because these issues are clo
Publicado em: 2005
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15. Algorithm not affected by frequency changes applied in digital generator protection. / Algoritmo imune a variações de freqüência aplicado à proteção digital de geradores.
The main pourpose of that work is inquire an adaptive algorithm to compensate the errors in the power system phasors calculation when occur significant changes in the frequency of the current and voltage signals. The main benefit of that technique is to permit errors compensation with constant sampling frequency and constant data window, making possible cons
Publicado em: 2005
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16. Development and application of shunt active filters for three-phase four-wire systems / Estudo e aplicação de filtros ativos paralelos para sistemas trifasicos com quatro fios
Electricity power quality has gained increased importance in the past few years. The growing number of power electronicsbased loads has created a preoccupation about harrnonic distortion in electric systems. Electricity power quality is an important issue both for energy utilities and consumers. Harrnonic poIlution may cause severe problems to electricity ut
Publicado em: 2005
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17. Investigações relativas ás linhas de transmissão horizontal e vertical de perdas elevadas
This document presents the laboratory measurements and time and frequency domain simulations and calculations regarding the high loss horizontal and vertical transmission lines aiming at improve the knowledge of their performance and well understand the electromagnetic interaction between the lightning channel and the electrical facilities. Impulsive and har
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 12/07/2004
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18. Locomotivas de C.A : uma analise harmonica da corrente
AC thyristor controlled electric traction became very usual around the world. Thyristors provide good control performance but they always cause problems to the traction electric system. Overvoltages may arise in the contact line feeding the locomotive and also harmonics generated in the thyristors may affected the grid to which the whole system is connected.
Publicado em: 1993
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19. Gradadores de ciclo integral para acionamento de fornos a resistencia
The objective of this thesis is to research the behavoir of RESISTANCE ELECTRICAL FURNACE THYRISTOR-CONTROLLED BY INTEGRAL-CYCLE TRIGGERING and to develop the equations which govern its functioning and also to study some properties of this especial load. A three-phase digital thyristor controlled prototype of furnace, was developed.lt presents synchronous st
Publicado em: 1992
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20. RESONANT OVERVOLTAGES DUE TO TRANSFORMER ENERGIZATION IN THREE PHASE SYSTEMS / ANÁLISE DE SOBRETENSÕES RESSONANTES DEVIDO A ENERGIZAÇÃO DE TRANSFORMADORES EM SISTEMAS TRIFÁSICOS
Transient overvoltages involving transformer energization, in three phase HV systems, deserve special attention in insulation coordination studies due to the very high values that voltages can reach in a period of a few seconds. Some resonant effects can possibly occur due to harmonics in the magnetizing inrush current. The objective of the present study is
Publicado em: 1982
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21. Correct tonotopic representation is necessary for complex pitch perception
The ability to extract a pitch from complex harmonic sounds, such as human speech, animal vocalizations, and musical instruments, is a fundamental attribute of hearing. Some theories of pitch rely on the frequency-to-place mapping, or tonotopy, in the inner ear (cochlea), but most current models are based solely on the relative timing of spikes in the audito
National Academy of Sciences.
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22. Interaction of apical and basal membrane ion channels underlies electroreception in ampullary epithelia of skates.
The exquisite sensitivity of elasmobranch fishes to electric fields is thought to reside in electroreceptive organs called ampullae of Lorenzini. We measured the stimulus-response behavior of ampullary organs excised from skates. Under open-circuit conditions, the ampullary organ showed three distinct response states: spontaneous repetitive spikes, evoked sp
The Biophysical Society.
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23. Localization and function of the electrical oscillation in electroreceptive ampullary epithelium from skates.
A steady, spontaneous current oscillation (1 nA p-p) occurs in voltage-clamped, isolated ampullary organs (canal, ampulla, and nerve) from skates (Raja). Spectral analysis showed that energy in the oscillation was confined to a narrow band of frequencies (3 Hz) about a fundamental frequency (32 Hz at 20 degrees C) and in harmonics. The frequency of the oscil