Electrical Power Quality
Mostrando 37-48 de 81 artigos, teses e dissertações.
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37. Analise dos sistemas de proteção e controle de instalações industriais com geradores sincronos durante operação ilhada / Protection and control systems analysis of industrial plants with synchronous generators during islanded operation
Modern industrial systems are very sophisticated installations with a high number of automatic processes and capability of isolated (islanded) operation after contingences by using onsite generators composed mainly by synchronous machines and steam turbines. Such installations, in the presence of generators, are generically called autoproducers. Since many o
Publicado em: 2009
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38. SYNTHESIS METHODOLOGY FOR SIMPLIFIED ZVT TOPOLOGIES APPLIED TO BIDIRECTIONAL PWM POLES / METODOLOGIA DE SÍNTESE DE TOPOLOGIAS ZVT SIMPLIFICADAS APLICADAS A PÓLOS PWM BIDIRECIONAIS
Among the soft-switching techniques, the zero-voltage-transition (ZVT) technique has been accepted well by the industry due its attractive characteristics, such as simplicity, low losses in the auxiliary commutation circuit (ACC), operation with soft-switching for a wide load range, and closest operation to the PWM converter counterpart. In three-phase volta
Publicado em: 2009
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39. Avaliação do impacto de motores de indução trifásicos em redes de distribuição de energia elétrica e uma proposta de regulamentação para seu acesso às redes de baixa tensão. / Evaluation of the impact of induction motors in electrical distribution networks and a regulation proposal to their access to low voltage networks.
Este trabalho tem por objetivo apresentar e discutir alguns modelos desenvolvidos para a avaliação do impacto de motores de indução trifásicos nas redes de distribuição de energia elétrica partindo de seus dados de placa e utilizando algoritmos evolutivos para o cálculo dos parâmetros elétricos do circuito equivalente do motor. A discussão é de
Publicado em: 2009
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40. ELECTRIC DISTRIBUTION POWER SYSTEMS RELIABILITY OPTIMIZATION: An Approach Considering the Selection and Allocation of Protection and Switching Devices / OTIMIZAÇÃO DA CONFIABILIDADE DE SISTEMAS DE DISTRIBUIÇÃO DE ENERGIA ELÉTRICA: Uma Abordagem Considerando a Seleção e Alocação de Dispositivos de Proteção e Manobras
One of the main goals of the electric utilities is to provide energy to its customers in a reliable and low cost way. Traditionally, the electricity sector regulatory commissions impose continuity targets, which must be carried out, to avoid great penalties. For many years, the electric utilities have adopted the practice of allowing the increment of tempora
Publicado em: 2009
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41. Mel de abelhas nativas e africanizadas do estado de Alagoas : composição química, segurança microbiológica e atividade terapêutica. / Honey of beens native and africanized state of Alagoas State : chemical composition,security microbiological and activity therapy.
The rational development of bees is one of the most promising agricultural activities, since it is essentially self-sustaining family and therefore helps to maintain and restore the environment, through their role in pollination, and guarantee income to the producer who employs his family on it. Honey is the main product of this activity, being generated by
Publicado em: 2009
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42. Conservação de energia elétrica: um enfoque em consumidores residenciais / CONSERVATION OF ELECTRIC ENERGY AN APPROACH IN RESIDENTIAL CONSUMERS
This work investigates the most used forms of electric energy conservation, especially in Brazil, without neglecting the power quality aspect, emphasizing residential loads. Among the investigated issues, the technological is a very important one since it comprises the application of efficient equipment. However, it is not forgotten the human actions, with g
Publicado em: 2008
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43. Estimação de estados de distorções harmônicas em sistemas elétricos de potência utilizando estratégias evolutivas. / Power systems harmonic distortion state estimation using evolutionary strategy.
The aim of the present thesis is to develop a Harmonic Distortion State Estimation algorithm for Power Systems. Although the cost of Power Quality Meters has decreased for a while now, it is still not practicable the use of one meter for each real system bus. This demands a Harmonic Distortion State Estimation (HDSE) algorithm to find the harmonic components
Publicado em: 2008
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44. Fuzzy logic and particle swarm optimization for reactive power and voltage control / Logica nebulosa e tecnica de otimização particle swarm aplicados ao controle de tensão e de potencia reativa
Due to the growing electrical power demand and the lag of transmission system infrastruc ture, the operation of transmission systems approaches to its limits and increases the complexity of the system operation. ln this context, in order to satisfy the more rigid operating conditions, managing voltage profile and power flow in a more effective way becomes ve
Publicado em: 2008
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45. Automação como recurso de planejamento de redes de distribuição de energia elétrica. / Automation as resource for distribution systems planning.
Concerning the components of an electrical distribution network and their susceptibility to functional failures or need for maintenance actions, planning and project criteria should be adopted to assure continuity of energy supply even though some components may be out of work. Traditionally the power systems, especially in power transmission and distributio
Publicado em: 2008
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46. OUTFLOW FORECAST BASED ON ARTIFICIAL NEURAL NETORKS AND WAVELET TRANSFORM / PREVISÃO DE VAZÃO POR REDES NEURAIS ARTIFICIAIS E TRANSFORMADA WAVELET
The hydroelectricity system is responsible for 83.7% of the electric energy generated at Brazil. Therefore, the generation of electric power in Brazil depends basically on the natural flow rates distributed by twelve basins in the country. The quality of prediction of natural flow is of crucial importance for the Brazilian governmental agency, ONS (from the
Publicado em: 2008
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47. Avaliação da disponibilidade energética em atividade física realizada em bicicleta estacionária
Nowadays, the search of better life quality is related, invariably, to the developed practice of physical activity mainly at gyms. Although in these places, there is considerable expenditure of human energy, they are not characterized as an energy management model that can reflect in considerable economy in monthly electric energy consumption. The conception
Publicado em: 2008
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48. Eutrophication of Cruzeta reservoir in the representative basin of the Seridó river - RN. Natal / Eutrofização do Reservatório Cruzeta na bacia representativa do rio Seridó RN
Eutrophication has been listed as one of the main problems of water pollution on a global level. In the Brazilian semi-arid areas this problem takes even greater proportions due to characteristical water scarcity of the region. It is extremely important to the predictive eutrophication models development and to the reservoirs management in the semi-arid regi
Publicado em: 2008