859 resultados para Energia elétrica - Desenvolvimento sustentável


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As técnicas qualitativas disponiveis para a modelagem de cenários têm sido reconhecidas pela extrema limitação, evidenciada no principio das atividades do processo, como a fase inicial de concepção. As principais restrições têm sido: • inexistência de uma ferramenta que teste a consistência estrutural interna do modelo, ou pela utilização de relações econômicas com fundamentação teórica mas sem interface perfeita com o ambiente, ou pela adoção de variações binárias para testes de validação; • fixação "a priori" dos possíveis cenários, geralmente classificados sob três adjetivos - otimista, mais provável e pessimista - enviesados exatamente pelos atributos das pessoas que fornecem esta informação. o trabalho trata da utilização de uma ferramenta para a interação entre uma técnica que auxilia a geração de modelos, suportada pela lógica relacional com variações a quatro valores e expectativas fundamentadas no conhecimento do decisor acerca do mundo real. Tem em vista a construção de um sistema qualitativo de previsão exploratória, no qual os cenários são obtidos por procedimento essencialmente intuitivo e descritivos, para a demanda regional por eletricidade. Este tipo de abordagem - apresentada por J. Gershuny - visa principalmente ao fornecimento de suporte metodológico para a consistência dos cenários gerados qualitativamente. Desenvolvimento e estruturação do modelo são realizados em etapas, partindo-se de uma relação simples e prosseguindo com a inclusão de variáveis e efeitos que melhoram a explicação do modelo. o trabalho apresenta um conjunto de relações para a demanda regional de eletricidade nos principais setores de consumo residencial, comercial e industrial bem como os cenários resultantes das variações mais prováveis das suas componentes exógenas. Ao final conclui-se que esta técnica é útil em modelos que: • incluem variáveis sociais relevantes e de dificil mensuração; • acreditam na importância da consistência externa entre os resultados gerados pelo modelo e aqueles esperados para a tomada de decisões; • atribuem ao decisor a responsabilidade de compreender a fundamentação da estrutura conceitual do modelo. Adotado este procedimento, o autor aqui recomenda que o modelo seja validado através de um procedimento iterativo de ajustes com a participação do decisor. As técnicas quantitativas poderão ser adotadas em seguida, tendo o modelo como elemento de consistência.

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A energia elétrica é fundamental para o desenvolvimento de qualquer país e o Brasil atravessa atualmente uma crise energética devido ao baixo nível de seus reservatórios, então diversos temas sobre o sistema elétrico brasileiro vêm à tona a fim de dar mais confiabilidade e evitar futuros racionamentos, permitindo assim que a escassez de energia não seja um impeditivo para o crescimento econômico do país. O presente estudo calcula o potencial de redução de demanda por energia elétrica no estado do Rio de Janeiro através do modelo de preço variável, que consiste em ter tarifas distintas para o horário de ponta e fora de ponta. Este é um entre diversos programas de eficiência energética existentes no mundo atualmente. Para tal cálculo as principais premissas são a projeção de demanda máxima coincidente, o número de consumidores por classe e a elasticidade preço da demanda por energia elétrica. A partir dai são sugeridos três cenários de penetração de AMI (Advanced Metering infrastructure), e três cenários de variação de preço, chegando assim a nove resultados possíveis.

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Electrical energy today is an essential element in the life of any human being. Through the access to electrical energy it is possible to enjoy dignified conditions of life, having in mind the possibility of making use of minimal material conditions of life. The lack of access to electricity is directly linked to poverty and degrading conditions of life, in which are some communities in Brazil, especially the more isolated from urban centers. Access to the electric service is a determining factor for the preservation of human dignity, constitutional principle inscribe in the art.1 of the Federal Constitution, and the promotion of development, being a right of everyone and a duty of the State to promote universal access. For that reason, focuses mainly on the analysis of their setting as a fundamental social right and its importance for national development. For this, the theoretical and descriptive method was used, with normative and literary analysis, in particular the Constitution of 1988. This study also discusses the form of action of the State in the energy sector, to give effect to the fundamental social right of access to electricity, the characteristics of public service and the principles that guide it, in addition to the role of public policies in universalization of access, in particular the analysis of the Program Luz para Todos, and the function of regulation in the implementation of these policies and the provision of adequate public services.

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The recent insertion of biodiesel derived from oily vegetables in the Brazilian energetic matrix calls for the study of some aspects that belong to it. The analysis of the carbonized energetic pattern concerns the paradigm of economic development that is constitutionally enshrined sustainable development which make environmental protection compatible with the needs of the economic rationality. This text is structured according to the ideas of modern hermeneutic that sees substantial value in the principles capable of create a harmonious relationship between law and society. The study of the constitutional principles to conduct a legal analysis about the National Program for Production and Use of Biodiesel - PNPB. The aim of the research is the study of PNPB ahead with the constitutional principles governing the economic order. To achieve this end we studied the sustainable development as a constitutional principle. We start with the notion that the thematic principles, and fundamental to understanding the dimension of sustainable development institute, since its concept is closely related to the applications of the principles enshrined in virtually all the constitutional order of the Western world. Then this was the National Energy Policy, initiating the approach by guiding principles of the National Energy Policy to develop the theme of public policy in the energy sector. Therefore, we studied the National Program of Biodiesel Production and Use - PNPB. From a technical introduction to the concept of biodiesel and a brief historical background, analyzing their advantages compared to fossil fuels predominantly used. Then it became a regulatory overview of the Brazilian legislation on the subject, central to understanding the plans and objectives pursued by the Brazilian government with encouraging the production of biodiesel. Finally discussed the tax incentives for production and use of biodiesel in Brazil. From the idea of federalism, characterized the tax as an instrument of state intervention in the economy. And finally it brought the tax incentives of Law No. 11.116/2005 in the face of the constitutional principles of economy and tax, and tax incentives from projects related to the Kyoto Protocol

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It is verified worldwide an increasing concern with the protection of natural resources in the planet, a fact that became relevant in Brazil since the promulgation of the Constitution of 1988, based on the viewpoint of sustainable development, which seeks to promote economic activities in the country according to the need for conservation and preservation of natural resources for the use of present and future generations. In addition, we seek to reduce the differences that occur in our society by determining as a fundamental objective to be persecuted by the Federative Republic of Brazil the reduction of social and regional inequalities. A value that should also be observed in the context of economic activities developed here, since it is a general principle of financial and economic order of the country. Therefore, considering the exhaustion of world s reserves of fossil fuels, as well as the impacts on the environment, especially for the large emission of greenhouse effect gases, the debate about the need to change the global energy matrix increases while alternative energy sources appears as a bet to fulfill the contemporary aspirations for sustainability, and Brazil emerges in a very favorable position, because it has the essential natural conditions to allow this sector s full development. In this perspective, the work has the scope to analyze how the production of alternative energy sources may act in the search for concretization of constitutional values, to promote sustainable development for present and future generations, and to reduce regional and social inequalities in an attempt to improve the quality of life of the population. It will also be observed the current regulatory framework of alternative energy sources in the national laws to verify the existence of legal and institutional security, which is necessary to guarantee the full development of the sector in the country. And to investigate the expected results, it will be observed through the concrete evaluation of specific practices adopted in the industry, analyzing their actual compliance with the constitutional provisions under analysis, based on the examination of the possibility of using renewable biomass sources for biofuel production, promoting development to the country, indicating the opening lines about how this important sector can act to solve the energy challenge today

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The gradual inclusion of biofuels is a necessary change that countries must include in their energy mixes. Energy sources still widely used in the world, such as oil and coal, are endowed with a high pollution load to the environment, bringing damages to the water, to the air and to humans as well. In addition, although there are conflicting studies, they are also identified as major causes of the greenhouse effect and the global warming phenomenon. They are, moreover, finite sources of energy, given that its reserves will surely run out. However, even if the introduction of biofuels, such as ethanol, in the energy mix is crucial for the survival of the present and future populations, this insertion cannot settle so disorderly and, thus, one must ensure the quality of these resources and promote transparency in international trade. In this manner, a certification process for ethanol is essential to attest that this biofuel meets the sustainable requirements defined for its production. Hence, this study sought to address the importance of the adoption of certification in the ethanol industry, according to the principle of sustainable development, by analyzing the evolution of its concept, its combination with the fundamental objectives sculptured in the Constitution of 1988, its regulation under Brazilian laws and the need for a balance between economic activities and the mentioned principle. The work also encompassed the criteria used to establish certification standards and their participating actors, combined with a study of ongoing initiatives. Finally, the consequences of the adoption of a certification process for ethanol in Brazil were presented, both in terms of sustainable development and in international trade

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Most algorithms for state estimation based on the classical model are just adequate for use in transmission networks. Few algorithms were developed specifically for distribution systems, probably because of the little amount of data available in real time. Most overhead feeders possess just current and voltage measurements at the middle voltage bus-bar at the substation. In this way, classical algorithms are of difficult implementation, even considering off-line acquired data as pseudo-measurements. However, the necessity of automating the operation of distribution networks, mainly in regard to the selectivity of protection systems, as well to implement possibilities of load transfer maneuvers, is changing the network planning policy. In this way, some equipments incorporating telemetry and command modules have been installed in order to improve operational features, and so increasing the amount of measurement data available in real-time in the System Operation Center (SOC). This encourages the development of a state estimator model, involving real-time information and pseudo-measurements of loads, that are built from typical power factors and utilization factors (demand factors) of distribution transformers. This work reports about the development of a new state estimation method, specific for radial distribution systems. The main algorithm of the method is based on the power summation load flow. The estimation is carried out piecewise, section by section of the feeder, going from the substation to the terminal nodes. For each section, a measurement model is built, resulting in a nonlinear overdetermined equations set, whose solution is achieved by the Gaussian normal equation. The estimated variables of a section are used as pseudo-measurements for the next section. In general, a measurement set for a generic section consists of pseudo-measurements of power flows and nodal voltages obtained from the previous section or measurements in real-time, if they exist -, besides pseudomeasurements of injected powers for the power summations, whose functions are the load flow equations, assuming that the network can be represented by its single-phase equivalent. The great advantage of the algorithm is its simplicity and low computational effort. Moreover, the algorithm is very efficient, in regard to the accuracy of the estimated values. Besides the power summation state estimator, this work shows how other algorithms could be adapted to provide state estimation of middle voltage substations and networks, namely Schweppes method and an algorithm based on current proportionality, that is usually adopted for network planning tasks. Both estimators were implemented not only as alternatives for the proposed method, but also looking for getting results that give support for its validation. Once in most cases no power measurement is performed at beginning of the feeder and this is required for implementing the power summation estimations method, a new algorithm for estimating the network variables at the middle voltage bus-bar was also developed

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The usual programs for load flow calculation were in general developped aiming the simulation of electric energy transmission, subtransmission and distribution systems. However, the mathematical methods and algorithms used by the formulations were based, in majority, just on the characteristics of the transmittion systems, which were the main concern focus of engineers and researchers. Though, the physical characteristics of these systems are quite different from the distribution ones. In the transmission systems, the voltage levels are high and the lines are generally very long. These aspects contribute the capacitive and inductive effects that appear in the system to have a considerable influence in the values of the interest quantities, reason why they should be taken into consideration. Still in the transmission systems, the loads have a macro nature, as for example, cities, neiborhoods, or big industries. These loads are, generally, practically balanced, what reduces the necessity of utilization of three-phase methodology for the load flow calculation. Distribution systems, on the other hand, present different characteristics: the voltage levels are small in comparison to the transmission ones. This almost annul the capacitive effects of the lines. The loads are, in this case, transformers, in whose secondaries are connected small consumers, in a sort of times, mono-phase ones, so that the probability of finding an unbalanced circuit is high. This way, the utilization of three-phase methodologies assumes an important dimension. Besides, equipments like voltage regulators, that use simultaneously the concepts of phase and line voltage in their functioning, need a three-phase methodology, in order to allow the simulation of their real behavior. For the exposed reasons, initially was developped, in the scope of this work, a method for three-phase load flow calculation in order to simulate the steady-state behaviour of distribution systems. Aiming to achieve this goal, the Power Summation Algorithm was used, as a base for developping the three phase method. This algorithm was already widely tested and approved by researchers and engineers in the simulation of radial electric energy distribution systems, mainly for single-phase representation. By our formulation, lines are modeled in three-phase circuits, considering the magnetic coupling between the phases; but the earth effect is considered through the Carson reduction. Its important to point out that, in spite of the loads being normally connected to the transformers secondaries, was considered the hypothesis of existence of star or delta loads connected to the primary circuit. To perform the simulation of voltage regulators, a new model was utilized, allowing the simulation of various types of configurations, according to their real functioning. Finally, was considered the possibility of representation of switches with current measuring in various points of the feeder. The loads are adjusted during the iteractive process, in order to match the current in each switch, converging to the measured value specified by the input data. In a second stage of the work, sensibility parameters were derived taking as base the described load flow, with the objective of suporting further optimization processes. This parameters are found by calculating of the partial derivatives of a variable in respect to another, in general, voltages, losses and reactive powers. After describing the calculation of the sensibility parameters, the Gradient Method was presented, using these parameters to optimize an objective function, that will be defined for each type of study. The first one refers to the reduction of technical losses in a medium voltage feeder, through the installation of capacitor banks; the second one refers to the problem of correction of voltage profile, through the instalation of capacitor banks or voltage regulators. In case of the losses reduction will be considered, as objective function, the sum of the losses in all the parts of the system. To the correction of the voltage profile, the objective function will be the sum of the square voltage deviations in each node, in respect to the rated voltage. In the end of the work, results of application of the described methods in some feeders are presented, aiming to give insight about their performance and acuity

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Conselho Nacional de Desenvolvimento Científico e Tecnológico

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The opening of the Brazilian market of electricity and competitiveness between companies in the energy sector make the search for useful information and tools that will assist in decision making activities, increase by the concessionaires. An important source of knowledge for these utilities is the time series of energy demand. The identification of behavior patterns and description of events become important for the planning execution, seeking improvements in service quality and financial benefits. This dissertation presents a methodology based on mining and representation tools of time series, in order to extract knowledge that relate series of electricity demand in various substations connected of a electric utility. The method exploits the relationship of duration, coincidence and partial order of events in multi-dimensionals time series. To represent the knowledge is used the language proposed by Mörchen (2005) called Time Series Knowledge Representation (TSKR). We conducted a case study using time series of energy demand of 8 substations interconnected by a ring system, which feeds the metropolitan area of Goiânia-GO, provided by CELG (Companhia Energética de Goiás), responsible for the service of power distribution in the state of Goiás (Brazil). Using the proposed methodology were extracted three levels of knowledge that describe the behavior of the system studied, representing clearly the system dynamics, becoming a tool to assist planning activities

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Engenharia Elétrica - FEIS

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)