Navegando por Assunto "Harmonics (electrics waves)"

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Acesso aberto (Open Access)
Otimização multiobjetivo da compensação de potência reativa em redes de distribuição considerando restrições de distorção harmônica
(Universidade Federal do Pará, 2014-11-14) AZEVEDO, Manoel Socorro Santos; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813
The localization of capacitors banks in the electric power distribution networks, correctly sized, looks for to compensate eventual excesses of circulation of reactive power for transmission lines, what implies the reduction of operational costs for the reduction of the energy losses and an increase of the capacity of transmission of active power assuring the established levels of voltage and power factor simultaneously. The proliferation of the nonlinear loads produced a change in the scenarios of study of the electric power systems due to the degradation effects that the harmonic generated by them cause about the quality of the electric power. Considering this new scenario, this thesis has as general objective to develop a computational tool using computational intelligence supported in genetic algorithms (GA), for the multiobjective optimization of the reactive power compensation in distribution electric networks able to locate and size in a good way the necessary compensation units to achieve the best economic benefits and the maintenance of the indexes of quality of the energy settled down by the Brazilian norms. As technological innovation of the work, the developed computational tool allows to optimize the compensation of the reactive power to improve the power factor in polluted distribution networks with harmonics that, differently of previous methods, not alone it uses capacitors banks, but also harmonic filters with that objective. The NSGA-II algorithm is used to determine optimal solutions of Pareto for the problem and it allows the specialist to determine the most effective solutions. The formulation proposed in this thesis for the solution of the problem presents several novelties being able to highlight that the achieved solution allows to determine the compensation of reactive power in systems with certain harmonic penetration, complying with pertinent standards of power quality, with respect to the tolerated levels of harmonic distortion.
Acesso aberto (Open Access)
Projeto multicritério de filtros harmônicos passivos para instalações industriais utilizando técnicas de inteligência computacional
(Universidade Federal do Pará, 2013-05-29) LEITE, Jandecy Cabral; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
Due to the importance of the industrial growth in the North and in particular the Industrial Pole of Manaus (PIM), it is important to have mathematical tools that facilitate the expert decisions on the selection and sizing of harmonic filters needed to neutralize the harmful effects of harmonics generated by nonlinear loads of industry and achieve compliance with the power quality standards. Moreover, as the passive harmonic filters have the capacity to generate reactive power to the network, they are effective compensating reactive power means and therefore can achieve significant savings in sales of electric energy consumed by these industrial facilities. This thesis aims to develop a mathematical method and a computational tool for the selection of the configuration and the design parameters of a set of passive harmonic filters for industrial electrical systems. In this direction, the optimization problem of compensation of harmonics through passive filters is formulated as a multi-objective problem that considers both the goals of reducing harmonic distortion as the economic effectiveness of the project considering the characteristics of the Brazilian system of tariffs. Moreover, the presented formulation considers relevant restrictions imposed by the national and foreign standards. A computational solution to this problem was achieved using the NSGA-II genetic algorithm which determines a set of Pareto optimal solutions (Frontier) that enable the designer to choose the most appropriate solutions to the problem. Furthermore, the computational tool developed has several new features as: not only calculates the parameters that characterize the filters, but also selects the type of configuration and the number of branches of the filter in each candidate bus according to a set of predetermined settings; has implemented two standards for assessing the constraints of power quality (Prodist Modulo-8 and IEEE 519-92) that can be selected by the user; determines solutions with good performance indicators for various characteristic and non-characteristic scenarios of the system that allow to represent: the daily variations of the load as well as the variations of system parameters and filters; evaluates the cost of energy bills in a grid that has different industrial operating conditions (characteristic scenarios) and assesses the economic effect of harmonic filters as reactive power compensators. To develop the computational tool of this thesis, it was used a phase-coordinates model for the electric power grids of industrial and services installations to program additional computational tools. These tools comprise a frequency scan program, a harmonic power flow program for the harmonic current injection method and a fundamental frequency power flow program. The positive results of this thesis, from the analysis of several practical examples show the advantages of the developed method.