Voltage regulation in power distribution substation transformer using fuzzy implementation

Este trabalho apresenta um controlador fuzzy para realizar o ajuste automático de tensão em transformadores de subestação de distribuição de energia elétrica. Tal controle atuará em tempo-real nos transformadores dotados de comutadores de tap sob carga. O sistema inteligente foi empregado para tornar o relé regulador de tensão adaptativo. Ainda como foco do estudo, pretende-se atuar apenas na subestação de distribuição, realizando medições no barramento secundário e implementando ações de controle também neste barramento. A capacidade dos sistemas fuzzy em tratar incertezas, assim como sua habilidade em interpretar informações qualitativas, permitiu a formulação de uma estratégia de controle de tensão que atende a todas as regulamentações dos órgãos fiscalizadores brasileiros e, também, os anseios das concessionárias de distribuição frente aos aspectos relacionados com a qualidade de energia, pois os resultados obtidos foram bem satisfatórios.A fuzzy controller is introduced in this paper in order to make the voltage adjustment in power distribution substation transformer. The real-time controller in each case would act on power transformers equipped with under-load tap changers. Learning systems are employed to turn the voltage-control relays into adaptive devices. The scope of the present study has been limited to the power distribution substation, and both the voltage measurements and control actions are carried out on the secondary bus. The capacity of fuzzy systems to handle approximate data, together with their unique ability to interpret qualitative information, make it possible to design voltage control strategies that satisfy both the requirements of the Brazilian regulatory bodies and the real concerns of the electric power distribution companies in relation to the aspects involved with power quality, since the test results were highly satisfactory.FAPES

Estudo experimental do momento de inércia de um cone

Neste trabalho, mostra-se um caminho diferente para se estudar o momento de inércia de um corpo em rotação. Descreve-se um experimento que permite estabelecer como a inércia de um cone depende de sua massa e geometria. A partir de medidas de freqüência ou corrente elétrica, determinam-se parâmetros como os expoentes e a constante da convencional equação do momento de inércia de um cone. Para isso escolhem-se três cones de massas diferentes, tendo dois deles 10,0 cm e o outro 6,0 cm de diâmetros. Os resultados obtidos mostraram que o sistema e o procedimento de medida utilizado podem ser uma alternativa prática nos laboratórios de ensino.In this work, it is shown a different way to study the moment of inertia of a body. It is proposed an experiment that allows establishing how the inertia of a cone depends on its mass and geometry. The parameters are determined as follows: the exponents and the constant of the conventional equation of the cone's moment of inertia, starting from measurements of frequency or current. Three cones of distinct masses are used, two of them 10,0 cm of diameter, while the other ones 6,0 cm diameter. The obtained results show that the system and the procedure used can be an alternative in the teaching laboratories.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Experimental study of the moment of inertia of a cone

Neste trabalho, mostra-se um caminho diferente para se estudar o momento de inércia de um corpo em rotação. Descreve-se um experimento que permite estabelecer como a inércia de um cone depende de sua massa e geometria. A partir de medidas de freqüência ou corrente elétrica, determinam-se parâmetros como os expoentes e a constante da convencional equação do momento de inércia de um cone. Para isso escolhem-se três cones de massas diferentes, tendo dois deles 10,0 cm e o outro 6,0 cm de diâmetros. Os resultados obtidos mostraram que o sistema e o procedimento de medida utilizado podem ser uma alternativa prática nos laboratórios de ensino.In this work, it is shown a different way to study the moment of inertia of a body. It is proposed an experiment that allows establishing how the inertia of a cone depends on its mass and geometry. The parameters are determined as follows: the exponents and the constant of the conventional equation of the cone's moment of inertia, starting from measurements of frequency or current. Three cones of distinct masses are used, two of them 10,0 cm of diameter, while the other ones 6,0 cm diameter. The obtained results show that the system and the procedure used can be an alternative in the teaching laboratories

Experimental study of the centripetal force

We describe an experimental set-up for studying and determining the centripetal force acting on a body whose mass and radius of circular trajectory are known. The experimental behaviour is determined and compared with theoretical predictions by using a system that allows for the evaluation of the angular velocity by means of electric current measurements, and by assuming a potential dependence of the force on the body mass, radius and angular velocity. © 2007 IOP Publishing Ltd

Experimental study of the moment of inertia of a cone - angular variation and inertia ellipsoid

In this paper, an experimental set-up which differs from the traditional ones is established in order to determine the moment of inertia of a right circular cone. Its angular variation and inertia ellipsoid are determined by means of an experimental study. In addition, a system that allows for the evaluation of the angular acceleration and torque through electric current or frequency measurement is utilized

Power quality analysis applying a hybrid methodology with wavelet transforms and neural networks

A hybrid system to automatically detect, locate and classify disturbances affecting power quality in an electrical power system is presented in this paper. The disturbances characterized are events from an actual power distribution system simulated by the ATP (Alternative Transients Program) software. The hybrid approach introduced consists of two stages. In the first stage, the wavelet transform (WT) is used to detect disturbances in the system and to locate the time of their occurrence. When such an event is flagged, the second stage is triggered and various artificial neural networks (ANNs) are applied to classify the data measured during the disturbance(s). A computational logic using WTs and ANNs together with a graphical user interface (GU) between the algorithm and its end user is then implemented. The results obtained so far are promising and suggest that this approach could lead to a useful application in an actual distribution system. (C) 2009 Elsevier Ltd. All rights reserved.CAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior)CNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico)FAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo