Estabilizador de sistema de potência para máquinas síncronas de polos salientes utilizando a transformada Wavelet

The power system stabilizers are used to suppress low-frequency electromechanical oscillations and improve the synchronous generator stability limits. This master thesis proposes a wavelet-based power system stabilizer, composed of a new methodology for extraction and compensation of electromechanical oscillations in electrical power systems based on the scaling coefficient energy of the maximal overlap discrete wavelet transform in order to reduce the effects of delay and attenuation of conventional power system stabilizers. Moreover, the wavelet coefficient energy is used for electric oscillation detection and triggering the power system stabilizer only in fault situations. The performance of the proposed power system stabilizer was assessed with experimental results and comparison with the conventional power system stabilizer. Furthermore, the effects of the mother wavelet were also evaluated in this work

Uso de funções de alívio para estimar o efeito de chaveamentos corretivos na eliminação de congestionamentos em sistemas de potência

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Contribuições ao método de rastreamento de máxima potência para sistemas fotovoltaicos

The scarcity of natural resources and the search for alternative energy sources promote a rapid change in the energy world. Among the renewable energy sources, solar energy is the most promising, presenting technology of greatest growth rate nowadays. Researchers around the world are seeking ways to facilitate their progress, developing technologies with higher efficiency and lower cost. As a contribution to global progress, this master thesis proposes the development of a strategy of maximum power tracking based on perturbation and observation method for photovoltaic systems. The proposed control strategy is based on active power balance of the system, with a reduced number of sensors. It also allows the PV system to act as a regulator of the power quality at the point of commom coupling (PCC), compensating the harmonic distortion and power factor of the current netw

Projeto em FPGA de um controlador unificado para correção de fator de potência em retificadores boost bidirecionais monofásicos

The use of Field Programmable Gate Array (FPGA) for development of digital control strategies for power electronics applications has aroused a growing interest of many researchers. This interest is due to the great advantages offered by FPGA, which include: lower design effort, high performance and highly flexible prototyping. This work proposes the development and implementation of an unified one-cycle controller for boost CFP rectifier based on FPGA. This controller can be applied to a total of twelve converters, six inverters and six rectifiers defined by four single phase VSI topologies and three voltage modulation types. The topologies considered in this work are: full-bridge, interleaved full-bridge, half-bridge and interleaved half-bridge. While modulations are classified in bipolar voltage modulation (BVM), unipolar voltage modulation (UVM) and clamped voltage modulation (CVM). The proposed project is developed and prototyped using tools Matlab/Simulink® together with the DSP Builder library provided by Altera®. The proposed controller was validated with simulation and experimental results

A Hora e o Nevoeiro: discurso épico, vontade de potência e mal-estar da modernidade no poema Mensagem de Fernando Pessoa

Considering articles written for Fernando Pessoa in 1912 about The new Portuguese poetry , where he already proclaimed the appearance of the Super-Camões, poet that would be able to revolutionize Portuguese literature e, concomitantly, to make resurging from rubble the Portuguese nation; we understand that, decades before the writing of Message, the poet was already armed with a Will of Power , expression of Friedrich Nietzsche that incorporate the idea of resurgence to the man like creator of news values. Fernando Pessoa believed to make his poetical word, the epic, restoring word of the ideas of Messianism and Fifth Empire as the pushing force of the new Portuguese largeness. However, we look for to investigate the conditions of Malaise that surround the universe of the poem and that restrict its capacity of action on the reality in its return, a time that the space destined in modernity to the poet and to his poetry hindered him of a devoted and positive action, We select therefore theorist like Sigmund Freud e Walter Benjamin

As orquestras invadem as salas de estar: redefinição dos padrões e espaços para a escuta musical no Rio de Janeiro (1926-1931)

In the late nineteenth and early twentieth century, a series of technical innovations have been commercially and widespread on some urban groups everyday, in Brazil. Some of these technological innovations have played an important role in large-scale distribution of artistic works, which until then had an extremely limited potential for diffusion. Development of devices that can record and play music has been mechanically inserted into this logic, while the gramophones, phonographs, cylinders and discs became popular. By this time a new moment for production and consumption of music had started. Especially since the begging of electrical system for registration and production of sounds, this process bought important meaning to the way some peoples in Rio would leasing and sense music, besides it had contributed substantially to changes in the spatial references of these individuals

Nos tempos do blackout: cena musical, práticas urbanas e a ressignificação da Rua Chile, Natal-RN

This study aims to analyze the process of resignification of Chile Street, in Natal, from the development of a music scene in the late 1990s. Chile Street, as part of the Historic Centre of Natal, had its images constructed from the discursive practices and everyday life of its regular visitors, leading to a series of symbolic and imaging transformations throughout the twentieth century. Initially transformed into glamorous space as a result of urban actions of the new republic of Albuquerque Maranhão, in the early twentieth century, Ribeira and Chile Street, specifically, came to be seen as bohemian area, during the war time"; followed by a marginal phase, it was eventually transformed into the main rocker area of Natal, with the development of a musical scene in the second half of the 1990s. This music scene, its practices, economic interests, cultural events and identity ties created among their practitioners made Chile Street, "in the time of Blackout night club", an "alternative" space. As the historic centers, inserted in the logic of postmodern city marketing, both spaces are dynamic in their practices, as in their images, Chile Street also suffered changes in its meanings and symbols, around the year 2000 when the alternative-underground space became a pop space, where people from various parts of the city began attending its events and places, transforming it into a point of very heterogeneous sociability

A apreciação musical infantil: aspectos da constituição da infância contemporânea no discurso de crianças do Ensino Fundamental

Music can be found in peculiar historical and social context with distinct functions, such as religious rituals, ethic-esthetic education of subjects, therapeutic elements, critic and maintenance of established patterns, among others. Considered as language, music acts on dialogue dimensions of the body, the senses, the affectionate-cognitive and of social interactions. Their uses reveal the social forces that cross the culture and constitution of subjectivities. The attribution of senses by the subjects to musical production reveals the cultural voices in dialogue, that circumscribe determined social places to them. Our aim in this work is to investigate the child musical appreciation, with children about 7 to 9 years old, and, by attributing uses and senses to music, unveil the voices that settle the places intended and assumed by infancy in contemporaneity The child constructs its musical appreciation through cultural access and mediation, possible by circulation in several socializing groups like family, school, church, infant groups, community groups and, more recently, publicity and media These last two spheres, enabled by the development of the technological means of communication, contributed to the dissemination of the set of consume ideas and for the emergence of the cultural industry, characteristic of the capitalistic production way in its present configuration. They develop new possibilities of perception of the world, in which the limits between childhood and adulthood are not anymore the same that have been established in previous centuries. So, the child musical appreciation is constituted by homogeneity regarding the senses built and disseminated by cultural industry and by the logical merchandizing, and singularities, associated to the construction of senses in interaction with global, local, and multiple contexts, through which the subject circulates and constitutes himself polyphonically

Análise do Efeito Goos-Hanchen e Não-reciprocidade do fluxo de potência em antiferromagnéticos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior