Técnicas de simplificação de redes e otimização multiobjetivo para análise de variações de tensão em regime permanente provocadas por parques eólicos integrados ao sistema elétrico

This study presents a description of the development model of a representation of simplified grid applied in hybrid load flow for calculation of the voltage variations in a steady-state caused by the wind farm on power system. Also, it proposes an optimal load-flow able to control power factor on connection bar and to minimize the loss. The analysis process on system, led by the wind producer, it has as base given technician supplied by the grid. So, the propose model to the simplification of the grid that allows the necessity of some knowledge only about the data referring the internal network, that is, the part of the network that interests in the analysis. In this way, it is intended to supply forms for the auxiliary in the systematization of the relations between the sector agents. The model for simplified network proposed identifies the internal network, external network and the buses of boulders from a study of vulnerability of the network, attributing them floating liquid powers attributing slack models. It was opted to apply the presented model in Newton-Raphson and a hybrid load flow, composed by The Gauss-Seidel method Zbarra and Summation Power. Finally, presents the results obtained to a developed computational environment of SCILAB and FORTRAN, with their respective analysis and conclusion, comparing them with the ANAREDE

Controle Adaptativo Robusto para Filtros Ativos de Potência Paralelo

Conventional control strategies used in shunt active power filters (SAPF) employs real-time instantaneous harmonic detection schemes which is usually implements with digital filters. This increase the number of current sensors on the filter structure which results in high costs. Furthermore, these detection schemes introduce time delays which can deteriorate the harmonic compensation performance. Differently from the conventional control schemes, this paper proposes a non-standard control strategy which indirectly regulates the phase currents of the power mains. The reference currents of system are generated by the dc-link voltage controller and is based on the active power balance of SAPF system. The reference currents are aligned to the phase angle of the power mains voltage vector which is obtained by using a dq phase locked loop (PLL) system. The current control strategy is implemented by an adaptive pole placement control strategy integrated to a variable structure control scheme (VS-APPC). In the VS-APPC, the internal model principle (IMP) of reference currents is used for achieving the zero steady state tracking error of the power system currents. This forces the phase current of the system mains to be sinusoidal with low harmonics content. Moreover, the current controllers are implemented on the stationary reference frame to avoid transformations to the mains voltage vector reference coordinates. This proposed current control strategy enhance the performance of SAPF with fast transient response and robustness to parametric uncertainties. Experimental results are showing for determining the effectiveness of SAPF proposed control system

Software inteligente embarcado aplicado à correção de erro na medição de vazão em gás natural

This study developed software rotines, in a system made basically from a processor board producer of signs and supervisory, wich main function was correcting the information measured by a turbine gas meter. This correction is based on the use of an intelligent algorithm formed by an artificial neural net. The rotines were implemented in the habitat of the supervisory as well as in the habitat of the DSP and have three main itens: processing, communication and supervision

Algoritmos inteligentes para auto-correção, auto-verificação e auto-validação de medidas em sensores

This work presents a set of intelligent algorithms with the purpose of correcting calibration errors in sensors and reducting the periodicity of their calibrations. Such algorithms were designed using Artificial Neural Networks due to its great capacity of learning, adaptation and function approximation. Two approaches willbe shown, the firstone uses Multilayer Perceptron Networks to approximate the many shapes of the calibration curve of a sensor which discalibrates in different time points. This approach requires the knowledge of the sensor s functioning time, but this information is not always available. To overcome this need, another approach using Recurrent Neural Networks was proposed. The Recurrent Neural Networks have a great capacity of learning the dynamics of a system to which it was trained, so they can learn the dynamics of a sensor s discalibration. Knowingthe sensor s functioning time or its discalibration dynamics, it is possible to determine how much a sensor is discalibrated and correct its measured value, providing then, a more exact measurement. The algorithms proposed in this work can be implemented in a Foundation Fieldbus industrial network environment, which has a good capacity of device programming through its function blocks, making it possible to have them applied to the measurement process

Implementação experimental de filtro ativo paralelo de potência com aplicação a gerador de indução trifásico

This work describes the experimental implementation of a shunt active power filter applied to a three-phase induction generator. The control strategy of active filter turned to the excitation control of the machine and to decrease the harmonics in the generator output current. Involved the implementation of a digital PWM switching, and was made a comparison of two techniques for obtaining the reference currents. The first technique is based on the synchronous dq reference method and the second on the theory of instantaneous power. The comparison is performed via simulation and experimental results. To obtain the experimental results, was mounted a bench trial and the control and communications needed were implemented using DSP - MS320F2812. The simulation results and experimental data proved the efficiency of the filter to apply, highlighting the technique of instantaneous power

Desenvolvimento de Modelos no Programa DigSILENT PowerFactoryTM para o Estudo de Estabilidade Transitória em Sistemas Elétricos de Potência com Aerogerador

This work presents a description of models development at DigSILENT PowerFactoryT M program for the transient stability study in power systems with wind turbine. The main goal is to make available means to use a dynamic simulation program in power systems, widely published, and utilize it as a tool that helps in programs results evaluations used for this intent. The process of simulations and analyses results starts after the models setting description phase. The results obtained by the DigSILENT PowerFactoryT M and ATP, program chosen to the validation also international recognized, are compared during this phase. The main tools and guide lines of PowerFactoryT M program use are presented here, directing these elements to the solution of the approached problem. For the simulation it is used a real system which it will be connected a wind farm. Two different technologies of wind turbines were implemented: doublyfed induction generator with frequency converter, connecting the rotor to the stator and to the grid, and synchronous wind generator with frequency converter, interconnecting the generator to the grid. Besides presenting the basic conceptions of dynamic simulation, it is described the implemented control strategies and models of turbine and converters. The stability of the wind turbine interconnected to grid is analyzed in many operational conditions, resultant of diverse kinds of disturbances

Desenvolvimento de modelos no programa digSILENT powerfactoryTM para o estudo de estabilidade transitória em sistemas elétricos de potência com aerogerador

This work presents a description of models development at DigSILENT PowerFactoryTM program for the transient stability study in power systems with wind turbine. The main goal is to make available means to use a dynamic simulation program in power systems, widely published, and utilize it as a tool that helps in programs results evaluations used for this intent. The process of simulations and analyses results starts after the models setting description phase. The results obtained by the DigSILENT PowerFactoryTM and ATP, program chosen to the validation also international recognized, are compared during this phase. The main tools and guide lines of PowerFactoryTM program use are presented here, directing these elements to the solution of the approached problem. For the simulation it is used a real system which it will be connected a wind farm. Two different technologies of wind turbines were implemented: doubly-fed induction generator with frequency converter, connecting the rotor to the stator and to the grid, and synchronous wind generator with frequency converter, interconnecting the generator to the grid. Besides presenting the basic conceptions of dynamic simulation, it is described the implemented control strategies and models of turbine and converters. The stability of the wind turbine interconnected to grid is analyzed in many operational conditions, resultant of diverse kinds of disturbances

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

Análise do comportamento mecânico de espumas cerâmicas a base de alumina obtidas pelo método da réplica

Ceramics with porous cellular structure, called ceramic foams, have a potential use in several applications, such as: thermal insulation, catalyst supports, filters, and others. Among these techniques to obtain porous ceramics the replication method is an important process. This method consists of impregnation of a sponge (usually polymer) with ceramic slurry, followed by a heat treatment, which will happen the decomposition of organic material and sintering the ceramic material, resulting in a ceramic structure which is a replica of impregnated sponge. Knowledge of the mechanical properties of these ceramics is important for these materials can be used commercially. Gibson and Ashby developed a mathematical model to describe the mechanical behavior of cellular solids. This model wasn´t for describing the ceramics behavior produced by the replica method, because it doesn´t consider the defects from this type of processing. In this study were researched mechanical behavior of porous alumina ceramics obtained by the replica method and proposed modifications to the model of Gibson and Ashby to accommodate this material. The polymer sponge used in processing was characterized by thermogravimetric analysis and scanning electron microscopy. The materials obtained after sintering were characterized by mechanical strength tests on 4-point bending and compression, density and porosity and by scanning electron microscopy. From these results it was evaluated the mechanical strength behavior compared to Gibson and Ashby model for solid cellular structure and was proposed a correction of this model through a factor related to struts integrity degree, which consider fissures present in the structure of these materials besides defects geometry within the struts

Simulação das temperaturas diárias na cidade de Natal-rn

Information retrieval is of paramount importance in all areas of knowledge. Regarding the temperatures of Natal, they were simulated and analyzed. Thus, it was possible to recover, with some accuracy, the temperatures of days they were not collected. For this we constructed a software that displays the temperature value at each moment in the city. The program was developed in Delphi using interpolated polynomial function of third degree. The equations were obtained in Excel and data were collected at the Instituto Nacional de Pesquisas Espaciais (INPE). These functions were changed from a correction factor in order to provide values to temperatures between those who were not collected. Armed with this program you can build tables and charts to analyze the temperatures for certain periods of time. The same analysis was done by developing mathematical functions that describes the temperatures. With the data provided by this software is possible to say which are the hours of highest and lowest temperatures in the city, as the months have indexes with the highest and lowest temperatures.

A prática de correção textual por professoras de língua portuguesa do ensino médio

Cette recherche analyse les pratiques de correction de textes de l'enseignement du 1, 2 et 3 ème niveau. Nous avons parti de discutions avec les professeurs de Langue Portugaise des troisièmes annèes d‟une école appartenant au enseignement publique, située à la ville d‟Assu RN. L'étude a les postulats théoriques de Cruz (2007), Dellagnelo (1998), Oliveira (2005), Pécora (1999), Ruiz (2001), Serafini (1989), et d‟autres. La méthodologie est de nature qualitative et d‟interpretation, dont le matériel a été constitué à partir des rapports des enseignants professionnels, ainsi que les 92 textes recueillies entre juillet et août 2008. Les dés montrent que la correction se configure comme un travail pratique, qui vise à aider les étudiants à améliorer leur écriture. Les professeurs font la correction d‟une forme mélangée, c'est-à-dire dans le texte apparaissent les corrections orthographiques, lexicales, etc., mais la prédominance de la correction est par rapport aux idées, pour le contenu du texte. Dans ce sens, les professeurs se rendent compte du valeur et de la hiérarchisation des idées discutées par les élèves, les reconnaître comme l'organisation de la sémantique et la séquence du texte. Tous les autres aspects (structurelles, grammaticaux) sont importants, cependant, en général, dans la pratique de correction des études, l‟exposition les idées occupent une place importante. Les marques de correction apparaissent sous la forme de petits billets, qui apprécie également toutes les étapes de l'écriture de texte

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

O jogo das identidades como fator de mobilização político-eleitoral nas campanhas de Dilma Rousseff e Rosalba Ciarlini em 2010

Starting from the premise that we live in the society of spectacle, as proclaimed by Guy Debbord, and, in this context, the media feeds itself off of this spectacularization and constructs a culture of images and production of goods, providing templates from which the subject can identify himself/herself as being male or female, successful or unsuccessful, powerful or powerless. In other words, the culture conveyed by the media produces material for the creation of identities through which individuals insert and recognize themselves in contemporary society. Observing the election campaigns, we can see clearly that this profusion of identities is fairly explored in the advertising propaganda used by the candidates, particularly in the propaganda broadcasted on the Free Electoral Time on TV. Instigated by the explicit relation between the media and politics within the society of the spectacle, this study aims to investigate the main identities that emerge in the discursive practices of the media in the election campaigns of 2010 for president of the Republic and governor of the State of Rio Grande do Norte that had as protagonists the candidates at that moment Dilma Rousseff (PT) for president and Rosalba Ciarline (DEM) for governor. To do so, we based ourselves on the theory of Bakhtin Circle, which considers the statement as a unit of verbal communication and conceives language as a dialogical phenomena and a discursive practice and also in the conceptions of dialogical relationships, social voices and chronotope formulated by the previous mentioned theory. Still in the theoretical field, we have established an interconnection with the theories coming from the Cultural Studies (Hall, Woodward) about the identity, which conceives it as multiple, fragmented, non-fixed, so that, the subject assumes different identities, not always coherent, at different times, depending on the context in which they are approached. The research is situated in the frames of Applied Linguistics, which considers language as the center of its studies and settles on the border of an open number of areas of knowledge expanding its possibilities of investigation by means of the interdisciplinary. Our corpus consists in 20 electoral propaganda videos aired on TV during the Free Election Time in 2010 campaign; among these, 14 videos are Dilma Rousseff s propaganda and 06 videos are Rosalba Ciarline s propaganda. We seek for the purpose of the analysis to identify the identities which emerge from the discourses about the candidates in propaganda videos broadcasted in the referred campaign, as well as realize the dialogical relations established in these discourses and even if the identity construction of these subjects is located in the same axiological axis. The corpus analysis revealed that the multiple cultural identities of the candidates campaigning emerge in the discourses circulating in the electoral propaganda aired on TV such as: the identities of pioneer woman, competent, sensitive, mother, grandmother, religious. And, yet, those are changeable as the electoral demands, in other words, the need to obtain support and votes, outline a fluid identity construction about the candidate to the position in question

As origens históricas do Zaratustra nietzcheano: o espelho de Zaratustra, a correção do mais fatal dos erros e a superação da morte de Deus

Through a careful examination of the relationship between Zoroastrianism and the Western tradition, and a detailed and critical reading of the writings of Nietzsche, this work aims at showing to what extent the character Zarathustra , his discourses and poetical-philosophical thoughts, and related passages from many distinct Nietzschean works, directly or undirectly reflect a philosophy that harvests contributions from the Zoroastrian tradition or its headways (in the Judeo-Greco-Christian tradition, and furthermore in the whole Western philosophical tradition). Supplied with this provisions, and with the interpretation cast upon them, Nietzschean philosophy questions the entire Western tradition of thought, and proposes its replacement by a new attitude towards life. This work also intends to show the way the Nietzschean Zarathustra was built up, in the writings of the German philosopher, together with the idea of making, out of the namesake character of the ancient Iranian prophet (Zarathushtra or Zoroaster, the founder of Zoroastrianism), the herald of that important text that intended to bring the German language to its highest perfection , clumping together, and leading to a prophetic-poetic climax consonant with the meaning of the Earth , Nietzsche s key ideas about the rectification of the most fatal of errors and about the death of God . An elaborate investigation has been pursued after the reasons and manners of the building up of Nietzsche s Zarathustra mirroring its Iranian namesake (sections 1.1 to 1.6), and a survey of the works of Nietzsche has suggested unquestionable relations with the Zoroastrian tradition, mostly through the Jewish, Greek or Christian repercussions of this tradition. These relations have been put in context, in many framings (sections 2.1 to 2.3.2), in the ambit of the most fatal of errors - the - creation of morals in the very occasion of its transposition to metaphysics (Ecce Homo, Why I am a destiny , 3). Through an evaluation of the possible circumstances and repercussions of the death of God , the relations between Nietzsche s writings and Zoroastrian tradition have been investigated (sections 3.1 to 3.7), allowing the understanding of this event as an essential component, and tragic outcome, of the rectification of the most fatal of errors