A Computational Approach to Optimal Damping Controller Design for a GCSC

This paper presents a computational approach for an offline measurement-based design of an optimal damping controller using adaptive critics for a new type of flexible ac transmission system device-the gate-controlled series capacitor (GCSC). Remote measurements are provided to the controller to damp out system modes. The optimal controller is developed based on the heuristic dynamic programming (HDP) approach. Three multilayer-perceptron neural networks are used in the design-the identifier/model network to identify the dynamics of the power system, the critic network to evaluate the performance of the damping controller, and the controller network to provide optimal damping. This measurement-based technique provides an alternative to the classical linear model-based optimal control design. The eigenvalue analysis of the closed-loop system is performed with time-domain responses using the Prony method. An analysis of the simulation results shows potential of the HDP-based optimal damping controller on a GCSC for enhancing the stability of the power system

A não linearidade entre a reação de quem copia e de quem é copiado

This article offers an account of experiences related to the problem of third-party copyright infringement, as well as some measures adopted by Coppe (the Alberto Luiz Coimbra Institute for Graduate Studies and Research in Engineering, at Rio de Janeiro Federal University) to curb potential problems in this area, including formal and educational measures. The title suggests that the issue is still poorly understood among undergraduate and graduate students (and professors), and that a wholly nonlinear reaction is common between those who copy or those who are copied. We end the article with some suggestions on measures that could be adopted to eliminate (minimize) problems of plagiarism and raise awareness on matters of integrity in research.Este artigo apresenta um relato de experiências relacionadas ao problema de violação de direitos autorais de terceiros, bem como algumas medidas adotadas pela Coppe da Universidade Federal do Rio de Janeiro, de forma a coibir possíveis problemas nessa área, incluindo medidas formais e educativas. O título sugere que o tema ainda é pouco esclarecido entre os alunos (e professores) de graduação e pós-graduação, sendo comum a reação totalmente não linear entre quem copia ou quem é copiado. Conclui-se o trabalho com algumas sugestões sobre medidas a serem adotadas para se eliminar (minimizar) problemas de plágios e conscientizar dos problemas de integridade na pesquisa

Improved Superconducting Magnetic Energy Storage (SMES) Controller for High Power Utility Applications

Superconducting magnetic energy storage (SMES) systems are getting increasing interest in applications of power flow stabilization and control in the transmission network level. This trend is mainly supported by the rising integration of large-scale renewable energy power plants into the high-power utility system and by major features of SMES units. In a SMES system, the power conditioning system (PCS) is the crucial component for controlling the power exchange between the superconducting coil and the ac system. The dynamics of the PCS directly influences the validity of the SMES in the dynamic control of the power system. This paper describes a novel PCS scheme of SMES to simultaneously perform both active and reactive power flow controls. Moreover, a detailed model of the SMES unit is derived and a three-level control scheme is designed, comprising a full decoupled current control strategy in the dq reference frame with a novel controller to prevent PCS dc bus capacitors voltage drift/imbalance. The dynamic performances of the proposed systems are fully validated by computer simulation.Fil: Molina, Marcelo Gustavo. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Mercado, Pedro Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Hirokazu Watanabe, Edson. Universidade Federal do Rio de Janeiro; Brasi

Analysis of integrated STATCOM-SMES based on three-phase three-level multi-pulse voltage source inverter for high power utility applications

This paper is aimed to investigate the operating characteristics of a static synchronous compensator (STATCOM) integrated with superconducting magnetic energy storage (SMES) for high power applications in the transmission network level. The STATCOM controller topology comprises multi-level multi-pulse neutral-point clamped-type (NPC) voltage source inverters (VSIs) using the harmonics cancellation technique, and incorporates a SMES coil. An innovative two-quadrant multi-level dcdc converter is proposed to effectively interface the STATCOM with the superconducting coil using a buck-boost topology with neutral point voltage control capabilities; thus enabling to simultaneously control both active and reactive power exchange with the high voltage power system. A detailed analysis of major system variables is presented, including analytical results and digital simulations using the MATLAB/Simulink environment. Moreover, a three-level control scheme is designed, including a full decoupled current control strategy in the dq reference frame with a novel controller to prevent the STATCOM dc bus capacitors voltage drift/imbalance and an enhanced power system frequency controller.Fil: Molina, Marcelo Gustavo. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Mercado, Pedro Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Watanabe, Edson H.. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; Argentin

Shunt active filter for power quality improvement

This paper describes the development of a low cost shunt active power filter with digital control, which allows dynamic power factor correction and both harmonics and zero-sequence current compensation. The active filter controller is based on the instantaneous power theory (p-q theory) and was implemented using a standard 16 bits microcontroller. The p-q theory is introduced followed by the presentation of some active power filters topologies. Then a brief description of the implemented solution is made, including references to software tools used for simulation and system development. Experimental results are also presented, showing the good performance of the developed active filter

Filtro ativo paralelo com controle digital de baixo custo

Este artigo descreve o desenvolvimento de um filtro ativo paralelo de baixo custo utilizado para a melhoria da qualidade de energia elétrica. O filtro permite a correção dinâmica do fator de potência e a compensação dinâmica dos harmônicos e da componente de sequência zero de corrente. O sistema de controle do filtro ativo é baseado na teoria p-q (teoria da potência instantânea), e foi implementado com um microcontrolador standard de 16 bits. Neste artigo a teoria p-q é apresentada de forma sucinta, o filtro ativo paralelo desenvolvido é descrito e são apresentados alguns resultados experimentais

Selective active filter applied to an arc furnace adjusted to harmonic emission limitations

This paper describes how to calculate the dif-ferent harmonic sequences that should be filtered with ashunt selective active filter, for two control alternatives: load current measurement or line current measurement. These results are then generalized for shunt hybrid selective filters. Passive parameters are chosen considering the resonances with the electric system that appear. Design basis are defined in order to obtain a minimum cost filter which also meet the applicable regulations requirements. Finally, results showing the potentiality of the selective filter controlled for the proposed methods are reported

Selective active filter with remote harmonic distortion control

PostprintThis paper presents the calculation methods for the different filtering blocks of a selective active filter in order to minimize the active filter inverter size, keeping the harmonic emissions at the limits stated by the applicable regulations. Since it may be necessary to comply with the regulations at a remote place with respect to the active filter location, the method has been extended to this case. In order to validate the simulations, measurements which were made at a real application - and arc furnace - were used. Finally, the simulated results obtained with a remote hybrid filter were compared with those obtained when an active filter is installed directly at the place where the harmonic emission regulations must be met. The comparison shows that remote compensation is an alternative to be seriously considered. The results are similar to those obtained with local compensation and the cost may be substantially lower

O USO DE MASSA CONGELADA NA PRODUÇÃO DE PÃO

O artigo apresenta revisão de literatura sobre o uso de massa congelada na produção de pão. São abordados os diferentes tópicos que compõem o assunto, desde a escolha da farinha mais adequada até às condições de forneamento do pão produzido, passando pela formulação e condições de mistura, fermentação, congelamento e descongelamento da massa. Conclui que é difícil esclarecer as questões mais freqüentes sobre o assunto, relativas ao melhor tipo de congelamento (criogênico ou mecânico), à fermentação (antes ou depois do congelamento) e às condições de congelamento e de descongelamento (rápido ou lento). Isto porque a literatura disponível trata de massas destinadas à produção dos mais variados tipos de pães e do processo como um todo, o que dificulta a adaptação da tecnologia existente ao pão francês consumido no Brasil. Abstract This paper reviews the use of frozen dough in bread production. The several steps of the breadmaking process for this sort of product are surveyed, from choosing a suitable flour to the baking conditions in the oven, and others such as formulation, mixing conditions of dough, fermentation, freezing and thawing. It concludes that it is very difficult to answer to the most common questions about the subject, relative to the best freezing conditions for dough (mechanic or cryogenic), to the fermentation (prior or after freezing) and to the proper freezing and thawing conditions (fast or slow), once the literature available on the subject deals with different types of dough used to produce several types of breads, and never studies the process as a whole, which difficult the adaptation of the existing technology to the production of frozen French bread in Brazil

Optimal Dynamic Neurocontrol of a Gate-Controlled Series Capacitor in a Multi-Machine Power System

This paper presents the design of an optimal dynamic neurocontroller for a new type of FACTS device - the gate controlled series capacitor (GCSC) incorporated in a multi-machine power system. The optimal neurocontroller is developed based on the heuristic dynamic programming (HDP) approach. In addition, a dynamic identifier/model and controller structure using the recurrent neural network trained with backpropagation through time (BPTT) is employed. Simulation results are presented to show the effectiveness of the dynamic neurocontroller and its performance is compared with that of the conventional PI controller under small and large disturbances