Dynamic voltage restorer development and testing

The growing use of sensitive loads in the electric power system, especially in industrial applications, increases voltage sags related production losses considerably, stimulating a demand for power electronics' based solutions to mitigate the effects of such problems. This paper shows the implementation and some industrial certification tests of a power equipment prototype designed to correct sags and swells, a dynamic voltage restorer, which is one of the many possible solutions for voltage sags and swells problems Experimental results of a 75kVA prototype are shown both in laboratory and full load conditions, in a certification institution (IEE-USP). © 2011 IEEE.

Produtividade, estabilidade e adaptabilidade em progênies de Myracrodruon urundeuva F.F. & M.F. Allemão-Anacardiaceae

The use and inadequate exploitation of natural resources is restricting the occurrence of aroeira (Myracrodruon urundeuva F.F. & M.F. Allemão), which now is on the FAO list of endangered species. This exploitation causes a decrease in the genetic base of M. urundeuva populations, which makes it difficult to find genotypes with stability and adaptability to different growing conditions. This study aimed at estimating the genetic variation and productivity, stability and adaptability of progenies of a M. urundeuva natural population, from the Ecological Station of Paulo de Faria-SP, under different planting systems. DBH (diameter at breast height) was evaluated in four progeny tests of M. urundeuva: i) planted with Anandenanthera falcata and Guazuma ulmifolia (TP-AMA); ii) single (TP-ASO); iii) planted with annual crops (TP-SAF) and iv) planted with Corymbia citriodora (TP-EUCA), installed in Selvíria-MS. The experimental design consisted of complete randomized blocks with three replications and a variable number of plants per plot in each of the four planting systems. From the joint analysis of the planting systems studied, it was found that: i) there were variations among planting systems particularly in TP-SAF; ii) only in TP-EUCA it was possible to detect variations among the progenies; iii) the effects of the genotype x environment interaction were not significant. Thereby, the harmonic mean of genotypic values (MHVG), the relative performance of genotypic values from the mean of each site (PRVG) and the harmonic mean of the relative performance of genotypic values (MHPRVG) for DBH showed, respectively: progenies with greater stability, adaptability, and stability and simultaneous adaptability within different planting systems. The use of these selection criteria provided a more refined selection of the best progenies of M. urundeuva under the different planting systems studied.

Digital filtering of oscillations intrinsic to transmission line modeling based on lumped parameters

A correction procedure based on digital signal processing theory is proposed to smooth the numeric oscillations in electromagnetic transient simulation results from transmission line modeling based on an equivalent representation by lumped parameters. The proposed improvement to this well-known line representation is carried out with an Finite Impulse Response (FIR) digital filter used to exclude the high-frequency components associated with the spurious numeric oscillations. To prove the efficacy of this correction method, a well-established frequency-dependent line representation using state equations is modeled with an FIR filter included in the model. The results obtained from the state-space model with and without the FIR filtering are compared with the results simulated by a line model based on distributed parameters and inverse transforms. Finally, the line model integrated with the FIR filtering is also tested and validated based on simulations that include nonlinear and time-variable elements. © 2012 Elsevier Ltd. All rights reserved.

Strategies to reduce the number of variables and the combinatorial search space of the multistage transmission expansion planning problem

This paper proposes strategies to reduce the number of variables and the combinatorial search space of the multistage transmission expansion planning problem (TEP). The concept of the binary numeral system (BNS) is used to reduce the number of binary and continuous variables related to the candidate transmission lines and network constraints that are connected with them. The construction phase of greedy randomized adaptive search procedure (GRASP-CP) and additional constraints, obtained from power flow equilibrium in an electric power system are employed for more reduction in search space. The multistage TEP problem is modeled like a mixed binary linear programming problem and solved using a commercial solver with a low computational time. The results of one test system and two real systems are presented in order to show the efficiency of the proposed solution technique. © 1969-2012 IEEE.

Improving the grid operation and reliability cost of distribution systems with dispersed generation

In this work, a mathematical model to analyze the impact of the installation and operation of dispersed generation units in power distribution systems is proposed. The main focus is to determine the trade-off between the reliability and operational costs of distribution networks when the operation of isolated areas is allowed. In order to increase the system operator revenue, an optimal power flow makes use of the different energy prices offered by the dispersed generation connected to the grid. Simultaneously, the type and location of the protective devices initially installed on the protection system are reconfigured in order to minimize the interruption and expenditure of adjusting the protection system to conditions imposed by the operation of dispersed units. The interruption cost regards the unsupplied energy to customers in secure systems but affected by the normal tripping of protective devices. Therefore, the tripping of fuses, reclosers, and overcurrent relays aims to protect the system against both temporary and permanent fault types. Additionally, in order to reduce the average duration of the system interruption experienced by customers, the isolated operation of dispersed generation is allowed by installing directional overcurrent relays with synchronized reclose capabilities. A 135-bus real distribution system is used in order to show the advantages of using the mathematical model proposed. © 1969-2012 IEEE.

Um método para detecção e classificação de curtos-circuitos em redes de distribuição de energia elétrica baseado na transformada de Fourier e em redes neurais artificiais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Eletroestimulador funcional de oito canais com malha de realimentação utilizando Controlador Digital

Pós-graduação em Engenharia Elétrica - FEIS

Previsão de carga multinodal utilizando redes neurais de regressão generalizada

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Aplicação do método de Newton desacoplado para o fluxo de carga continuado

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Restauração automática de redes de distribuição de energia elétrica de grande porte com geração distribuída

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Previsão de cargas elétricas através de uma Rede Neural Híbrida Back-ART Fuzzy

Pós-graduação em Engenharia Elétrica - FEIS

Proposição de uma técnica de parametrização geométrica para o fluxo de carga continuado baseado nas variáveis tensão e fator de carregamento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise do aproveitamento energético do biogás produzido numa estação de tratamento de esgoto

Pós-graduação em Engenharia Mecânica - FEIS

Programa computacional para análise do faturamento do consumo de energia elétrica através do k-hiperbolóide de carga e potência em empresas frigoríficas abatedoras de bovinos

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Potencial de redução de consumo de energia elétrica em entreposto frigorífico: um estudo de caso

Pós-graduação em Engenharia Mecânica - FEB