Navegando por Assunto "Multiobjective metaheuristics"

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Acesso aberto (Open Access)
Alocação e dimensionamento multiobjetivo de bancos de capacitores em redes de distribuição considerando restrições de ressonância harmônica
(Universidade Federal do Pará, 2017-03-13) LIMA, Áthila Santos de; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
The changes the electric sector has undergone over the last decades have imposed new challenges to the utility companies, which have driven researches for improvements in the distribution system without giving up the optimal use of resources. The adequacy to sector regulations, constant search for reduction in losses, increasing demand and the insertion of new paradigms, such as distributed generation, have been widely studied topics. The use of properly allocated Capacitor Banks has long been one of the main strategies used to maintain electrical variables such as voltage, power factor and feeder loading within the appropriate levels. On the other hand, the increasing presence of harmonics in the network adds limitations to this strategy. In this context, this work proposes the use of NSGA-II, a multiobjective metaheuristic, in solving the Problem of Capacitor Banks Allocation in three-phase radial distribution networks, considering harmonic resonance phenomena due to the presence of nonlinear loads. The multiobjective approach allows the user to choose from a range of solutions, one that best suits their needs. The results showed great relevance of harmonic distortion and resonance index analysis to obtain optimized solutions for the allocation problem, allowing increased quality of the energy delivered to the consumer and lifespan of the equipments that constitute the distribution network.
Acesso aberto (Open Access)
Avaliação de algoritmos evolucionários multiobjetivo para o problema de alocação de bancos de capacitores na presença de harmônicos
(Universidade Federal do Pará, 2017-08-10) KATAOKA, Vitor da Silva; BEZERRA, Ubiratan Holanda; http://lattes.cnpq.br/6542769654042813; TOSTES, Maria Emília de Lima; http://lattes.cnpq.br/4197618044519148
The rapid growth of urban areas bring, as a consequence, an increase in the amount of loads connected to the distribution grids. Furthermore, the increase in the demand implies in equal raise in reactive loads, which are known to cause losses in the network. Thus, the utilities have a great challenge ahead, as the dynamics of the load require a greater effort in terms of expansion and improvements of the grid. In an attempt to mitigate the problems caused, the allocation of capacitor banks can become a practical, economical and technically robust solution. Nevertheless, it is extremely important to analyze the sizing and positioning of the banks, in order to achieve the best possible outcome. In parallel, the increasing use of nonlinear loads cause harmonics to appear in the system. When in conjunction with capacitor banks, it is possible to develop the far more dangerous phenomenon of resonance, where the amplitude of some of the harmonics goes beyond acceptable limits, resulting in undesirable effects. In this context, this work proposes a comparison between two multiobjective optimization tehcniques, NSGA-II and SPEA2, to solve the problem of sizing and placement of capacitor banks in electric energy distribution grids, considering the effects of harmonics produced by nonlinear loads.