Estudo de estratégias de controle de corrente aplicadas a conversores estáticos conectados a rede através do filtro LCL

Abstract

This work presents a study of a current control strategies applied to grid-connected converters with the inductive-capacitive-inductive (LCL) filter. Because of the growing concern about the use of renewable energy sources in the world, there is a growing use of distributed generation systems connected to the grid. Because of the characteristics present in such equipment, such as the presence of harmonics, power inverters cannot be directly connected to the grid, requiring a filtering stage, which is usually done by an LCL filter. These filters, although present good attenuation of the harmonics from the inverters, have a resonance peak, which makes its use a little inconvenient, since this peak can cause problems in the grid. In order to attenuate the peak resonance of the filter and to ensure that the current injected into the electrical grid has proper behavior, a current controller must be used. In the present work, two project methodologies for a proportional resonant controller will be studied, where the first one aims to select the parameters of the controller using the root locus method and the second one through phase margin and gain margin criteria. For this, the mathematical model of the filter and the controllers will be obtained in the continuous and discrete time, the controller will be projected using both methodologies and its results will be proven through simulation.