Factors such as environmental restrictions and technological advances have enabled the insertion of renewable energy sources (e.g. photovoltaic and wind systems) as distributed generators (DG), in the electrical grid. However, because of the intermittent nature of the energy in solar radiation and wind, control strategies for regulating the DG power flow are necessary to ensure a proper connection of these systems to the grid. These control strategies are applied to the DG and the grid interface, which is implemented by grid-connected power converters. Grid-connected power converters can be controlled to operate as a controlled current source (grid-feeding converters) or as a controlled voltage source (grid-forming converters), in which the grid-feeding power converter (GFD-PC) systems are suitable to deliver power to an energized grid, while grid-forming power converter (GFO-PC) systems can contribute for regulating the grid voltage and frequency. When connected to a low voltage grid, GFD-PC systems can cause voltage deviation in the grid, and GFO-PC systems are subject to active and reactive power coupling. These drawbacks can be overcome with the use of the virtual impedance concept, which is a technique that can change the output impedance of power converters. Therefore, it can modify the equivalent impedance between the power converter and the grid, thus improving the power flow control of GFO-PC, and achieving voltage support of GFDPC systems. In this direction, this doctoral thesis proposes implementations of virtual impedances to overcome the drawbacks of GFO-PC and GFD-PC systems connected to the low voltage grid to meet the requirements of power flow control in DG systems. ; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES ; Fatores como restrições ambientais e avanços tecnológicos têm possibilitado a inserção de fontes de energias renováveis (por exemplo, sistemas fotovoltaicos e eólicos), na forma de geradores distribuídos (GD), na rede elétrica. Entretanto, devido à natureza ...