Three Different Approaches to Control a Photovoltaic System Connected to an Unbalanced Three Phase Power Grid

This paper presents three different control strategies for a photovoltaic system connected to an unbalanced three-phase grid. All the strategies are based on the Double Synchronous Reference Frame (DSRF), which is a structure that makes use of the symmetrical components of the current to achieve the aim. The first control scheme aims at injecting balanced three-phase currents by the photovoltaic system into the electrical grid. The second and third strategies aim to amortize, respectively, the oscillations in active and reactive power. Besides, all three control possibilities enable the photovoltaic system to perform the ancillary service of reactive injection into the grid. The computer simulations show the good performance of the strategies for the proposed system. Besides, it was verified that the proposed system can maintain a good functioning of the electric grid under unbalanced conditions.