Control strategy for DC micro grid to supply AC loads

In recent years the number of grids connected to renewable energy based grids in electrical grids is increased. On the other hand, the importance of integrating distributed generations has been increased. This article represents a simple control strategy to integrate a micro grid, including a photovoltaic (PV) system and energy storage for supplying AC loads in various grid states. The proposed control strategy provides high amount of power generation. The micro grid is controlled by inverter, which is controlled by hysteresis current control in the case of connecting to grid, and controlled through controlling a closed voltage loop in the case of islanding mode, to supply load voltage. In order to achieve the system operation in the islanding mode, a strategy for PV, the battery, and load management are proposed. Seamless transition of the PV converter control between maximum power point tracking (MPPT) and voltage control modes, of the battery converter between charging and discharging and control of inverter are ensured for different grid operation modes by the proposed control methods. Simulation results represented in this paper show performance of proposed strategy.