The microgrid concept provides a quite appealing solution for overcoming the challenges of integrating renewable energy sources and distributed generators into power grids. Advances in the microgrids control have improved the microgrids potential to be integrated into the conventional electrical systems in a higher capacity. This improvement not only covers their internal control performance and connection/disconnection procedures in order to limit the negative dynamic impacts in the network and other connected microgrids, but also includes the grid support functionalities to enhance the global operation of distribution networks. In this paper, a general overview of the main control loops is presented. The microgrid control strategies are classified into four control levels: local, secondary, central and global, where the first three levels are associated with the operation of the microgrid itself, and the fourth level demonstrates to the coordinated operation of the microgrid and neighbor grids as well as the main/host grid.
