Primary and Secondary Control of Grid Connected Micro Grids using ANFIS Controller

Abstract

The microgrid has been defined to cope with the large penetration of distributed generations (DGs). The microgrid is capable of operating in grid-connected mode (GC) and islanded mode (IS). In microgrid, distributed generations (DGs) are always connected to power network via power inverters. In the Grid Connected mode, DGs commonly acts as current controlled sources to retain a high grid-current quality and a fast dynamic response in the photovoltaic and wind generation systems. However, this current controlled DGs cannot work alone without the voltage/frequency support from utility-grid. Islanding occurs when a portion of a micro-grid becomes electrically isolated, yet continues to be energized by DGs connected to the isolated subsystem. In islanding mode, the inverter-interfaced DGs work as voltage-controlled sources. As system voltage and frequency are not determined by utility-grid, DGs should take care of the voltage/frequency stability. Moreover, the power sharing should be guaranteed according to their individual ratings to avoid circulating currents among DGs. The operation and control of existing utility networks are becoming more and more complex due to the increased interconnection of a DG systems with diverse characteristics. So this paper intends to address the above problems and come out with a proper control strategy using ANFIS controller that could be implemented for the successful operation of a microgrid.