Intelligent management of immediate operation of micro grid in fault and load change based on adaptive fuzzy PI controller

The use of power electronic converters for connection to the grids is causing harmonics. In this paper, for elimination of harmonics and increasing the quality of the voltage and output current of inverter, a three-level inverter is used, which connects micro-grid to a commercial electric power distribution system (utility one). An adaptive fuzzy PI controller was also used to control it, which then has a high pace of reply with a good performance in sudden changes of loads. The performance of micro grid in case of faults from utility grid was also analyzed. In this condition, the micro grid is disconnected from utility grid and act islanded. The connection and disconnection act of micro grid from the utility grid should happen rapidly. A simple method with a high speed is presented for this purpose. In the presented method, voltage domain and phase angel of both grids are compared. In case of outgoing of synchronism mode, micro grid is disconnected from the grid. The reconnection of micro grid happens when it is synchronized with the utility grid. Simulation results declare the accuracy of the proposal method.