This study proposes a communication assisted fuzzy based adaptive protective relaying scheme for fault detection, fault classification and faulty phase identification of microgrid along with a solution to isolate the microgrid from the utility grid by disconnecting the static-switch. Any fault in the utility grid causes the microgrid to be isolated from the utility grid whereas if there is a fault in the microgrid it continues to operate with the utility grid. An adaptive fuzzy inference system has been developed using a separate fuzzy rule base for the two modes of operation of microgrid, i.e. islanded mode or grid connected mode. The Central Grid Status Communication System (CGSCU) is considered which monitors the status of PCC and sends a command signal to the relays so that the relay settings are updated with new rules for any transition in the mode of the microgrid. The fundamental phasor amplitude and zero sequence component of current signals are used as input features, fault detection, fault classification and faulty phase identification. A standard microgrid model IEC 61850-7-420 was simulated using MATLAB/SIMULINK. The proposed method is tested for all types of faults by varying fault parameters and also for dynamic situations such as connection/disconnection of DGs and loads. The test results substantiate the effectiveness of the method.
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