Abstract Conventional power system protection methods are not suitable for protection microgrids. Therefore, new methods based on communication infrastructure, such as adaptive protection, wide-area protection, an‎d using different setting groups in numerical relays, have been proposed. However, these methods are not suitable for all architectures an‎d configurations of microgrids an‎d in the presence of inverter-based resources. This research examines the protection challenges of microgrids an‎d limitations of common schemes based on current, voltage, impedance, differential quantities, an‎d advanced communication-based schemes such as adaptive an‎d optimization-based methods. Then, considering the challenges an‎d existing gaps in these schemes, a protection scheme based on Discrepant Impedance is studied. This scheme identifies faults in the microgrid feeders by calculating the impedance seen from both ends of the feeder, with limited communication an‎d without the need for real-time monitoring of network configuration. This scheme not affected by microgrid architecture an‎d configuration, type of source, inverter control method, an‎d fault current level. For further investigation, a test network consisting of inverter-based resources with droop control an‎d current limiting, is simulated in MATLAB/Simulink. Then, by examining different disturbances, the behavior of the Discrepant impedance-based protection scheme in normal conditions an‎d various short-circuit types on different feeders was eva‎luated. The results show high selec‎tivity, an‎d reliability of the method in different short circuit conditions, an‎d the fault detection time is less than half a cycle. This scheme specifically related to the feeder under its protection an‎d is not affected by protection of other feeders in the network. Keywords 1-Microgrids 2-Protection 3-Discrepant Impedance 4-Inverter-Based Resources

محمداسماعيل همداني گلشن

محمد امين لطيفي , محسن حمزه