A Composite Magnitude-Phase Plane of Impedance Difference for Microgrid Protection Using Synchrophasor Measurements

This article presents a protection scheme based on the magnitude-phase plane of impedance difference (ID) using wide-area positive sequence components of current and voltage signals for the microgrid. The computation of the ID of the line is performed by extracting signals from the phasor measurement units complied with IEEE C37.118 standards. The composite magnitude-phase plane obtained from the magnitude of the ID and the angle of ID is considered as the key index for the detection of faults. The feasibility to include the proposed microgrid protection technique is examined by the extensive fault cases simulation with substantial variation in fault conditions, including types of fault and fault at different line length and for the grid-connected and islanding modes of microgrid operation. The fault study is carried out on a medium-voltage 15 bus test microgrid and a standard IEEE 34 bus microgrid testbed. The impact of several critical no-fault conditions is also investigated to analyze the possibility of false operation. The proposed ID-based scheme is extensively tested on MATLAB/Simulink platform and validated on the real-time digital simulator. The test results indicate that the magnitude-phase plane of the ID-based scheme can provide a dependable microgrid protection measure.