Fuzzy Logic Based Scheme for Directional Overcurrent Detection and Classification for Transmission Line

This paper proposes a fuzzy logic-based scheme to detect the direction of the overcurrent faults (phase-phase) in the transmission lines through polarized voltage. The fault detection is crucial to avoid the overlap action for the protection relays in fault conditions which are led to the mal-operation in the transmission grid with unwanted tripping for healthy lines. When the fault occurs, the magnitude of the voltage and the current direction is changed (dip in voltage and rise in current) according to the type of fault in the grid. Three-phase voltage and current are measured to generate the inputs for the proposed fuzzy logic-based scheme. The typical IEEE 9-Bus Bars transmission grid has been used to implement the test for the fuzzy scheme using Simulink and Simpower systems toolbox in MATLAB software. The proposed scheme is applied to six-phase to phase faults cases in forward and reverse direction. Results show the effectiveness of the directional fault detection scheme using the fuzzy logic system.