Fault detection & classification using innovative MFCDFT based slope tracking method for digital distance protection

Abstract

The critical requirements for numerical distance protection used for transmission line protection are reliable and fast phasor estimation of input signals to determine correct impedance reach. Factors influencing accurate phasor estimation are Fault Resistance (R F ), Fault Type (FT), Fault Inception Angle (FIA), Fault Location (FL) and Power Flow Angle (PFA). In this paper, an innovative slope tracking method is presented which is based on Modified Full Cycle Discrete Fourier Transform (MFCDFT) and its application has been validated for distance relaying. Fault signals are simulated in PSCAD for all possible types of faults and validation is performed in MATLAB®. For transmission line protection, impedance trajectory is adaptively calculated from Ground Distance Function (GDF) using estimated values of voltages and currents. Moreover, the proposed technique calculates operating time, fault location and fault type, which are the key attributes of multi functional numerical relay. The obtained results are compared with existing methods and found precise and faster. Error in fault location estimation is achieved within 1.23% with fault classification accuracy of 100%.