A novel superimposed component‐based protection method for multi‐terminal transmission lines using phaselet transform

This paper presents a novel protection method for transmission lines that estimates the superimposed component phasor using phaselet transform. The phaselet transform computes the phasors over variable‐lenfgth data window at the instant of a fault, so it can estimate the phasor less than one full cycle. The presented method phaselets are used to extract the superimposed component instead of the samples and the initial phase angle difference (IPAD) of the superimposed currents between terminals is used to detect internal and external faults. The main contribution of this method is an accurate, fast and robust superimposed component‐based algorithm that uses the phaselet transform to estimate the phasor of the superimposed component for distinguishing internal faults from external faults; this method is also reliable against transients such as current transformer (CT) saturation and capacitor bank switching. To evaluate the performance of the proposed method, a three‐terminal transmission line is modelled in the alternative transients program/electromagnetic transients program (ATP/EMTP) software and several cases including fault and transients are simulated; finally, the data has been analyzed in MATLAB software. The simulation results show that the proposed method is able to quickly and accurately distinguish internal faults from external faults and is not affected by transients. In this paper a novel method for fault detection in multi terminal transmission lines based on superimposed component is proposed.