Fault Events Recognition to Design a Current Based Transmission Line Protection Scheme Using Signal Processing Techniques

The current signals recoded on one terminal of a transmission line were processed using Stockwell transform (ST) and Hilbert transform (HT) in this paper to create a fault recognition algorithm (HT). There are two proposed indices: a Hilbert amplitude frequency index (HAFI) and a Stockwell summation median index (SSMI). Using a proper weight factor, the HAFI and SSMI are multiplied to get the combined fault index (CFI). The CFI is differentiated to compute the Hilbert Stockwell Derivative Fault Index (HSDFI) which is utilized for identification of faulty phases by comparing with a pre-set threshold value. The number of faulty phases is used to classify defective occurrences. Ground involvement was determined using a Hilbert Stockwell derivative ground fault index (HSDGFI), which was calculated using the same methodology that was used to analyse the zero sequence currents. Line to ground (LG) faults, double line (LL) faults, double line to ground (LLLG) faults, and three phase faults with ground are among the faults investigated (LLLG). This research is MATLAB-validated.