Fault Nature Identification Based on Local End Data for Single Phase Adaptive Autoreclosing Scheme

Fault nature identification is deemed indispensable for protection of transmission lines. As the overhead transmission lines are prone to atmospheric conditions. Therefore most of the faults, appears on high voltage (HV) or extra high voltage (EHV) transmission lines are temporary in nature. Temporary faults are followed by a secondary arc. Therefore the identification of secondary arc extinction instant is also important to perform a safest reclosing. Hence, adaptive auto-reclosure is one of the promising solutions for the same. In this paper a Continuous wavelet transform with Fast Fourier transform (CWTFT) based algorithm is presented to first identify the fault nature i.e. temporary or permanent, as well as to detect the secondary arc extinction instant in minimum time. Fault nature identification is done by computing an index. The index will retain a high value during secondary arc period and will attain a zero value after the arc is extinguished. This fact is used to detect arc extinction instant. The technique is also compatible with both shunt compensated and uncompensated transmission lines and is tested under various compensation levels. The efficiency of the presented algorithm is tested using MATLAB software for laborious simulations and for a diversity of fault conditions i.e. at different fault locations, load angles and fault resistance, where in all cases, maximum consistency has been achieved.