Fast adaptive autoreclosing technique for series compensated transmission lines

Abstract

Auto-reclosing renders fast restoration of the line for arcing faults which constitutes almost 80% of transmission line faults and thus improves system stability. Existing methods, using harmonics of voltage and current, have drawbacks in series-compensation environments because of associated dynamics and control mechanisms. This research work proposes a technique for adaptive autoreclosing in case of line-to-ground faults for series compensated transmission line. A technique is devised that utilises the cumulative sum of energy (CSE) calculated using the fast sparse S-transform coefficients to derive an index (PI) which discriminates between permanent and transient faults. Another extinction index (EI) is computed using CSE during the secondary arc to identify the arc extinction. This parameter is employed to alter the dead time set for the recloser and thus reclosing during fault process is avoided. The performance validation on the real-time digital simulator platform for both single- and double-circuit line with shunt compensation and neutral reactor, enhances the applicability of the proposed protection scheme for adaptive autoreclosing.