Study of Single-Ended Traveling-Wave Protection for Transmission Line Unsymmetrical Grounded Faults

The identification of reflection wave is the primary trouble of the existing single-ended traveling-wave protection schemes. The paper proposes a novel single-ended protection for EHV/UHV transmission line unsymmetrical grounded faults, which only needs initial traveling wave. The protection principle is based on the propagation time gap between aerial-mode and zero-mode traveling waves. The propagation time gap rises monotonously with the fault distance increasing. Under various fault situations, the performance of this novel traveling-wave protection scheme is investigated with a number of PSCAD/EMTDC simulation data. Theoretical analysis and testing results show the proposed protection scheme is ultra-high-speed and feasible.