Hybrid Time-Domain Fault Location in Long Transmission Lines ‎Considering Variable Ground-Mode Velocity and Asynchronous ‎Measurements

Abstract

 Precise fault location is needed in high-voltage transmission lines for reliable operation. The classical TWA methods tend to deteriorate estimation accuracy because of the assumption that the wave propagation velocity is constant, and need strictly synchronized terminal observations. This paper presents a new hybrid time-domain fault location algorithm that overcomes this drawback using a distributed-parameter line model combined with an arbitrary spatially varying ground-mode velocity profile. The model follows a quadratic fit for the frequency-dependent ground-mode velocity attenuation along the line between receivers. In addition, an asynchronous expression based on TDOA between air/ground modes is developed to estimate and eliminate synchronization inaccuracies between line terminals. We consider a method of characteristics, which is modified to solve telegrapher’s equations on piecewise-uniform segments. Extensive simulations on a 300 km testbed transmission line model verify the effectiveness of the proposed approach. The performance results show that our solution provides a noticeable accuracy improvement, as errors below 0.06% are obtained even for far-away faults and in the presence of synchronization time offsets as large as , outperforming classical constant-velocity models.