Tree-related high impedance fault location using phase shift measurement of high frequency magnetic field

Tree-related high impedance faults (THIFs) are one complex type of high impedance faults which occurs when power lines come in contact with live vegetation. These faults could not cause the overhead line to be removed by power line over-current protection during the first cycles. But if the fault current continue to flow through the vegetation, the THIF will eventually go to flashover. Furthermore, the physical changes created by a transient THIF current flowing through the vegetation are irreversible. So, if subsequently a THIF again occurs on the previous vegetation, the fault current goes directly to flashover and line tripping after a very brief delay. Consequently, the failure to early location of THIFs may results in blackout. Therefore, determining the exact distance of the THIFs efficiently contributes to increase reliability of power systems. Given that available high-impedance fault location techniques are not fully effective in the case of a THIF, the need for a more accurate method seems obvious. So in this paper, a novel single-terminal location method based on noncontact magnetic field strength measurement is proposed for THIFs. Suggested technique determines the exact distance of the THIF fault from the sensing point based on the total phase shift of the high frequency component of the magnetic field strength in the plane perpendicular to the conductor axis. Indeed, this study is a follow up to a previous study (Bahador et al., 2017).