Travelling wave fault locator for mixed overhead and underground teed transmission feeders

Society is increasingly concerned about the environmental impact of energy systems, and prefers to locate power lines underground. This is especially true in regions of outstanding natural beauty or if they affect environmental/political/planning constrained areas. However, the use of underground sections within a predominantly overhead feeder introduces significant problems for the auto-reclosure of circuit breakers. Auto-reclosure is important on an overhead feeder, since most faults are transient and, once the feeder has been de-energized, the insulation strength of the air at the fault recovers and the line can be restored to service. Faults on an underground cable are different because, once the insulation is damaged, the fault is normally permanent. In addition, if the breaker is allowed to reclose onto a cable fault, the area of damage increases and health and safety concerns exist for humans in the vicinity of the faulted cable section. The main purpose of the traveling-wave-based measurement scheme described in this paper is to locate a fault on a teed transmission feeder with mixed overhead and underground sections. Simulation results demonstrate that the fault locator can accurately locate all realistic faults, including ones that are high resistance or occur at nonideal points on wave. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.