Distributed Optical Fiber Sensing of Temperature Rise During 110 kV Conductor-Ground Wire Ice-Shedding Discharge

Ice-shedding on overhead transmission lines can easily lead to jump discharge and subsequent line tripping, and effective monitoring methods are still lacking. To address this problem, this study proposes a distributed optical fiber sensing approach based on Brillouin optical time-domain reflectometry (BOTDR) for detecting ice-shedding discharge on 110 kV conductor-ground wire. The optical fibers embedded in an optical fiber composite overhead ground wire (OPGW) are used as sensing elements. Through simulated ice-shedding discharge experiments under different icing conditions, the Brillouin frequency shift (BFS) characteristics along the OPGW fiber are investigated, and the relationship between the BFS increment caused by the discharge-induced temperature rise and the discharge parameters is revealed. The experimental results show that ice-shedding discharge produces a localized temperature-rise region in the OPGW fiber, with an axial extent of 20-40 cm and a duration of 2-4 s. The maximum BFS increment due to the discharge temperature rise, Δv_Tm, is strongly dependent on the icing condition. Under conditions of no icing, light rime, and glaze ice on the conductor only, Δv_Tm remains within 5.43-7.94 MHz, whereas when both the conductor and ground wire are covered with glaze ice, Δv_Tm decreases significantly to 2.91-3.76 MHz. Further analysis indicates that, to satisfy the requirements for detecting ice-shedding discharge, the BOTDR must achieve a spatial resolution better than 0.1 m and a temporal sampling rate of no less than 5 Hz. These findings verify the feasibility of using distributed optical fiber sensing technology to detect ice-shedding discharge and provide experimental support for studies on the associated discharge mechanisms.