Research on the critical current of self-heating ferromagnetic anti-icing devices for transmission lines
摘要
Transmission lines operating under severe icing conditions are prone to faults such as galloping, line breakage, and tower collapse, which seriously threaten the safety of the power grid. To address the issues of low efficiency and poor applicability of traditional mechanical de-icing and short-circuit de-icing methods, this paper proposes a method that uses a ferromagnetic material sleeve to attach the conductor, thereby generating heat through hysteresis loss and eddy current loss to prevent icing. Based on heat transfer theory, a calculation model for the critical anti-icing current of a ferromagnetic sleeve–conductor coupling system is established, and the influence of environmental parameters on the critical anti-icing current is analyzed. Experiments were conducted using LGJ-400/35 conductors to measure the critical anti-icing current of conductors with ferromagnetic sleeves under different ambient temperatures, and the equivalent heating power of the sleeves was calculated using the heat balance equation. The results show that the heating power of the sleeve first increases and then tends to level off as the ambient temperature decreases. This paper models the heating effect of the sleeve as an equivalent heat source and incorporates a critical current model to conduct a detailed parametric analysis involving wind speed, Liquid Water Content (LWC), and Median Volume Diameter (MVD). Under varying wind speed conditions, at a wind speed of 4 m/s, the critical anti-icing current required for a sleeved conductor is approximately 29% lower than that for a bare conductor. Furthermore, as wind speed increases, the effectiveness of this reduction exhibits a diminishing trend, with the magnitude of the reduction decreasing from approximately 55% at 2 m/s to about 13% at 10 m/s. The critical anti-icing current increases with increasing LWC and MVD; specifically, when LWC reaches 4 g/m3, the critical anti-icing current can increase by approximately 420 A, whereas the influence of MVD becomes insignificant when it exceeds 100 μm. The research presented in this paper provides a theoretical basis and practical engineering reference for utilizing ferromagnetic materials to assist in preventing ice accretion on power transmission lines.