DC ice-melting model for wet-growth icing conductor and its experimental investigation

Abstract

Icicles are often formed under the downside surface of conductor in the wet growth icing of overhead power line. When the ice deposit around overhead power line is molten by Joule heat produced by current, the pattern of heat transfer of ice deposit with icicles is dissimilar to that without icicle, so the ice-melting model for the columnar icing conductor cannot be applied to icicle-shaped icing conductor. According to the heat-transfer characteristic of the icicle-shaped icing conductor, this paper puts forward a DC ice-melting model for the icicle-shaped icing conductor. Because this full model includes three-dimensional heat-transfer and interface movement, which cannot be solved in closed form, a finite element scheme in space-domain and a finite difference scheme in time-domain are employed to discretize the governing equations. Firstly the whole ice-melting process on the icicle-shaped icing conductor is simulated by this model. Then the simulated results are validated by ice-melting experiments in the artificial chamber. The study from the model and the experiments shows that the size and length of icicle as well as the space between the adjacent icicles are factors to affect ice-melting. With the shorter icicle space, the bigger icicle size and the longer icicle-length, the surface of ice layer is enlarged and then more heat is taken away by the convection and radiation, so the ice melting time will get longer. power line, icing, ice storm, ice melting, icicle Citation:Fan S H, Jiang X L, Shu L C, et al. DC ice-melting model for wet-growth icing conductor and its experimental investigation.

DC ice‐melting and temperature variation of optical fibre for ice‐covered overhead ground wire

“…where I denotes the ice-melting current; r T denotes the ice-melting resistance of OPGW at T°C; Г 01 denotes the interface between the ice layer and the external environment (Fig. 2); h denotes the heat exchange coefficient between the ice surface and the external environment [16], watts/(square metres degrees centigrade) [W/ (m 2°C )]; T i denotes the outer surface temperature of ice; T a denotes the ambient temperature; ρ i denotes the density of ice, kilograms cubic metres; L F denotes the latent heat, L F = 335,000 J/ m 3 ; ΔS denotes the ice-melting area in the cross-section; θ denotes the element of area in the cross-section; ρ θ and C θ denote the density and specific heat of the region θ, respectively; and dT is the temperature change in time span Δt.…”

“…denotes the heat flux of the interface Г 01 in the normal direction (W/m 2 ) and h denotes the heat exchange coefficient between the outer surface of the ice and the ambient environment [16], which is related to the outer surface temperature of the ice. The temperature distribution of the outer surface of the ice is uneven during the ice-melting process, and the heat exchange coefficient is calculated by using its mean value.…”

Control scheme of the de‐icing method by the transferred current of bundled conductors and its key parameters

“…The heat flux dissipated by convection and radiation with ambient air on the outer surface is expressed as where h is the heat transfer coefficient [12],W/(m 2 ·°C).…”

“…According to Fan et al . [12], the heat‐transfer coefficient h under the experimental conditions specified below can be expressed as …”

Model for ice wet growth on composite insulator and its experimental validation

“…Glaze icing, which is always growing with icicles during ice wet-growth process, can bridge the adjacent insulators and shorten creepage distance significantly, subsequently, leading to flashover easily [1,2]. Different from some cold regions having serious rime icing problems [3], wet-growth icing is common instead of rime icing in south China, where complex terrains and climate contribute to wetgrowth icing events, including insulators and transmission lines [4][5][6]. In early 2008, a rare ice storm attacked most provinces of south China and caused countless conductor galloping or breaking, pole leaning or collapse, ice flashover and a large area power outages [7,8].…”