针对输电导线热力融冰安全隐患小但耗时长, 机械冲击除冰简单快速, 但可能损伤输电线路等特点, 该文提出一种结合初始热力融冰与机械冲击除冰的复合式除冰技术。该技术首先开启初始热力融冰, 使导线接触面冰层融化, 覆冰与导线之间的黏附力接近0;随后开启机械冲击除冰, 仅需较小的冲击力即可使覆冰脱落。为验证复合式除冰技术的有效性, 该文首先利用FLUENT流体动力学仿真软件建立了覆冰导线融冰模型, 并设定环境温度、覆冰厚度和融冰电流等关键参数, 模拟初始热力融冰过程, 确定了初始热力融冰时间; 然后, 利用ABAQUS有限元分析软件基于覆冰导线融冰模型开展了仅考虑冰层内聚力的除冰过程计算, 获得了临界冲击加速度; 最后, 对比复合式除冰技术所需融冰时间和临界冲击力(临界加速度)与单独采用热力融冰所需时间和单独采用机械冲击所需冲击力。结果表明：采用复合式除冰技术的除冰时间仅为单独采用热力融冰的10.00%~20.00%, 临界冲击力约为单独采用机械冲击除冰的40.00%。该文所提复合式除冰技术既能在短时间内除冰又不易损伤输电线路, 同时除冰后导线表面无残留薄冰, 可为输电线路的除冰提供参考。

Objective: Considering the characteristics of thermal de-icing of transmission lines, which is safe but time-consuming, and those of mechanical impact de-icing, which is simple and fast but may damage the transmission line components, this article proposes a combined de-icing technology involving initial thermal and mechanical impact de-icing. Methods: The combined de-icing technology first uses thermal de-icing to melt the ice layer at the contact surface between the ice and the conductor, thereby reducing the adhesion force between the ice and the conductor to nearly 0. Mechanical impact de-icing is then initiated, where only a small impact force is required to exceed the cohesion force of the ice and cause the ice to fall off. To verify the effectiveness of the combined de-icing technology, a complete numerical model for de-icing of ice-covered conductors was established in stages. Using FLUENT, a heat transfer model for melting ice in ice-covered conductors (considering factors such as Joule heating and latent heat of the phase change) was established, and key parameters (such as ambient temperature, ice thickness, and the de-icing current) were set. Through transient thermal flow coupling calculations, the initial melting process was simulated, and the time threshold for initial thermal ice melting under different working conditions was determined. Subsequently, using ABAQUS (a de-icing model for ice-covered conductors considering the anisotropic mechanical properties of the ice layer) was established based on the ice melting model of ice-covered conductors. The cohesive element was introduced, and the failure behavior of the ice cohesive force was simulated through the maximum stress and the ice shedding criterion. A calculation of the de-icing process was conducted, considering only the ice cohesive force. In terms of load application, the explicit dynamics analysis method was adopted, and the critical (impact force) impact acceleration for ice shedding was obtained by applying transient impact loads. Results: The results showed that during the initial thermal ice melting stage, the lower the ambient temperature was, the greater the wind speed, and the smaller the de-icing current was, the longer the ice melting time. The ice thickness had no significant effect on the initial thermal ice melting time. Under the condition of no adhesion force, the increased in the cohesive strength of the ice increased the impact force required for ice shedding. The de-icing time of the combined de-icing technology was approximately 10.00%-20.00% less than that of thermal ice melting alone, and the impact force (critical acceleration) was approximately 40.00% less than that of mechanical impact de-icing alone. Conclusions: This study proposes a combined de-icing technology that achieves efficient and low-damage de-icing through staged coordinated action. This technology first uses the Joule heating effect to cause a phase change at the conductor-ice interface and generate a water film, reducing the interface adhesion force to below the critical value. A mechanical impact load is then applied, and only the cohesive force of the ice needs to be overcome to achieve ice shedding, reducing both the de-icing time and the impact force of mechanical impact de-icing. The mechanical impact de-icing test results under the condition of no adhesion force verify the feasibility of this combined de-icing technology for transmission lines. De-icing is achieved in a short time with negligible damage to transmission lines, and no residual ice is left on the conductor surface following de-icing. As such, the economy and safety of de-icing operations are significantly improved.