导线脱冰跳跃引发的大幅振动极易造成输电线路跳闸放电, 威胁电网运行安全。现有研究在分析风载荷和脱冰共同作用时, 未考虑覆冰形状或忽略了导线脱冰扭转引起的风攻角时变情况, 导致计算工况与真实情况存在偏差。该文基于用户自定义单元子程序, 模拟了导线脱冰过程中风攻角和风荷载时变特性, 并通过有限元仿真, 研究了冰风耦合条件下风速、平均风、脉动风和脱冰率对导线运动特性的影响规律。结果表明: 考虑风攻角的时变特性后, 导线脱冰垂向跳跃高度和运动轨迹均发生显著变化; 不考虑风攻角的时变特性会高估或低估风载荷对脱冰轨迹的影响, 在典型算例中偏差可达72.3%;相较于平均风, 脉动风引起的导线脱冰垂向跳跃高度较大; 导线脱冰垂向跳跃高度在脱冰率为50%时最大, 最大水平摆幅与脱冰率呈负相关。该文研究结果有助于精确计算真实冰风耦合条件下导线脱冰跳跃动力响应, 可为脱冰跳跃易发地区输电线路电气间隙设计提供参考, 从而提升电网抵御覆冰灾害能力。

Objective: Large-amplitude vibrations induced by conductor ice shedding can readily cause trip discharge in transmission lines, posing a serious threat to power grid security. Ice shedding often occurs under wind loads, leading to more complex conductor motion trajectories. Significant discrepancies exist between these dynamics and calculations based on current design codes that neglect wind effects, thereby increasing the probability of discharge failures. Therefore, accurate computation of conductor motion characteristics under combined ice shedding and wind load is essential to provide a scientific basis for setting electrical clearances in transmission lines. However, previous studies on coupled wind and ice-shedding effects generally assumed that the wind load acting on the remaining ice remains constant during vibration, neglecting the time-varying wind attack angle induced by conductor torsion after asymmetric ice shedding. This simplification ignores the dynamic variation of the wind attack angle during ice-shedding vibration, resulting in deviations between simulated and actual conditions. Consequently, such approaches may either overestimate or underestimate the influence of wind load on the ice-shedding trajectory. Methods: This study employs a user element subroutine to simulate the time-varying wind attack angle and corresponding wind load during ice shedding, using crescent-shaped ice accretion as an illustrative case. Finite element simulations are conducted to investigate the effects of wind speed, mean wind, fluctuating wind, and ice-shedding rate on the vertical jump height, horizontal displacement, and motion trajectory of conductors under coupled ice-wind conditions. Results: The results indicated that: (1) The torsional angle of the conductor during ice shedding varied significantly with wind speed. Higher wind speeds led to larger torsional angles, which markedly affected the vertical jump height, horizontal displacement, and motion trajectory. Neglecting this torsional effect introduced errors in calculating jump height and swing displacement that were inconsistent with actual behavior. (2) Conventional methods based on fixed wind loads either underestimated or overestimated the influence of wind on ice-shedding jump height. In a representative case, the calculated jump height based on a fixed wind attack angle deviated by up to 72.3% compared with that obtained under time-varying wind load. (3) The mean wind and fluctuating wind models exerted distinct effects on conductor dynamic responses. At lower wind speeds, differences in motion trajectories between the two models were negligible, whereas at higher wind speeds, fluctuating wind significantly increased jump height and horizontal swing distance. (4) The maximum vertical jump height occurred at an ice-shedding rate of 50%, while the horizontal swing amplitude was negatively correlated with the ice-shedding rate. The peak jump height and maximum horizontal swing did not occur simultaneously. After ice shedding, the conductor midpoint first reached the maximum jump height, after which the vertical displacement decreased while the horizontal displacement increased rapidly until the maximum swing position was reached. Conclusions: This study improves the computational accuracy of conductor ice-shedding dynamic responses under realistic coupled ice-wind conditions, provides guidance for the design of electrical clearances in ice-shedding-prone transmission lines, and enhances transmission line resilience against ice disasters. For refined and differentiated anti-icing design of transmission line sections susceptible to ice-shedding jumps, ice-shedding simulation models incorporating time-varying wind attack angles should be adopted. These models enable the calculation of conductor ice-shedding jump trajectories and envelopes, thereby providing a scientific basis for determining tower head dimensions and electrical clearances between conductors and ground wires, as well as between phases. This approach mitigates risks associated with insufficient electrical clearances while avoiding unnecessary material costs arising from overly conservative designs.