微地形条件下220 kV朝峰线覆冰断线机理分析

为了深入研究微地形对覆冰线路不平衡张力及覆冰断线冲击的扩大效应，针对处于微地形区朝峰线输电线路覆冰断线事故，建立事故区4塔3档塔线体系有限元模型，定量计算不同工况下塔线体系临界覆冰厚度及断线冲击响应情况，提取不同覆冰工况及不同地形下数据对比分析。结果表明，该微地形下形成的重度覆冰和大高差档距扩大了塔线体系不平衡张力，覆冰断线造成的冲击动力响应远大于非微地形区覆冰断线情况，微地形区形成的重度覆冰及大档距高差扩大了断线冲击效应。

Analysis of the Breakage Mechanism of Iced-Wire for a 220 kV Transmission Tower-Line System Considering the Microtopography

In order to analyze the effect of the microtopography on the imbalance tension of iced transmission lines and the amplifying effect when the iced wires are breaking, a finite model is developed for a four-tower-three-level tower-line system for the accident area. The model is applied to determine the critical thickness of the icing under different working conditions and the corresponding shocking responses when ice covered wires are breaking. Data is collected and cross-compared for different icing conditions and microtopographies. The results show that the heavy ice formulation in the microtopography and the large height difference between towers increase the imbalance tension. Further, the dynamic response effect caused by the breakage of the iced wires in the microtopography is significantly higher than in a non-microtopography area. Finally, the heavy formation of ice in the microtopography and the large height difference between towers increase the shocking effect of wire breakage.