山地风场特性及其对输电线路风偏响应的影响

山地风场的复杂性和显著的三维特性是困扰山区输电线路抗风设计的关键问题。该研究采用CFD数值模拟与风洞试验相结合的方法研究典型单山脉地形和双山脉峡谷型地形的三维平均风场和脉动风场特征。由于风洞试验测点数及试验风速的限制，输电线路沿线各点的三维平均风场基于CFD数值模拟得到。由风洞试验获取山脉地形的湍流度、湍流积分尺度、沿线路方向的衰减系数等脉动风场参数，在此基础上采用POD法重构生成输电线路沿线各点的三维脉动风速时程，并分析比较跨越峡谷、山脊的输电线路沿线风场特征。建立连续三跨输电线路有限元模型，采用时域法研究山地风场特性对输电线路风偏响应的影响。研究结果表明：山顶、峡谷处风速显著增大，且气流爬坡将导致局部位置产生上升气流；由于近地风场加速效应的影响，沿山脊布置的输电线路全档风偏响应增幅较大，跨峡谷输电线路其爬坡段风偏响应增幅较大；上升气流主要使导线竖向风偏位移增大；山地地貌下考虑脉动风速的影响，绝缘子串风偏角风振系数宜取1.2~1.3。该研究为完善山区输电线路的抗风偏设计提供借鉴。

Properties of mountainous terrain wind field and their influence on wind-induced swing of transmission lines

The complexity and remarkable three-dimensional properties of mountainous terrain wind field are the key problems of wind-resistance design of transmission lines in mountainous areas. The properties of three-dimensional mean wind field and fluctuating wind field of typical single mountain terrain and parallel-sided valley terrain are studied by CFD numerical simulation and the wind tunnel test. Three-dimensional mean wind field at each point along the transmission lines was given by CFD numerical simulation because of the limited measuring points and wind speed in wind tunnel test. Based on the turbulence intensity, turbulence integral scale, attenuation coefficient along the lines and related fluctuating wind field factors obtained from wind tunnel test, three-dimensional fluctuating wind speed time-histories at each point along the transmission lines were generated by POD method, and the wind field properties along transmission lines cross the ridge and valley were analyzed and compared. A 3-span finite element model was built to study the influence of the mountainous terrain wind field properties on the wind-induced swing response of conductor based on the time domain method. The results show that wind speed at the top of the mountain and at the valley area increase significantly, and the climbing airflow generates updraft in the local position. The speed-up effect results in a significant increase in wind-induced swing of all lines along the ridge of single hill as well as the climbing sections of spanning valley transmission lines. The updraft mainly increases the vertical displacement of the conductors. Dynamic response factor of wind-induced swing angle of insulator string should be taken between 1.2 and 1.3 when considering the effects of fluctuating wind in mountainous terrain. This research results can provide reference for the wind-induced swing resistant design of transmission lines in mountainous areas.