北极风电送出输电线路风、冰荷载初步探讨

以10个北极地区国际交换站气温数据及模式分析得到的边界层高度变化规律为基础,对比分析了基本风压、风压高度变化系数与中低纬度地区的差异。-70 ℃温度下空气密度比-10 ℃温度下增加了29.7%;在北极年平均气温条件下,喀拉海沿岸地区的基本风压比标准空气密度对应的基本风压增大了7.3%~8.7%。北极地区大气边界层高度也比中低纬度地区大,使得风压高度变化系数有所减小,不计入边界层高度的变化,其取值偏于安全。提出了北极覆冰区输电线路需要考虑的荷载类型,给出了研究北极地区输电线路覆冰荷载的静动力分析模型。针对北极地区强风伴随低温条件的特点,结合IEC规范提出了北极地区输电线路风冰荷载概率组合建议。

Preliminary Discussion on Wind Loads and Accreted Ice Loads of Transmission Lines for Developing Wind Power in the Arctic Regions

Based on the temperature data from ten International Exchange Stations and the varying trend of the boundary layer height determined by metrological model analysis, the reference wind pressure and the exposure factor in the Arctic regions were compared with those in mid-low latitude regions. The air density at -70 ℃ temperature is higher than the value at -10 ℃ temperature by 29.7%. At the average temperature in 20 years in a typical Arctic region(Karskoe More areas), the reference wind pressure is higher than the value at standard atmosphere pressure by 7.3% to 8.7%. The boundary layer height in the Arctic regions is higher than that in the mid-low latitude regions, which can induce the decrement of the exposure factor of wind pressure. If the effect of the boundary layer height is ignored, the exposure factor for wind pressure calculation is on the safety side. The typical load types of transmission lines in accreted ice areas of the Arctic areas were proposed. The static and dynamic analysis models for calculating ice loads of transmission lines in the Arctic regions were established. According to the climate feature of strong wind accompanying with extreme low temperature, the probabilistic combination method of wind load and accreted ice load based on IEC standard was suggested.