台风天气山区地貌某线路跳线风偏事故分析

Wind-induced Flashover Incident Analysis of Jumper Considering the Effect of Typhoon and Mountainous Topography

以某500 kV发生绕引跳线风偏事故的实际线路为研究对象,对跳线及其相连导线建立精细化有限元模型。在平坦地形下利用谐波叠加法模拟了6种湍流度的脉动风场,并由大涡模拟获得考虑真实山区微地形影响的台风脉动风场,分别计算这7种脉动风场下的跳线风偏响应峰值因子、均方根、风偏位移极值等参数,分别分析了台风下微地形及湍流强度对跳线风偏的影响。跳线风偏形态表明,绕引跳线风偏危险点在跳线1/4跨处,而不是跳线绝缘子串挂点处。跳线风偏位移受台风期间高湍流度影响显著,跳线风偏响应与来流湍流强度几乎线性相关,据此给出了风偏位移拟合公式。在山区微地形环境下,风场受地势抬升、狭道效应等真实微地形影响,平均风速显著增大;微地形下相比更大湍流度的平地工况,跳线风偏位移仍有明显增加,跳线距塔身最小间隙仅0.65 m,小于规范最小绝缘间隙1.2 m;大涡模拟结果显示该山地微地形环境可按1.5倍修正绕引跳线10 m高度设计风速,即提升跳线设计风速至40 m/s,可满足该线路跳线防风偏要求。

A wind-induced flashover incident involving a circuitous jumper on a 500 kV transmission line is researched,and a refined finite element numerical model of jump lines is established.The harmonic-wave superposition method is used to simulate the synoptic wind speed with six different turbulence intensities adapted to flat terrain,and the large eddy simulation is used to simulate the typhoon wind speed adapted to realistic mountainous microtopography.The peak factor,root mean square and extreme value of jumper swing response in seven wind fields are calculated,respectively,to analyze the effect of turbulence intensity on the typhoon wind field.The wind-induced swing morphology of jumper shows that the wind-induced swing should be judged based on the displacement of quarter-span instead of the insulator string.The displacement of the jumper is significantly affected by the high turbulence intensity during the typhoon,and the root-mean-square of the jumper displacement in the middle span is almost linearly correlated with the incoming turbulence intensity.A fitting formula for the extreme value of jumper swing response in the middle span is proposed.In mountainous microtopography,the wind field is affected by realistic microtopography such as terrain uplift and the effect of narrow,and the mean wind speed increases significantly,while the fluctuating wind speed does not change much or even decreases.The wind-induced swing response of jumper in the microtopography,which has less turbulence intensity than in flat terrain,still increases significantly,indicating that the microtopography has a significant amplifying effect on the wind speed.The minimum gap between the jumper and the tower is only 0.65 m according to the simulation,which is less than 1.2 m in specification.The results of the large eddy simulation show that the design wind speed at 10 m height can be amended by 1.5 times due to the effect of the mountainous microtopography,that is,to enhance the design wind speed to 40 m/s,which can satisfy the requirements of the jumper against wind-induced swing incidents.