2008年初江西省输电线路舞动气象因素分析

摘要

利用2008年初江西省输电线路舞动故障资料以及同期的南昌站地面观测、探空和NCEP fnl分析资料，分析了输电线路舞动期间（2008年1月13-14日）的天气背景，从层结稳定度、垂直运动、水汽输送、风速和风向等方面研究了影响输电线路舞动的气象因素。结果表明：1）500 hPa高度层我国西南地区存在南支槽，受槽前引导气流影响，江西中北部对流层中层（750 hPa）为暖湿西南风或西风。地面西伯利亚冷高压东南移，冷高压前沿的冷锋自西北向东南逐渐过境南昌，受锋面抬升的影响，在冷锋过境前后南昌出现了少量降水。2）南昌地区对流层中层受南支槽前暖湿气流控制，近地层受冷锋后的强烈冷气流控制，这使得输电线路舞动期间南昌上空925-800 hPa出现了强烈的逆温层，导致南昌的降水形态转为冻雨。3）与温度垂直结构相似，线路舞动期间南昌地区近地层至对流层中层也出现了显著的逆湿层，其不仅为降水提供有利的水汽条件，还有利于逆温层的形成和维持。4）输电线路舞动与风速、风向密切相关。舞动前，风向与导线走向夹角都小于45°，且风速较小；随着冷锋南移，风向由东北风转为北风，风向与导线走向夹角大于45°，风速不断增大，舞动现象也随之出现。%With electric transmission line galloping data, conventional observation data, sounding data and the NCEP/NCAR reanalysis data, effect of meteorological factors on Jiangxi electric transmission line galloping in early 2008 was analyzed. Results showed that: 1) Affected by the steering flow ahead 500-hPa southern branch trough over southwest China, Jiangxi was mainly controlled by warm and wet westerly or southwesterly above 750-hPa. As the cold front moved southeastward, Nanchang had a small amount of precipitation impacted by the frontal uplift, with the rapid decrease of temperature to form wire icing. 2) There was a strong temperature inversion between 925-800 hPa over Nanchang due to the warm and wet flow at mid-troposphere and the cold flow near surface, which induced raining to freezing over Nanchang during electric transmission line galloping. 3) Specific humidity was relatively large at middle troposphere while was relatively small near-surface over Nanchang, which formed a typical humidity inversion layer and was conducive to long-lasting snow and freezing weather. 4) Electric transmission line galloping was closely related to wind speed, wind direction, the included angle between the wind direction and the wire direction, before electric transmission line waved, the included angle between wind direction and wire direction was less than 45°, however, with the passage of cold front, the wind direction changed to northerly, the included angle between wind direction and wire direction was larger than 45°, and the wind speed increased,the galloping occurred.