青藏直流联网工程空气间隙的海拔校正

Altitude Correction of Air Gaps for the DC Interconnection Project From Qinghai to Tibet

青海-西藏直流联网工程海拔超过2880m，最高达到5300m。为保证工程的安全可靠运行，线路杆塔和换流站设备的空气间隙放电电压需要进行海拔修正。通过分析比较已有的海拔修正方法，并结合在不同海拔地区包括北京、昆明、西宁、青海大武以及西藏羊八井等地获得的部分试验数据，提出空气间隙放电电压的海拔校正因数；在此基础上，计算并推荐了当额定电压分别为±400kV和±500kV，操作过电压倍数为1．7，青藏直流线路在海拔3000～5300m的范围内时，该工程线路杆塔及换流站的最小空气间隙距离。

The DC interconnection project from Qinghai to Tibet is planned to be located above the altitude of 2 880 m with the highest of 5 300 m. To ensure the safe operation of the interconnection project, the flashover voltage of the air gaps on the line tower and in the converter station devices should be revised with the consideration of altitude, or altitude correction factors should be reconsidered. In this paper the altitude correction factors were given by analyzing and comparing some test data obtained at the different altitude areas such as Beijing, Kunming, Xining, Dawu in Qinghai province and Yangbajing in Tibet autonomous region with common altitude correction methods. On the basis of above research results, and under the condition that switching overvoltage was below 1.7pu and the altitude was from 3 000m to 5300m, the minimum air gaps on the line tower and in the converter stations for DC interconnection project from Qinghai to Tibet were suggested with the rated voltage of±400 kV and ±500 kV.