1000kV线路杆塔空气间隙距离选择

Selection of Air Clearance of 1000 kV Transmission Line Tower

特高压(UHV)线路空气间隙距离研究是UHV线路工程设计的基本参数,而前苏联、日本的相关工程参数也与我国情况不同。为此介绍了中国晋南荆1000kV输电线路杆塔空气间隙距离选择的原则、方法和结果。由于塔宽和试验电压波前时间对特高压线路杆塔空气间隙的放电电压有明显的影响,故采用特高压真型杆塔进行空气间隙的放电电压试验,操作冲击试验电压的波前时间为1000μs,和特高压线路操作过电压的实际波前时间比较接近。工作电压下空气间隙距离的选择考虑了最大工作电压、100a一遇的最大风速、多间隙并联对放电电压的影响并取闪络概率为0.13%,得到海拔500、1000、1500m时工作电压下的最小空气间隙距离分别为2.7、2.9、3.1m。操作冲击下空气间隙距离的选择考虑了沿线最大的统计(2%)操作过电压水平为1.7p.u.、操作过电压波前时间取1000μs、多间隙并联对放电电压的影响、计算风速为0.5倍最大风速、闪络概率为0.13%,得到海拔500、1000、1500m时的最小空气间隙距离中相分别为6.7、7.2、7.7m,边相分别为5.9、6.2、6.4m。试验结果表明,边相导线对杆塔的空气间隙距离受工作电压控制,中相导线对杆塔的空气间隙距离受操作冲击电压控制。雷电冲击下的空气间隙距离对杆塔塔头尺寸不起控制作用,可以不规定雷电冲击下的空气间隙距离要求值。

This paper presents the principle, method and the results to select air clearance of 1 000 kV Jin-Nan-jing transmission line in China. The tower width and front time of test impulse voltage have obvious influence on the clearance flashover voltage of the UHV tower. The real tower of UHV is used to do the air clearance impulse voltage flashover test in this study. The front time of switching impulse test voltage is 1 000 μs, which is close to the switching over voltage of real UHV transmission line. The selection of air clearance under operation voltage considers the following facts （1） the maximum operation voltage ; （2）the maximum wind speed happened in last 100 year; （3）the rate of flashover is 0.13%. The minimum operation voltage air clearance for altitude 500 m; 1 000 m and 2 000 m requires 2.7 m; 2.9 m and 3.1 m. The selection of air clearance under switching voltage considers the following facts （1 ）the 1.7 p. u. of maximum statistic 2% overvoltage level along the line, the front time of which is 1 000 μs （2）the influence of the multiply clearances connected in parallel on flashover voltage; （3）the ratio of flashover is 0.13%. The minimum switching impulse air clearance related to altitude 500 m; 1 000 m and 2 000 m requires 6.7 m; 7.2 m and 7.7 m for central phase. For side phase it requires 5.9 m.6.2 m and 6.4m. The air clearance of side phase is controlled by operation voltage and the air clearance of central phase is controlled by switching impulse voltage. The lightning impulse voltage dose not control the distance of tower air clearance. The requirement of air clearance under lightning impulse voltage can not be specified.