1000kV/500kV同塔混压4回输电线路的防雷性能

Lightning Performance of Quadruple-circuit Transmission Line with Dual Voltage 1000 kV/500 kV on the Same Tower

在线路走廊比较紧张的东部地区,特高压电网考虑架设同塔混压多回输电线路,特高压同塔混压多回输电线路相比常规线路在防雷性能上有没有其自身的特点,这是目前期待解决的问题。针对这一问题,利用电磁暂态程序(PSCAD/EMTDC)和改进的电气几何模型(EGM)计算了1000 kV/500 kV同塔混压4回输电线路的反、绕击跳闸率,分析了避雷线保护角θs、1000 kV线路底层横担和500 kV线路顶层横担之间距离H及500 kV线路顶层横担宽度l对线路绕击跳闸率的影响,比较了1000 kV/500 kV同塔混压4回输电线路和其他电压等级同塔混压线路的防雷性能。结果表明,线路的反击跳闸率较低,但存在500 kV双回反击跳闸的可能性。线路的绕击跳闸率高于其他电压等级的同塔混压线路,1000 kV绕击跳闸率随着θs和H的增加而增大,随着l的增加而减小。500kV绕击跳闸率不受θs的影响,随着H的增加而先减小后增大,随着l的增加而增大。线路整体绕击跳闸率随着θs、H和l的增加而增大。为了减小线路的绕击跳闸率,可减小θs和H,在19.06～25.06 m范围内适当增加l。

Mixed-voltage multi-circuit transmission line on the same tower can be considered in UHV grid in eastern area where line corridor is tensional.Aiming at the problem whether there are any different characteristics in lightning performance between UHV mixed-voltage multi-circuit transmission lines on the same tower and conventional transmission lines,back flashover and shielding failure trip-out rate of quadruple-circuit transmission line with dual voltage 1000 kV/500 kV on the same tower were calculated with PSCAD/EMTDC and improved EGM.Moreover,the influences of distance H between bottom cross arm of 1000 kV and top cross arm of 500 kV,protection angle θs,and width l of top cross arm of 500 kV line,on shielding failure lightning performance was analyzed.Furthermore,the lightning performance of quadruple-circuit transmission line with dual voltage 1000 kV/500 kV on the same tower and other voltage level mixed-voltage transmission line on the same tower were compared.The results show that back flashover trip-out rate of line is lower,but there is the possibility of double-circuit back flashover trip-out of 500 kV line.Shielding failure trip-out rate of line is higher than that of other voltage level mixed-voltage transmission line;with θs and H increasing,shielding failure trip-out rate of 1000 kV line（n21） becomes larger,and n21 decreases with l increasing.Shielding failure trip-out rate of 500 kV line（n22） is unaffected by θs,n22 decreases first then increase with H increasing and n22 increases with l increasing.The integral shielding failure trip-out rate of transmission line increases with θs,H and l increasing.In order to reduce the shielding failure trip-out rate of transmission line,θs and H can be reduced and l can be increased appropriately in range of 19.06~25.06 m.