±500kV直流极线与接地极线同塔架设时的感应过电压

结合南方电网某±500kV高压直流输电工程在运行中因雷击极线而造成的直流系统双极闭锁的实际情况,利用电磁暂态仿真软件EMTDC/PSCAD进行了仿真重现,研究分析了该直流系统中当直流极线遭受雷击时,其同塔架设的接地极线上产生的感应过电压造成其绝缘发生闪络并形成电弧,导致直流系统双极闭锁。研究结果表明:同塔架设直流极线和接地极线时,由于其绝缘水平差距较大,所以当直流极线遭受雷击时,在同塔架设的接地极线上将产生很高的感应过电压,并且在雷电波传播过程中,感应过电压具有累积效应,将多次达到其绝缘水平,使得接地极线沿线绝缘发生多点击穿闪络。在设计同塔架设不同电压等级线路时该研究结果具有指导意义,应考虑该问题并进行核算。

Induced Overvoltage While ±500 kV Pole Line and Neutral Line Using Common-tower

Combined with the actual situation that bipolar block comes from lightning on DC pole line on one ±500 kV HVDC project in China Southern Power Grid,the recurrence was given by electromagnetic transient analysis software EMTDC/PSCAD.We researched and analyzed that the neutral line in common-tower caused the induced over-voltage and insulation flashover,leading to DC system bipolar block,when HVDC pole line was hit by lightning in the DC system.The results show that,in the common-tower with the pole line and neutral line,due to the big insulation difference,when HVDC pole line is hit by lightning,the neutral line on the common-tower will produce very high induced over-voltage and lightning wave propagation process,and the induced voltage of the neutral line has a cumulative effect to reach its insulation levels many times,thus,multi point flashover occurred in the insulation of neutral line.The results of this study on the common-tower with different voltage grade line are of significance to the design.