高海拔地区直流输电线路鸟粪闪络模拟试验研究

为掌握高海拔地区直流架空输电线路的鸟粪闪络特性,在海拔高度为4 300 m的西藏羊八井高海拔试验基地对直流V串绝缘子的鸟粪闪络问题进行了试验研究。研究表明:中等黏度的鸟粪易于形成连续的鸟粪通道,闪络概率较高,且正极性的鸟粪闪络概率略高于负极性;在1.9～20.9 mS/cm的电导率范围内,鸟粪电导率对鸟粪闪络概率影响很小;增加垂直间隙距离可降低鸟粪闪络概率。基于试验提出了±400k V柴拉直流线路垂直间隙距离推荐值,考虑风偏修正和鸟类泄粪角度的影响,在4 500～5 000 m海拔地区,防护半径宜设置为3.5 m。鸟粪闪络属于空气间隙击穿与沿鸟粪通道沿面放电相结合的混合放电过程,在海拔高度4 300 m处,其间隙最低击穿电位梯度约为2.1 kV/cm,鸟粪与均压环间隙的放电可近似等效为棒–棒间隙。

Simulated Experimental Research on the Bird Streamer Flashover of DC Transmission Line in High Altitude Area

In order to get the bird streamer flashover characteristics in high altitude area, the discharge of DC V-string insulators was studied in theYang Bajing high-altitude test base at an altitude of 4 300 m. The study results show that medium viscosity bird streamer is easy to form continuous channel and cause flashover. The flashover probability on the positive polarity transmission lines is slightly higher than that on the negative ones. The conductivity of bird excrement has a negligible effect on the flashover probability in the range of 1.9~20.9 mS/cm. Increasing the vertical air gap distance can reduce bird streamer flashover probability. Based on the experiment results, the recommended vertical air gap distance values of ±400 kV Chaila DC transmission line were proposed. After the influence of wind and bird streamer falling angle were taken into consideration, the protection radius was recommanded to set 3.5 m at 3 500~5 000 m altitude area. Bird streamer flashover is a mixed discharge of air gap breakdown and the surface discharge along the bird streamer channel, at the altitude of 4 300 m area, the minimum breakdown potential gradient is about 2.1 kV/cm, and the discharge between bird streamer and corona ring can be approximately equivalent to rod-rod gap discharge.