棒形悬式复合绝缘子内部缺陷对电场分布的影响

Influence of Internal Defects in Rod Suspension Composite Insulator on Electric Field Distribution

为了对棒形悬式复合绝缘子断裂事故原因进行分析,借助于有限元软件,建立了220 kV复合绝缘子几何模型,对有内部缺陷存在时电场分布特性进行仿真分析。结果表明,气隙周围局部电场增大,且护套内外表面畸变程度不同,存在一个场强梯度,易引起护套击穿;随着气隙长度的增加,电场畸变程度有减弱趋势;水气渗入气隙后,绝缘子护套内外表面电场均减小,但仍存在较大场强差值。电场畸变严重将引起局部放电,若进一步发展会沿电场方向造成碳化通道,加上腐蚀性气体的影响,绝缘子机械性能会大大降低,易引起断裂。

In order to analyze the cause of fracture accident of the rod suspension composite insulator, a 220 kV polymeric insulator geometry model is established by means of finite element software and the electric field distribution characteristics is simulated when there are internal defects. The results show that local electric field around the air gap increases remarkably, and there is a electric field gradient between the inner surface and outer surface of the mandril, which make it easy to cause sheath breakdown; With the increase of air gap length, the electric field distortion degree has a weakening trend; After moisture permeate into the air gap, the electric field distortion degree weakens, but the electric field gradient still exist. Serious electric field distortion will cause partial discharge, and further development will cause carbide channel along the direction of the electric field,then the mechanical performance of the insulator will be reduced greatly combined with the influence of the corrosive gas, which make it easy to cause fracture.