500kV GIL三支柱绝缘子炸裂故障分析与防范措施

为了解决一起500 kV GIL三支柱绝缘子炸裂故障,对故障GIL开展现场检查、返厂解体、应力仿真计算、缺陷模拟研究,采用同站运行的GIL单元为试品,开展GIL整体和关键部件工频耐压局放测试分析。研究结果表明:GIL三支柱绝缘子炸裂原因为三支柱绝缘子低电位金属嵌件与环氧树脂交界面存在小间隙,在运行过程中,小间隙逐渐劣化,导致交界面电场畸变,从局放异常发展为三支柱绝缘子炸裂。最后结合GIL三支柱绝缘子炸裂原因和三支柱绝缘子生产工艺流程提出了预防性的措施,为后续工程GIL生产运维提供借鉴。

Analysis and Protecting Measures on Burst Fault of Three-Pillar Insulator of 500 kV GIL

In order to investigate the reasons of the burst fault of three-pillar insulator used in 500 kV GIL, different methods such as on-site inspection, disintegration in the factory, stress and defects simulations were applied. The AC withstand voltage and partial discharge tests were carried out on a GIL unit and a three-pillar insulator. The GIL unit under test has the same type as the one broken in the burst fault. The results show that the burst was aroused by a small gap located at the interface between metal insert and epoxy resin. The metal insert was installed in a low potential region of the three-pillar insulator. The small gap was gradually carbonized due to the strong electric field. The small gap leaded to the distortion of the electric field distribution and partial discharge. The abnormal partial discharges eventually developed into the burst fault in the three-pillar insulator. Finally, some protecting measures are put forward according to the burst reasons and manufacturing processes of three-pillar insulators. This experience provides a reference for operation maintenance and manufacture of GIL and its three-pillar insulators.