35 kV干式空芯并联电抗器匝间绝缘故障综合分析

Comprehensive Analysis of Turn-insulating Fault of 35 kV Dry-type Air-core Reactors

深入开展35 kV干式空芯电抗器匝间绝缘击穿放电机理研究,对改进35 kV干式空芯电抗器制造工艺和提高35 kV干式空芯电抗器的可靠运行具有重要意义。为此,基于现场试验、ATP-EMTP及有限元仿真计算开展了35 kV干式空芯电抗器系统过电压、匝间电场分布以及匝间绝缘材料的空间电荷等研究。通过研究发现：安装有RC阻容吸收器的情况下,开断电抗器产生的过电压标幺值仅为2.0,但系统过电压的累积效应会造成绝缘材料性能下降。同时,存在于绝缘材料层间的间隙将导致电抗器匝间电场畸变度达到5.5倍,另外,热老化会引起绝缘材料空间电荷特性改变和工频击穿场强的下降。在上述3个方面影响下,35 kV干式空芯电抗器匝间绝缘容易发生击穿事故。

To find the mechanism of turn-insulating fault caused by switching-off shunt reactor in 35 kV system, which is of an important significance to the manufacturing process of dry-type air core reactor and improve its reliability, we researched the system overvoltage of the dry-type air-core reactor and distribution of the inter-turn electric field based on the field tests, ATP-EMTP,and finite element simulations. The space charge properties in inter-turn insulation were also measured. The analysis results indicate that the over-voltage caused by switching-off shunt reactor is 2.0 p.u. with R-C protector on the reactor＇s side, but the accumulation effect of overvoltage can lead to the degradation of insulation. The distortion of electric field intensity resulting from the gap between turn-to-turn insulation is 5.5 times. In addition, the influence of thermal aging on the change of space charge characteristic and the decrease of breakdown voltage are the main factors that lead to the breakdown failure of turn-to-turn insulation of 35 kV dry-type air-core.