摘要
为研究寒冷条件下油纸绝缘的沿面放电特性,建立了能够模拟最低温度为?50℃的高压低温试验系统,采用具有强平行电场分量的沿面电场模型,对比研究了?40℃及40℃条件下油纸绝缘的局部放电特性及击穿特性。研究结果表明:?40℃下局部放电的起始电压和熄灭电压分别比40℃下时高约18%及12%;局部放电发展过程可划分为3个阶段,?40℃下每阶段的平均放电量均小于40℃下的平均放电量,?40℃下局部放电图谱有明显的非对称特征;?40℃下的击穿电压比40℃下低约16%,首次引入水活度的概念对击穿电压下降的现象进行了机制解释,认为降温过程中变压器油游离水会析出形成微小冰粒,这部分冰粒积聚在纸板表面加剧了电场畸变,从而导致了击穿电压下降。最后,根据试验结果给出了特高压变压器的低温绝缘设计及试验检测的建议。研究结果有助于进一步理解低温下油纸绝缘的放电机制。
In order to analyze the surface discharge characteristics of oil-paper insulation under extremely-low temperature,the paper established a high voltage experimental system which could simulate extremely-low temperature extend to ？50℃.On the basis of the system,the partial discharge（PD） and breakdown characteristics of oil-paper insulation between ？40℃ and 40℃ were compared with the surface electrode model which could simulate the parallel electric field component.The results show that,the PD initial and extinction voltage under ？40℃ is about 18% and 12% higher than the voltage under 40 ℃ respectively.The PD development process can be divided into three stages.The mean discharge magnitude under ？40℃ of each stage are lower than that under 40℃,and partial discharge patterns show obvious asymmetric features under ？40℃.The breakdown voltage under ？40℃ is about 16% lower than that under 40 ℃.The water activity has been used to explain the mechanism for the first time,as a low temperature,the transformer oil could separate out unbound water that may become grain of ice which would distort the electric field.Lastly,the suggestions on UHV transformer insulation design and test commissioning were proposed.The results are useful to understand the discharge mechanism of oil-paper insulation under low temperature further.
出处
《中国电机工程学报》
EI
CSCD
北大核心
2016年第10期2827-2835,共9页
Proceedings of the CSEE
基金
国家电网公司科技项目(GY71-14-048)~~
关键词
油纸绝缘
寒冷条件
沿面电场
局部放电特性
击穿特性
水活度
oil-paper insulation
extremely-low temperature
surface electrical field
partial discharge characteristics
breakdown characteristics
water activity
