【作者】 杨成；

【导师】 杜伯学；

【作者基本信息】 天津大学 ， 高电压与绝缘技术， 2008， 硕士

【摘要】 随着西部开发战略的实施以及超高压输电工程的启动,大跨度、长距离输电线路将运行在各种环境条件下。由于输电线路广泛采用复合绝缘子,对复合绝缘子在各种环境条件下的老化及闪络研究也愈为迫切。在我国高原地区,紫外线辐射强度大,紫外辐射对复合绝缘子的影响不容忽视。超高压输电线路中电晕放电现象较为严重,复合绝缘子的电晕老化现象尤为突出,不同海拔条件下的电晕老化特征仍待研究。同时,在高山地区雾凇天气容易导致绝缘子表面发生局部放电甚至引发闪络故障。针对这些不利的复杂运行环境,本文采用RTV硅橡胶绝缘子为试样在实验室条件下研究了环境因素对表面憎水性和闪络特性的影响。针对日照中的紫外线辐射,采用UV-A,UV-B,UV-C三种波段紫外光源进行模拟,对绝缘子试样进行5000小时的紫外辐射,总辐射量可达36~54 kJ/cm~2,相当于高原地区5年左右的紫外辐射量,然后采用静态接触角法测量试样表面憎水性的变化。结果表明:UV-A,UV-B紫外辐射后的试样表面接触角基本保持不变,UV-C辐射下表面接触角降低约20°。在电晕老化实验中,通过减压容器模拟不同海拔下的大气条件,采用多针-板电晕放电模型对硅橡胶绝缘子试样进行600 min的电晕老化试验。研究发现:随着环境气压的下降,表面憎水性丧失愈为严重,试样在60 kPa环境下老化后憎水性丧失最多,表面接触角降低60°以上,之后,随着气压继续降低,憎水性丧失减缓;在开始电晕老化的60 min内,接触角下降速度最快。针对雾凇环境,在实验室条件下模拟雾凇环境,将试样垂直悬挂于人工雾室中,待雾凇在绝缘子表面凝结后施加电压直至发生闪络。根据对闪络现象的观察与分析将闪络过程分为六个阶段,通过对闪络过程中泄漏电流均值、方差以及频谱图进行综合分析发现:随着闪络过程的发展,泄漏电流幅值呈不断上升的趋势,电流脉冲冲击起伏不断增大;电流信号在前三个阶段时低次谐波较多,在临闪阶段电流信号及谐波能量均大幅增加,但低次谐波含量减少,高次谐波含量增加。更多还原

【Abstract】 With implementation of western developm ent, completion of Qingzang railway as well as developm ent of ultra-H V tr ansmission project, long distance power transmission lines will be in service under dif ferent environm ents. As polym er insulators are widely accepted in these lines, it is ur gent to investigate the aging and flashover problems under different conditions.UV-light source with dif ferent wave ba nds UV-A, UV-B, UV-C were adopted to simulate the ultraviolet radiation in sun light, after radiation of 5,000 hours, contact angle of silicone rubber specim ens was m easured to get changing tendency of the hydrophobicity. Results showed that afte r being irradiated by UV -C, surface hydrophobicity of the samples declined appr eciably, while samples under UV-A and UV-B did not change apparently . Meanwhile, the rig idity and co lor varia tion of samples were observed.In corona aging experiments, a decompression chamber was employed to simulate different ambient pressures ass ociated with various high-al titude regions. Multi-needles to pla te ele ctrode model were used to produce corona dischar ge. Results sho wed that surface hydrophobicity got worse with the d ecrease of environmental pressure to 60 kPa, whereafter the deterioration situation got better.In rime flashover experim ent, an artificial chamber was applied to simulate the rime conditions with the specim ens vertically hung in the cham ber. Once the rime was condensed on the insulator su rface, the source voltage was applied until th e flashover occurred. Accord ing to visual observation, the flashover process was separated into six stages. Mean value, variance and frequency spectrum of leakage current were analyzed. It is found that amplitude of the current increased and signal pulse got sharper in the process. There were more low frequency components in first three stages while less in the following sections.更多还原