分裂导线混合凇带电覆冰后的起晕电压跌落研究

Research on Decrease Regularity of Corona Onset Voltage of Bundle Conductor after Energized Mixed-Phase Icing

混合凇会使导线形态发生变化从而改变起晕电压;目前国内外学者针对导线覆冰做了大量研究,但往往忽略输电线路覆冰过程中仍然带电运行,并常用缩比模型研究实际分裂导线,且尚未深入研究混合凇对导线起晕电压的影响;为探求其规律,本文在多功能人工气候室内利用紫外成像技术及曲线拟合法完成对实际实际单分裂、双分裂和三分裂导线带电混合凇覆冰后的起晕电压测量试验,根据不同覆冰形态建立有限元模型分析导线表面场强畸变规律;试验及仿真结果表明:带电混合凇覆冰会严重降低导线起晕电压50%以上;不同电场下混合凇覆冰后的导线起晕电压也不同;覆冰时间的增加会导致起晕电压连续降低,但速度逐渐减慢并最终饱和;相同覆冰时间内,子导线数越多的分裂导线残余起晕电压值越高;电导率不会改变混合凇覆冰形态及导线起晕电压值;混合凇冰柱越长越尖则引起越严重的电场畸变,导线起晕电压也越低;本文结论可为混合凇频发地区输电线路设计提供理论依据。

Mixed-phase ice will make conductor surface extremely rough which leads the electric field distorted seriously. The domestic and foreign scientists had done much research on icing conductor, but they always neglecting that operation conductor energized icing and scaled wire was applied to study actual line, even there has been no in-depth analysis of how energized mixed-phase icing influents corona onset voltage. As to explorer effect law, a series AC corona test of single, double and triple bundle conductors were implemented in the artificial climate chamber, UV imaging technology and I-U curve fitting were applied to analyze inception voltage, and then established the finite element model to analyze the distortion rule of conductor surface electric field. Results show that energized mixed-phase ice can cause the inception voltage value down above 50% significantly, Icing in diverse electric field makes different corona onset voltages. As the icing time increase, corona onset voltage will decrease continually, but it will gradually become saturated. In the same icing time, the bundle conductors with more sub-conductors will obtain the higher corona onset voltage. Icing morphology and the corona inception voltage dose not vary with the difference of the freezing-water conductivity. Icicle growing longer and sharper will make electric field distorted more and more seriously. The conclusion of this paper can provide selection reference and onset voltage calculation for the overhead transmission line in mixed-phase iced area.