【作者】 黄斌；

【导师】 蒋兴良；

【作者基本信息】 重庆大学 ， 电气工程， 2008， 硕士

【摘要】 绝缘子覆冰闪络严重威胁输电线路安全运行,是电力系统安全运行亟待解决的关键技术之一。国内外对覆冰绝缘子闪络特性已进行大量研究,但这些研究多是在不带电情况下进行的,与实际运行情况有差异,事实上电场对输电线路绝缘子覆冰的影响不可忽视。本文在人工气候室内模拟自然覆冰条件,研究电场强度对复合绝缘子覆冰形态、密度、覆冰量和覆冰速度的影响,并与电场对XP-160型普通悬式瓷绝缘子的影响进行对比。根据高速摄像机拍摄的放电过程图片,分析带电与不带电情况下覆冰复合绝缘子放电特性的差异,利用有限元方法建立复合绝缘子电场计算模型,通过电场仿真,验证试验得到的结果。研究结果表明:交流电场不仅影响绝缘子覆冰外观、重量、密度和速度,而且其影响程度与覆冰环境条件有关,带电覆冰时复合绝缘子冰闪电压与不带电覆冰的情况有差异。随外加电压的升高,绝缘子覆冰表面粗糙度增加;冰凌中气泡增大、增多。外加0~20kV电压覆冰15min时,冰重随外加电压的升高增加,外加超过20kV电压覆冰15min时,冰重随外加电压的升高减轻。带电覆冰时,雾淞密度增大,雨淞密度随外加电压的增大减小,雨淞冰厚的增长会出现饱和。电吸力的作用使得覆冰量与覆冰密度增加;极化作用、粗糙度、泄漏电流以及绝缘子表面各类放电现象使得覆冰量与覆冰密度减小。电场强度较小时,电场的吸引作用为主,覆冰量与冰密度增加;电场强度较大时,极化作用为主,覆冰量与冰密度降低。带电覆冰时,冰凌在生长过程中向复合绝缘子芯棒弯曲,弯曲的冰凌会导致各个伞裙上冰凌尖端电场加剧,缓和绝缘子芯棒表面电场分布的不均匀性。外加30kV电压覆冰25min后,部分冰凌尖端电场强度大于空气击穿场强,存在稳定燃烧的电弧,使得冰凌不易被桥接。无论是哪种覆冰情况,覆冰复合绝缘子放电时都是高压端先起弧。带电覆冰情况下电弧首次出现到稳定燃烧的时间、电弧稳定燃烧到绝缘子串闪络的时间均较短。带电覆雾淞情况下复合绝缘子闪络电压下降;带电覆雨淞情况下复合绝缘子闪络电压上升。更多还原

【Abstract】 In recent years, AC flashover programs of iced insulators is one of the severe problems for external insulation of transmission lines and has been one of the key technologies to assurance the electric power system safely operated which should be solved as soon as possible. There are a lot researches about the AC flashover performance and voltage correction, but most of these researches are under non-energized condition. Actually the influence of AC electrical field on the icing process of the transmission line insulators can’t be neglected. As a result, Experiment investigations are carried out on composite insulators and porcelain insulator string in the artificial climate chamber of Chongqing University. Anises the influence of AC electrical field stress on the shape, weight, density and speed of grow of ice. According to the photos carried on the flashover process of composite insulators covered-with ice using ultra-high-speed camera. Study on the influence of AC electrical field stress on the discharge characteristics of composite insulators covered with ice non-energized and on energized.Build the finite element surface electric field calculation model of composite insulators to proof the experiment result.Based on the test results, The influence of AC electrical will change the shape, weight, density and speed of grow of ice, the degree of the influence has relationship with ambient conditions of icing process. The flashover voltage of composite insulators covered with ice non-energized and on energized is different.As the voltage carried out on the insulator goes on, the degree of roughness, the amount of air bubbles in ice slush increased. The weight of the ice will increase with the increase of the voltage when ining on a voltage under 20kV for 15 min, and reduce with the increase of the voltage when ining on a voltage above 20kV for 15 min. The density of rime is great and the density of glaze will reduce with the voltage increase when icing on energized. The increase speed of glaze will saturate when icing on energized.The absorption is the reason of the weight and density of the ice increasing. And the polarization, the roughness of ice, leakage current and the discharge on the insulator will reduce the weight and density of the ice. The absorption is strong and increases the weight and density of the ice at weak electrical field. And the polarization is strong and reduces the weight and density of the ice at strong electrical field.The slush on energized will bend forward the core rod when icing on energized, which increase the electric field of icicles tips and reduce the inhomogeneity of the electric field along the composite insulator core. The electric field of some icicles tips will above breakdown field strength when the insulator icing at 30kV for 25 min.The arc will create at this place and make the energized insulators hard to be bridged by icicles.The discharge happened at the high voltage at first when icing non-energized and on energized. The times of the stage of pause arc appear and the development stage of pause arc when icing on energized is shorter than that icing non-energized. The flashover voltage reduced when the insulator covered with rime with voltage and increase when the insulator covered with glaze icing on energized.更多还原