ABSTRACT
As an important part of the transmission lines, Insulators are widely used in power system. Ice disaster occurred frequently due to iced insulators of transmission lines, which posed a serious threat to the security and stability of power system operation. Nowadays numerous studies have been conducted on the icing flashover mechanisms, however, there are rarely researches on ice flashover warning and the well-recognized characteristic parameters to assess the iced insulators’ operating state haven't been proposed. So in this paper，based on a large number of artificial icing tests on 110kV composite insulators, leakage current and ultraviolet photon number under operating voltage in different icing conditions in the process of melting ice are collected to extract the characteristic parameters of leakage current that accurately indicate the operating state of iced insulators. The study investigates the relationship between the salt density, ice amount and characteristic parameters and then establishes two evaluation models to predict the ice flashover voltage. Finally, a method of iced insulators hierarchical flashover early warning is proposed.
The main achievements are as follows:
①In this paper, 110kV composite insulators icing tests in total 30 icing conditions in consideration of fiv
e kinds of icing degree, six kinds of salt density are carried out in the multifunctional artificial climate chamber. In order to extract the characteristic parameters of the leakage current effectively reflecting the state of iced insulators and thus to obtain the relationship among them, the changing process of leakage current in the process of melting ice is analyzed as well as the impact of salt density and ice amount on leakage current.
② The ultraviolet photon number of 110kV iced insulators in different degree of ice is collected and the change of the ultraviolet photons in the ice melting process is analyzed. Then the study extracted the characteristic parameters of the ultraviolet photon that effectively reflect the degree of discharge and the average number of ultraviolet photon photons (N). The relationship between the salt density, ice amount and the average number of ultraviolet photon (N) is given. According to the flashover voltage experiments，Ice flashover voltages under different salt density and ice amount are obtained so as to fit the relationship among them.
③The paper puts forward two kinds of iced insulators flashover voltage evaluation models, which are the generalized regression neural network (GRNN) model and minimum support vector machine (LS-SVM) model. By trainings and experiments, the accuracy of the models is verified well. The results show that maximum error of two modes is 9.04% and 9.04% respectively. After that，a metho
d of iced insulators hierarchical flashover early warning method is proposed.
Keywor ds: Composite insulators, icing, leakage current, Flashover voltage assessment, ultraviolet photon
目录
中文摘要.................................................................................................................................. I 英文摘要................................................................................................................................ II 1 绪论 (1)
1.1研究目的与意义 (1)
1.2国内外现状综述 (2)莹石球
1.2.2 覆冰绝缘子串闪络预警参量的研究 (3) 1.2.3 绝缘子运行状态评估模型 (6)
1.3本文研究内容 (7)
2 实验装置、试品及试验方法 (9)
2.1 试验装置 (9)
2.1.1 交流覆冰实验原理 (9)
2.1.2 人工气候实验室以及实验电源 (9)
2.1.3 测量仪器 (10)
2.1.4 泄漏电流采集装置 (12)
2.1.5 紫外光子采集装置 (15)
2.2 试品 (16)
2.3 试验程序与方法 (17)
后视镜套2.3.1 试验条件 (17)
2.3.2 选择盐密（SDD）和覆冰量（W） (17)
2.3.3泄漏电流以及紫外光子图像采集 (18)
2.4 本章小结 (19)电容式触摸开关
3 覆冰绝缘子特征参量提取 (20)
3.1绝缘子融冰过程中泄漏电流和紫外光子的变化趋势 (20)
3.1.1 融冰过程中不同阶段泄漏电流波形特征 (21)
3.1.2 覆冰绝缘子融冰过程不同阶段的紫外光子数 (22)
3.2 泄漏电流波形特征 (25)
乳化液废水处理3.2.1泄漏电流波形时域特征 (25)
3.2 .2 泄漏电流波形的频域特征 (27)
3.3 泄漏电流和紫外光子特征参量的提取 (29)
无人机管控
3.4 盐密(SDD)以及覆冰程度(W)与特征量之间的关系 (30)
3.5 覆冰绝缘子的闪络电压结果和分析 (37)
3.6本章小结 (38)
4绝缘子闪络电压评估和预警方法研究 (39)
4.1绝缘子闪络电压的评估模型 (39)
4.1.1广义回归神经网络（GRNN） (39)
4.1.2 基于最小支持向量机的评估模型 (42)
4.2 覆冰绝缘子闪络电压评估 (44)
4.2.1 训练样本的选取 (45)
4.2.2模型的训练 (45)
4.3覆冰绝缘子预警方法研究 (48)
4.3.1覆冰绝缘子状态评估流程 (48)
4.3.2基于闪络电压预测的绝缘子运行状态评估 (49)
4.4本章小结 (51)
5 结论与展望 (52)
5.1 结论 (52)
5.2 展望 (52)
致谢 (54)
参考文献 (55)
附录 (59)
A. 作者在攻读学位期间发表的论文目录 (59)
B. 作者在攻读学位期间参与的科研项目目录 (59)
1 绪论
1.1研究目的与意义
电能是一种清洁、健康的二次能源，能够利用煤炭、核能以及水能等一次能源进行转换，电能是我国经济发展快速的保障。我国的经济发达地区在沿海一带，而能源的聚集地在我国的西部和北部地区[1]，这时候就需要通过高电压输电线路将电能传输到一些经济发达的地区，从而满足居民和工业用电的需求[2]。我国在能源规划中已经规划了南北和东西各三条特高压输电骨干线路，将西南地区的丰富水电资源输送到华东以及华中地区。但是我国的西南地区的气候环境复杂，微气象条件多种多样，高压输电线路会遇到很多覆冰、覆雪的情况。 我国地缘辽阔，而且我国的高电压输电网络较为发达，因此输电线路覆冰情况是世界上最严重的国家之一，大量的经验表明输电线路覆冰之后会导致绝缘子串闪络、倒塔等严重危害电力系统安全运行的事故[1]。在2003年的电网数据统计中表明，绝缘子冰闪事故是所有造成电网非计划停运事故中的第二大因素。2008年1月到2月，我国南方地区出现了一次非常剧烈的冰雪天气，这一场冰雪灾害给电力系统造成了巨大的损失。其中湖南省是受灾最为严重的省份，湖南省的35kV及其以上等级的输电线路杆塔出现了3318座倒塔事故，有1544座杆塔出现了变形，出现输电线路断线事故的有4425处。同时其他的配电网部分也受到的巨大的破坏，其中的29条500kV输电线路发生了126次的覆冰闪络跳闸故障，220kV 输电线路发生了683次跳闸事故。线路板制作
输电线路绝缘子在经过一些覆冰地带时，绝缘子处于高空中，具有较大的风速，出现冰雪天气或者冻雨天气时就会形成绝缘子的覆冰，覆冰属于一种特殊形态的污秽，绝缘子表面覆冰之后，其有效爬电距离大大的减小，而且冰具有较高的电导率，容易导致绝缘子发生闪络事故。绝缘子覆冰后，绝缘性能大幅度的降低，试验表明绝缘子冰闪电压仅为湿闪电压的40%左右[1-2]，如果绝缘子串被雨凇完全的包裹或者桥接了2/3以上时，绝缘子的覆冰闪络电压会很低，闪络电压随着电导率或者绝缘子表面盐密的增大而降低；覆冰绝缘子串较短时，绝缘子的最低闪络电压同绝缘子长度之间是线性关系[3]；对于长串覆冰绝缘子，虽然其最低交流闪络电压随串长的增加而增大，但不存在线性关系[1-2]；绝缘子严重覆冰时，绝缘子表面的冰棱全部桥接，绝缘子覆冰融化会产生大量的融冰水，绝缘子表面形成水膜之后，表面电阻降低，泄漏电流增大，在一些断口出会出现局部的电弧，这些电弧会促使泄漏电流增大，最终导致绝缘子闪络[1]。
随着我国特高压输电工程的开工建设，输电线路的可靠运行越来越重要。而
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