【作者】 赵紫辉；

【导师】 胡劲松；

【作者基本信息】 西南交通大学 ， 高电压与绝缘技术， 2012， 硕士

【摘要】 随着超／特高压电网的快速发展,输电线路的高度、传输容量及传输距离都在不断的提高。输电线路经常遭受各种雷电过电压的侵袭,引发停电事故,雷击故障已经成为影响输电线路安全运行的第一因素,为了更经济合理地制定防雷措施以防止雷害事故发生,深入研究输电线路雷击事故的性质,准确评价输电线路上的雷电过电压性能就显得极为重要。通过模拟雷电过电压波在超高压交流输电线路中的传播过程,找到雷电过电压的影响因素,探索其特性规律,具有非常重要的理论意义和工程应用价值。本文根据雷电过电压的发生机理和500kV超高压交流输电线路的实际情况,利用电磁暂态仿真程序PSCAD/EMTDC搭建了包括雷电流模型、线路杆塔模型、绝缘子闪络模型以及输电线路模型等在内的输电线路雷击模型,模型考虑了冲击电晕和工频电压等因素带来的影响,更能真实地模拟输电线路上的雷电过电压情况。基于搭建的仿真模型对输电线路反击、绕击和雷击未造成故障时产生的雷电过电压暂态特征进行了仿真分析,发现了雷击塔顶和导线时绝缘子两端过电压波形的主要物理特征以及塔顶和三相导线、避雷线上的过电压特征,并确定了雷电过电压波及输电线路的范围,对比了考虑冲击电晕前后雷电过电压的变化。利用PSCAD/EMTDC软件仿真研究了雷电流波形与幅值、避雷线布置方式、杆塔塔型、导线布置方式(包括导线排列方式、导线分裂数)、接地电阻等因素变化时,塔顶或导线上雷电过电压的特点及其参数关系,找到了影响超高压交流输电线路反击和绕击过电压的关键因素。结果表明：雷电流幅值与波形、杆塔塔型、接地电阻对输电线路的反击过电压有着较大的影响；而雷电流幅值与波形、避雷线布置方式、导线分裂根数对输电线路的绕击过电压有较大的影响。本文的研究结果为输电线路雷电过电压研究奠定了一定的理论基础,对现有输电线路雷电防护水平的提高和新建线路的防雷设计提供了参考。更多还原

【Abstract】 With the rapid development of Power Grid at Extra and Ultra High Voltage Level, the height of transmission lines, transmission Capacity and distance are constantly increasing. Transmission lines often suffer the invasion of various lightning overvoltage leading to blackout accident, thus lightning fault has become the first factor to affect safety operation of transmission lines. In order to draw up more economical and rational lightning protection measures to prevent lightning fault, it is extremely important to further research the lightning properties and accurate evaluate the lightning overvoltage performance of transmission lines. Through simulating propagation process of lightning overvoltage along EHVAC transmission lines, to find its influence factors and explore its characteristic regularity will be of great theoretical significance and value for engineering application.In this paper, according to the occurrence mechanism of lightning overvoltage and the actual situation of500kV EHV AC transmission lines, the lightning models of transmission lines including lightning current model, transmission line tower model, insulator flashover model and the transmission line model etc. are established by using Electromagnetic transient simulation program PSCAD/EMTDC. The impact of impulse corona and power frequency voltage has been taken into account in these models, thus the lightning overvoltage of transmission lines could be more realistically simulated. Based on the established simulation models, the lightning overvoltage transit features of transmission lines are analyzed on the situation of back striking, shielding failure and lightning without fault respectively, the main physical characteristics of overvoltage waveform at both ends of the insulator and the overvoltage feature of the tower top, three-phase conductors, ground wires are found, the propagation range of lightning overvoltage along the transmission lines are determined, the lightning overvoltage change considering the impact of corona or not is contrasted.By using PSCAD/EMTDC simulation program, the characteristic of lightning overvoltage and the relationship of parameters on tower top or conductors are studied when the lightning current waveform, amplitude, arrangement mode of ground wires, tower type, conductor configuration including arrangement mode and split number as well as grounding resistance are changed, and the key factors which affect back striking and shielding failure overvoltage of EHV AC transmission lines are found. The results show that the back striking overvoltage of transmission lines is affected by lightning current waveform, amplitude, tower type and grounding resistance, while the shielding failure overvoltage is influenced by lightning current waveform, amplitude, arrangement mode of ground wires and split number of conductors. These results could lay a theoretical foundation for the study of lightning overvoltage of transmission lines, and be available for reference to increase the lightning protection level of existing transmission lines and design lightning protection of new lines.更多还原