特高压直流输电线路电晕起始场强与线下合成电场的研究

发布时间：2018-04-30 10:40

本文选题：电晕起始场强 + 合成电场　；参考：《重庆大学》2014年硕士论文

【摘要】：发展具有输电容量大、输电距离远等特点的特高压直流输电是我国目前的国情需要，但特高压直流输电线路电晕效应造成的线下电磁环境改变、无线电干扰和可听噪声等问题无法回避。目前直流线路电晕起始特性的研究主要集中在电晕起始场强和电晕起始电压两方面，对直流线路电晕起始特性的计算一般忽略正负极导线起晕机理的差异。直流线下合成电场的水平是线下电磁环境的重要指标，而对线下合成电场的研究大多以线路结构参数对合成电场的影响为主，随着特高压直流输电工程建设的快速发展，促使我们需要考虑到直流线路经过房屋建筑物与邻近人体等复杂环境的合成电场分布情况。本文从直流线路正负极导线不同的起晕机理出发，以典型的特高压直流线路电晕起始场强和邻近房屋与人体时的合成电场为研究重点，主要开展了如下的工作：首先，阐述正负极电晕自持放电起晕判据与直流线下合成电场形成机理，推导了利用模拟电荷法对导线表面空间电场与标称电场计算过程，建立基于Deutsch假设的合成电场计算模型，为研究线路起晕场强和线下合成电场奠定基础。其次，分别提出正负极直流电晕自持发展的条件，建立以光电效应电子辐射机理为依据的正负极直流导线电晕起始计算模型，分别讨论了子导线半径、导线对地高度、分裂间距、导线极间距和不同绞线结构等参数对典型双极直流线路各极子导线电晕起始场强和电晕起始导线外加电压的影响，从工程上分析了减轻线路电晕效应的方法。并通过对同塔双回线路不同极性排布方式时起晕场强和电晕起始电压的比较，得出-+/-+排布方式线路的电晕程度最低。再次，以两种不同的房屋模型为例，建立特高压直流输电线路邻近建筑物时合成电场的计算模型，开发直流线路邻近房屋附近合成电场的三维计算方法，比较了三维与二维计算结果的差异。分析了邻近房屋的合成电场分布受不同房屋结构、房屋高度、房屋与线路中心距离等因素的影响，对比同塔双回不同排布方式下邻近房屋合成电场的计算结果，，提出线路下方房屋的高度限制以及房屋与线路中心的规避距离。最后，探究了人体位于特高压双极直流线路下方的合成电场的分布问题。选取合理的人体简化模型参数，在人体模型直接接地的条件下，绘制人体模型分别位于正极与负极导线两侧时人体附近合成电场分布的等值线图。讨论并分析了人体不同站位方式、不同身高和与线路中心不同距离对人体附近合成电场的畸变作用。
[Abstract]:It is necessary to develop UHV HVDC with large transmission capacity and long transmission distance, but the off-line electromagnetic environment is changed due to corona effect of UHVDC transmission line. Problems such as radio interference and audible noise cannot be avoided. At present, the research on the corona initiation characteristics of DC lines is mainly focused on the two aspects of the corona starting field strength and the corona starting voltage. The difference of the corona initiation mechanism of the positive and negative conductors is generally neglected in the calculation of the corona initiation characteristics of the DC lines. The level of the synthetic electric field under DC line is an important index of the electromagnetic environment under the line, but the research of the synthetic electric field under the line is mostly based on the influence of the line structure parameters on the synthetic electric field. With the rapid development of the UHV HVDC project construction, the level of the synthetic electric field below the DC line is very important. It is necessary to consider the distribution of electric field in complex environments such as buildings and adjacent human bodies. Based on the different halo generation mechanism of the positive and negative electrode conductors of DC lines, this paper focuses on the initial field intensity of corona of typical UHV DC lines and the synthetic electric field when the buildings are adjacent to the human body. The main work is as follows: First of all, the criteria of self-sustained discharge of positive and negative corona and the formation mechanism of synthetic electric field under DC line are expounded, and the calculation process of space electric field and nominal electric field on conductor surface using simulated charge method is deduced. The calculation model of synthetic electric field based on Deutsch hypothesis is established, which lays a foundation for studying the intensity of line halo field and the above line synthetic electric field. Secondly, the conditions of self-sustaining development of positive and negative direct current corona are put forward, and the calculation model of corona initiation of positive and negative direct current conductors based on the mechanism of photoelectron radiation is established, and the radius of sub-conductors and the height of conductors to the ground are discussed respectively. The effects of the parameters such as split spacing, wire pole spacing and different strands structure on the initial field strength of corona and the external voltage of the corona starting conductor in typical bipolar DC lines are discussed. The methods to reduce the corona effect are analyzed in engineering. By comparing the intensity of corona field and the initial voltage of corona in different polarity arrangement mode of double-circuit line of the same tower, it is concluded that the corona degree of -r-arrangement line is the lowest. Thirdly, taking two different building models as an example, the calculation model of composite electric field in buildings adjacent to UHVDC transmission lines is established, and the three-dimensional calculation method of composite electric field near buildings is developed. The difference between three-dimensional and two-dimensional calculation results is compared. The composite electric field distribution of adjacent buildings is analyzed, which is influenced by different building structure, building height, and distance between the building and the center of the line, and the calculation results of the composite electric field of the adjacent buildings under different arrangement modes of the same tower are compared. The height limit of the house under the line and the circumvention distance between the house and the center of the line are proposed. Finally, the distribution of synthetic electric field under UHV bipolar DC line is investigated. Selecting reasonable parameters of human body simplified model, under the condition that the human body model is directly grounded, the isoline diagram of the synthetic electric field distribution near the human body is drawn when the human body model is located on both sides of the positive and negative electrode conductors, respectively. This paper discusses and analyzes the distortion of synthetic electric field near human body by different stations, different height and distance from the center of the line.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM721.1

【参考文献】