基于FDTD的雷击杆塔浪涌分析

发布时间：2018-06-05 07:50

本文选题：细导线FDTD + 杆塔结构　；参考：《西南交通大学》2017年硕士论文

【摘要】：电力设施中产生的浪涌信号估计是在电力系统的雷电保护设计中的关键步骤。在电力设备的雷击浪涌分析中,使用电磁暂态分析软件已经大大提高了准确性。但是电磁暂态分析软件仿真是基于一个粗略的简易模型,雷击的空间传播过程分析仍有待研究,比如说在地面上浪涌沿着导体的不均匀传播,垂直于或倾向于导体的传播,仍旧亟待解决。这就衍生了沿着传输杆塔、沿着输电线路、沿着地线传播的浪涌的分析。在国内的雷电保护设计中的雷击分析大部分是通过电磁暂态分析软件分析杆塔受到雷击并且产生回击的情况。因为雷击杆塔时传播的电磁波为非横电磁波,对尺寸更大、构造相对复杂的输电杆塔来说,使用EMTP软件仿真结果会有一定误差。使用时域有限差分法从电磁场的角度对雷击杆塔进行模拟仿真,可以比较精确的模拟出杆塔内部的瞬态过程,可以更加有效的估计输电线路和杆塔绝缘子的耐雷水平。本文首先介绍了国内外时域有限差分法在雷击领域的应用背景,并简单的描述了时域有限差分法的基本原理以及基于准静态场推导的细导线等效处理方法;详细阐述了基于时域有限差分法的雷击杆塔浪涌分析的仿真建模过程,包括雷电通道在时域有限差分法中的建模、输电线路和避雷线的建模、绝缘子的建模以及杆塔主体模型的近似等效建模,细导线等效模型的误差在2%以内;使用时域有限差分法对雷击杆塔的浪涌进行仿真分析,对同塔双回路杆塔进行仿真得到了杆塔上输电线路和避雷线上的浪涌电流波形、绝缘子两端的电压波形,各相线上电流在绝缘子被击穿后显著地增加并短时间达到峰值,上相线和中相线的绝缘子分别在322ns和375ns发生击穿,击穿电压均约为1400kV,而下相线的绝缘子则在824ns才发生击穿,击穿电压约为1100kV;并且在不添加绝缘子的条件下,对同塔双回路杆塔进行了仿真,得到了线上的浪涌电流和空间电场,同时对档距为350m的两个同塔双回路杆塔进行了仿真,分析了线上电流的波形变化,传播到第二座杆塔的电流幅值相对第一座杆塔有小幅提高;在ATP-EMTP中建立了同尺寸杆塔的多波阻抗模型并进行了仿真,线上电流波形与FDTD仿真结果对比可知,FDTD结果和ATP-EMTP程序的避雷线仿真结果比较接近,而上相线上电流峰值FDTD仿真结果比EMTP仿真结果低275A,并且在波形之后的衰减中FDTD仿真结果始终要比ATP-EMTP仿真结果低900A左右,产生这种现象的原因主要是流动在传输杆塔和架空线路的雷电流的电磁感应现象,ATP-EMTP软件仿真并未考虑空间的电磁波传播问题,造成ATP-EMTP分析结果要偏大。
[Abstract]:Surge signal estimation is a key step in the lightning protection design of power system. In the lightning surge analysis of power equipment, the accuracy of electromagnetic transient analysis software has been greatly improved. However, the simulation of electromagnetic transient analysis software is based on a rough and simple model. The analysis of the spatial propagation process of lightning strike still needs to be studied, such as the uneven propagation of surges along conductors on the ground, perpendicular to or inclined to the propagation of conductors. It still needs to be solved. This gives rise to the analysis of surges along transmission towers, along transmission lines, along earth lines. In the design of lightning protection in China, the analysis of lightning strike is mostly carried out by electromagnetic transient analysis software. Because the electromagnetic wave propagates when lightning strikes the tower is non-transverse electromagnetic wave, for the transmission tower with larger size and more complicated structure, the simulation results with EMTP software will have certain error. The finite difference time domain (FDTD) method is used to simulate the lightning tower from the point of view of electromagnetic field. The transient process inside the tower can be simulated accurately and the lightning resistance level of transmission line and tower insulator can be estimated more effectively. In this paper, the application background of FDTD method in lightning strike field is introduced, and the basic principle of FDTD method and the equivalent processing method of thin wire based on quasi static field are briefly described. The simulation modeling process of surge analysis of lightning rod tower based on finite-difference time-domain method is described in detail, including the modeling of lightning channel in finite difference time-domain method, the modeling of transmission line and lightning protection line. The modeling of insulator and the approximate equivalent modeling of the main body model of the pole tower, the error of the equivalent model of thin wire is less than 2%, the surge of the lightning tower is simulated and analyzed by using the finite difference time domain method, the finite difference time domain (FDTD) method is used to simulate the surge of the tower. The surge current waveform on transmission line and lightning protection line and the voltage waveform at both ends of insulator are obtained by simulating the double-loop tower of the same tower. The current on each phase line increases significantly after the insulator is broken down and reaches the peak value in a short time. The insulators of the upper phase line and the middle phase line are breakdown at 322ns and 375ns respectively, the breakdown voltage is about 1400kV, and the breakdown voltage of the lower phase line insulator is about 1100kV when the 824ns is not added, and the insulator is not added to the insulator, and the breakdown voltage of the insulator is about 1100kV when the insulator is not added. The surge current and space electric field on the same tower are obtained by simulation. At the same time, two double-loop towers of the same tower with a distance of 350 m are simulated, and the waveform changes of the current on the line are analyzed. The amplitude of current propagating to the second tower is slightly higher than that of the first tower, and the multi-wave impedance model of the same size tower is established in ATP-EMTP and simulated. Compared with the simulation results of FDTD, the current waveform on line is close to that of ATP-EMTP program. On the other hand, the peak current value of FDTD is 275A lower than that of EMTP, and the result of FDTD simulation is about 900A lower than that of ATP-EMTP in attenuation after waveform. The main reason for this phenomenon is the electromagnetic induction phenomenon of the lightning current flowing in the transmission tower and overhead line. The simulation of ATP-EMTP software does not consider the problem of electromagnetic wave propagation in space, which results in the larger ATP-EMTP analysis result.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM86

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