基于FDTD方法的油库区设施雷击电磁辐射研究

发布时间：2018-05-31 00:33

本文选题：雷电电磁脉冲 + 时域有限差分　；参考：《中国石油大学(华东)》2015年硕士论文

【摘要】：雷电是自然界物理过程必不可少的组成部分,且由其产生的强电磁场辐射是一种极强的电磁干扰源。它不仅影响油库区的空间电磁环境,还可以通过耦合作用进入油库区电力系统,造成高压供电线路停电、DCS(Distributed Control System,分布式控制系统)死机等事故,对各类通讯设备和电力系统危害极大。因此,认识雷电电磁脉冲对周围环境的辐射影响,以及其对电力系统的耦合作用,对于油库区雷电危害的防护具有十分重要的现实意义。本文从雷电回击模型的建立入手,模拟了北京地区实测雷电流波形,并对其进行频谱分析,得出该雷电流能量集中分布在几十千赫兹及以下的特低频和甚低频频段内,在油库区自动化系统中可以采用RLC电路组成滤波器泄放低频雷电波,保护高频有用信号,降低雷电危害。接下来以此雷电流为前提,采用时域有限差分方法计算了油库区遭受雷击时,该雷电流在油库区和地下油罐所处空间中产生的电磁场,通过计算结果分析得出:雷击时地面电磁场主要受500m高度范围内雷电流的影响,其强度在雷电流上升阶段增长较快,在距离雷击通道较近(25m左右)的径向范围内,地表电磁场数值较大且随径向距离增大迅速衰减约一个数量级;雷击电磁波在地下的传播过程中,土壤对垂直电场分量Ez具有较大的衰减,地下空间内部电场分量Ez高于其与土壤接触部分。最后,本文将油库区电力系统简化分为线缆终端的负载电阻和只考虑电感效应的电力线两部分,在雷击近场范围内分别对其进行时域有限差分计算分析,并提出了防雷措施。计算结果表明:线缆终端负载上感应的电压和电流峰值可达数百千伏和数百安培,在尖峰过后存在一个振荡过程,其振荡电压峰值仍可高达上万伏,且随线缆长度的增加,耦合作用增强;电力线通过感性耦合方式感应出的浪涌电压集中在雷电流波的上升阶段,沿雷击通道径向铺设与垂直地面铺设的电力线两端感应电压和末端感应电流较大,其峰值可达数千伏和数百安培。
[Abstract]:Lightning is an essential part of physical processes in nature, and the strong electromagnetic radiation generated by it is a very strong electromagnetic interference source. It not only affects the space electromagnetic environment in the oil depot area, but also can enter the power system of the oil depot area by coupling action, resulting in the power failure of the high-voltage power supply line and the breakdown of the distributed Control system (distributed control system). It is harmful to all kinds of communication equipment and power system. Therefore, it is of great practical significance to understand the radiation effect of lightning electromagnetic pulse on the surrounding environment and its coupling effect on power system for the protection of lightning damage in oil depot area. Starting with the establishment of lightning return stroke model, this paper simulates the measured lightning current waveform in Beijing area, and analyzes its frequency spectrum. It is concluded that the lightning current energy is concentrated in the ultra-low and very low frequency bands of tens of kHz and below. In the automatic system of oil depot area, the filter composed of RLC circuit can be used to release the low frequency lightning wave, to protect the high frequency useful signal and to reduce the lightning harm. On the premise of the lightning current, the electromagnetic field generated by the lightning current in the space of the oil depot and the underground oil tank is calculated by using the FDTD method when the oil depot is struck by lightning. Through the analysis of the calculation results, it is concluded that the ground electromagnetic field is mainly affected by the lightning current in the height range of 500m, and its intensity increases rapidly in the rising stage of the lightning current, and in the radial range of about 25m from the lightning strike channel. The electromagnetic field of the earth surface is larger and decays rapidly with the increase of radial distance by about one order of magnitude, and the soil has a great attenuation to the vertical electric field component Ez during the propagation of lightning electromagnetic wave. The electric field component in the underground space is higher than that in the soil contact part. Finally, this paper simplifies the power system in the oil depot area into two parts: the load resistance of the cable terminal and the power line which only considers the inductance effect. The finite difference time domain (FDTD) analysis of the power system is carried out in the near-field range of lightning strike, and the lightning protection measures are put forward. The results show that the peak voltage and current induced on the cable terminal load can reach hundreds of kV and hundreds of amperes. After the peak, there is an oscillating process, and the peak value of the oscillation voltage can still be as high as ten thousand volts, and with the increase of cable length, The surge voltage induced by inductive coupling mode is concentrated in the rising stage of lightning current wave, and the inductive voltage and terminal inductive current at both ends of the power line laying along the lightning strike channel and vertical ground are larger. Its peak can reach thousands of volts and hundreds of amperes.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE88

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