地面建筑物防雷系统中雷电效应研究

发布时间：2018-09-13 12:36

【摘要】：近年来,由于现代建筑物的高度不断增加因此更容易受到雷击的侵害。当建筑物遭受直接雷击时,强大的雷电流自雷击点注入防雷系统,沿各分支导体传播,经接地体最终散入大地。在此暂态过程中,各分支导体上传播的雷电流将在建筑物内产生脉冲电磁场,危害电子设备的安全可靠运行；同时还会在各分支导体上产生热效应,影响建筑物钢筋框架结构的稳定性,并且在接地体周围的地面上产生电位抬高,危及地面活动人员的人身安全。因此,本文旨在对高层建筑物遭受雷击情况下的电磁效应和热效应进行仿真分析和计算,为建筑物的防雷设计提供可信的依据,从而降低建筑物的雷害损失。针对建筑物多导体系统构成的大规模电网络的雷电暂态求解,本文提出了一种降阶模型。该模型基于Arnoldi算法,计算该电网络的全等变换矩阵。通过建立多导体系统的状态方程,求出等效网络的传递函数。最后运用拉普拉斯反变换和卷积定理,求出多导体系统在时域下的暂态响应。根据以上算法,本文计算了实际建筑物的雷电暂态响应,并且将计算结果与运用未降阶电路法和有限差分法得出的结果进行对比,同时还考察了雷电流波形、电磁耦合、计算步长、分段长度等因素对暂态响应的影响,并进行了缩减尺寸钢筋框架模型的雷击模拟试验。从计算得出的防雷系统中各分支导体的暂态电流响应入手,推导出在计及和不计集肤效应这两种情况下导体温升的计算公式；分析了不同雷电流幅值和波形、导体横截面积、不同金属材料对导体温升的影响;开展了导体在冲击电流作用下的温升测量试验。基于麦克斯韦方程组,本文采用混合法,推导出建筑物室内空间任意一点处的暂态电场和磁场的时域计算公式,通过对时间和空间的离散化处理,得出了电场和磁场的数值解法。在求得室内电磁场分布的基础上,运用两线传输线模型求出线路电涌感应过电压。通过确定室内电源线路电涌过电压水平,并设计出了配套的电涌保护器电路。本文根据接地体等效电路,建立了接地网暂态计算模型,求出各接地体暂态响应,并运用积分法计算地面电位分布。其次,运用网络分割法建立人体集总参数等效电路模型,并且给出了人体各主要部分电气参数的计算公式,定量地计算了流过人体的暂态电流和能量。最后考察了不同雷电流幅值、不同雷电流波形以及人站在不同位置时对跨步电压和人体电流的影响。
[Abstract]:In recent years, due to the increasing height of modern buildings, it is more vulnerable to lightning damage. When the building is directly struck by lightning, the powerful lightning current is injected into the lightning protection system from the lightning strike point, and propagates along each branch conductor, and eventually spreads into the earth through the earthing body. During this transient process, the lightning current propagating on each branch conductor will produce pulse electromagnetic field in the building, which will harm the safe and reliable operation of electronic equipment, and will also produce thermal effect on each branch conductor. The stability of reinforced frame structure of buildings is affected, and the potential elevation occurs on the ground around the earthing body, which endangers the personal safety of the ground activists. Therefore, the purpose of this paper is to analyze and calculate the electromagnetic and thermal effects of high-rise buildings under lightning strike, so as to provide a reliable basis for the lightning protection design of buildings and to reduce the lightning damage loss of buildings. In this paper, a reduced order model is proposed to solve the lightning transient of a large scale electrical network composed of a building multi-conductor system. The model is based on Arnoldi algorithm to calculate the full transformation matrix of the network. The transfer function of the equivalent network is obtained by establishing the state equation of the multiconductor system. Finally, by using Laplace inverse transformation and convolution theorem, the transient response of multi-conductor systems in time domain is obtained. Based on the above algorithms, the lightning transient response of actual buildings is calculated, and the results are compared with those obtained by using the unreduced circuit method and the finite difference method, and the lightning current waveform and electromagnetic coupling are also investigated. The effect of step size and segment length on transient response was calculated and the lightning stroke simulation test of the reduced size reinforced frame model was carried out. Starting with the transient current response of each branch conductor in lightning protection system, the calculation formulas of conductor temperature rise under the condition of considering and disregarding the skin effect are derived, and the different lightning current amplitude and waveform, conductor cross section area are analyzed. The effect of different metal materials on the temperature rise of conductors and the measurement of temperature rise of conductors under the action of shock current were carried out. Based on Maxwell's equations, the time-domain formulas of transient electric field and magnetic field at any point in the indoor space of a building are derived by using the mixed method, and the time and space are discretized. The numerical solution of electric field and magnetic field is obtained. On the basis of the distribution of indoor electromagnetic field, the line surge induced overvoltage is obtained by using the two-wire transmission line model. The surge overvoltage level of indoor power line is determined and the circuit of surge protector is designed. Based on the equivalent circuit of grounding system, the transient calculation model of grounding grid is established, the transient response of each grounding system is calculated, and the ground potential distribution is calculated by integral method. Secondly, the equivalent circuit model of lumped parameters of human body is established by using the method of network segmentation, and the calculation formulas of the main electrical parameters of human body are given, and the transient current and energy flowing through the human body are calculated quantitatively. Finally, the effects of different lightning current amplitudes, different lightning current waveforms and different positions on stride voltage and human body current are investigated.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU895

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