基于3-D FDTD微型塔电磁模型电流衰减机制

Mechanism of Attenuation Current Along Micro-tower Based on Electromagnetic Model Supported by 3-Dimension FDTD

为研究雷电流在高塔中的传输过程和衰减机制,本文基于三维时域有限差分法(3-D FDTD),建立高度为45cm的微型塔电磁模型,应用理想导体边界条件求解高斯脉冲电流沿塔体表面的时空分布。结果表明,不同形状塔体,表面电流衰减特征不同。锥形塔的表面电流衰减具有方向性,自塔顶向塔底传播时,幅值几乎无衰减,方向相反时,有显著衰减。柱形塔的表面电流自塔顶向塔底以及反向传播时,幅值均有明显衰减。塔体不同高度处电流的衰减程度随着锥形塔顶角和柱形塔半径的增大、激励源频宽的减小而增大。

Supported by three-dimensional finite difference time domain method( 3D-FDTD),electromagnetic model of 45cm-micro-tower is simulated in order to interpret the attenuation mechanism of lightning current transmitting in the tower. In applying perfectly conducting boundary conditions on tower-air interface,distribution of Gaussian pulse currents along micro-tower can be solved. It is shown that different shapes of tower have different effects on currents. Current pulses suffer almost no attenuation when they propagate downward from the apex of conical tower to its base,but attenuate significantly as they propagate from the base of the tower to its apex. When that excited at one of its extremities of a cylindrical tower,current pulses suffer apparent attenuation both from two directions. Current attenuation becomes more pronounced as thickness of cylindrical tower,the angle of conical tower increases,or the pulse width decreases.