L型及T型气体绝缘开关模型中电磁波传播特性的仿真研究

采用有限时域差分方法对L型及T型气体绝缘开关(gas-insulated switchgear，GIS)模型中电磁波的传播特性进行仿真计算，分析L型及T型结构GIS中电磁波的分布及其对自身传播特性的影响。研究表明，受速率色散特性的影响，在GIS腔体的直线部分，随着接收点远离激励源，接收电磁波信号的峰-峰值呈衰减分布，但总体能量变化不大。对于L型及T型结构的GIS，在经过L型及T型结构后，信号能量衰减很大。信号频域分析表明，在0°方向存在横电磁波和横电波的11型模波TE11、21型模波TE21和31型模波TE31等高次模波，而在90°方向只存在横电磁波和T21型模波，且信号频率分量的不同导致在不同接收方向上信号能量的分布也会有差异。

Simulation Study on Electromagnetic Wave Propagation Characteristics Within L-Type and T-Type Gas-Insulated Switchgear Model

By use of finite difference time domain (FDTD) method, the simulation of propagation characteristics of electromagnetic wave (E-M wave) within L-type and T-type gas-insulated switchgear (GIS) model is performed. The distribution and its impact of E-M waves within the GIS with L-type and T-type structure on their own propagation characteristics are analyzed. Study results show that affected by speed dispersion characteristic, at the straight portion of GIS cavity the peak-to-peak value of the received E-M wave signal distributes by attenuation law along with the receiving point away from the excitation source, however, the total energy changes little. For GIS with L-type and T-type structure, after the signal passing through these structures the signal energy attenuates remarkably. Results of the signal frequency analysis show that in the direction of 0° there are transverse electromagnetic (TEM) wave and high order model waves such as TE11, TE21 and TE31 and so on, yet in the direction of 90° there are only TEM wave and TE21 model wave. The differences of signal frequency components lead to the discrepancy of signal energy distribution in different receiving directions.