GIS中局部放电电磁波同轴传播特性仿真研究

Simulation on Propagation Characteristics of Partial Discharge Electromagnetic Signals in GIS with Coaxial Structure

为了对GIS中局部放电产生的电磁信号的同轴腔体传播特性以及结构影响因素进行较为深入的研究,笔者采用有限时域差分方法(FDTD)建立GIS同轴模型,对同轴谐振腔、电磁能量泄漏、发射天线条件等不同因素对局部放电电磁波传播的影响进行了仿真分析。仿真分析可知,两端金属封闭条件下电磁波传播模式不再是简单的同轴腔体下的传播形式,而可看作为一个电磁传输品质系数较低的同轴谐振腔,从而引发更为复杂的高次模波频率成分;盆式绝缘子连接处电磁波能量的径向泄漏会影响后端检测的信号幅值,并且传播模式较高电磁波成分经过绝缘子后衰减较大;金属尖刺或突起不仅起到电磁波激励源的作用,其存在同样也有利于电磁波的传播。

In order to obtain the attenuation characteristics of EM in GIS with coaxial structure, a simplified model of coaxial GIS is built by using FDTD method to simulate the inferences of the resonant cavity, energy leakage and transmitting antenna on propagation of partial discharge electromagnetic signals. Simulation shows that the end enclosed coaxial structure can be viewed as a coaxial resonant cavity with low quality factor, which would induce more complex EM signal components of higher-order mode. The position of insulator would reduce the components of higher-order modes in EM signal propagation to result in a decay of amplitude in measurement. The protrusion on conductor plays a role of excitation source of EM signals, and facilitates the propagation of the EM waves.