GIS局部放电超高频电磁波的传播特性研究

Simulation Study on the Characteristics of Ultra-high Frequency Electromagnetic Wave in GIS

SF6气体中的局部放电过程可激发产生超高频电磁波。为研究GIS中超高频电磁波的传播特性,采用时域有限差分法仿真计算GIS中超高频信号的传播特性。仿真计算表明,GIS中局部放电产生电磁波在传播过程中存在延迟现象,有利于局部放电点的定位。因GIS中存在不连续点,超高频信号在传播过程中产生衰减,通过绝缘子时平均衰减3dB,通过T型接头时最严重的支路信号平均衰减10dB,而传播过程中产生的谐振使其衰减变慢。

Ultra-high frequency electromagnetic wave can be radiated by partial discharge （PD） in gas insulated switchgear （GIS） that is filled with SF6. In order to explore the relationship between ultra-high frequency （UHF） signals and PD sources in HIS, the characteristics of UHF signal produced by partial discharge within GIS are investigated by using finite difference-time domain （FDTD）. By changing the parameters of PD sources and sensors, the characteristics of the time-delay effect, reflectance effect, resonance effect and reduction effect of ultra-high frequency electromagnetic wave signal are calculated by simulation. The simulation result shows there is the time-delay effect in electromagnetic wave propagation in GIS, and this characteristic is benefit to e fix position of PD within GIS. The amplitudes of the UHF signals have linear relation to that of PD pulses; the UHF signals can be affected by the radial position, discharge channel length, and the shape of the PD sources in addition to the angle between a PD source and a sensor. Ultra-high frequency signal is reduced because of a discontinuance path for electromagnetic wave propagation in GIS, it reduces 3 dB averagely at insulators and 10 dB in T type contacts in GIS. Electromagnetic wave reduction rate is slowed because of resonance effect.