GIS浇注孔传播内部局部放电UHF电磁波的特性

Distribution of Electric Field Strength and Spectral Characteristic of UHF Signal of Partial Discharge Inside GIS at Resin Sprue of Metal Ring

运行中的大多数气体绝缘关设备(gas insulated switchgear,GIS)上未安装内置式特高频(ultra-high-frequency,UHF)传感器,并且盆式绝缘子被金属环覆盖,因此,常规的检测方法无法检测其内部局部放电的UHF信号,检测金属环浇注孔处辐射出来的UHF信号成为实现GIS局部放电UHF检测的唯方法。在理论分析浇注孔对UHF电磁波的传播衰减特性的基础上,基于时域有限差分法(finitedifference-time-domain,FDTD)仿真了局部放电UHF信号在GIS中的传播过程,重点分析了浇注孔处的电场强度分布和频谱特性,并在GIS平台上进行了试验验证,取得了较好的致性。研究表明,浇注孔处UHF信号的电场强度主分量的方向平行于孔的窄边,其主要能量集中在0.7?2 GHz之间。此结论为改进UHF检测系统的性能提供了重要的指导方向和理论依据。

For the majority of gas insulated switchgear （GIS） being operated the built-in ultra-high-frequency （UHF） coupler has still not been installed, and in view of that the basin-type insulator is overlaid by metal ring, the conventional detection method cannot detect the UHF signal of partial discharge inside the GIS, therefore the detection of the UHF signal radiated out from the resin sprue of the metal ring becomes the only method to detect the partial discharge inside the GIS. On the basis of analyzing the impact of the resin sprue on the propagation and attenuation characteristics of UHF electromagnetic wave, the propagation process of UHF signal of the partial discharge inside the GIS is simulated by finite-difference-time-domain （FDTD）, and the distribution of electric field strength and its spectral characteristic are emphatically analyzed, and the experimental verification is performed on the platform of GIS and a better consistence is achieved. Research results show that the direction of the principal component of electric field strength of UHF signal at the resin sprue is parallel to the narrow side of the sprue, and the energy mainly concentrates on the frequency range from 0.7 GHz to 2 GHz. This conclusion offers important theoretical foundation and guidance for improving the performance of UHF partial discharge signal detection system.