中文摘要：

为发展气体绝缘组合电器（ois）局部放电的检测与诊断方法，提出利用盆式绝缘子的内部均压屏蔽环作为诊断GIS局部放电的一种新型超高频（UHF）传感器。采用时域有限差分（FDTD）法仿真研究了局放UHF信号传播的主要波导模式和内部均压屏蔽环作为UHF传感器的频率响应特性，进而开展了该新型传感器诊断3种典型绝缘缺陷的试验研究，并与商用UHF传感器的检测特性进行了比较。仿真结果表明：模型GIS的横电磁（TEM）模式分量最大、TE11其次，高次波导模式的截止频率主要分布在250MHz-1GHz附近；在3GHz范围内，均压屏蔽环的共振频率点比较丰富，140MHz左右存在1个最大谐振点。试验结果表明：该新型传感器的灵敏度明显高于外置式传感器，略低于内置式传感器；高压尖端和悬浮电位缺陷的主要频谱分布〈1．5GHz，与主要波导模式的截止频率仿真相符；均压屏蔽环UHF信号的最大共振频率约为115MHz，与仿真值140MHz相近。

英文摘要：

In order to further develop the detection and diagnosis measures of partial discharges （PDs） in gas insulated switchgear（GIS）, we proposed to adopt the inner grading electrode inside insulting spacer as an ultra-high frequency（UHF） sensor for PDs. Using the finite difference time domain （FDTD） method, we studied the main waveguide modes of GIS and the frequency response characteristics of the inner grading electrode. Then, we used the proposed UHF sensor to test the PD characteristics of three typical defects, and compared the sensor with commercial UHF sensors in aspects of detec- tion characteristics. The simulation results show that the TEM mode component of the GIS model is the largest and the TE 11 follows when there is PD in the GIS. The cutoff frequencies of high-order waveguide modes distribute around 250 MHz-1 GHz, and there are a number of resonance frequencies below 3 GHz for the grading electrode UHF sensor, while the largest resonance frequency appears at about 140 MHz. The experimental results show that the PD detection sensitivi- ty of the grading electrode UHF sensor is much higher than that of external sensors, however, it is slightly lower than that of interior sensors. The main frequency spectra of both metal protrusion on high voltage conductor and floating potential defects distribute below 1.5 GHz, which is consistent with the simulation of the cutoff frequencies of high-order wave- guide modes. According to the experiments, the largest resonance frequency of grading electrode UHF sensor is about 115 MHz, close to the simulation value, 140 MHz.