基于特高频法检测电气设备局部放电的改进Vivaldi天线

为提高检测变电站电气设备局部放电产生的特高频(UHF)信号的有效性,基于超宽带渐变槽线天线理论,在传统Vivaldi天线的侧边增加渐变槽线和谐振腔后,通过仿真及实测发现,改进后的天线工作频段由1.2~3GHz扩展至0.5~3GHz。同时提高了天线的指向性,而保持工作频段上天线相位中心不变。改进后的天线在工作频段上具有更高的增益和灵敏度,在2GHz时增益达到7.9d Bi,平均灵敏度大于12mm。为验证所设计天线效果,在实验室搭建了基于预制缺陷变压器的试验平台,结果表明所设计的天线可以有效检测到局部放电的UHF信号。与传统Vivaldi天线、加脊TEM喇叭天线和螺旋天线相比,改进Vivaldi天线检测灵敏度较高,脉冲时域响应特性更好,利于进一步的信号分析。

Modified Vivaldi Antenna Applied to Detect Partial Discharge in Electrical Equipment Based on Ultra-High Frequency Method

The designed antenna in this paper is used for detecting the ultra-high frequency (UHF) signal of partial discharge (PD) radiated from electrical equipment at substations. This paper modified the conventional Vivaldi antenna (CVA) based on the tapered slot antenna theory. A tapered slot edge with resonant cavity structure is embedded on the edge of the CVA. The simulation and measured results show that impedance bandwidth of the modified Vivaldi antenna (MVA) is extended from 1.2~3GHz to 0.5~3GHz. Directivity of the MVA is improved without changing the phase center. Gain and sensitivity of the MVA are both improved, where the maximum gain value is 7.9dBi (2GHz) and the average sensitivity value is higher than 12mm. A test platform is constructed in laboratory to verify the effect of the MVA. The test results show that the MVA is appropriate for detecting UHF PD signal. The MVA has higher detection sensitivity compared with the CVA, the ridged TEM horn antenna and the spiral antenna. The impulse response characteristic of time domain signal received by MVA is better, which is helpful for further data processing.