局部放电超高频信号时频特性与传播距离的关系

Relationship Between Characteristic in Time and Frequency Domain of Partial Discharge Ultra-high Frequency Signals and the Radiation Distance

超高频(UHF)检测法具有频带宽、信息量大、抗干扰能力强等一系列优点,近年来在局部放电检测中得到了广泛应用。为此,建立了变压器油纸绝缘局部放电模型,研究了超高频电磁波信号与脉冲电流之间的对应关系,以及超高频电磁波信号与传播距离的关系。实验结果表明:1)随着传播距离的增加,超高频电磁波信号的能量和幅值均呈非线性衰减趋势;2)局部放电超高频电磁波信号幅值与脉冲电流幅值成正比关系,超高频电磁波信号能量与脉冲电流幅值的平方成正比关系,且比例系数随着超高频电磁波信号传播距离增加而减小;3)超高频电磁波信号中高频分量随着传播距离增加而衰减很快。以上结论有助于更加详细地了解局部放电超高频电磁波信号的辐射规律,是超高频检测法用来检测电力设备局部放电的依据。

The ultra-high frequency（UHF） method has been widely used for partial discharge（PD） monitoring in recent years for its striking advantages,such as having broad bandwidth,rich information,and strong anti-interference performance and so on.Thus,an oil-filled paper-insulated void discharge model is set up to investigate the relationship between the pulse current and the electromagnetic wave with ultra-high frequency electromagnetic wave（UHFEMW） and the relationship between UHFEMW and its radiation distance.The experimental conclusions are drawn as follows.1） as propagation distance increases,the energy and amplitude of UHFEMW decrease gradually and non-linearly.2） There are proportional relations between the amplitude of UHF PD signals to the amplitude of pulse current and between the energy of UHFEMW and the square of the amplitude of PD current,of which both the ratios decrease with increasing radiation distance.3） The high frequency components of UHF PD signals decrease sharply with the increasing radiation distance.The conclusions above contribute to a more detailed understanding of propagation characteristic of the UHF PD signals,and they can provide a solid basis for applying UHF method in detections of transformer insulation faults.