电力变压器局部放电特高频信号外部传播特性研究

Propagation Characteristic of Partial Discharge Ultra High Frequency Signals Outside Transformer

针对变压器箱体的接缝处可以衍射出局部放电特高频(UHF)电磁波信号的现象,在分析变压器箱体接缝对局部放电特高频电磁波传播影响的基础上,探讨了接收天线外部检测特高频信号的可行性,并通过实验研究了局部放电特高频电磁波的外传播特性,通过对信号进行小波包分析,比较了外部接收和内部接收信号的差异.结果表明,特高频电磁波可以透过变压器箱体接缝衍射出来,且频两者谱能量分布并非完全一致,外部检测到的特高频信号距离接缝的远近具有不同的表现形式,强度随着变压器箱体缝宽增大而增大.研究工作为变压器局部放电外部检测提供了理论指导.

It is found in field detection that ultra high frequency （UHF） signals can diffract from the joint of transformer. The feasibility of using external UHF sensor for detecting partial discharge activities is discussed, and the external propagation characteristic of UHF electromagnetic wave is investigated via the lab experiment. The wavelet packet analysis of signals shows that the frequency distribution of external signals and the inside signals is quit difference. The relationship between distance of joint and UHF sensor is also researched and the results show that UHF signals may leak outside the transformer through the joints after multiple refraction and reflection in the transformer tank, and the electromagnetic wave expression varies with difference distance.