电力电缆XLPE绝缘上的声波衰减实验研究

为了探究声波在交联聚乙烯(XLPE)电缆绝缘上的衰减特性,制备了220 kV电力电缆横向XLPE绝缘环状切片,搭建了声波衰减研究实验系统,进行了正弦声波衰减实验和声脉冲信号衰减实验,研究了正弦声波信号和声脉冲信号在XLPE绝缘中的衰减与频率的关系。在进行频率分析时,还提出了抵消锆钛酸铅后电陶瓷传感器(PZT)多点测量时PZT和绝缘切片之间难以计算的耦合误差的数学方法。研究结果表明,当声源是正弦信号时,频率在155~350 kHz之间的声波幅值衰减速度依次大于频率在355~500 kHz之间和1~150 kHz之间的声波幅值衰减速度,而1~150 kHz之间的声波幅值几乎不衰减。频率在155~350 kHz之间和355~500 kHz之间的声波幅值在检测位置为45°~90°之间衰减速度最快,90°~315°之间趋于平缓。当声源是声脉冲信号时,声波幅值的衰减也呈现出了高频快速衰减的规律,同时随着传播距离的增加,频谱的主频主要分布在1~50 kHz。

Research on attenuation of acoustic waves on XLPE insulation of power cable

The attenuation characteristic of ultrasonic wave in power cable is very important for exploring the ultrasonic testing technology of partial discharge. In order to explore the attenuation characteristics of acoustic waves on XLPE cable insulation, the transverse XLPE cable insulation annular slices of 220 kV power cables were prepared. and the experimental system of acoustic attenuation was built. The sinusoidal attenuation experiments and acoustic pulse signal attenuation experiments were carried out respectively, and the relationship between the attenuation and frequency of sinusoidal acoustic signals and acoustic pulse signals in XLPE insulation was studied. In the frequency analysis, a mathematical method was also proposed to counteract the coupling error between PZT and insulation chips, which is difficult to calculate when PZT multi-point measurement is carried out.The results show that the attenuation rate of acoustic wave amplitude in XLPE insulation is related to the frequency and propagation distance of acoustic wave under experimental conditions. When the sound source is a sinusoidal signal, the attenuation velocity of the amplitude of the sound wave with the frequency of 155~350 kHz is successively higher than that of the frequency of 355~500 kHz and 1~150 kHz, and the amplitude of the sound wave with 1~150 kHz is almost unattenuated. The amplitude of acoustic waves with frequencies of 155~350 kHz and 355~500 kHz is the fastest between 45°and 90°, and tends to be flat between 90°and 315°. When the sound source is an acoustic pulse signal, the attenuation of acoustic amplitude also shows the law of high frequency and fast attenuation. At the same time, with the increase of propagation distance, the main frequency of the spectrum is mainly distributed in 1~50 kHz.