10 kV交联聚乙烯电缆中超声波传播规律

The propagation characteristics of ultrasonic wave on 10 kV XLPE cable

电缆局放会产生超声波,利用超声波可以进行局放定位和大小估计.为了研究电缆中局放超声波的传播规律,利用COMSOL建立了基于10 kV交联聚乙烯电力电缆本体的声压场仿真模型,探究了超声波在电缆中的扩散过程和电缆表面超声波峰峰值随传播距离的变化规律之间的关系,并在真实10 kV单相交联聚乙烯电缆上进行了超声波衰减实验,探究了真实电缆表面超声波峰峰值随传播距离的衰减规律.结果表明:电缆表面声波峰峰值随传播距离的衰减符合指数规律,衰减系数α=0.07 Np/mm(或0.62 dB/mm),并且是电缆内部声波的扩散过程导致了电缆表面声波峰峰值的严重衰减.据此,针对10 kV交联聚乙烯电缆,建议将局放超声传感器安装在距离局放易发位置100 mm以内,还提出了判断电缆中局放超声波扩散过程结束位置的方法,为确定其他类似型号电缆安装超声传感器的位置提供参考.

The partial discharge of cable will produce ultrasonic wave,which can be used to estimate the location and size of partial discharge.In order to study the propagation law of the ultrasonic wave of partial discharge in the cable,a simulation model of the sound pressure field based on the body of 10 kV XLPE power cable is established by using COMSOL.The relationship between the diffusion process of the ultrasonic wave in the cable and the variation law of the peak-to-peak value of the ultrasonic wave on the cable surface with the propagation distance is explored.The ultrasonic attenuation experiment is carried out on the real 10 kV single-phase XLPE cable.The attenuation law of the peak-to-peak value of ultrasonic wave on the real cable surface with the propagation distance is studied.The results show that the attenuation of the peak-to-peak value of acoustic wave on the cable surface with the propagation distance conforms to the exponential law,and the attenuation coefficient = 0:07 Np/mm (or 0.62 dB/mm), and it is the diffusion process of acousticwave inside the cable that causes the serious attenuation of the peak-to-peak value of acoustic wave on the cablesurface. Accordingly, for 10 kV XLPE cable, it is suggested to install the partial discharge ultrasonic sensorwithin 100 mm from the place where the partial discharge is easy to occur, and the method to judge the endposition of the diffusion process of partial discharge ultrasonic inside the cable is also proposed, which providesa reference for determining the place where other similar cables are installed with the ultrasonic sensor.