The Application of Distributed Partial Discharge Synchronous Detection with Wireless Communication on HV Cable Withstand Voltage Test

Partial discharge (PD) synchronous detection is an effective means to improve the quality of the handover test when the withstand voltage test is carried out on the high-voltage cable line, because it is easier to find the hidden defects when the voltage is higher than the operating voltage. However, PD detection of cable lines requires that PD sensors and signal processing devices must be installed at each cable junction or termination. The detection signals distributed in each joint of the cable must be transmitted and collected to the central processing unit for centralized analysis and display. For those several kilometers to more than ten kilometers of buried cable line, if there is no pre-wired communication network, the only way to rely on wireless communication. Due to the complex conditions of the test site, the speed and the stability of the wireless communication network are difficult to guarantee the data transmission of more than 3M bytes/s required by PD measurement. A new distributed PD detection system with wireless communication has been successfully developed and used in recent voltage tests of several 110 kV and 220 kV cable lines. A hybrid wireless communication system was used at the trial site, utilizing 4G/5G communication between the local distributed signal processors and Wi-Fi communication between the central signal processing unit. This communication method can not only meet the data needs of PRPD and PRPS graphs for displaying PD detection signals distributed in the whole line synchronously, but also realize the display of point-to-point signal waveform, and ensure the trend observation effect of each distributed signal and the synchronous comparison function of multi-point signal actograms. This paper attempts to briefly describe the composition and technical parameters of the PD detection system, the form of field application and the system method through a 110kV cable circuit withstand voltage test case.