A New Method for Detecting Partial Discharge in T-Type Terminals of Power Cable
Binxian Lu, Xinyu Sun, Haoshuo Yang, Jun Xiong, Zheng Wu, Fei Hu
Abstract
Breakdown accidents in T-type terminals of power cables occur occasionally and abruptly, causing severe explosions and seriously threatening the reliable operation of the distribution grid. As we know, there have not been any practical sensors to detect partial discharge (PD) online in the T-type terminals with a rated voltage of 10 kV up to now. A novel method for detecting PD in T-type terminals is proposed in this article. Keeping the original structure of the T-type terminal intact, a sensor is embedded inside the T-type terminal plug to measure the PD induced voltage signal. The equivalent circuit is built. The measurement mechanism of the proposed method is studied. Two kinds of defects are manufactured in the T-type terminals, which are the stress tube displacement and the lack of the stress tube. The discharge tests are carried out and the PD induced voltage pulse signals are detected by the proposed sensor. Although the aim of this article is to validate the proposed method, the characteristics of the PD induced voltages with different defects are compared. It is found that compared with the defect of the lack of the stress tube, the initial discharge voltage is large for the defect of the stress tube displacement. The dominant frequencies and the increased rate of PD induced voltage are very different. The device can be deployed in the cable system to achieve the purpose of online PD monitoring.