Electroacoustic Transition of Partial Discharge in Insulating Oil: From the Correlation of Acoustic Wave and Discharge Energy
Junjie Zhou, Zhicheng Wu, Jiahe Zhu, Haowei Xu, Jing Wang, Qiaogen Zhang
Abstract
Ultrasonic detection is one of the main methods for insulation diagnosis of power equipment. Intrinsically obtaining the characteristics of the acoustic wave excited by discharge and mastering the acoustic and electrical correlation regularity can effectively improve the effectiveness and accuracy of ultrasonic detection. This article established an acoustic and electrical joint experimental platform for partial discharge (PD) in oil-paper insulation to obtain the acoustic-electrical correlation regularity. The results show that PD energy is the core factor that determines the characteristics of the acoustic wave. The peak value of the acoustic wave increases with the increase of PD energy, and the increasing rate gradually decreases. The equivalent frequency of the acoustic wave gradually decreases as the PD energy increases, which can be fitted by a power function. The fitting exponent is related to the electric field nonuniformity. It is worth noting that the weaker the PD, the higher the frequency of the acoustic wave excited. PD causes local heating of the insulating oil to form a low-density area. The expansion and contraction process of the low-density area stimulates acoustic waves. The expansion and contraction range of the low-density area is related to the PD energy and the unevenness of the electric field, which in turn affects the characteristics of the acoustic wave. The study clarified the correlation regularity between PD and the excited acoustic wave, which has important engineering value for ultrasound-based PD detection.