Partial discharge detection using the fiber-optic Mach-Zehnder interferometer system for XLPE cables

Partial discharge (PD) detection is essential for evaluating the cross-linked polyethylene (XLPE) cable insulation. The acoustic waves originating from PD carry important characteristic information, which can be used for PD detection. In this paper, a fiber-optic Mach-Zehnder interferometer (MZI) has been constructed to detect PD of an air gap sample of simulated XLPE cable terminal. The results indicated that the MZI could effectively detect the acoustic signals of 88 pC PD in the insulating oil and 499 pC internal discharge in the sample. The pulse signal in the MZI sensing signal contains the acoustic information of PD. Its phase distribution map has good phase and amplitude correspondence with the phase-resolved partial discharge map of the HFCT sensing signal to identify PD. The application of fiber-optic sensing technology is beneficial to the construction of smart grid.