Measurement and simulation of partial discharge using optical signal based on crystal fluorescent fiber

Partial discharge (PD) radiates optical signals in the process of discharge. By analyzing the characteristics of optical signals, the intensity of PD can be judged and the insulation status of equipment can be evaluated. The sensor for PD monitoring is prepared by the SiO2 cladding YAP:Ce crystal core fluorescent fiber (SYCF). In this work, the PD fault source with needle-plate electrodes model is established, the PD sensing responses between current transducer (CT) and SYCF are compared and the relationship between SYCF sensing responses and applied voltage is studied. The results indicate that the number of discharge optical pulses and applied voltage from 3 kV to 7 kV have a linear relationship with an R2 value of 0.96122, and the first pulse integral value of discharge signals and applied voltage from 3 kV to 7 kV have a linear relationship with a fit degree of 0.99223. The variation of electron density and N2 density between electrodes are studied by finite element simulation software. As the applied voltage increases, the electron density increases, and the time for streamer head to reach the cathode is gradually shortened. The density of N2 decreases and more photons will be produced. Through the analysis of theory, experiment and simulation, this research can provide a basis for measuring the intensity of PD by means of optical signals sensing by crystal fluorescent fiber.