Coupling Simulation and Experimental Verification of Partial Discharge Sound Field and External Optical Fiber in Insulation Air Gap of Cable Joint

In this paper, the finite element model of the spike defect of the high-voltage conductor in the 10 kV cable joint is built, the propagation characteristics of the acoustic signal during the insulation air gap partial discharge are simulated, and the coupling function between the partial discharge acoustic wave of the cable joint and the external sensing fiber is established. The results indicate that for this type cable joint air gap partial discharge, it is most suitable to choose an external sensing fiber winding width of about 30 mm; When the external voltage of the cable joint is 19 kV and the partial discharge of the air gap defect is 250 pC, the maximum phase change of the corresponding sensing fiber is about 0.3 rad; The main component of sound waves received on optical fibers is within 2 kHz, and high-frequency signals rapidly decay. And a high-voltage testing system was built, and the phase change of the external optical fiber during partial discharge of the corresponding cable joint was measured using a coherent optical time-domain reflectometer. The correctness of the simulation results was verified through experiments. This analysis can provide basis for acoustic partial discharge detection of cable joints.