| Partial discharge (PD) is an important cause of insulation breakdown, soelectrical equipment within PD online monitoring can predict early detection oflatent faults，and prevent from sudden failure before complete failure of theinsulation, and reduce the impact on social and economic caused by poweroutages. PD acoustic detection method is not only anti-electromagneticinterference, but also capable of real-time monitoring, and is used to soundsource localization, which attracts wide attention. But this detection method haslow sensitivity and is not a quantitative measurement. An extrinsic Fabry-Perotsensor is designed to detect acoustic signal generated from PD in cable terminal.The sensor is embedded into liquid medium to get high detection sensitivity.The propagation characteristic of ultrasonic which cause by PD in cableterminal is studied in COMSOL software based on finite element method (FEM).in liquid-solid composite medium, compared the simulation results withexperimental verification.The issue starts in experimental environment, simulating PD of cableterminals with main way of insulated is liquid-solid composite insulation:Placing pressboard on the center of Needle–plate electrode model,and applyingan alternating voltage variable transformer both ends of the electrodes；Usingfiber extrinsic Fabry-Perot sensors (EFPI) which is self–made, PZT sensor as thedetector for PD acoustic detection and ERA for electrical measurements，tosimultaneous detection of PD acoustic signal and electrical signal of ERA.Compared the voltage magnitude with acoustic energy of signal detected by ERAdetection system, proposed a effective way of measure the severity of the samePD discharge source acoustic by the energy calculation in the frequency domain.At last, combined the simulation analysis in liquid-solid composite insulation ultrasonic propagation, all the issue provide a reasonable solution for areasonable place fiber optic sensors, to improve measurement sensitivity. |
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