Partial Discharge Ultrasound Detection Method With Fiber Fabry-Perot Sensor In Solid Insulation

Cross-Linked Poly Ethyline(XLPE)cable has become one of the most important power transmission equipment in the power system,and its operation condition is important to the safety of the power system.Partial discharge detection is one of the best methods to evaluate the insulation of XLPE cables.By measuring earlier partial discharge signals,potential faults can be found and insulation breakdown can be prevented.The extrinsic fiber Fabry-Perot interferometer(EFPI)PD acoustic wave sensing technology has the advantages of high sensitivity,anti-corrosion,anti-electromagnetic interference,and has the potential to detect PD in solid insulation.Based on the dynamic and static parameter test of MEMS fiber Fabry-Perot sensor,the method of extrinsic fiber Fabry-Perot sensor to detect the acoustic signal of solid insulation partial discharge is studied,and two arrangements of EFPI sensors on the surface of XLPE cable are proposed: One is that the normal direction of the diaphragm is perpendicular to the medium surface,and the other is that the normal direction of the diaphragm is parallel to the medium surface.The 110 k V XLPE cable body section model is established by multi-physics finite element simulation,and the propagation process of ultrasonic waves in the cable structure is analyzed.At the same time,the response of EFPI sensors to different frequencies of sound waves in different arrangements is compared and analyzed.The simulation results show that the diaphragm normal direction is perpendicular to the medium surface,and efficiency of coupling partial discharge sound waves is higher.Based on the establishment of ultrasonic detection and analysis system for the EFPI sensor,the relationship between sound wave attenuation and sound frequency in hoop and radial direction in cable solid structure is studied.The experiment compares the acoustic wave coupling efficiency of the EFPI sensor with the normal and parallel direction of cable medium surface.Partial discharge ultrasonic detection system for the cable was established,and the needle-shaped discharge model was used to simulate the partial discharge fault in XLPE cable insulation.By comparing the detection results of two different EFPI arrangements,it was shown that the normal direction of the EFPI sensor diaphragm,which is perpendicular to the cable medium plane,is easier to detect PD acoustic signals in cable insulation.