Distributed Strain Measurement On Insulator Surface Based On OFDR Technology

Manufacturing process of basin insulator may lead to strain concentration,which will cause the insulator cracking after long-term operation.Especially for UHV basin insulator,the stress problem is even worse.Measuring the stress and strain distribution of the basin insulator can control the product quality and improve the manufacturing process.In the past,strain sensors can only measure single point,and they are complicated to measure the strain distribution.It is difficult to find insulator stress defects.Recent years,OFDR is rapidly developed in the field of optical sensing.OFDR is a long distance,high spatial resolution measurement technology that combines the advantages of simple optical sensing topology and immunity to electromagnetic interference.Moreover,OFDR also has large detection capacity and multiple detection channels lacking in previous optical sensing technologies.In this thesis,in order to realize the distributed strain measurement of GIS insulation spacers,following works are carried out based on the advanced optical sensing technology:(1)A distributed sensing method based on OFDR technology was developed.The OFDR sensor system was designed and built.The problem of nonlinearity of the light source was solved by adding auxiliary interferometers,and distributed measurement of more than 480 measuring points was realized.The sensing has a spatial resolution of 10mm.(2)Based on the equal-intensity beam strain test system,a strain measurement calibration experiment was carried out on the distributed strain measurement system.The test results show that the strain linearity correlation coefficient of the system is more than 0.999,and the strain sensitivity is between 0.815pm/?? to 0.900pm/??.(3)The OFDR system was used to build 126kV insulation spacers hydrostatic test platform.Through the experiment,the development trend and distribution of insulator surface strain were obtained,and the spatial resolution of measurement was 10mm.The results show that the size of the strain in the loop area at 2cm around the center conductor basically does not change with the pressure.The stress in the area of the 3 cm ring of the insulator arc varies greatly.The distributed measurement of the surface strain of GIS insulators based on OFDR technology is realized.