Combined Detection Technology of Trace Acetylene Gas Photothermal Interference and Multi-harmonic Signal
Acetylene is the main characteristic gas for fault diagnosis of oil-immersed transformers.Its dissolved concentration in transformer oil can reflect the insulation status of the transformer.Photothermal spectroscopy gas detection technology is a new method for online monitoring of electrical equipment.Based on the principle of photo-thermal interference,a multi-harmonic trace acetylene gas detection method based on the 2+4th harmonic joint anal-ysis and the 2+4+6th harmonic joint analysis is proposed in this paper.The modulation depth of different harmonic detection methods is optimized and is experimentally verified by the Fabry-Perot interferometer based on hollow-core fiber.Compared with the single 2nd harmonic analysis method,the combined signal fluctuation amplitude of multiple harmonics within 0.5 h is less than 1%,the linear goodness of fit R2 is higher than 0.999,and the detection limit of the 2+4th harmonic combined analysis method and the single 2nd harmonic analysis method are both about 125 ppb(1 ppb=1×10-9).The results show that the combined analysis of multi-harmonic signals for the detection of trace acetylene gas would be helpful to improve the stability and linearity of detection.
万方数据
维普
