48 / 2022-03-07 10:51:44

Detection of Dissolved Gas in Transformer Oil Based on multi-reflection enhanced Photoacoustic Spectroscopy

methane,photoacoustic spectroscopy,multi-reflection,Increased sensitivity

Photoacoustic spectroscopy can effectively detect dissolved methane in transformer oil. In recent years, the on-line monitoring indicators of dissolved gas in oil of ultra-high voltage transformers have been further improved. The traditional photoacoustic spectroscopy detection technology is difficult to meet the detection needs Further research on photoacoustic signal enhancement technology is required.In this paper, the generation mechanism of the photoacoustic signal is analyzed in depth, and the multi-reflection photoacoustic cell is designed by combining the photoacoustic cell with the multi-reflection TDLAS cell. The photoacoustic signal was detected by a diaphragm fiber optic microphone. In the photoacoustic cell, the laser light used to excite the photoacoustic signal is reflected multiple times to realize the enhancement of the photoacoustic signal.The fabricated photoacoustic cell was used to detect the characteristic methane dissolved in transformer oil. The stable detection limit of CH4 is obtained as 0.15ppm. The detection range of CH4 is 1000 ppm. The detection accuracy is not lower than 96.8%, and the detection deviation is not higher than 7.16%.In conclusion, the photoacoustic cell based on the multi-reflection cell can realize the highly sensitive detection of dissolved methane gas in transformer oil.