Cavity-enhanced Raman Spectroscopy Detection Technology Based on Optical Feedback for Dissolved Fault Gases in Transformer Oil

Oil-immersed transformers play an important role in the power system, and it is necessary to monitor their operating status in real time. The concentration of transformer fault characteristic gases (CO
2
, CO, H
2
, CH
4
, C
2
H
6
, C
2
H
4
, C
2
H
2
) is a key indicator to reflect the fault and aging state of oil-immersed power transformers. In this paper, a linear Fabry-Perot (F-P) cavity-enhanced Raman spectroscopy detection method based on optical feedback is studied. The power gain factor of the F-P cavity is 4000, and the incident laser power of 80 mW can generate 320W intracavity power. Under the conditions of laser power of 80W, exposure time of 60 seconds and pressure of 1 bar, the detection limit (LOD) of each gas can reach ppm level (CO: 15.2 ppm; CO
2
: 7.2 ppm; C
2
H
2
: 1.8 ppm). This study fully proves that the linear F-P cavity Raman spectroscopy can achieve more sensitive gas detection, which is of great significance to realize the on-line monitoring of Raman spectroscopy of transformer fault characteristic gas.