Detection of methanol dissolved in transformer oil by laser Raman spectroscopy

The analysis of methanol concentration is regard as a new means of evaluating the aging degree of insulating paper in power transformers. Using Laser Raman Spectroscopy (LRS) to detect the concentration of methanol in transformer oil can overcome many shortcomings of traditional detection techniques and realize fast test. In this paper, the application of LRS in detecting methanol concentration has been studied. First of all, Gaussian 09W was used to build the structure model of methanol molecule and analyze the Raman spectrum of methanol molecule. LRS liquid detection test platform was built based on confocal Raman technology. Standard samples of transformer oil were tested utilizing this test platform directly, and the Raman characteristic peak at 1030 cm⁻¹ was selected for quantitative analyses. In order to further improve the detection sensitivity, extraction technology was applied. At last, applying the least squares method, the quantitative analysis method was built between the areas of Raman characteristic peak and methanol concentrations. The experimental results showed that LRS method can effectively detect the concentration of methanol in transformer oil, which proposes a new way to realizing the fast test of methanol in transformer oil.