Study On Transformer Oil Dissolved Gas Raman Spectrum Data Processing Method

As an integral part of the power system,the power transformer plays an extremely important and critical role in the substation.The oil-immersed transformer which is most widely used,usually produce 7 kinds of gases（CH₄、C₂H₆、C₂H₄、C₂H₂、CO、CO2、H₂）due to special structure and influenced by heat,electricity,aging and other factors.And this seriously affects the insulation performance of the oil-immersed transformer.But on the other hand,the 7 kinds of gases provide objects for the study on the on-line monitoring of the transformers.gases chromatography,Photoacoustic spectroscopy and some other methods are developed because of this.The Raman spectroscopy is a indirect analysis method without separation and pollution,but because the Raman scattering is weak and vulnerable to external interference.So the research on Raman spectral data processing methods in this paper aims at weakening the limitations of the weak Raman signal.This paper analyzed some calculation methods of the Raman spectra of 7 kinds of fault gas and made comparisons.Molecular structure optimizations and Raman spectra analysis of 7 kinds of fault gases have been finished based on density functional calculations,meanwhile,Raman simulations of 7 kinds of fault gases have been completed.This paper analyzes the actual environment of the transformer oil,permeation principle in the separation of oil and gases and the selection of the membrane.The oil and gas permeation cycle apparatus and the Raman spectroscopy detection platform are designed by analyzing the principle of Raman spectrum and the present situation of the experiment accessories,and the Raman spectra detection experiment is completed.In this paper,the spectra data pretreatment method is established based on polynomial fitting and the Savitzky-Golay polynomial smoothing.And the same is the peak homing model based on the comparison method.Thus the basic requirements of Raman data processing is met fast and efficiently.Voigt line and it’s optimization are established based on the Raman frequency shift,the spectrum peak height and the half peak width,through the analysis of Raman spectral lines.And complete analysis the Voigt line based on the spectrum homing peak method,the experimental results show that the parameters such as spectral peak height and center position are in conformity with the output data of the model.Finally,combined with the actual measurement and the simulation,the Raman frequency of H₂、CH₄、C₂H₆、C₂H₄、C₂H₂、CO、CO₂ are defined as:4155cm-1、2924 cm-1、2954 cm-1、1346 cm-1、1976 cm-1、2142 cm-1、1390 cm-1.Analyses of methane gas under different light powers show that under the same frequencies of light,the Raman frequency shift is not affected by light power,but the spectral intensity would be affected.In the last,the least squares model based on spectral peak parameters is established using external standard method.The methane gas is used to verify the linear relationship between concentration,spectral intensity and the peak area.The establishment of the Raman spectrum data processing method can effectively applied to the specific analysis the 7 kinds of fault gases dissolved in transformer oil,and the study of transformer diagnosis is of great significance.