Study On Photoacoustic Spectroscopy Detection And Response Characteristic Of Carbon Monoxide

Carbon monoxide (CO) gas is one of the main fault feature gases dissolved intransformer oil, which can effectively reflect overheat and aging process of solidinsulating material in running power transformers. Through detection of carbonmonoxide gas can forecast latent faults and its development for oil-paper insulationtransformer, and achieve early diagnosis, which has important significance for ensuringthe safe operation of transformer. Photoacoustic spectroscopy (PAS) is a trace gasdetection technology based on photoacoustic effect, which has a good prospect in thedetection of gas dissolved in transformer oil with some advantages including no carriergas consumption, good selectivity, large dynamic range, etc.Combined with the research status of gas photoacoustic spectroscopy detectiontechnology, the paper starts from the theory of gas absorption spectral, and analysis thebasic principles of gas photoacoustic spectroscopy detection in-depth. Finally, thecorrespondence between photoacoustic signal and light source intensity, absorptioncoefficient was established. The theoretical analysis results laid the foundation for gasphotoacoustic spectroscopy detection.According to the characteristics of radiation source and the selection principle ofgas absorption spectral line, the characteristic absorption line of carbon monxide wasselected, and a distributed feedback (DFB) diode laser-based gas photoacousticspectroscopy test platform was established. The working principle of DFB diode laserand laser control unit were studied. The impact of working temperature and injectioncurrent on radiation wavelength and output power was tested.The influence that the pressure and temperature on the gas infrared absorptionproperties of carbon monoxide was discussed, indicating that the gas peak absorptioncoefficient and the line width are related with the pressure and temperature closely. Theresponse characteristics of resonant photoacoustic spectroscopy were studied. Therelationship between the photoacoustic signal of carbon monoxide and laser power, gasconcentration was studied, indicating that when gas absorption saturation does not occur,photoacoustic signal increases linearly with the increase of laser power and gasconcentration. The high resolution photoacoustic spectrum of R(8) in3v band of COwas given by narrow linewidth and wavelength tunable characteristics of DFB diodelaser. A photoacoustic quantitative analysis model for carbon monoxide was built based on least squares regression. To calculate gas concentration using this model, the modelcalculation results coincide with the analysis results by gas chromatography. Thereasons that lead to the gas absorption saturation were analyzed. The impact of highconcentration gas on the resonant frequency and gas absorption saturation, and theimpact of buffer gas pressure on gas absorption saturation were studied experimental.