Research On SO₂F₂ Spectral Absorption Characteristics And Concentration Measurement Based On Spectroscopy Technology

Gas insulated switchger（GIS）has the advantages of small footprint,less susceptibility to interference,and high operational reliability.It has become an important equipment for high-voltage and UHV substations.However,the high tightness of the GIS switch makes it difficult to carry out the daily maintenance work of the equipment,and it is impossible to find the fault in time.Sulfuryl fluoride gas（SO₂F₂）is a characteristic decomposition product generated when a GIS switch fails.By measuring the concentration of sulfuryl fluoride gas in the equipment,the fault can be quickly and accurately identified.The position of the characteristic absorption peak of sulfuryl fluoride gas and the change of its spectral absorption characteristics under different conditions are the basis for the concentration measurement using spectroscopy technology.The thesis first comprehensively compares and analyzes the spectrum of sulfuryl fluoride gas and its coexisting interference gas in GIS switch,and selects sulfuryl fluoride at 3619 nm as its characteristic absorption peak.At the same time,this thesis builds a spectrum analysis system based on FTIR infrared spectrometer to study the changes in the spectral absorption characteristics of sulfuryl fluoride gas under different temperature and pressure conditions.The paper designs and builds a gas analysis system based on ICL laser.First of all,the problem of low resolution of the sulfuryl fluoride absorption spectrum in the measured data of the spectrometer and the HITRAN database is addressed.The high-precision absorption spectrum measurement of sulfuryl fluoride was completed using the spectrogram stitching method.At the same time,the paper uses the direct absorption method and the wavelength modulation method respectively to complete the sulfuryl fluoride concentration detection.When the operating temperature is 35℃,the emission wavelength of the inter-band cascade laser can completely cover the absorption spectrum at the center wavelength of the SO₂F₂ gas at 3619 nm.Using the direct absorption method,by taking the logarithm of the ratio of the incident light intensity and the transmitted light intensity,the direct absorption spectrum of the SO₂F₂ gas after subtracting the background absorption is obtained.The results show that the gas concentration has a good linear relationship with the absorption intensity,and the fitting coefficient R² is 0.997.Collect 300 sets of data,the collection time is 50 minutes,the relative standard deviation is 0.5%;the wavelength modulation method is used to obtain the second harmonic spectrum of the SO₂F₂ gas after absorption.The research results show that the gas concentration has a good linear relationship with the absorption intensity,and the fitting coefficient R² is 0.998.Collect 300 sets of data,the collection time is 50 minutes,and the relative standard deviation is 0.3%.This method can provide a new method for the optical detection of SO₂F₂ gas,and then provide a reliable experimental basis for the detection of the SO₂F₂ concentration of SF₆ decomposition products in GIS equipment,provide a new idea for detecting GIS faults,and ensure the stability of the power system Operation is of great significance.