Study on the quantitative detection of SO2F2 based on spectral analysis combined with laser spectroscopy

Abstract

Accurate monitoring of insulation failure in SF₆ gas-insulated equipment is essential for ensuring power grid reliability. In the early stages of equipment failure, the characteristic decomposition product SO₂F₂ is generated. By detecting its concentration and variation, insulation defects can be identified. In this paper, SO₂F₂ detection based on laser absorption spectroscopy was studied. The infrared spectral characteristics of SO₂F₂ and its coexisting gases were analyzed. It was found that SO₂F₂ exhibits a strong absorption peak at 2763 cm⁻¹, which is not affected by interference from its coexisting gases. An ICL laser with a wavelength of 3619 nm was selected for SO₂F₂ detection. A laser absorption spectroscopy experimental platform was established to conduct quantitative research on trace levels of SO₂F₂. The detection performance of two methods—direct absorption spectroscopy and harmonic modulation—was compared. The results demonstrate that both methods can accurately detect SO₂F₂ within the 0–600 ppm concentration range, with the harmonic modulation method exhibiting significantly better sensitivity and repeatability. The response to the direct absorption spectroscopy system is 0.782 mV ppm⁻¹, with a repeatability error of 2.525 ppm and a detection limit of 3.94 ppm. The harmonic modulation system shows a response of 11.433 mV ppm⁻¹, which is about 15 times higher than that of the direct absorption spectroscopy. Its repeatability error is 0.937 ppm, which is only 0.37 times that of direct absorption spectroscopy, and the detection limit is 357.56 ppb, which is about 11 times lower than that of direct absorption spectroscopy.