142 / 2022-03-14 10:18:54

Frequency-Shifted Interferometry Cavity Ring-Down Acetylene Sensing Based on Photonic Crystal Fiber

frequency-shifted interferometry cavity ring-down,dual-wavelength differential optical absorption,photonic crystal fiber,dissolved gas analysis,Acetylene

IEEE ICHVE 2022 / 1-PAGE ABSTRACT

Frequency-Shifted Interferometry Cavity Ring-Down Acetylene Sensing Based on Photonic Crystal Fiber

Zhanglin CHEN, Yangyang XIE, Houxian DU, Yuan WANG, Guoming MA

State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing, China

chenzhanglin08@163.com



Purpose/Aim

Dissolved gas analysis (DGA) is important to the early detection of transformer faults. Frequency-shifted interferometry cavity ring-down (FSI-CRD) technique has advantages same as traditional cavity ring-down spectroscopy (CRDS), for example, the fluctuation of laser output has little effect on detection, and the absorption pathlength gets increased. Moreover, CRDS requires high-speed detector for time-resolved detection, but FSI-CRD greatly reduces the performance requirements for the date acquisition equipment by detecting continuous signal in space domain instead of time domain. In this paper, we realized the detection of trace C₂H₂ dissolved in transformer oil by FSI-CRD technique.

Experimental/Modeling methods

A novel gas cell named hollow-core photonic crystal fiber (HC-PCF) was used in this gas detection system. The volume of gas cell becomes more compact because of longer gas-light interaction distance and higher gas-light interaction efficiency along HC-PCF. In this study, dual-wavelength differential optical absorption demodulation method was applied with FSI-CRD technique. The absorption wavelength locating at the absorption line of the target gas records both absorption loss and inherent cavity loss, and the reference wavelength locating out of the target gas absorption line only records inherent cavity loss. By doing differential processing of the ringdown signals at two wavelengths, more precise absorption loss can be measured. Then, the concentration of C₂H₂ can be calculated from absorption loss.

Results/discussion

A dissolved gas sensing platform was built based on HC-PCF gas cell, and the detection of C₂H₂ with different concentrations was realized by FSI-CRD technique. Moreover, the lower limit of detection and better stability, compared with existed FSI-CRD technique, were achieved.

Conclusions

This work provided a new scheme for detection of trace C₂H₂ dissolved in transformer oil, in which more stable and precise detection of C₂H₂ concentration can be achieved by dual-wavelength differential optical absorption demodulation method. Moreover, the lower limit of detection of C₂H₂ concentration can be obtained by the use of FSI-CRD technique with HC-PCF, which is significant to the early detection of transformer insulation faults.