Transformer oil-dissolved acetylene detection with photonic crystal fiber loop ringdown spectroscopy

• Published in: Sensors and actuators. B, Chemical Chemical, 2021-11, Vol.346, p.130590, Article 130590
• Main Authors: Wang, Yuan, Ma, Guo-ming, Zheng, Diya, Qin, Wei-qi, Jiang, Jun, Zhou, Hong-yang, Yan, Chao
• Format: Article
• Language: English
• Subjects: Acetylene; Crystal fibers; Dissolved gas analysis; Electric power systems; Fiber loop ringdown spectroscopy; Focused ion beam; Photonic crystal fiber; Photonic crystals; Power transformer; Renewable energy sources
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2021.130590

•A photonic crystal fiber is used as a gas cell to ensure a long absorption pathlength and make the structure compact.•Focused ion beam technique is used to process optical fiber microstructure and shorten gas diffusion saturation time.•Fiber loop ringdown spectroscopy further lengthen the absorption pathlength by laser's multiple propagations in gas cell.•Dual-wavelength-based fiber loop ringdown spectroscopy improves the system’s long-term stability. When faults happen in a power transformer, a variety of small-molecular gases will generate and dissolve in transformer oil. Therefore, dissolved gas analysis is one of the important methods to monitor the operating status of transformers. This paper proposes an optical acetylene sensing method based on hollow core photonic crystal fiber (HC-PCF) and fiber loop ringdown spectroscopy (FLRDS). Focused ion beam technique is used to complete the processing of micro-sized channels along a HC-PCF. It takes about 11 min to fully fill the entire length of a 0.83 m HC-PCF with acetylene. Furthermore, the FLRDS system based on the dual-wavelength method achieves a minimum detection limit of 0.71 ppm. This detection system improves detection stability and provides a new idea for online monitoring of dissolved gases in transformer oil.