变压器油中溶解一氧化碳气体的光纤传感技术

为了满足变压器中绝缘纸板因过热或者放电故障产生的一氧化碳气体的在线监测需求, 提出了一种基于光纤光声传感的油中溶解一氧化碳气体检测技术。采用光声光谱气体检测技术、并结合光纤传感和膜分离技术, 设计了集成油气分离和气体检测功能于一体的光纤光声传感探头, 油中溶解的一氧化碳气体通过油气分离膜进入到光纤探头中的微型气腔; 采用两根光纤将探头连接到解调仪器, 分别传输近红外激发光和探测光; 气体吸收光能产生的光声信号被光纤法布里-珀罗传感器探测, 并被设计的光纤光声解调模块进行信号处理, 获得系统对一氧化碳气体体积分数的检测灵敏度为0.345pm/10-6。结果表明, 所设计的光纤传感系统对油中溶解一氧化碳气体体积分数检出限达到5×10-6。该研究具有精度高、抗电磁干扰、脱气简单的优势, 为变压器油中溶解一氧化碳气体的检测提供了新方法。

Optical fiber sensing technology for detection of dissolved carbon monoxide gas in transformer oil

In order to realize the online monitoring of carbon monoxide gas generated by overheating or discharge failure of insulating paperboard in transformers, a detection technology of carbon monoxide gas dissolved in oil based on optical fiber photoacoustic sensing was proposed. Combining photoacoustic spectroscopy, optical fiber sensing, and membrane separation technology, a fiber optic photoacoustic sensing probe that integrates oil and gas separation and gas detection functions was designed. The carbon monoxide gas dissolved in the oil enters the miniature air cavity in the optical fiber probe through the oil and gas separation membrane. Two optical fibers were used to connect the probe to the demodulation instrument, and transmit near-infrared excitation light and probe light respectively. The photoacoustic signal generated by the absorption of light energy by the gas was detected by the optical fiber Fabry-Perot sensor and processed by the designed optical fiber photoacoustic demodulator. The detection sensitivity of the system for volume fraction of carbon monoxide gas was 0.345pm/10-6. The experimental results show that the designed optical fiber sensing system has a detection limit of 5×10-6 for the volume fraction of dissolved carbon monoxide gas in oil. This research has the advantages of high accuracy, anti-electromagnetic interference, and simple degassing, and provides a new method for detecting carbon monoxide gas dissolved in transformer oil.