高灵敏度全光纤内腔式光热变压器油溶解气分析技术研究

Dissolved Gas-in-oil Analysis (DGA) is the most effective mean for diagnosing transformer failures. A novel all-fiber photothermal (PT) DGA monitoring scheme is proposed in this project. A high power output broadband tunable erbium doped fiber laser combined with hollow-core photonic bandgap fiber intra-cavity and fiber Fabry-Perot PT interferometer based on Phase Generated Carrier (PGC) demodulation are applied in the new PT DGA monitoring system. The new integration of these advanced techniques results in a significant improvement of the performances of the PA DAG monitor system. A sub-ppb level detectable concentration limit for C2H2 and sub-ppm level detectable limits for CH4, CO, CO2 and H2O gases are expected. As the gas sensing unit is an all-fiber detector, the system is immune from electromagnetic and mechanical vibration interference. To take the advantages of ultra-sensitive for failure gases, a further investigation of correlation between transformer failures and dissolved gas concentration is also presented. The results of the study will provide a clear theoretical model and experimental data for transformer’s early fault evolution. Thence a new transformer’s early diagnosis and infancy fault warning guide rule is expectantly established.

为实现变压器早期故障诊断，进一步提高变压器油溶解气分析（DGA）的检测灵敏度成为必要，急需对光声DGA技术进行结构和机理上的深入探索和创新。本项目提出一种创新的全光纤内腔式光热DGA检测技术方案，采用高功率可调谐光纤激光器作为光源，结合空心光子晶体带隙光纤（HC-PBF）有源内腔，集成基于相位生产载波解调的高灵敏度光纤FP光热传感器构成新型的变压器DGA光热检测系统。通过对HC-PBF内腔光热光谱气体感测机理研究，揭示光热现象引起的HC-PBF相位调制机制，完成HC-PBF内腔光纤激光器结构的优化设计；对HC-PBF复合腔结构的光纤光热传感器中存在的偏振和相位衰落、多模干涉等问题进行研究，获得稳定的信号解调方式和优化的传感器结构，最终实现具有抗机械振动干扰、电磁免疫能力的多故障特征气体的高灵敏度测量，为变压器故障的早期预警提供新的理论和技术支撑，为电网安全运行提供有力保障。

为实现变压器早期故障诊断，进一步提高变压器油溶解气分析（DGA）的检测灵敏度成为必要，急需对光声DGA技术进行结构和机理上的深入探索和创新。采用高功率近红外可调谐光纤激光器作激发光源，设计、研制适用于光声探测的高灵敏度光纤F-P腔式声波传感器用于光声信号检测，结合激光腔内置式微型光声池和多种气体成分光声信号分析方法，研制出能够对乙炔、二氧化碳、一氧化碳、甲烷等多种变压器故障气体进行高灵敏度、高分辨率测量的新型光纤光声光谱气体探测器。气体的检测灵敏度可达到ppm（part per million）和ppb（part per billion）数量级，最终实现具有抗机械振动干扰、电磁免疫能力的多故障特征气体的高灵敏度测量，为变压器故障的早期预警提供新的理论和技术支撑，为电网安全运行提供有力保障。实验过程发现该系统也可以对氨气、氨气与高浓度二氧化碳和水汽混合气体进行高灵敏度检测，对氨气的检测灵敏度达到亚ppb量级，因氨气是区分正常人和肾功能衰竭患者的特种气体，所以该项研究也可以应用于医学诊断和治疗监测，特别是肾功能衰竭患者血液透析过程的无创、实时监测。本项目共发表相关研究论文5篇，申请专利3项，培养硕士研究生4人，完成了项目计划的研究内容，实现了项目预期的目标和成果。