微量气体光反馈频率锁定V型腔增强拉曼光谱检测技术研究

Accurate detection of trace fault characteristic gases is the key to ensure safe service of power transformer. Nowadays, the existing defection method for the fault characteristic gases have problems on gas cross interference, aging, and so on. Raman Spectroscopy has bottleneck problems of limited minimum detectable concentration and detection accuracy. So this project carries out the technical research of trace gases detection based on optical-feedback frequency-locking V-shaped cavity enhanced Raman spectroscopy. Study on trace gases detection method based on optical-feedback frequency-locking V-shaped cavity enhanced Raman spectroscopy, further study and achieve optical-feedback frequency-locking for diode laser in the visible region, reveal the influence rule of cavity length, laser power in the cavity and effective interaction length on Raman scattering enhancement; Study on the accurate quantitative analysis method of gases by Raman spectroscopy, further study on spectra preprocessing method like baseline correction method by a genetic algorithm based cubic spline smoothing, and study on optimal detection integration time by Allan variance, establishing an accurate quantitative analysis model based on internal standard N2; Explore gas detection characteristics based on Raman spectroscopy, the influence rule of detection parameters and environmental factors on the detection characteristics, aiming to achieve accurate detection of trace fault characteristic gases based on Raman spectroscopy. Which have significant academic values and practical significance for promoting development of gas sensor technology of Raman spectroscopy and improving on-line monitoring level of power transformer fault characteristic gases.

微量故障特征气体准确分析是保障电力变压器安全运行的关键。针对目前故障特征气体分析传感器易老化、气体交叉干扰及拉曼光谱气体分析受限的最小检测浓度、检测准确度等技术瓶颈，项目开展微量气体光反馈频率锁定V型腔增强拉曼光谱检测技术研究。研究微量气体光反馈频率锁定V型腔增强拉曼光谱检测方法，深入研究并实现可见光区半导体激光器的光反馈频率锁定方法，揭示腔长、腔内激光功率及有效作用长度对气体拉曼散射增强的影响规律；研究微量气体拉曼光谱检测准确定量分析方法，深入研究基于遗传/三次样条平滑融合的基线校准算法等预处理及基于阿伦方差分析的最优积分时间确定方法，建立基于N2内标的拉曼光谱准确定量模型；研究故障特征气体的拉曼光谱检测特性及检测参数、环境因素对其影响规律；实现微量故障特征气体拉曼光谱准确检测。对促进拉曼光谱气体检测传感技术的发展，提升电力变压器故障特征气体在线监测水平都具有重要的学术价值和实际意义。

微量故障特征气体准确分析是保障电力变压器安全运行的关键。针对目前故障特征气体分析传感器易老化、气体交叉干扰及拉曼光谱气体分析受限的最小检测浓度、检测准确度等技术瓶颈，项目开展了微量气体光反馈频率锁定V型腔增强拉曼光谱检测技术研究。①构建了H2、CO、CO2、CH4、C2H2、C2H4和C2H6等7种故障特征气体的分子模型及具有拉曼活性的分子振动模型，获得了各气体拉曼频移谱线位置、谱峰强度、拉曼活性等光谱参数；② 研究了腔增强、频率锁定及激光谱线变窄等基本原理，基于光反馈频率锁定技术实现了可见光区半导体激光器有效锁定V型增强腔的谐振频率，证明了气体拉曼散射强度与腔内激光功率及有效作用长度线性相关，腔长对气体拉曼散射强度几乎无影响；③ 开展了7种变压器微量故障特征气体拉曼光谱检测实验，证明了OF-FL-V-CERS的增强特性，达到350多倍；研究了不同检测条件对气体腔增强拉曼光谱检测的影响规律，确定了最佳检测条件：较高的气体压强、激光功率以及较低的检测温度；④ 建立了基于遗传/三次样条平滑融合的基线校准方法及基于N2内标的拉曼光谱准确定量模型，实现了H2、CO、CO2、CH4、C2H2、C2H4和C2H6等7种变压器微量故障特征气体的同时拉曼光谱检测分析，最小检测浓度分别达到16.42 μL/L、29.61 μL/L、18.74 μL/L、2.52 μL/L、3.63 μL/L、10.21 μL/L和7.40 μL/L，其检测准确度高于84.72%。项目研究成果促进了拉曼光谱气体检测传感技术的发展，推动了电力变压器故障特征气体在线监测水平的进步。