基于频率锁定吸收光谱技术的变压器故障特征气体检测研究

Detection Study of Transformer Fault Characteristic Gases Based on Frequency-locking Absorption Spectroscopy Technology

高准确度、高灵敏度检测故障特征气体是基于油中溶解气体分析的变压器早期潜伏性故障诊断的关键。该文开展了基于频率锁定吸收光谱技术的变压器故障特征气体检测研究。基于电四极跃迁理论,论证了H_2等同核双原子分子同样存在吸收效应;为提高H_2最小浓度的检测极限,搭建了频率锁定腔增强吸收光谱气体检测平台,首次实现了基于吸收光谱技术的变压器故障特征气体H_2的定性与定量检测分析,检测准确度与重复性分别达到约93.82%及94.35%。腔内气体压强为101k Pa时,H_2最小检测浓度的实验值约为7.5μL/L,与计算值的相对偏差仅为3.8%。此外,基于激光器阵列技术,实现了其他6种变压器故障特征混合气体CO、CO2、CH_4、C_2H_2、C_2H_4与C_2H_6的吸收光谱检测,其检测准确度与最小检测浓度同样满足变压器油中溶解气体分析的需求。该研究为研制基于频率锁定吸收光谱技术的变压器故障特征气体现场检测系统提供了理论依据和技术支撑。

Highly accurate and sensitive detection of fault characteristic gases is the key to diagnosing incipient transformer faults through dissolved gas analysis. In this paper, the detection study of transformer fault characteristic gases based on the frequency-locking absorption spectroscopy technology was carried out. Based on electric quadruple transitions theory, it had been proved that homonuclear diatomic molecule, such as H2, also exist absorption effect. To improve the detection limit of minimum concentration of H2, a frequency-locking cavity enhanced absorption spectroscopy platform for gas measurement was built up. The qualitative and quantitative analysis of fault characteristic gas H2 in transformer was achieved for the first time, the detection accuracy and repeatability is about 93.82% and 94.35%, respectively. The experimental value of minimum detectable concentration of H2 reaches approximately 7.5μL/L, the relative deviation of is only 3.8% when comparing to the calculated value. In addition, based on laser array technology, the measurement of other 6 kinds of fault characteristic gas-mixtures （CO、 CO2、 CH4、 C2H2、 C2H4 and C2H6） was achieved, the detection accuracy and minimum detectable concentration of which satisfy the requirement of dissotved gases analysis in transformer oil. All of which provides a theoretical basis and technical support for develop a live detection system for transformer fault characteristic gas based on frequency-locking absorption spectroscopy technology.