基于光强调制型光热干涉法的绝缘油中乙炔传感

Intensity Modulated Photothermal Interferometry-based Acetylene Detection in Insulation Oil

实时跟踪变压器油中乙炔气体对保障油浸式变压器稳定运行具有重要意义。新型光学光热干涉技术(photothermal interference,PTI)具有“零背景”、高灵敏度、无接触测量和抗电磁干扰等的优点,在变压器油中溶解气体分析领域具有巨大潜力。该文提出一种基于Herriott气室的光强调制型光热干涉技术的乙炔传感技术。首先,对单光束激发乙炔光热效应的过程进行仿真建模,研究光热效应引起的温度分布、脉冲激励动态响应和正弦激励的频率响应;进一步,开展参数优化实验。结果表明,增大激励光光强能有效增大光热相位,而提高调制频率不利于光热效应的充分激发;最后,开展模拟故障状态下的油中乙炔检测,PTI乙炔系统的检测灵敏度为0.15(m V·L)/μL,检测下限达到0.94μL/L,满足在运高电压等级变压器油中乙炔含量的监测需求,验证光热干涉法在油中溶解气体检测的可行性和潜力。

Real-time tracking of acetylene in transformer oil is of great significance for ensuring the stable operation of oil-immersed transformers.The novel photothermal interference(PTI)optical technique,characterized by"zero background",high sensitivity,non-contact measurement,and immunity to electromagnetic interference,has tremendous potential in dissolved gas analysis of transformer oil.In this paper,an acetylene sensing scheme based on Herriott gas cell and intensity-modulated photothermal interference technique is proposed.First,the process of acetylene photothermal effect excited by single-beam is modeled and simulated to study the temperature distribution,pulse excitation dynamic response,and frequency response of sinusoidal excitation.Parameter optimization experiments are conducted,revealing that increasing the pump intensity effectively enhances the photothermal phase,while higher modulation frequency hinders sufficient excitation of the photothermal effect.The detection of acetylene in oil under simulated fault conditions is carried out,and the PTI system achieves a detection sensitivity of 0.5(mV⋅L)/μL with a lower limit of 0.94μL/L,which meets the needs of monitoring acetylene in transformer oil with high voltage levels during operation.The feasibility and potential of PTI technique in detecting dissolved gases in oil are demonstrated.