基于微纳光纤倏逝场传感的变压器油中微水含量检测

Detection of Moisture in Transformer Oil Based on Micro-nano Fiber Evanescent Field Sensing

变压器油的状态监测对变压器维护起着重要的作用。变压器油的绝缘性能主要取决于其击穿电压,而击穿电压受变压器油中微水含量影响较大。为克服现有检测方法易受现场电磁环境干扰等不足,提出了一种基于微纳光纤倏逝场传感的变压器油中微水含量检测方法,该方法利用微水含量改变引起折射率变化,影响微纳光纤倏逝场分布情况,进而导致输出光功率变化来进行检测。进一步地,搭建了微纳光纤熔融拉锥平台,制备了直径为10~125μm的微米量级光纤传感器。实验结果表明:光纤直径是影响油中微水检测的重要因素,随着微纳光纤直径的减小,微纳光纤传感器的灵敏度提升。当光纤直径达到10μm时,微水质量浓度检测下限低于5 mg/L,可以满足现场油浸式电力变压器的检测需求。这种新型微纳光纤传感器实现了油浸式电力变压器油中微水含量的实时测量,可用于油浸式电力变压器的在线监测。

Condition monitoring of transformer oil plays an important role in transformer maintenance.The insulation performance of transformer oil mainly depends on its breakdown voltage which is greatly affected by the moisture quantity in transformer oil.In order to overcome the shortcomings of the existing detection methods that are susceptible to electromagnetic interference,this paper proposes a detection method based on Micro-nano fiber(MNF)evanescent field sensing.The method is based on the principle that the change of moisture quantity causes the change of refractive index,affecting the distribution of evanescent field of the MNF,thereby resulting in the change of output optical power.Then,an MNF fusion taper platform was built up to prepare MNF with the diameter of 10~125μm.The experimental results show that the diameter of MNF is an important factor which affected the moisture quantity detection in transformer oil.As the diameter of MNF decreases,the sensitivity increases.When the diameter reaches 10μm,the sensitivity of the moisture quantity detection is higher than 5 mg/L,therefore it meets the requirements of field oil immersed power transformers.The MNF sensor can achieve real-time measurement of moisture quantity detection in transformer oil and can be used for on-line monitoring of oil-immersed power transformers.