提高分布式温度传感器测温准确度的降噪方法

Noise Reduction Method to Improve Temperature Measurement Accuracy of Distributed Temperature Sensor

为了减小拉曼散射光波长相关损耗、光电探测器附加噪声及散射光中的瑞利噪声对分布式光纤温度传感器测温误差的影响,通过分析分布式光纤温度传感系统的解调原理提出了一种反斯托克斯光降噪方法。将光纤按照环形结构铺设,以每次测量的反斯托克斯光信号中菲涅耳反射峰后的基底噪声平均值作为动态本底噪声,利用两段处于不同温度的光纤消除动态本底噪声后的瑞利噪声。反斯托克斯光降噪解调法从原理上避免了参考斯托克斯光引入的测温误差,消除了本底噪声和瑞利噪声导致的测温误差。实验结果表明,修正的分布式光纤温度传感系统的最大测温误差从5.4℃降低到0.6℃,测温准确度有明显提高。

To reduce temperature measurement error caused by the wavelengthrelated loss of Raman scattering light and extra noise of photodetector and Rayleigh noise in scattering lights of the Ramandistributed temperature sensor system,an antiStokes optical noise reduction method developed by analyzing the demodulation principle of distributed optical fiber temperaturesensing system in this paper.The optical fiber is laid according to the ring structure.The average value of the base noise following the Fresnel reflection peak in each measured antiStokes optical signal is taken as the dynamic background noise.Two sections of the optical fiber at different temperatures are used to eliminate the Rayleigh noise after the dynamic background noise.In theory,the antiStokes light noise reduction demodulation method prevents the temperature measurement error introduced by the reference Stokes light and eliminates the temperature measurement error caused by background noise and Rayleigh noise.The experimental results demonstrate that the maximum temperature measurement error of the modified distributed optical fiber temperaturesensing system is decreased from 5.4℃to 0.6℃,and the temperature measurement accuracy is significantly improved.