卡尔曼滤波结合数字锁相放大器的弱光声信号降噪方法研究  

Research on Denoising Method of Weak Photoacoustic Signal by Kalman Filter Combined with Digital Lock-in Amplifier

作　　者：吴铁洲[1] 李炎 祁军 焦磊明 宋鹏才 WU Tie-zhou;LI Yan;QI Jun;JIAO Lei-ming;SONG Peng-cai(Hubei Key Laboratory of Solar Energy Efficient Utilization and Energy Storage Operation Control,Hubei University of Technology,Wuhan 430068,China;Shenzhen Linke Electric Development Co.,Ltd,Shenzhen 518126,China)

机构地区：[1]湖北工业大学太阳能高效利用及储能运行控制湖北省重点实验室,湖北武汉430068 [2]深圳市林科电气发展有限公司,广东深圳518126

出　　处：《仪表技术与传感器》2020年第10期98-102,共5页Instrument Technique and Sensor

基　　金：国家自然科学基金(51677058);重大研发专项(2018AAA056)。

摘　　要：采用光声光谱法对变压器油中溶解气体的浓度进行在线监测时,低浓度气体激发的弱光声信号中夹杂有强噪声,传统的单一数字锁相放大器难以将其高效滤出,导致该方法对低浓度气体的检测精度低、稳定性差。为了进一步的降低噪声干扰、提高对低浓度气体的监测精度,提出卡尔曼滤波结合数字锁相放大器的光声信号降噪方法,在锁相放大环节中加入卡尔曼滤波器,利用卡尔曼滤波的降噪作用,使叠加在锁定频率信号中的噪声进一步减小,从而提高对低浓度气体的监测精度。在Matlab/Simulink中进行仿真,结果表明在信噪比相同情况下所提方法输出信号波形的波动率比传统方法减小了53.51%;通过实验验证,结果表明在测量标准浓度为5 ppm的C 2H 2气体时,所提方法的测量精度较传统方法提高了11.6%;仿真和实验皆验证了所提方法的合理性与有效性。The on-line monitoring of the concentration of dissolved gases in transformer oil by photoacoustic spectroscopy,the photoacoustic signal excited by the low concentration gas is mixed with strong noise,traditional single-lock-in amplifiers are difficult to filter out it efficiently,lead to this method has low detection accuracy and poor stability for low concentration gases.In order to further reduce noise interference and improve the monitoring accuracy of low concentration gases,a Kalman filter combined with a lock-in amplifier for weak photoacoustic signal denoising is proposed,adding a Kalman filter to the phase-locked amplification,using Kalman's noise reduction,the noise superimposed on the locked frequency signal is further reduced,thereby improving the on-line monitoring accuracy of low concentration gas.Simulation in Matlab/Simulink according to the actual application,the results show that the volatility of the output signal waveform of the proposed method is reduced by 53.51% compared with the traditional method under the same SNR;The experimental results show that the measurement accuracy of the proposed method is improved by 11.6% compared with the traditional method when measuring the C 2H 2 gas with a standard concentration of 5 ppm,both simulation and experiment verify the rationality and effectiveness of the proposed method.

关 键 词：光声光谱 在线监测 弱光声信号 数字锁相放大器 卡尔曼滤波器 信噪比 

分 类 号：TM407[电气工程—电器]