Study On The Precision Optimization Method Of Gas Concentration Monitoring System In Transformer Oil By Photoacoustic Spectroscopy

Transformer,as the core equipment of electric energy transmission and conversion,its safe and stable operation ability has a direct impact on whether the power grid works safely.Oil-filled transformers are currently widely used in China,Transformer oil is used as an insulating medium,Its insulation performance is directly related to the safe operation capability of the entire equipment,The insulation performance of transformer oil is directly related to the concentration of dissolved gas in oil,Therefore,on-line monitoring of the concentration of dissolved gas in oil can make life prediction and fault diagnosis of power transformers.Photoacoustic spectroscopy has the advantages of high sensitivity and good selectivity,and is widely used in the field of power system monitoring.As the power industry gradually enters the era of high voltage and large power grids,the reliability requirements of fault diagnosis technology for power equipment are becoming higher and higher,so the accuracy requirements for the detection of dissolved gas concentration in oil are also becoming higher and higher.The paper analyzes the principle of photoacoustic spectrum detection in detail,expounds the basic principles of photoacoustic effect and photoacoustic signal detection,and derives the relationship between the photoacoustic signal intensity and the gas concentration;In-depth analysis of the process of noise reduction of the photoacoustic signal by the lock-in amplifier.For a single lock-in amplifier,it is difficult to efficiently filter out the strong noise in the weak photoacoustic signal,which results in low detection accuracy of low concentration gas and poor stability,Carry out in-depth research on a problem,and propose a Kalman filter combined with a lock-in amplifier for noise reduction of photoacoustic signals;By adding a Kalman filter to the phase-locked amplification link,the prediction and correction of the Kalman filter are used to further reduce the noise within the cut-off frequency of the low-pass filter superimposed on the photoacoustic signal,thereby improving the system’s dissolution in oil Gas concentration monitoring accuracy.The thesis analyzes the basic principles of Kalman filter noise reduction,theoretically derives the two-stage filter noise reduction process of Kalman filter combined with lock-in amplifier,and designs Kalman filter combined with digital lock-in amplification noise reduction technology.In Matlab/Simulink builds a simulation,the results show that under the same signal-to-noise ratio of the input signal,the wave rate of the output signal waveform of the proposed method is reduced by53.51%compared with the traditional method;In order to further verify the feasibility of the proposed method,an experimental platform was established for verification.The results show that when monitoring C₂H₂ gas with a standard concentration of 5 ppm,the measurement accuracy of the proposed method is improved by 11.6%compared with the traditional method;simulations and experiments show that The proposed noise reduction method of photoacoustic signal has obviously improved the accuracy of the on-line monitoring system of dissolved gas concentration in transformer oil,and it is easier to realize in engineering applications and has certain application value.