Research On Detection Method Of Hydrogen In Transformer Dissolved Gas-in-oil

With the continuous improvement of the voltage level of state grid of our country,higher requirements are put forward for the stability and reliability of transformer operation.The development of high-precision and high-performance hydrogen sensors,especially high-sensitivity hydrogen sensors that measure low-concentration hydrogen,is of great significance for online monitoring and fault diagnosis of transformer operating status.At present,there is no ideal monitoring method for hydrogen in transformer dissolved Gas-in-oil at home and abroad.Therefore,the development of a high-sensitivity,high-performance and low-cost hydrogen sensor system is the key to solving this problem.This paper uses semiconductor and optical methods to study low-concentration hydrogen sensor measurement technology,and designs and develops a low-concentration hydrogen sensor monitoring system.The main contents are as follows:In order to realize the quantitative detection of low-concentration hydrogen in transformer dissolved Gas-in-oil,two ideas are used to introduce the principle of semiconductor hydrogen sensor and optical method to measure hydrogen and the current research status at home and abroad from the aspects of electronics and optics,and build hydrogen sensor testing system,testing the hydrogen concentration in the range of 10-1000 ppm,providing a new solution for the detection of hydrogen transformer dissolved Gas-in-oil.The electrical hydrogen sensor test system designed in this paper is equipped with two semiconductor hydrogen sensors,which measure hydrogen with a concentration of10-1000 ppm under constant temperature but different humidity conditions.The experimental results show that the TGS821 hydrogen sensor has good repeatability and high sensitivity,while the SGAS701 sensor also has a high sensitivity and resolution in the range of 10-100 ppm hydrogen concentration,but the repeatability index is slightly lower than that of the TGS821.In addition,the stability of the measurement results of the SGAS701 sensor under high hydrogen concentration(>300ppm)is relatively poor,which may be caused by the poor constant current control effect of the sensor drive current.By calibrating the TGS821 sensor at a hydrogen concentration of 10-1000 ppm,a three-dimensional fitting curve and expression are given,and the obtained fitting curve expression is optimized to realize the continuity of the segmented calibration fitting curve.Based on the volume expansion effect of palladium metal absorbing hydrogen,this paper proposes a new optical hydrogen sensor design.Through the theoretical simulation of ansys software,the change trend of the cantilever-type fiber optic Fabry-Perot(F-P)cavity sensor cavity length when the palladium film of different thicknesses are completely reacted with the introduction of different concentrations of hydrogen is simulated.The production process of the optical hydrogen sensor is introduced in detail,and the sensitivity and resolution of the sensor is tested and analyzed.The drift of cavity length is compensated in the test process,and the changes of the sensitivity and resolution indexes before and after compensation are compared.It is concluded that there are obvious responses at 300 ppm,500ppm,and 1000 ppm hydrogen concentration,and the response sensitivity before cavity length compensation reaches0.163nm/ppm,and the resolution is 42.09 ppm.After cavity length compensation,the sensitivity and resolution under 1000 ppm hydrogen concentration are 0.227nm/ppm and30.22 ppm respectively.The experimental results verify the feasibility of the hydrogen measurement scheme based on the palladium-coated cantilever beam optical fiber F-P sensor,and provide a new solution for the monitoring of low-concentration hydrogen in transformer dissolved Gas-in-oil.