Research On The Key Technology Of GMM-FBG Current Sensor Applied In Electric Power Equipment

With the rapid development of digital and intelligent power system,the accuracy and reliability of current measurement are directly related to the safe,reliable and economical operation of power system.The traditional electromagnetic current transformer is vulnerable to electromagnetic interference and not conducive to the connection with electronic equipment,which restricts its development and application to a certain extent.The continuous development of fiber Bragg grating sensing technology and its extensive application in engineering practice provide a new idea for current measurement.The optical current sensing system designed by the combination of supermagnetostrictive material GMM and fiber Bragg grating FBG has excellent performance and can meet its measurement requirements.However,the sensor is affected by a variety of physical factors,such as temperature,magnetic field intensity,magnetic field direction,stress,etc.,so it is necessary to study the characteristics of optical current sensor.In this paper,the current situation of optical current sensor is analyzed.Aiming at the problem of GMM magnetostrictive coefficient and FBG's sensitivity to temperature,a temperature compensation scheme is proposed for the sensor.In view of the accurate measurement of the current in the L-bus between IGBT of insulated gate bipolar transistor in practical power system,the finite element analysis of the l-bus and the magnetic conductivity loop is carried out.Supermagnetostrictive material GMM and fiber Bragg grating FBG are used to construct the current sensor for electric power equipment.In order to study the nonlinear results of GMM-FBG current sensor output,the coupling model of GMM magnetic field and temperature was constructed,and the experimental test system based on GMM-FBG current sensor was built.This experimental system adopts Terfenol-D and FBG combination package as the sensor probe,using stabilized voltage power to drive the excitation coil to generate magnetic field to build the magnetic circuit system,and uses the tunable scanning light source without mechanical components to build the demodulation system,which can realize multi-channel rapid measurement,and carry out the calibration of current and center wavelength as well as the electrical current cutoff experiment.To solve the problem for giant magnetostrictive materials,GMM magnetostrictive coefficient is sensitive to temperature and affect the accuracy of GMM-FBG optical fiber current sensor response problem,based on GMM coupling model of magnetic field and the temperature,temperature sensing experiment,the current response of different magnetic field direction,design the cross sensing probe,using GMM magnetic field is not sensitive to the direction of the vertical magnetic field current sensor temperature compensation.The results show that the center wavelength in direction perpendicular to the magnetic field sensor value variation of plus or minus 0.005 nm,can ignore the influence of magnetic field,after removing the fitting curve and on-off test fitting curve is the sum of squared residuals is 0.0112,almost completely overlap,can eliminate the influence of temperature on the GMM-FBG current sensor,make current measurement more accurate,improve the accuracy of the GMM-FBG optical fiber current sensor response,and realize the electric current and temperature measurements at the same time,can meet the application requirements of modern electric power system.Based on the excitation coil current measurement scheme,the research and design of IGBT L-shaped bus current measurement scheme is carried out,which provides a reliable reference for the detection of bus current signal.To improve the measurement accuracy of sensor practical application,this paper,by using COMSOL Multiphysics software to design the L-shaped copper busbar and electromagnetic field sensor magnetic circuit structure of 3 d finite element simulation and numerical analysis,determine the optimum magnetic circuit structure of the sensor and cross sensing probe the best placement of the structure design,make the busbar current signal detection more accurate,to improve the practical application of the sensor is active and important reference significance.