Modeling Analysis And Optimization Study On Temperature Characteristic Of All-fiber Optical Current Transformer

Fiber-optic current transformer(FOCT)has overcome many defects of the traditional electromagnetic current transformer,which has a wide application prospects in the field of power system measurement.However,the temperature stability is a major problem that restricts the development of FOCT.Therefore,this paper will mainly study the linear birefringence caused by temperature of FOCT,and propose the corresponding optimization scheme to improve its measurement performance.First of all,linear birefringence effect model is established,which reveals the fundamental cause of linear birefringence in essence.The influence of linear birefringence on FOCT measurement performance is analyzed from the aspects of current measurement accuracy and sensitivity.Secondly,temperature's effect on linear birefringence is explained in essence,whereby the model of linear birefringence caused by temperature is deduced.Combined with the temperature characteristics of Verdet constant,the mathematical model of temperature characteristic of FOCT is obtained.By using COMSOL,the coupling of optical field,magnetic field,temperature field and stress field is realized with finite element method,finally the effect of temperature on the FOCT measurement accuracy is finally obtained.Mathematical model of linear birefringence's influence on fiber-optical current transformer is established,where intrinsic linear birefringence,linear birefringence caused by bending and linear birefringence caused by temperature was analyzed comprehensively.Temperature variation,fiber bending radius and fiber winding turns are three major factors which affect FOCT's accuracy and sensitivity.On this basis,a concrete optimization method is proposed.Finally,experiment platform of FOCT is designed and set up.Signal processing procedure of FOCT is programming based on the Kalman filter algorithm in the Lab VIEW.The test of FOCT is performed accordingly.The optimal fiber bending radius and winding turns are selected,which satisfies the requirements of both accuracy and sensitivity during temperature fluctuation.Correctness of the theoretical analysis is verified by the results of simulation and experiment.