Theoretical And Experimental Research On The Temperature Compensation Of Optical Current Sensor

With the development of the power system,the defect of the traditional electromagnetic induction current transformer has exposed,and the advantage of the optical current transformer is continuously emerging.As the new type of electronic current transformer,the optical current transformer possesses a bright future.Because of the measurement accuracy of the optical current transformer is affected by the ambient temperature,the optical current transformer has not been promoted on a massive scale.Much effort has been taken to solve these problem,but the practical method is few,thus the study for the temperature compensation of the optical current transformer is significant.In this paper,we propose two temperature compensation methods respectively for the current transformer that based on magneto-optical crystal and the current transformer that based on magnetostrictive materials,and the theoretical and experimental research are carried out.The finished work are as follows:1)We propose a temperature compensation method based on the dual-wavelength configuration of optical current sensor that based on the magneto-optical crystal.The feasibility of the method is proved by theory analysis.The hardware platform and the software are built for experimental purpose.The temperature characteristic of the optical current transformer that based on the magneto-optical crystal is studied to explore the variation of the Verdet constant with temperature under the two wavelengths.The analytic solutions of temperature and magnetic field are obtained based on the relation between Verdet constant and temperature.The standard deviation of measurement value of temperature and the relative error of measurement value of magnetic flux density are analyzed.The experiment of single wavelength and the experiment that the temperature is known precisely are done.The experimental results show that the temperature compensation based on the dual-wavelength configuration is effective.2)The temperature compensation method based on double-FBG configuration for optical current transformer based on magnetostrictive material is proposed.The two FBGs that with the same specifications are stuck on the two giant magnetostrictive materials which has the same shape,same thermal expansion coefficient and orthogonal magnetostriction direction as the sensing heads.The temperature characteristic and magnetostriction characteristic of the two sensing heads are studied.The variation of wavelength difference with magnetic field at different temperatures is investigated and the magnetic field was measured based on the wavelength difference of the two sensing heads.The measurement error is analyzed.The experiment results show that this method can effectively reduce the temperature influence on the measurement accuracy for the optical current transformer based on magnetostrictive materials.3)Compare the two optical current sensors.Summarize the completed work that we have done,and analyze the shortcoming of our experiment.The future direction of the research also be discussed.