Optimization On Sensing Unit Of Optical Current Transducer Based On Rare Earth Magneto-optical Glass

With the rapid development of UHV fields of state grid, The traditional electric-magneto current transformer has exposed a lot of problems. Optical current transducer(OCT) which has advantages of small size and having no magnetic saturation cuts a striking figure in the field of smart grid gradually. Research shows that, instead of the diamagnetic material in the sensing unit of OCT, the use of paramagnetic material with rare earth doped can effectively improve the response sensitivity of the sensing unit. But the paramagnetic material to improve the performance of the sensing unit is affected by some factors. Therefore this thesis takes the paramagnetic glass with rare earth doped as the research object. The optimization characteristics of sensing unit based on rare earth glass was researched under the conditions of different sizes with spatial position, wavelengths of incident light and rare earth doped concentration.First of all, the related characteristics of OCT were researched in turn, including the principle of Faraday effect, the Verdet constant theory, the linear birefringence in isotropic medium and the factors influencing the performance of rare earth doped material. By using Jones matrices of optical devices, the light path model of the sensing unit of OCT was deduced to obtain the math models for analyzing optimization characteristics of rare earth glass in the sensing unit. According to the theoretical model, the establishment of a Faraday effect experiment system and an experiment system used for measuring the linear birefringence of rare earth glass was included in this thesis.Through the computer simulation and optical experiments, the optimization characteristics were researched from three aspects mentioned above. The significance of the optimal length of rare earth glass for the optimization on the response sensitivity of sensing unit was demonstrated. The influence of wavelength of incident light on the Verdet constant and the linear birefringence of rare earth glass in the OCT was analyzed. Besides the response sensitivity and the measurement precision of rare earth glasses in the sensing unit with different doped concentration were compared. The best parameter combination was obtained.The significant improvement was found both on response sensitivity and on accuracy after optimization. The research results will provide effective reference for the research and application of OCT based on rare earth glass.