Research On A New Optical Current Transducer Based On Fiber Bragg Grating

The current transducer is the important device for power metering and relaying. Its precision and reliability is closely related to the safety and economy of operation in electric power system. With the development of power industry, conventional current transducer can't meet demands. While optical current transformer (OCT) has potential application cost because of its unique advantages, and will be used to replace conventional current transducers in the future.Firstly, in this paper, the present research situation, design techniques and existing problems in the field of OCT are reviewed and analyzed through extensive reading of the scientific papers and reports. After carefully studying the principle of fiber Bragg grating (FBG) sensor and magnetostriction effect, the models of strain viability and temperature sensor are established respectively. Based on FBG susceptibility to strain and the magnetostriction effect of giant magnetostrictive materials (GMM), this paper proposes a new OCT design method.Secondly, the nonlinearity character of GMM is inhibited effectively by using optimal design of the sensor head structure and adding proper bias magnetic field and pre-stressing force, and the magnetic hysteresis of magnetostrictive material is reduced as well, therefore, the linear tuning relationship between FBG wavelength shifts and the GMM axial strain variable can be achieved. The temperature compensation system is designed by using the series characteristic of FBG to solve shift problem induced by temperature while the FBG is modulated by GMM, which makes the repeatable metering of current possible.In this paper, the OCT based on FBG and GMM is researched significantly and fundamentally, and a new research approach for OCT is established.