The Research Of Current Sensing Based On GMM And FBG

The current transducer is the important device of power metering and relaying. Its'precision and reliability related the safety and economy of operation in electric power system closely. With the development of power, conventional current transducer can't meet requirements. While optical current transformer (OCT) have potential application cost because of its'unique advantages, will be used to replace conventional current transducers in the future. In this paper, the present situation and state of R&D, existing problems in the field of OCT is reviewed and analyzed through extensive reading of the scientific papers and reports. A novel electrical current sensing configuration was constructed based on fiber Bragg grating (FBG) and giant magnetostrictive material. The AC/DC current sensing is researched by means of theoretical analysis,computer simulation and experimental investigation. The linearity scope of GMM magnetostrictive performance was used to realized DC current sensing. The sensing performance using optic spectrum analyzer demodulation was verified by experiment. The experimental result demonstrated the relationship between Bragg wavelength shift and current is linear, and repeatability was very good. Two kinds of light intensity demodulation methods: double gratings correlation and ASE spectrum character correlation were discussed by theoretical deduction and computer simulation. ASE correlation method was used demodulated the AC current generated wavelength shift finally. The strain sensitivity was demarcated by experiment using spectrum character of ASE demodulation. AC current sensing was realized by DC bias condition and without DC bias condition. In the two conditions magnetic field strength —strain relation of GMM appeared hysteresis loop character. The loop curve was obtained by computer reconstruction of input current and output signal data. The FBG current sensor based on GMM was researched significantly and fundamentally in this paper. A new research field on optic current sensing was established.