Papers by Keyword: Fiber Bragg Grating (FBG)

Abstract: The paper presents a comparative study of three fiber optic sensors based on the fiber Bragg grating (FBG). The basic monitored parameter is the respiratory rate of the human body. Fiber-optic sensors are immune to electromagnetic interference (EMI). This fact singles them out as ideal for use in magnetic resonance environments (typically in MRI - magnetic resonance imaging) as a prediction of hyperventilation states in patients. These patient conditions arise as a result of the closed tunnel environment in MR scanners. The results (10 volunteers with written consent) were compared with the results using the conventional respiratory belt (RB) in a laboratory environment and processed using the objective Bland-Altman (B-A) method.

Abstract: This paper presents a method for the detection of transmission tower. It is a common phenomenon that high voltage and strong magnetic field exist in the environment of high voltage transmission tower. Compared with electronic sensor system, fiber Bragg grating sensing technology could resist harsh environment effectively. As a kind of passive devices, fiber Bragg grating tilt sensor can monitor the tilted state of high voltage tower easily. With the help of on-line monitoring system, we can effectively raise maintenance strategy for high voltage tower and analyze the variation trend of the tower. The system is convenient to repair and maintain the high voltage tower at the same time.

Abstract: FBG concentration chenical sensor with three layer structure is proposed in this paper. And through experimental study and reasoning calculation to verify the three layer structure of the optical waveguide model, so the sensitivity characteristic of the Bragg wavelength to the refractive index of chemical solution is obtained. And the relationships between the concentration and the shift of Bragg wavelength of sucrose, ethanol, and Nacl solution are achieved. Finally the shifts of the Bragg wavelength with the external concentration are obtained by experiments.

Abstract: This study considered the application of fiber Bragg grating (FBG) to a composite material leaf spring as a vehicle loading sensing system. The loading of the vehicle by the leaf spring was calculated by the period change of the fiber grating caused by deformation of the composite material leaf spring under loading. From the experiment results, a good linear relationship between loading and Bragg wavelength shift for light. The R-squared value for the linear regression reached 0.99. The loading sensitivity is about 0.267 nm/N.

Abstract: Snow and ice disasters on power system safe and reliable operation of the transmission line has a great threaten.An overhead conductor tension sensor based on fiber Bragg grating is developed.The sensor contains a strain sensor module and a temperature compensation module which can offer temperature compensation for strain sensing module.The sensor connected to the tower and the insulator with metallic clamps.If there is ice on the transmission line,the tension of the sensor sensing module of the center wavelength will corresponding change,and the ice condition of the transmission wires can be reflected by the center wavelength variation.Experiment indicates that the tension sensitivity coefficient of the sensor is 9.8 pm/kN,the repeatability error is 1.78% FS,the nonlinear error is2.4% FS, the hysteresis is 1.5% FS.

Abstract: On-line monitoring of high voltage transmission lines can prevent or reduce the accidents of transmission reduced by icing,wave,breeze vibrations of electric wires and the dropping of electrical insulators.An on-line monitoring system of high voltage transmission lines based on optical fiber sensing technology is setted in this paper.Fiber optic signal demodulation instrument in the transformer substation receives the signal sent by the optical fiber Bragg grating sensors fitted on transmission lines and electric power towers,and then the signal was sent to the transmission line monitoring center by the power system network.Field hang net experiments shows that the system can monitor the high voltage transmission lines accurately for a long time.

Abstract: The large power current is sampled by Rogowski coil, then transforms the sampling signals from AC to DC and regulates the signals, the current detection unit is formed with FBG (Fiber Bragg Grating) and GMM (Giant Magnetostrictive Material), the current measurement is achieved based on the F-P interferometer filter demodulation system, finally, linear relationship between the Bragg wavelength shift and external current is validated by experiment.

Abstract: Based on the relation between the wavelength shift of sensing FBG and the strain, a flow measuring device of the circular target binding Fiber Bragg Grating with the cantilever is designed and the mathematical model based on a circular target flow measurement system is established. Through the flow experiment, we can get the flow test result. The experimental data error analysis can be concluded to verify the feasibility and precision of the design.

Abstract: On-line monitoring of lightning,ice,short circuit on electric transmission line and insulator's operation state is of great significance to ensure the safe and stable operation of the electric transmission line.An intelligent composite insulator,in which the core rod has fiber Bragg gratings is developed.lightning,ice,short circuit on electric transmission line and insulator's operation state can be reflected by monitoring the center wavelengths of the fiber Bragg gratings.The temperature, strain response and electrical performance testing experiments on 110 kV fiber composite insulator were done,the result indicates that the optical fiber composite insulator can measure the temperature accurately;the load of composite insulator can be monitored approximately by no. 2 and no.4 monitoring sites;the110 kV fiber composite insulator’s dry lightning impulse withstand voltage is 421 kV,the normal polarity of steep wave impulse voltage withstand voltage is 434 kV(steepness:1206kV/μs),the negative polarity withstand voltage is 444 kV(steepness:1132kV/μs)and the dry power frequency withstand voltage is 230 kV at the altitude of 1970m.

Abstract: The temperature sensing characteristic of Fiber Bragg Grating (FBG) has been studied. The temperature sensing equation of FBG is revised. The accurate analysis results are obtained. The center wavelength drifts of the tested FBG are displayed in the screen of Optical Spectrum Analyzer (OSA).The experimental results show that the center wavelength of FBG is thermally red-shift with the rise of the temperature and blue-shift with the decrease of the temperature. The results are agree with the revised temperature sensing equation. It is noticed that the transmission spectrum width (SPEC-WD) of FBG fluctuates with the change of temperature. Nevertheless, the trend of the fluctuation is demonstrably towards increase, which perhaps is some potential auxiliary sensing function in future.