Research On Fiber Bragg Grating Sensing And Demodulation System Based On Multiplexing Technology

Closely centering on the actual needs of smart grid on-line monitoring,using high-performance fiber-optic sensing technology as the core,breaking key common technologies related to fiber-optic sensing applications in strong electromagnetic fields and harsh environments,researching and developing new fiber Bragg grating temperature for smart grid on-line monitoring applications Sensors and large-capacity,high-precision demodulation instruments use a hybrid multiplexing technique combining wavelength division and spatial division to form a distributed fiber Bragg grating sensor demodulation system.The specific research content is as follows:(1)Study fiber grating sensing characteristics.Based on the analysis of the development of fiber grating sensing technology at home and abroad,this paper elaborates the temperature and strain sensing principle of fiber grating,and discusses the temperature-strain cross-sensitivity problems involved in fiber grating sensing.The research of demodulation technology provides a theoretical basis.(2)Ceramic packaging technology applied to fiber grating temperature sensor.For the problem of temperature-strain cross-sensitivity existing in the process of fiber grating sensing,a ceramic encapsulation method is adopted for the fiber grating sensor,so that the Bragg wavelength is only affected by the temperature change,and the sensitivity to temperature measurement is improved.The experiment proves that the accuracy of temperature measurement of the FBG sensor after ceramic encapsulation is within ±0.5?.(3)Selecting the wavelength division and space division multiplexing technology to set up a distributed sensor network to achieve high-capacity distributed temperature online measurement of high-voltage electrical equipment in smart grids.The single-channel maximum measurement sensor points are 20,and the maximum number of monitoring points is 640 points(which can be extended to 2560 points),which can meet the application requirements of temperature online monitoring of a complete digital power grid.(4)The F-P filter demodulation method was established as a system demodulation method.Based on the analysis of the advantages and disadvantages of several commonly used demodulation methods,the tunable F-P filter demodulation method was finally adopted for practicality and feasibility considerations.In view of this,first introduced the selection of the main optical devices involved in the system,and then completed the hardware circuit based on the FPGA core controller.(5)The K-L transform algorithm is proposed for smart grid FBG demodulation system.In order to solve the shortcomings of the traditional denoising methods,the KL transform is applied to the fiber Bragg grating demodulation system.The signal and noise can be completely separated for a single or multiple FBG sensors,and a good denoising effect is achieved,making the system The demodulation resolution reaches 1pm.(6)The online monitoring software based on the Lab VIEW platform was designed to achieve real-time online monitoring of the entire FBG sensor network,and the platform was used to verify the performance indicators of the FBG sensor demodulation system.The experimental results show that the system demodulation accuracy is within ±5pm,meets the requirements of the preset indicators,and meets the needs of practical engineering applications.