Application Research Of High Voltage Switchgear Based On Fiber Bragg Grating Temperature Sensing Technology

The research and application of fiber Bragg grating(FBG)sensing technology has been a research hotspot in the field of optical communication.Because FBG sensors have considerable advantages,such as high temperature response sensitivity,good wavelength selectivity,small structure size,anti-electromagnetic interference and convenient realization of quasi distributed measurement.Therefore,it has great application value in thermal power generation industry.Such as totally enclosed within the high voltage switchgear in the power plant as application object.Because of the narrow switchgear interior space,strong electromagnetic interference.Traditional temperature measurements are difficult to achieve the real-time temperature monitoring and switchgear in existence resulted from abnormal current cabinet temperature anomaly and cause the risk of switchgear burned.Therefore,the temperature measurement system based on FBG is designed to realize the temperature monitoring of the switchgear.The main research contents as follows:1.Starting from the etching mechanism and methods of FBG on fiber,the principle of grating etching by phase mask method widely used at present is introduced emphatically,the principle of light wave transmission and temperature sensing of FBG is analyzed and the theoretical relation of reflected spectral signal changing with temperature is deduced based on the coupling mode theory.2.I formed a set of suitable for switchgear temperature real-time monitoring of the FBG temperature sensing system.In the laboratory,I used electrothermal blowing dry box to simulate temperature rise.The sensitivity of the ceramic encapsulated fiber grating sensor was tested and the system was applied to the actual power plant in the switchgear.The current-temperature change data of switchgears of different equipment in different time periods were collected.I analyzed the influence of outgoing current,ambient temperature and busbar current on the temperature in the switchgear.3.Affected by the narrow interior space of switchgear,for parts contained in the heat position to decorate the problem of FBG sensing unit.The paper uses the Fluent software to simulate the temperature fluid field of the actual high voltage switchgear.The heat condition of critical components as switchgear busbar and contacts are obtained.It is of great significance to analyze the temperature of the whole conduction parts in actual switchgears.4.Type Ⅰ FBG has the optical decay phenomenon of wave peak dropping in long-term high temperature environment and many temperature monitoring parts in the plant are in high temperature environment.In order to expand the application field of FBG in high temperature environment,regenerated fiber Bragg grating(RFBG)was developed using type Ⅰ FBG as the original fiber in a high-temperature tubular furnace in the laboratory.The heat-resistant RFBG was prepared by setting different annealing temperatures.The performance of the grating samples obtained after the experiment was analyzed and the feedback temperature was fitted with the wavelength of the grating demodulation center.