Tilted Fiber Bragg Grating Vibration Sensor And Its Application In Power Monitoring

In China's coastal areas,the impact of wind vibration on large-range overhead transmission systems is widespread,especially before and after typhoon landing.Wind vibration causes fatigue damage of the transmission tower tower metal fittings,causing wire wear and even wire breakage,which seriously threatens the safety of the transmission system.In order to prevent and cope with the impact of wind vibration on transmission lines and towers,it is necessary to develop field rapid detection means and monitoring instruments under live operation.The optical fiber sensor uses optical signals as the transmission medium to realize real-time,high-sensitivity sensing and long-distance signal transmission to the externally measured information.In addition,the fiber optic sensor has the advantages of compact structure,high sensitivity,anti-electromagnetic interference,good insulation,fast response,corrosion resistance,safety and convenient multi-point networking,which provides a new direction for the development of modern sensor technology.It is applied to power transmission systems with traditional electronic sensors.Based on the actual demand of power grid monitoring,based on the new fiber-optic sensor device of tilted fiber grating,this paper developed two types of tilted fiber grating vibration sensors and measuring systems,which are“double-clad type”and“thin core type”,and completed the transmission line shockproof.Experimental testing of the hammer and field monitoring of the transmission tower.This paper,we will conduct research from the following aspects:(1)Experimental test of anti-vibration hammer performance of high voltage transmission lines.The"double-clad"tilted fiber grating vibration sensor and real-time signal demodulation system were designed and developed.The experimental test and performance analysis of the shock-proof hammer performance of the transmission line were completed,and the fast response to the vibration signal with frequency below 10 Hz was realized.High-sensitivity measurement,the acceleration measurement accuracy is 2×10~-2m/s~2,and the acceleration measurement range is 0.2-6 m/s~2,which satisfies the anti-vibration hammer frequency response range and measurement accuracy requirements.(2)Wind-induced vibration field monitoring of transmission towerThe"fine core"tilted fiber grating vibration sensor and real-time signal demodulation system were designed and developed,and the whole system was applied to the wind vibration monitoring of the actual transmission tower in the field.Under the condition of ensuring the reliability and high sensitivity of the system,the system is miniaturized and integrated,and the wavelength demodulation is replaced by the light intensity demodulation means,which reduces the system demodulation cost.Based on the system,real-time on-line monitoring of low-frequency vibration of the tower under different wind speed conditions is completed,and the acceleration response output with linearity deviation less than 1.5%is realized.By monitoring the small change in the resonant frequency of the transmission tower,it is possible to predict the health of the tower structure and predict safety hazards.