Research On Surface Fiber Bragg Grating Detection Method For Temperature Rise Of Composite Insulator

Composite insulator is widely used in power grid,and its operation state is often evaluated by detecting the temperature rise.Optical fiber has the characteristics of small volume,good insulation performance and free from electromagnetic interference.This paper studies the feasibility of detecting the surface temperature rise of composite insulator with fiber Bragg grating,and proposes to build a fiber-optic temperature sensing system,which provides a quasi distributed,reliable and convenient detection method for laboratory research on abnormal temperature rise of composite insulator.Firstly,fiber Bragg grating is fixed on the surface of 110 k V and 500 k V composite insulator to detect its temperature rise.Compared with infrared detection technology,temperature calibration test,grating arrangement and composite insulator temperature rise test,composite insulator axial and circumferential temperature rise distribution test,composite insulator high voltage terminal abnormal temperature rise test are carried out.The test results show that the FBG fixed on the surface of composite insulator will not affect the electrical performance of composite insulator,and the measured temperature rising trend and amplitude are consistent with the measurement results of infrared thermal imager,which can simultaneously detect the time and space evolution of axial and circumferential temperature rise of composite insulator.The feasibility of the method is verified.Then,this paper proposes a practical design for the detection method.The fiber Bragg grating is made of ceramic packaging and external parts.The temperature rise detection program based on Lab VIEW is designed to collect,process and display the temperature rise data.On this basis,a composite insulator surface temperature rise sensing system based on Fiber Bragg grating is proposed to realize quasi distributed,real-time and accurate measurement of insulator surface temperature rise by fiber.The sensor system is used to detect the surface temperature rise of 110 k V and 220 k V composite insulators.The temperature calibration test,sensor arrangement and composite insulator temperature rise test,and the influence of moisture on composite insulator temperature rise test are carried out.The test results show that when the optical fiber temperature sensor is fixed on the surface of composite insulator,the temperature sensitivity coefficient will not change,and the electrical performance of composite insulator will not be affected.The difference between the detection accuracy and the infrared thermal imager is within 0.5 ℃,which proves that the optical fiber temperature rise sensing system can be used to measure the surface temperature rise of composite insulator.At the same time,the test shows that the temperature rise of composite insulator is obvious under the working voltage after being immersed in water,and there is almost no temperature rise after being exposed to the sun,which proves that water has a direct impact on the temperature rise of composite insulator.Finally,the defects of 110 k V composite insulator were detected by ultrasonic phased array and ultrasonic phased array There is a defect between the jacket surface of k V composite insulator and the interface between the jacket surface and the core rod.The defect position is consistent with the temperature rise position of composite insulator under the working voltage after being immersed in water,which proves that the water remaining in the defect has polarization loss under high voltage,resulting in abnormal temperature rise of composite insulator.