Research On Two-dimensional Fiber F-P Cavity And Its Intensity Demodulation Technology

With the rapid growth of the social economy,higher and higher requirements are put forward for the development of various industries.The electric power industry supports the progress and development of the whole society,so the stability and safety of electric power is the top priority of development.At present,the most popular method for detecting the operating status of high-voltage power equipment is to use the F-P cavity sensor to receive ultrasonic signals for detection,F-P cavity sensors have a long history of development and perfect fabrication technology,and are often seen in various complex and extreme environments.According to the different demodulation principles of the fiber F-P cavity sensor,it is divided into two methods: intensity demodulation and phase demodulation.Compared with phase demodulation,the experimental setup and algorithm of intensity demodulation are relatively simple,but this method has a temperature drift problem that seriously affects the measurement results.Therefore,this paper plans to use a dual wavelength light intensity demodulation F-P cavity.By keeping the square sum of dual wavelength trigonometric functions constant,the detection light intensity value is constant,so as to solve the problem of poor accuracy of the intensity demodulation F-P cavity caused by temperature changes.The specific work of the research is as follows:(1)Introduce and analyze the characteristics of intensity demodulation and phase demodulation.Compared with phase demodulation,intensity demodulation has cost advantages in detecting fewer points.It studies the causes of temperature drift when single wavelength intensity demodulation is used in F-P cavity,proposes dual wavelength intensity demodulation technology,and designs the hardware circuit of dual wavelength intensity demodulation F-P cavity sensor probe system,including power module,memory module,serial communication module,and control module,Test the experimental effect of dual wavelength intensity demodulation technology to solve the problem of temperature drift.(2)Based on the interference principle of F-P cavity sensor,an optical fiber cantilever beam model with uniform load is designed,a new two-dimensional F-P cavity sensor probe is made,the sensitivity of the sensor probe is improved,and the longitudinal and transverse wave signals in the ultrasonic wave are received.(3)The dual wavelength intensity demodulation technology is used to demodulate the new two-dimensional F-P cavity sensor probe.An experimental platform is built according to the mechanism of ultrasonic generation by partial discharge,and an online partial discharge sensing system is designed.Through the system,the ultrasonic signal generated by partial discharge is monitored in real time.Because the longitudinal wave and transverse wave signals in the ultrasonic wave have different propagation speeds in the cable,the location of local discharge is calculated and analyzed.Based on the research content of this paper,the dual wavelength intensity demodulation technology has solved the problem of temperature drift,verified the feasibility of the new two-dimensional F-P cavity sensor probe with dual wavelength intensity demodulation,and has high application value for online detection of high-voltage cables in practical projects.