Novel Fiber Optical Current Sensor And Its Application

Current measurement is widely used in many fields,such as power transmission in the industry,all-electric propulsion in military ships,and ultra-short pulse current monitoring in scientific research applications,all of which involve current measurement.With the development of technology,the measurement demand for various current signals is also increasing.The traditional electromagnetic current transformers expose transient response,easy saturation,difficulty in insulation,and operating costs associated with increased voltage levels.High defects,and optical current sensors based on Faraday magneto-optical effect can overcome these defects well,showing great application potential,especially the fiber optical current sensor(FOCS)is the most obvious.Compared with the traditional current transformer,the closed-circuit design not only has the characteristics of being free from external electromagnetic interference,but also has the advantages of large measuring dynamic range,good electrical insulation,small size and light weight,and can cover different fields.Current measurement needs have received increasing attention.Based on the research status quo at home and abroad,summarizes the advantages and disadvantages of various current sensors,and proposes a new all-fiber current sensor based on the principle of polarization modulation.It adopts the same closed optical path design as the interference fiber optic current sensor,but does not need Additional optical signal modulation,the measurement accuracy can meet the requirements of general engineering applications,so there is a great cost advantage.In this paper,the optical path and algorithm design are expounded and a test prototype is built.Based on practical engineering applications,focuses on the application of power frequency current measurement and lightning protection as the research object.Firstly,by adjusting the position of the mirror and zero offset compensation,the closed loop error and system zero offset error are satisfied.Application requirements,and then to solve the typical technical difficulties of the practical application of all-fiber current sensor-the temperature is affected,the complex nonlinear temperature characteristics are analyzed in detail,and the nonlinear mapping performance through BP neural network For the variable temperature experiment,the ratio coefficient of the sensing fiber coil is nonlinearly fitted with the corresponding temperature data,and the obtained temperature compensation curve is used for online temperature compensation,so that the new all-fiber current sensor meets the 0.5-level requirement specified in the national standard within the temperature range of-5 °C to +50 °C.Finally,starting from the actual engineering application,combined with the rapid response of the sensor,it is applied to lightning protection measurement.In the test,Pearson current sensor measurement results were used as reference.The new all-fiber current sensor was used to accurately and quickly measure the full-wave real-time waveform of 8/20?s lightning current.It was optimized by software and hardware to make it in the range of 2kA~1500kA lightning current.Meet the needs of industrial applications.