Study On Application Of Optical Fiber Sensing Technology In High-temperature Superconducting Cables

A wide range of domestic and international scholars concern about H-T-S cables because of its high flow capacity, low line loss, compact structure, etc. but H-T-S cables generally operated in liquid nitrogen environment, once the H-T-S cable destroy, it will lead temperature changes dramatically and bring a significant impact on the power system. The traditional cryogenic temperature sensors such as PT-100 platinum resistance was vulnerable to interference by high voltage, strong electromagnetic, etc. But fiber optic sensing technology was widely used in the engineering field because of its advantages such as anti-electromagnetic, etc. So it has an important significance to apply fiber optic sensing technology to H-T-S cable’s temperature monitoring.This paper aim at the temperature monitoring requirements of H-T-S cable, study on low temperature sensing characteristics, sensors low temperature calibration, sensor’s signal processing, cryogenic sensing system built and comparison of H-T-S cable’s DC critical temperature sensing of both fiber bragg grating sensing technology and backward Raman scattering distributed optical fiber sensing technology, related research results are as follows:(1) we made a comparison on temperature sensing properties of five different fiber Bragg grating sensors at low temperature, and we get its wavelength-temperature sensing characteristic curve under low temperature, and the influence of coating materials & packaging materials to sensors, we made an accurate calibration of sensor through low temperature calibration platform. At last, the signal was processed by wavelet and we proposing a peak searching algorithm with less calculation & high accuracy.(2) Taking AP-Sensing distributed fiber measuring hosts as the mainstay, and design a set of Raman scattering distributed optical fiber temperature sensing system, and we found that this system has stable measuring under low temperature through the comparison of PT-100 platinum resistance.(3) we made a 0.2m long H-T-S cable, PT-100 platinum resistance, fiber Bragg grating sensor and distributed fiber optic sensor was embedded into it, then we made a DC critical experiment, the results show that:both fiber Bragg grating sensor and distributed optical fiber sensor could reflect the temperature change of H-T-S cable, but the temperature data of distributed optical fiber sensor has a certain delay.This paper made a exploratory study on application of fiber optic sensing technology at low temperature, the data and results provide important support on practical application of optical fiber sensing technology at H-T-S cable, and has certain practical significance and reference value.