On-line temperature monitoring in power transmission lines based on Brillouin optical time domain reflectometry

The Brillouin frequency shift in single-mode fiber is linear to the temperature change around the sensing fiber, so on-line temperature monitoring of three-phase cables could be realized through measuring the Brillouin frequency shift of contained fiber used for fiber communication. Electrifying 100 m compound transmission lines with different time, and monitoring the temperature variation, experimental results shows that the temperature along the lines increases generally with the time lengthening, presenting monotonic increasing property. Moreover, the temperature distribution across the line section is analyzed, and the temperature difference between the cable line and the fiber is 0.018 °C. All the results shows that the BODTR sensing system could be used for the on-line temperature monitoring on the power transmission lines and provide technical support for the smart grid.