Long-distance Transmission Line Monitoring Based on Brillouin Optical Time-domain Reflectometer

On-line monitoring of transmission lines is essential for power grid security. With the length of tens of kilometers, transmission lines are hard to be fully monitored. Distributed optical fiber sensing based on Brillouin scattering is able to detect temperature distribution of each point along the long-distance fiber, which is suitable for transmission lines condition monitoring. However, the sensing distance of the distributed optical fiber sensors is not enough for long transmission lines, and the calibration method of laid lines is unclear. This work proposed an effective method to achieve a sensing distance of 100 km in the laboratory. To calibrate the data measured in the field, fiber Bragg grating (FBG) sensors were installed onto the power tower, and the field test was carried out on a 220kV transmission line.