Online ice-coating monitoring research on overhead transmission lines with Brillouin optical time domain reflectometry

摘要

Online monitoring the ice-coating status along the overhead transmission lines under extreme weather is important for the safe operation and pre-warning of power-communication system. For the loose-tube composite fiber-optic ground wire, the external strain applied on the cable caused by the coated ice are directly measured and the ice-coating status are estimated based on the spontaneous Brillouin scattering in the single-mode fiber within the composite cable. When the applied strain is less than 60% of the rated breaking force, the optical fiber is not influenced by the external force. When the applied strain is larger than 60% of the rated breaking force, the Brillouin frequency increases linearly with the external strain. With the same force 85 KN, the 10 mm and 20 mm thickness of coated ice caused 11.3 MHz and 33.19 MHz frequency increase of the Brillouin scattering, corresponding to 226 mu epsilon and 663.8 mu epsilon strain change on the fiber. Experimental results show that BOTDR sensing system is feasible for the ice-coating monitoring of loose-tube composite fiber-optic ground wire, and could provide technical support for the further scientific analysis.