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Brillouin-based optical fiber sensing system has been taken more and more attentions in power transmission line in
recent years. However, there exists a temperature cross sensitivity problem in sensing system. Hence, researching on
strain separation technology of fiber brillouin sensing system is an urgent requirement in its practical area. In this paper,
a real-time online distributed strain separation calculation technology of fiber Brillouin sensing combining an electric
power optical fiber cable is proposed. The technology is mainly composed of the Brillouin temperature-strain
distributed measurement system and the Raman temperature distributed measurement system. In this technology, the
electric power optical fiber cable is a special optical phase conductor (OPPC); the Brillouin sensing system uses the
Brillouin optical time domain analysis (BOTDA) method. The optical unit of the OPPC includes single-mode and
multimode fibers which can be used as sensing channel for Brillouin sensing system and Raman sensing system
respectively. In the system networking aspect, the data processor of fiber Brillouin sensing system works as the host
processor and the data processor of fiber Raman sensing system works as the auxiliary processor. And the auxiliary
processor transfers the data to the host processor via the Ethernet interface. In the experiment, the BOTDA monitoring
system and the Raman monitoring system work on the same optical unit of the OPPC simultaneously; In the data
processing aspect, the auxiliary processor of Raman transfers the temperature data to the host processor of Brillouin via
the Ethernet interface, and then the host processor of Brillouin uses the temperature data combining itself
strain-temperature data to achieve the high sampling rate and high-precision strain separation via data decoupling
calculation. The data decoupling calculation is achieved through the interpolation, filtering, feature point alignment, and
the singular point prediction algorithm etc. Testing in the laboratory and the transmission line test base all show that the
simultaneous temperature and strain distribution measurement system can work effectively and reliably. This system
provides a good solution reference to solve the temperature cross sensitivity problem in Brillouin-based optical fiber
sensing system, and demonstrate a great practical value in power system applications.
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