Research On High-voltage Transmission Line Condition Monitoring Based On Optical Fiber Sensing Technology

In the West-East electricity transmission project, most of the long-distance overheadtransmission lines need to cross high altitude, snow cover, and ice coating areas. These areasare generally coupled with complex topographical conditions, which bring great difficulties totransmission line patrol and maintenance. Even a lot of manpower and material resourceswere costed to detect the overhead lines, it is difficult to obtain and feedback accuratemonitoring data in time. Hence, reliable and effective method for on-line monitoring of thestatus of the long-distance transmission lines is an important measure for power systemsecurity, stability, reliability and other operational targets.In recent years, domestic and all over the world universities, research institutions, andcompanies have paid more and more attention to research and development the monitoring ofoverhead transmission line. Electronic sensors are used in most of the existing transmissionline monitoring devices. However, electronic sensor will bring a lot of problem, such as shortlife, deterioration of performance in harsh environments. In addition, the electronic sensor issusceptible to strong electromagnetic interference of high-voltage transmission lines, andadditional energy supply and communication devices were needed to install, which may causemany factors of instability to affect the long-term reliability of existing transmission linemonitoring device. Therefore, there is an urgent need to study the new transmission linecondition monitoring method and device to meet the requirments of the real-time monitoringof the transmission line.With the development of optical fiber sensing technology, the measuring performance ofoptical fiber sensor is improved rapidly. Compared with the traditional electronic sensors,optical fiber sensor’s advantage is increasingly emerging. Optical fiber communication hasbeen widely used in power system, which is very convenient for the optical fiber sensingtechnology used in the on-line monitoring of transimission line. Therefore, this paper makescientific exploration of optical fiber sensing technology and its application used intransmission lines online monitoring, the research work and achievements are as follows:1. A fiber grating sensor measure the overhead transmission line load was researched.The overhead transmission line load change and the insulator fittings micro-strain generatedby the load were analysed; The FBG (fiber Bragg grating) sensors and its ancillary fittingsused in overhead transmission line load were developed; The transfer coefficient between thesensor fittings and FBG stress sensors was researched; Temperature compensation was taken to eliminate the influence of temperature change in the measurement of the FBG sensors; andthe stress calibration experiment was carried on, the relationship between the measurementaccuracy and measurement range was fitted.2. Experimental Study of the FBG sensors measure the overhead transmission line load.The prototype experiment of FBG sensors measuring transmission line simulation ice coatingwas carried on at the±800kV DC transmission test line in the Southern Power Grid UHVEngineering Technology National Engineering Laboratory; wavelet was used to analyse theexperimental data to determine the time point of the transmission line load changes; variabletime window difference algorithm was presented to analyse and early warning the loadchanges of the transmission line; the feasibility of fiber grating sensors measure thetransmission line load change was verified.3. The online monitoring of the distributed Brillouin optical fiber sensing technologyused in overhead transmission lines was presented. Distributed Brillouin optical fiber sensingsystem for the online monitoring of the transmission line was developed; GPU was used toaccelerate the FFT spectrum analysis of the Brillouin distributed optical fiber sensing systemthough CUDA (Compute Unified Device Architecture), which greatly improved thecomputation speed and response time of the measurement; Theoretical discuss the feasibilityof the distributed Brillouin optical fiber sensing system measuring the transmission linetemperature and stress.4. Experimental research of distributed Brillouin optical fiber sensing system measuredtemperature and stress of OPPC (optical fiber composite phase line) and OPGW (fibercomposite ground wire). In in artificial climate room, different temperature and icingconditions were simulated, the distributed Brillouin optical fiber sensing device was used tomeasured OPPC/OPGW temperature; OPPC with different external force was simulated, thedistributed Brillouin optical fiber sensing device was used to measure the stress change ofOPPC/OPGW.5. The application of optical fiber sensing technology for transmission line was discussed.Established a3D model of conductor galloping, simulate the mechanical relationship ofvarious locations when the conductor galloping. Theoretical Study on stress distributionmeasurment of conductor galloping, which was monitored by overhead transmission linedistributed Brillouin fiber sensor; FBG sensors measure and record the overhead transmissionline load changes wrere used to estimate the frequency and amplitude of conductor galloping.The sag, the icing warning, dynamic capacity increase was proposed by using overheadtransmission line distributed Brillouin fiber sensor temperature distribution measurement.