Transmission Line Tower Stress Analysis And On-line Monitoring Technique Research

In the construction process of ourcountry’s EHV and UHV transmission line,the transmission line inevitablely pass through coal mining areas,soft soil areas,hill land,riverbed and other special areas.Affected by terrain,track structure and natural disasters,more overhead line towers had appeared tower incline,deformation,or even falling down and other accidents.Therefore,how to analyze the safe running state of transmission tower becomes an urgent problem.In view of this,a finite element model of tower-line system has been built which uses the ANSYS software to analyze the stress characteristics of tower under different working conditions in this paper,on this basis,a transmission line tower stress monitoring system has been designed.The system mainly consists of Fiber Bragg Grating stress sensor(FBG),fiber grating demodulation unit,stress condition monitoring device(CMD),the monitoring center and other parts.Stress information of key points is collected on real-time by FBG sensor.Optical sensing signal is demodulated by demodulation unit.Then the data would be processed by CMD and uploaded by the Fiber/LAN.Finally,the overall stress is analyzed by the monitoring center expert software.When the external load of the tower is too large,it will give the warning signal ahead of time.Firstly,the finite element model of tower-line system is established by the ANSYS simulation software.Based on the loads calculation formula of tower-line system structure,the mechanical characteristics of different working conditions including the icing,wind loads and settlement of tower-leg is analyzed.The main stress value of the key links of transmission tower has been obtained,and the key links of transmission tower distribution under the different loads has been found out,which provide the evidence for the installation of the sensor.In addition,the monitoring terminal of tower stress is developed,FBG stress sensors are mainly studied including the principle analysis,structure design and performance analysis,and studied the CMD design mainly consisting of analysis of main function modules,the hardware circuit design and software design.Finally,the performance testing of the transmission line tower stress monitoring system is completed,the test experiment respectively includes sensitivity calibration test of sensor,electromagnetic compatibility test of monitoring system,etc.The test results meet the design requirements.This system has been run on the 110 kV experimental lines,and the monitoring data shows that the tower stress change obviously under the external load and the stress change is consistent with the load curve basically.The relevant results have referenced significance for overhead line condition maintenance and fault warning.