Dynamic Response Of Transmission Tower Line System In Ice Loads And Wind Loads

With the rapid development of the global industry,demand for electricity has become more and more urgent, transmission tower line system as an important lifeline project of power transmission carrier, it determines the safety of power supply system. High voltage,far distance, high-priced, light weight, thin appearance are features and trends of development of present transmission tower line. Vibration of icing transmission tower is one of the main reasons to endanger normal operation of transmission system, it not only seriously affects people's production, construction and the life order, but also may causes a lot of other disasters, even bring very serious consequences to people's production, the attention of related aspects of personnel had been attracted. Domestic and international's ice cover accident reported that overload cladding ice on transmission line and vibration of transmission lines in the wind loads are the reasons that caused pour tower damage。Research on icing transmission tower line system mostly focuses on mechanical mechanism, model, dancing mechanism, technology of preventing and removing ice and so on. In recent years, researchs on icing transmission tower line system involved cause and damage of pour tower, dancing of wire cladding ice and dynamic response in fluctuating wind load,and so on.Base on previous work, truss and beam mixed finite element calculation model is used and software giant general-purpose finite element abaqus are used to analys a straight free-standing transmission tower which looks like of a drum. Natural frequency of the icing transmission tower and icing transmission tower line system were calculated, dynamic response and reliability of icing transmission tower in wind load were analysed, all the above provides valuable results to vibration control of icing transmission tower line system and industrial application research.The contents this paper finished are as follows:1. Ice cover influence on pour tower of transmission tower line system were analysed and reviewed,as well as mechanical mechanism research on destroyed pour tower of transmission tower line system; 2. According to the space structure characteristics of transmission tower line system, transmission tower line system of truss and beam mixed finite element model was established;3. With the help of matlab software, according to Davenport spectrum, using the harmonic synthesis, the dynamic wind load role on the transmission tower line system were simulated;4. With the help of the finite element analysis software abaqus, take a straight free-standing transmission tower line system with a form of a drum as an example, the natural frequency of transmission tower line system with ice thickness of 5mm,10mm, 15mm 20mm,25mm,30mm were calculated seperatly, natural frequency and mode of vibration were caculated;5. Dynamic response of transmission tower line system with ice thickness of 5mm, 10mm,15mm 20mm,25mm,30mm in fluctuating wind load were calculated seperatly, displacement curves in 10 seconds were the results.According to the caculation and analysis in this chapter,we have conclusions as follows:1. Coupling action of towers and lines should be considered in the reaserch of icing transmission tower line system, and dynamic characteristics of wind load to transmission tower line system,to obtain pour tower mechanical mechanism of icing transmission tower line system;2.Natural frequence of transmission tower caculated by ABAQUS is smaller than that caculated by empirical formula by 9.8 percent; Coupling action of towers and lines makes natural frequence of transmission tower line system smaller then that of transmission tower;3. Vibration of transmission tower line system, former 16 order modes had shown a first-order string vibration,the vibratio order of line is vibration of wires in lower position,then ordinal upwards, until the vibration of landlines.when it vibrated, a first-order string vibrated in XOZ plane before,then a first-order string vibrated in XOY plane;4. Low-order modes showed the performance of a first-order string vibration of wires or landlines, high-order modes showed the performance high times string vibration of a wire or landlines,maybe vibration of wires more than one in different planes.when the wires vibrated,it accompaning vibration of transmission towers;5. Along with the increase of overburden ice thickness, while the cladding ice of lines only considered, vibration frequency of the tansmission tower line system showed a trend of decling. While considering cladding ice of lines and towers, vibration frequency of the tansmission tower line system showed a trend of increasing before then decling,the later could show the truth of the system;6. Along with the increase of overburden ice thickness, maximal displacement of node 440 and node 2022 in the top position of transimission tower is increasing,and displacement time-history curves in the same time, Its frequencies of displacement variation is increasing.