Research On The Dynamic Response Of Ice-shedding Due To Wind And Ruptured Wires Of Ice-adhesion Transmission Tower-line System

Transmissio n lines usually encounter the mult iple environment al loads such as strong wind, freezing rain and ice-adhesion. Transmissio n tower-line system often occur ruptured wires, ice-shedding and collapse of transmissio n towers. Therefore, it is of great pract ical significance t o study the behavior of the transmission lines under various environmental loads such as wind load, ice-shedding load and ruptured wires load for structure disaster prevent ion.In this paper, the finite element models of mult i spans transmission tower-line coupling system is established. Analysis about find-forming of lines and applicat io n of init ial stress are carried out and the accuracy of addit ional ice element method is verified. On the basis of this, the paper first analyzes the influence of ice-adhesio n on vibration modes and frequencies of transmission tower, conductors and tower line coupling system. Secondly, dynamic response of the structure under wind load is studied. Finally, the parameters of the transmissio n tower-line coupling system are analyzed when wires occur breaking. The research results are as follows:(1) Ice-adhesio n will lead to frequencies of transmission towers and wires becomes smaller, the larger ice thickness, the amplitude of frequencies decrease is greater. The ice-adhesio n on the surface of transmissio n tower has a limited influence on vibrat ion modes and frequencies of the whole coupling system, but it has a great influence on the frequencies of transmission tower. The lower order frequencies is more concentrated and wires ’ vibrat ion modes is main of the whole structure system.(2) Research on dynamic response of ice-shedding due to wind shows: when wind-induced vibrat ion occurs in the transmissio n line, the unbalanced tensio n of tower, the vert ical amplitude of midspan adjacent ice-shedding span, the maximum rebound height and the transverse amplitude of ice-shedding span show an increasing trend with the increase of the wind speed. When transmission lines system occur ice-shedding due to wind load, ice-adhesio n on the surface of ground wires is mo st likely to fall off, secondly, ice shedding will gradually extend from near transmissio n tower to midspan.(3) Parameter studies about transmissio n lines with ruptured wires show: The influence of ruptured conductorson the lines sys tem is larger than that of the ground wires. The dynamic response of direct ly connected posit ion with break point in the structure system is greatly influenced by the ruptured wires. The effect of insulator length on disconnect ion tensio n can be ignored, but its influence on tensio n of break point should be considered. During the process of vibrat ion, the insulator will swing back and forth, which will lead to the redistribut ion of vert ical load of transmissio n tower structure. Ice-adhesio n has a great influence on the disconnect ion tensio n, tension of break point, displacement of tower and vert ical amplitude adjacent span with ruptured wires. Wit h the increase of ice thickness, the growth of these values corresponding increase.