| Along with the massive construction of large-span, long-distance transmission lines, the security problem of power system operation are outstanding day by day. High voltage overhead transmission lines often across the rivers, mountains, valleys and other complex terrain, under certain conditions, the icing will adhere to the transmission line, which result in the transmission line sustains a large additional load, even beyond its design load, ice-shedding from the transmission line will produce serious unbalanced tension, follow with the transmission line broken, transmission tower damaged or even collapse. So it becomes very necessary to study the transmission line icing, ice-shedding and vibration control.The paper analyzes the key factors of transmission line icing, and does an in-depth study on the characteristics of transmission line icing growth based on the cylindrical icing model established by Makkonen. The paper also analyzes the icing collision characteristics and freezing characteristics, establishes the analytical formula for calculating collision coefficiency and freezing coefficiency, and establishes the analytical formula for calculating icing density based on the cylindrical icing model, Finally, the paper establishes the analytical formula for calculating icing load and icing thickness. Then, a numerical simulation program of icing growth model using MATLAB is established, the numerical results are used to make a detail study on the factors of transmission line icing growth and transmission line icing load.According to the information of a real 110 kV transmission line in Shaoguan area, a finite element model of the transmission tower and line system is established using the large general finite element software ABAQUS, and then the dynamic characteristic of tower line system model is analyzed. The key parameters of icing load is determined based on the icing information of Guangdong power grid, then the icing load calculated by simulation is applied to the transmission tower line system, the gravity effect of icing load is analyzed then. The paper slso sets up four cases of the ice-shedding according to the real situation of ice shedding, the nonlinear dynamic response of the transmission line ice shedding is calculated, some key nodes and elements are selected for analysis, the response of the transmission line and transmission tower after ice-shedding is compared, the results indicates that the full span ice-shedding make a great influence on the transmission line, and the unbalanced tension result from the asymmetric ice-shedding make significant influence on transmission tower.Finally, the vibration control of transmission tower is studied in this paper, the mechanics model of viscous damper is briefly introduced then, the dampers are installed to 5 different positions of the transmission tower, vibration control analysis under 5 damper distributed cases are studied, then the paper compares and analyzes the vibration control effect of 5 damper distributed cases, the results indicate that the the dampers distributed on the principal rods have a better vibration control effect than the dampers distributed on other positions, and the best vibration control effect appears when the dampers are distributed on the upper position of the transmission tower. |
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