| The galloping and ice-shedding of overhead transmission lines is a hard problem, which has been paid great attention to in the world. Along with the development of Ultra-high Voltage(UHV) transmission lines in China, the great span transmission line of electricity increases constantly. The harm caused by the galloping and ice-shedding of overhead conductors has been more and more serious, which can cause wear and fatigue damage to conductors, insulator strings, support hardware and tower components, even break the line and destroy the transmission tower. This result in heavy economic losses. In order to guarantee the safety and reliability of UHV electrical network, the dynamic mechanical properties of power transmission lines under the effect of icing accretion must be studied seriously.In this dissertation, the studies on the effect of icing accretion for long conductors of power transmission lines are performed. The research content includes: nonlinear finite element model of conductors, the determination of initial configuration of overhead lines, simulation calculation of the aerodynamic characteristics of the ice-accreted conductor, calculation and analysis of nonlinear galloping, calculation and analysis of ice-shedding. The primary task of this dissertation is attempting to explore a set of complete method that can be used for galloping analysis and ice-shedding analysis, and all sections of this dissertation are depicted on this aim.This dissertation derive the stiffness matrix and mass matrix of the two-node bar element according to the non-linear finite element theory at first, calculation formula for using single conductor to equal bundle conductors was put forward. Then the dynamic analysis of transmission lines were done by Runge-Kutta Method, and simulation calculation program has been compiled used FORTRAN.On the basis of analytical method of form-finding analysis of single-span power transmission lines, the solution flowchart of iterative computation the initial configuration of multi-span power transmission lines is given, which can consider the regulative action of suspension insulator, and a subprogram is compiled to find the initial configuration of multi-span power lines. This method can' t satisfy the application requirement of the case with more complex loads and more complex boundary condition. So a new method for form-finding analysis of cable structures is be proposed: the nonlinear finite element model of overhead conductors can be built according to the iterative solving result of initial configuration under the gravity action, then the non-linear FEM method can be used to find the configuration with complex loads and complex boundary conditions. This new method named Mixed form-finding, which integrate the advantages of iterative solving method and FEM method, has higher efficiency, rapid speed of convergence, is more concise and suits for analysis of more complex loads and complex boundary conditions.According to the characteristics of the crescent shape iced conductor models, numerical wind tunnel teclinology based on CFD numerical simulation is used to study the mean aerodynamic force coefficient of iced conductor at various angles of attack in this dissertation. After the space finite element model of multi-span power transmission lines are built, the Runge-Kutta Method is used to compute the galloping of power transmission lines acted by aerodynamic forces, and the corresponding program for galloping analysis is Compiled. Then the conductors of UHV Han-river long span transmission lines are token as an example, the calculation results of galloping of bundle transmission lines is obtained. The study results not only deepen the understanding of galloping mechanism, but also provide the theoretical basis for further study of prevention and cure of power transmission line galloping.After analyzing the mechanisms of conductor icing and ice-shedding, the computer program for calculating the dynamic response of conductors ice-shedding is developed by applying FORTRAN. Through comparing the calculation results with experiment of one transmission lines, the reliability and effectiveness of this program is verified. Then the overhead conductors ice-shedding simulation calculation of UHV Han-river long span transmission lines are done by using this program, and some meaningful conclusions are obtainedStudy the disaster of overhead transmission lines caused by ice is very important and difficult, this research has an important theoretical and engineering significance. There are no effective measures so far to solving this problem at present. This dissertation presents a new approach to solve the response of iced conductors, and provides the reference to the study of controlling the icing disaster of conductors.
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