Study On Mechanical Properties Of Transmission Tower-Line System In Different Iced Conditions By FEM

Transmission line accidents were occurred in the early stage of power grids construction and the repeated occurrences of that were taken place in a number of countries. Over the years, national and international researchers of institutes and universities have done plenty of researches on prediction and prevention methods for transmission line accidents for a long time based on theoretical analysis, computer simulations and experimental researches, and a great deal of useful research results were proposed. At present, there are problems in tower design, mechanical properties of operation lines, and prediction methods for accidents of iced lines and so on in China. To solve these problems, study on mechanical properties of transmission tower-line system in different iced conditions by finite element method (FEM) were proposed in this paper.Firstly, in this paper, a classification of commonly used towers in present transmission lines was made to make sure readers can know the structural commonness and characteristics of transmission towers clearly. Then took transmission towers and lines of the actual project as prototypes and extracted the key factors of that, combing with the mathematical characteristics of elements established the finite element models of towers, conductor wires, ground wires, insulator strings and some other main components of transmission line system. After that, the connectivity between the model nodes was determined based on the physical connection characteristics of each component. Finally, the transmission tower-line system as a whole finite element model was set up.Secondly, the nature and solutions of nonlinear problems of self-supporting transmission towers was discussed and the finite element implementation method was also discussed combing with analysis software. Then the initial shape analysis of conductor wires and ground wire was made based on cable structure characteristics. Taking the existing national and international transmission line structural load calculation standard as reference, completed the loads calculation of finite element model in this paper. And then, the imposed methods of different types of load and constraints were made.Thirdly, taking the finite element analysis software as research platform and the finite element model of transmission tower-line system as research object, study on mechanical properties of transmission tower-line system in uniformly iced condition was carried out. Typical selection of the main environmental parameters (ice thickness, wind velocity, etc.) which mainly influence the mechanical behavior of tower-line were made, then 38 simulated operation conditions were designed, and 282 stress values of key components of each tower were recorded. And the results revealed that the stress on tower cross arms increases exponentially with the increase of ice thickness and the stress on tower body increases exponentially with the increase of wind velocity by function fitting. At last, structure optimization and prediction methods for tower-line system were discussed based on the simulation results.Finally, considering the non-uniformly iced conditions, carried out study on mechanical properties of transmission tower-line system in 3 types of non-uniformly iced conditions, which were short span heavily iced, long span heavily iced and the middle section of span heavily iced the specific operation conditions were 33. Through comparative analysis reveals the influence mechanism of different iced conditions.This study will help to improve the security of grid operation and reliability and it has significance in both research and applications:â‘ strengthen and improve towers in different conditions by different measures, avoiding the costs increase in transmission line construction caused by using conservative design ideas;â‘¡provide operation information of tower-line system under severe weather conditions to electricity sectors;â‘¢provide suggestions to electricity sectors on arrangements of de-icing work;â‘£study on mechanical properties of transmission tower-line system in different iced conditions is the basic work of building a smart grid.