Research on Structure Strength and Stability of UHV Transmission Tower

Abstract

In 2019, China put forward the "New Infrastructure" project. As one of the seven construction fields mentioned, ultra-high voltage (UHV) has attracted special attention from the Chinese government. As a key part of UHV field, UHV transmission tower is the carrier of electric energy in the whole UHV power system, which plays a very important role. And the existing research lacks quantitative analysis, which puts forward new requirements for its consumables, load capacity and optimal design. Therefore, it is necessary to evaluate the structure and stability of ultra -high voltage (UHV) transmission tower in order to meet the demand of high-capacity power transmission of new power system. The main research contents and innovations of this paper are as follows: The shape finding of transmission tower, transmission line and insulator string is carried out according to the shape finding principle of UHV transmission tower and transmission line. Then, the initial state model and dynamic characteristics of tower line under the action of self-weight and horizontal tension are established. On this basis, the beam element is selected to simulate the tower, the tension element to simulate the transmission line and the rigid rod to simulate the insulator string. The finite element model is established through the finite element software MIDAS GEN, which simulated the dynamic characteristics of the transmission tower and transmission line. Based on the elastic-plastic increment method and elastic modulus reduction method, the ultimate load capacity and failure mode of UHV transmission tower structure are analyzed. Taking the space truss model, space rigid frame model and space beam truss combination model of UHV transmission tower as the object, the differences of the above three UHV transmission tower models are compared. The example analysis shows that the spatial rigid frame model and spatial beam truss composite model of drum transmission tower can reflect the ductile failure property of tower structure, while the calculation result of ultimate load capacity of beam truss composite model is partial to safety. The structural optimization model of UHV transmission tower and the leg optimization model of UHV transmission tower are proposed, and the model is solved with the commercial III solution software CPLEX in Python. Among them, the structural optimization model of transmission tower takes the minimum total weight of the structure as the goal, with the consideration of the strength constraints of the axial force of the rod element and the stability constraints of the axial compression of the rod element, and takes the 10 rod truss structure as an example to effectively verify the effectiveness of the model; The leg optimization model of UHV transmission tower takes the minimum total weight of transmission tower support as the goal, and takes into account the stress constraints, stability constraints, slenderness ratio constraints of member elements, node displacement constraints and angle constraints. Taking the wine cup linear tower as an example, the effectiveness of the model is effectively verified.