Papers by Keyword: Galloping

Abstract: In order to study the influence of some key factors such as the turbulence intensity related to micro topography and the diameter of conductor to the aerodynamic characteristics of iced conductor , the model is built based on the characteristic of iced conductor with crescent type ,to simulate the aerodynamic parameters for it and compare with the wind tunnel tests .The results show that we can make supplement reference to the wind tunnel tests through the numerical simulation method. Besides , we adjust the model and make research for the influence of diameter of conductor. The aerodynamic parameters we get can provide some reference to the research of galloping conductor.

Abstract: In galloping, reverse split wire plays an important role in. Through the study of split change sub conductor length of wire twisting motion estimation, the wire tension change caused by the torsion of sub conductors; besides considering some of the split wire torsion stiffness of the external factors, but also the influence of torsion wire tension change, caused by the conductor sag, line height worse, we deduced the general formula to calculate the new conductor spacer system torsional stiffness.

Abstract: According to the wind vibration shape of HVDC tower Under icing,the reason of guyed HVDC tower galloping is analysised.The mathematical model of icing guyed galloping and the vibration equation of HVDC tower is established .Using the measured wind data, the galloping dynamic characteristic of guyed HVDC tower under icing condition is completed in soft. The structure vibration situation drawing close to reality, the research results has been possible to provide the reference for wind disaster prevention.

Abstract: The theoretical study of galloping can effectively promote anti-galloping techniques. Cable element is utilized to imitate the bundled conductor, and beam elements are used to simulated the spacers, established galloping finite element analysis model which can consider sub-conductors wake interference. The finite element equation was solved by time integration method and the calculation program was compiled by MATLAB. Through numerical simulation analysis, compared the dancing in the case of considering the effect of the sub-conductor wake and ignoring the effect of the sub-conductor wake. The results showed that considering the effect of the wake on aerodynamic loads has a greater vertical vibration amplitude. This method can provide reference for the study of prevention technology on dancing.

Abstract: Nonlinear finite element model of a transmission tower-line system was set up and galloping of iced bundle conductors in the system was numerically simulated by means of ANSYS software. Based on galloping trajectories, vibration frequency, galloping order, conductor tension; unbalanced tension characteristics of iced conductors, it was shown that values of the conductor amplitudes by the tower-line system model are increased by 20% compared to the conductor model. The values of the strain tower unbalanced tensions by the tower-line system model are decreased by 20% and the values of the suspension tower unbalanced tensions by the tower-line system model are decreased by 62.5% compared to the conductor model conductor-insulator mode1. The galloping order is different for different span, due to the impact of the order of galloping. The amplitude of the vertical galloping is increasing while the increasing span, but it is not linear increase.

Abstract: This article is devoted to creation of mathematical models of overhead transmission lines (OHTL), taking into account the glaze. In the studying and designing of transmission lines is often necessary to construct mathematical model taking into account the influence of natural factors and all the basic physical parameters affecting or hindering them. The main difficulties arise when describing the equation of oscillations, as they nonlinear. Numerical experiments and comparative analysis with previously reported models was presented. The main setting is the critical velocity of the wind flow and its dependence on the angle of attack to OHTL.

Abstract: By used the assumed mode method to simulate the iced transmission line galloping,with three generalized coordinates to represent the iced transmission line galloping. In order to avoid the complicated calculation of vector,used the Lagrange equation to build the nonlinear equations of iced transmission line from the perspective of energy,used the Runge-Kutta numerical calculation to solve the equations of motion and get the iced transmission line’s across-wind,along-wind and the torsional response. Based on Lyapunov stability theory to deduce the critical wind speed of the iced transmission line galloping. And had used a test iced transmission line to verify the feasibility of the numerical solution and the critical wind speed.

Abstract: This paper analyzed the advantages and disadvantages of several current on-line monitoring approaches to transmission line galloping, noting the comparatively strong economy and feasibility in the Conductor Length Method. Based on the length method, taking the data measured at tension sensors and the angle sensors as the basic parameters, this paper established a calculation model for the monitoring of galloping. The paper applied this model into calculations, whose results basically consistent with the on-site monitoring data, which verifies the accuracy of the calculation model.

Abstract: The aerodynamic forces of two typical iced conductor models are obtained by high frequency balance technique in wind tunnel test. The effects of wind directions and turbulence intensity on aerodynamic forces coefficients are discussed. An analytical expression for predicting the galloping instability trends in arbitrary directions is derived. An aerodynamic model considering the dynamic swing is developed according to the quasi-steady theory. Galerkins procedure is employed to discrete the governing equations of transmission line, which is modeled as a suspended homogeneous elastic cable having a small equilibrium curvature and neglecting the shear deformation. The forth order Runge-Kutta method are applied to obtained the approximate numerical results of iced transmission line galloping.

Abstract: Based on the differences aerodynamic characteristics between each sub-conductor of iced bundled conductors, a two-node cable element with three translational and one torsional degrees of freedom at each node is utilized to imitate the bundled conductor and the two-node space beam elements are used to simulated the spacers. Established nonlinear finite element equations of bundled conductors based on the principle of virtual work and solved these equations using Newmark-β method. Numerical example was employed to demonstrate the reliable and efficient of the presented method and program.