| Overhead transmission line is a long-span flexible structure,which is prone to lowfrequency galloping under extreme environmental excitation.The overall dynamic characteristics of tower-line coupling will be more complex.The traditional anti-vibration measures have certain pertinence or limitations,and the damping effect is not obvious in most dangerous conditions.In this paper,a 220 k V transmission line in Hunan Province is taken as an engineering prototype.Based on the principle of dynamic similarity,a three-phase transmission line test model and variable stiffness interphase spacer are designed and manufactured,and a non-contact electromagnetic excitation system is designed and developed.Based on the above scaled model and equipment,the nonlinear dynamic characteristics of large amplitude vibration of transmission lines are analyzed in detail from both in-plane and out-ofplane directions.Considering the time delay coupling and coupling strength,the three-phase coupling vibration reduction test of transmission lines is carried out.The specific work is as follows:1.Based on the principle of dynamic similarity,the test model of two-tower single-span three-phase transmission line and the variable stiffness interphase spacer are designed and manufactured.The line shape and modal characteristics of the test model are analyzed and verified from three aspects of theoretical analysis,simulation calculation and test.2.According to the requirements of model test,a non-contact electromagnetic excitation system is designed and developed,and the electromagnetic field characteristics of the system are analyzed by finite element simulation.3.The non-contact excitation and test system is used to test and analyze the nonlinear dynamic characteristics of transmission line galloping,and the most dangerous excitation frequency condition is determined.4.Considering the factors of time delay coupling and coupling strength,the model test of three-phase coupling vibration reduction of transmission line is carried out,and the time delay parameter interval and coupling strength parameter interval of micro-amplitude vibration of transmission line are determined. |
