Research Of Galloping Mechanism And Anti-galloping Prevention Technology On Iced Ultra-high Voltage Transmission Lines

Transmission line galloping is due to the change of aerodynamic parameters after the conductor surface is covered with ice,thus causing large-scale low-frequency self-excited vibration under the action of wind.Iced-conductor galloping that in severe cases can cause interruption of power supply,even happening with tower fall accidents,causing enormous economic losses.The construction of super-high voltage(UHV)transmission line has not been completed in china,under the new power grid construction situation the environment of transmission line erection would be more complicated,line corridor is going to run into anti-galloping meteorological environment inevitably,so how to prevent the galloping of super-high voltage transmission line under ice coating environment is a big issue that needs to be addressed urgently.Therefore,grounded on further improvement of galloping mechanism and the accuracy of galloping judgment,intense research into economical and reliable galloping control technicians of super-high voltage(UHV)has thus taken on an even greater urgency and offered an essential significance both in terms of theory and practice.The main content of this paper is as follows:1.Study on galloping wind tunnel test for iced multi-bundled conductor:D-shape iced sectional model of 6-bundled and 8-bundled conductor was carried out,a new designed scaffolding three degree of freedom adjustable frequency of spring suspension device in wind tunnel system is adopted,aimed at three typical version of Den Hartog coefficient and Nigol coefficient's positive and negative combination,accurately emulate and record the three degree of freedom motion state of a wire segment model at different ratios of vertical to rotational natural frequency affected by a uniform wind field.The relation between characteristics of iced bundled conductor galloping and aerodynamic characteristics?natural vibration frequency of models also wind speed has been studied,due to the ratio of vertical to rotational natural frequency is greater than or less than one would appear two opposite characteristics of galloping under different aerodynamic conditions,that is to say the maximum amplitude of conductors vertical wave increase with wind speed or unsteadiness conductors galloping shows that the wind speed is limited to a certain range.2.Study on aerodynamic damping ratio and excitation mechanism of 3-DOF galloping for iced multi-bundled conductor:The wind tunnel test for D-shape iced conductors of 6-bundled and 8-bundled three degree of freedom sectional aeroelastic model was carried out,while the galloping is happening to aerodynamic damping ratio which was identified respectively based on the measured response and digital simulation,and also contrast it with calculated value of galloping theory of Den Hartog or Nigol.The relation between aerodynamic damping ratio of iced bundled conductor,aerodynamic characteristics,natural vibration characteristics and wind speed has been studied.The stability conditioned judgment of vertical-horizontal-torsional three degree of freedom motion of iced bundled conductor has been represented based on characteristic value perturbation method,analyzed three-degree-of-freedom coupling galloping mechanism.The phenomenon that unsteadiness galloping shows the wind speed is limited to a certain range which traditional galloping theory could not explain has been explained,and it has been verified by test.The galloping onset velocity of pratical transmission line was judged by experiment measured and non-linear calculation of galloping.3.Study on finite element simulation and excitation factors of MDOF system galloping for iced multi-bundled conductor:Precise and efficient simulation for finite element computing method of iced bundled conductor galloping that has come up by using ANSYS software,which was also compared to the non-linear finite element method based on both locally shaped function and global function,the accuracy of this method is determined.The multi-degree-of-freedom system of galloping stability judgment of iced bundled conductor under high tension ratio has been get by using a perturbation method,which has been compared with 3-DOF galloping.The numerical simulation of variable air velocity galloping in four typical states of iced structure parameters under seven typical wind attack angles has been carried out by using ANSYS software to simulate finite element computing method of galloping.The galloping unstable wind speed determined by the numerical calculation,multi-degree-of-freedom system of galloping stability judgment,and the traditional single degree of freedom galloping mechanism under different aerodynamic characteristics and action tensions has been compared.The galloping motivating factors of multi-degree-of-freedom system of galloping stability judgment of iced bundled conductor have been analyzed.The phenomenon of galloping which traditional galloping theory could not predict has been analyzed.4.Study on pneumatic prevention and control technology of transmission lines:A wind tunnel test of galloping has been carried out for twistable sub-conductor of conductor segmental model by using the newly designed galloping wind tunnel testing apparatus of iced bundle conductor,while the anti-galloping effect of new rotary clamp conductor spacer was being tested the optimal layout plan of rotary clamp conductor spacer has come up.The vibration test of iced 8-bundled conductor under multi wind angles and various ratios of vertical to rotational natural frequency has been replenished,the phenomenon of a specific wind speed which can cause galloping is restricted to a certain range has been reappeared,the proposed decision condition of galloping stability which was aimed at three degree of freedom conductor now has been verified.The analogy procedure of new type rotary spacer has been established,the finite element computing method of non-linear galloping which was aimed at the iced 8-bundled whole lines before and after installing new type rotary spacer has been carried out,the galloping control efficiency of new type rotary spacer has been identified.5.Study on structural prevention and control technology of transmission lines:The new type torsional suppression anti-galloping device has been designed,the mathematical model with torsional suppression anti-galloping device has been established which was based on the galloping equation of three degree of freedom system,the principle of anti-galloping for new type torsional suppression anti-galloping device has been analyzed,a new type torsional suppression anti-galloping device has been designed and installed for of three degree freedom sectional aeroelastic model of D-shape iced 6-bundled conductor while the galloping wind tunnel test research has been carried out to verify the anti-galloping effectiveness.Take D-shape iced 8-bundled conductor as an example,multi layout plans has come up for detuning sub-spacer,the impact of detuning sub-spacer can do to dynamic characteristics of transmission lines has been analyzed.Non-linear finite element numerical simulation of galloping for eight layout plans of detuning sub-spacer with different different structural parameters under different wind attack angles has been carried out based on ANSYS software.