| In order to have a better allocation of electricity,and meet the needs of large-scale power transmission,the UHV project in China developd rapidly and occupied leading place in the world in recent years.What's more,with the development of voltage level,the requirement of line insulation has become stricter each day,and the insulator string became longer.As the length and number of insulator string increased,it's lateral stiffness decreased,being more likely to apper windage,and that it strengthened the interaction between airflow and wake flow,then caused aeolian vibration.For the completed UHV transmission lines,windage and wind vibration have occurred many times.With the purpose of analyzing the mechanical properties of UHV insulator strings under the action of wind,this paper used the methods of the theoretical analysis,numerical simulation and wind tunnel test to complete the following contents:(1)We compared the shape coefficients of different disc insulator strings through wind tunnel tests,and used FLUENT to simulate the possibility and technology of the wind tunnel test for insulator strings,through which we found that both structured grids and assembled grids could well fit the wind tunnel test,as well as obtain the wind pressure distribution and wake characteristic.(2)We used finite element softwares to analyse the characteristics of windage yaw for V-shape composite insulator string,finding that in the process of windage yaw,maximum stress on the lee limb decreased first,then increased,and got to be minimum when wind amplification factor was 1.In addition,we also found that maximum stress on the wind limb became greater with the increasement of wind load.When the windage yaw just occurred on the insulator strings with small angle,stree on the insulator strings was close to the I-shape insulator string.However,with the aggravation of windage yaw,the lee limb pressured,and the ability resisting windage yaw enhanced.At this moment,the wind limb not only bear the wind load,but also bear the pressure from lee limb.With the increasement of angle of V-string,when the windage yaw occurred in early,the effect of lee limb on the massive structure kept increasing,while with the aggravation of windage yaw,the effect decreased gradually.With the increasement of angle of V-string,the maximum stress on lee limb declined gradually,the maximum stress curve of wind limb became gentle,the horizontal movement became small,and the ability of wind limb resisting windage yaw enhanced.The maximum wind yaw angle in actual related to the V-string angle.As the V-string angle became bigger,the difference between maximum wind yaw angle in actual and designed wind yaw angle was smaller.In addition,we conducted comparative analysis through windage yas simulation test,finding that the results about stresses from finite element software analysis can better fit the results from windage yas simulation test,while there was big difference between the results about displacement,and the reason for the difference was that the displacement of insulator was mainly caused by rigid body rotation of link fittings.Finally,the limb tensionwe derived from large deflection theory agreed quite well with the results from finite element software analysis,as well as the horizontal displacement of observation point,which indicated that the stress analysis of V-shape insulator string based on arge deflection theory was correct.(3)We discussed the factors influencing wind vibration of insulator string with the method of theoretical analysis,and compared the negative slope of lift coefficient to analyze the the possibility of wind vibration occurrence for different insulator strings.(4)We analysed how the spacers restrain the wind vibration occurrence,and worked out three different spacers to control the wind vibration.Meanwhile,we adopted the finite element software to analyse the influence of spacers on power distribution,finding that support structure had a small influence on the power distribution. |
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