Characteristics Of Windage In UHV Suspension Insulator Strings

UHV transmission project will have an increasingly important position in China’seconomic development and will be widely used since it had been included in the12thFive-Year Plan. In recent years, transmission line failure appeared frequently in the linesof the low voltage level due to windage of the insulator strings, which caused huge lossto the national product. UHV lines have a lower affordability to windage flashover, butits features make greater probability of occurrence of windage, therefore a study ofwindage is necessary. This article will do a more in-depth study on UHV lines windageon the basis of the work carried out in this field domestic. The main contents are asfollows:(1) The shape coefficient of conductor was calculated by Fluent with LES methodand three-dimensional models. Through the comparison of the single-conductorsimulation result with the classic wind tunnel test results of flow around a circularcylinder, the accuracy of the method was verified; then the method was extended to eightbundled conductors, the average shape coefficient of subconductor under different windspeeds was obtained, which turn out to have little difference between each other but lessthan the standard.(2) Based on the theory of WAWS, the fluctuating winds in characteristic line of theUHV were simulated by using double index frequency and FFT algorithm.(3) The wire-insulator strings finite element coupling models were established andthe static calculations were completed in ANSYS, while the wire shape coefficient wasassigned according to standard and the simulation results respectively. Then the values ofthe windage yaw were compared with the results of the rigid straight rod method.Fluctuating wind was applied to the coupling model and the time history analysis wasexecuted. By comparing the results that considering the fluctuating wind with those not,the pulsating amplification factors were raised. Finally, this article proposed correctionsto the rigid straight rod method.(4) This article established the insulator strings finite element models and studiedthe variation law of bending within insulator strings with different horizontal load,vertical load, insulator strings length and wind angle of attack. Tests were carried out toverify the simulation results. At last, the most serious bending cases in actual line wereselected and the influence of bending on electrical clearance is discussed.