Numerical Simulation Study On The Galloping Characteristics Of Iced Quad-bundle Conductors

Accidents such as lines tripping,fracturing and tower collapsing often occur due to the galloping of transmission line with the development of the electrical grid and the emergence of disastrous meteorological conditions.It seriously affects the safe operation of transmission lines.Therefore,the research on the galloping of transmission line and the analysis of the influence rules of transmission line parameters and environmental factors on conductor galloping characteristics has important engineering significance to the transmission line design,the prevention and early-warning of transmission line galloping.As a result,the main work and conclusion of this paper are as follows.(1)The research on numerical simulation method of conductor galloping is completed.The aerodynamic characteristics of the iced quad-bundle conductors are analyzed,at the same time the aerodynamic loads of each sub-conductor are obtained.And the refined finite element model of conductor is established and the simulation calculation of conductor galloping is completed.Compared with the observation data,the error of the numerical simulation results is about 4%,which verifies the correctness and feasibility of the simulation method..(2)The influence rules of span,height difference and initial tension on the galloping characteristics of isolated transmission lines is studied.The results indicate that,there is a phenomenon of energy exchange between torsion and transverse vibration in the process of galloping.The maximum amplitude of galloping may occur in the range of 1/6L?5/6L except in the typical positions of 1/2L and 1/4L.In a certain range,the amplitude of galloping increases with the increase of span.And,the amplitude of galloping is relatively small when the span within 300m?700m.When there is an altitude difference in the transmission line or the initial tension increases,the vertical amplitude of transmission line will increase.(3)The influence of wind speed and ice thickness on the galloping characteristics of isolated transmission lines is studied.The results show that,there is a critical wind speed when the transmission line galloping.In this paper,the critical wind speed isbetween 8m/s and 10m/s.When the transmission line is galloping,the amplitude and dynamic tension increase with the increase of wind speed and ice thickness.When the wind speed is 14m/s or the ice thickness is 0.5D,the galloping amplitude and dynamic tension have reached a significant level.If the wind speed and icing continue to increase,there is a great risk of transmission line trip and tower damage.(4)The influence rule of span number and span difference on galloping characteristics of continuous spans is studied.The results show that,there are obvious differences between the galloping response of continuous transmission line and isolated transmission line.With the same conditions,the galloping amplitude of continuous spans is greater than isolated transmission line,while the dynamic tension is less than it.The closer the conductor is to the tension tower,the stronger the galloping.When the transmission line is galloping,the maximum unbalanced tension of the tangent tower is 16% of the conductor tension and the tension difference of the tension tower is more than 50% UTS,which exceeds the design value of some towers.(5)According to the conclusion of this paper,some suggestions are put forward for engineering application.It can be considered to control galloping by restraining the torsion of conductor.After the transmission line is galloping,the scope of troubleshooting and repair of short-circuit and damaged points should be expanded to1/6L?5/6L.Considering the need of anti-galloping,the initial tension of transmission line in light ice area can be reduced properly.The monitoring and prediction indexes of wind speed and ice thickness can be considered to improve the existing galloping early warning mode.The requirements of the standard for the unbalanced tension of the linear tower and the tension difference of the tension tower can be properly raised.The requirements of the standard for the unbalanced tension of the tangent tower and the tension difference of the tension tower can be properly raised.