Analysis Of Transmission Line Galloping And Research On Anti-galloping Technology

Under certain wind velocity, iced transmission line often occurs galloping, which is a low frequency and large amplitude self-excited vibration.The galloping amplitude is usually large,which is a very big threat to the safe operation of the transmission line. With the construction of large-scale power development, studying deeply in galloping is a very urgent task.The galloping response simulation and galloping prevention was studied in this paper. The paper's main contents and results are:The uniform nonlinear dynamic differential equations of iced transmission line installed with weighting and detuning pendulum was derived using Lagrange Method. The differential equations were solved by Runge-Kutta Methods and the Average Method respectively to obtaine numerical and analytical solutions of galloping response.The formulas for critical wind speed and torsional stiffness of bundled transmission lines were presented. The main conclusion are:When the torsional angel is smaller than 90 degrees,the torsional stiffness of the bundled lines is constant,which can be used as the initial torsional stiffness.The single line can gallop in a certain range of wind speed,while the galloping amplitude of bundled lines increases with wind speed.The relationship between galloping amplitude of single line and bundled lines with sag are similar,both exist a worst sag to cause maximum galloping amplitude.The single line exist a worst span to cause maximum galloping amplitude,while the galloping amplitude of bundled lines increases with the span.The mass element matrix and stiffness element matrix of the three degrees cable element considered torsional degree was derived.The nonlinear finite element program to calculate galloping amplitude was designed.The coupled FEM model of tower and lines was set up.The impact of tower to line galloping was studied. The impact of velocity fluctuation and spatial correlation to galloping was researched.The main conclusions are:The upward tranverse galloping amplitude is larger by nonlinear FEM than by linear FEM,while the downward amplitude is reverse.The tension of galloping lines is larger than static lines.The tension is 15% more in galloping single line than in static line.The tension of bundled lines increase with wind speed,and when wind speed is 20m/s,the tension increases 25%.There is a slight impact of tower on galloping amplitude,and the impact is related with wind speed. The galloping amplitude increases slightly considering the velocity fluctuation.A new type of liquid damper was designed and its anti-galloping performance was studied.The effects of weight and detuning pendulum installed on single line and bundled lines were researched. The main conclusions are:If the new type of liquid damper was designed by the proposed method in this paper, its anti-galloping effect is good. If the design parameters are not appropriate, the anti-galloping effect is less satisfactory.The anti-galloping effect of weight is good for single line and less effective for bundled lines. The detuning pendulum is very effective in a single line, but little effective in bundled lines.The aerodynamic coefficient curves of iced transmission line, transmission line installed with air flow spoiler without ice and iced transmission lines installed with air flow spoiler were measured by wind tunnel test. The aerodynamic coefficient curve of air flow spoiler was simulated by CFD.The relationship between the air flow spoiler coverage with galloping amplitude was researched. The main conclusions are:All the air flow spoilers of different diameters have certain effects to prevent galloping and the air flow spoiler of 0.75D diameter has the best effect to prevent galloping.When the coverage of air flow spoiler is 30%, the galloping can be inhibited completely.