Numerical Simulation Study On Dynamic Response Of UHV Transmission Tower-line System After Ice-shedding

Ultra-high Voltage (UHV) transmission technology, which is beneficial for the conservation of resources and large-capacity transmission, has been widely used in engineering practice.Ice-shedding from transmission lines under certain conditions may cause vertical jump and horizontal swing of the lines, and in turn may lead to trip because of the too small clearances between any two different phase conductors and/or between a conductor and a ground wire during vibration, which usually jeopardizes the safe operation of power supply. Therefore it is important to investigate the dynamic responses of UHV transmission tower-line system after ice-shedding in heavy ice zones.The dynamic responses of typical sections of 1000 kV transmission tower-line in heavy ice zone after ice-shedding are numerically simulated comprehensively in this thesis. Firstly, The finite element models, including transmission towers, conductor lines, ground wires, insulators and spacers, of the transmission tower-line system are created in ABAQUS/CAE. The static load generated by the weight of the ice accreted on the transmission tower-line system and the dynamic loads induced by the ice-shedding from the electric lines are simulated by means of the modification of the density and the gravity acceleration of the lines. By the comparison with the results of transmission line model, it shows the deformation of tower have little effect on the jump height or horizontal amplitude of conductor after ice-shedding.The dynamic responses of the transmission line system with different structure parameters in different ice-shedding conditions are then numerically simulated with ABAQUS software, and the effects of various factors, including the span length, the ice thickness, the number of spans and the wind speeds, on the maximum jump height and horizontal amplitude of the electric lines after ice-shedding are investigated. It is shown that the maximum jump height and the maximum horizontal amplitude of the electric lines after ice-shedding go up with the increases of the span length ,ice-shedding rate and the ice thickness, and change very small with the number of spans for multi-span systems. A linear relation between the maximum jump height of a line after ice-shedding and the lag difference of the line before and after ice-shedding, and a linear relation between the maximum horizontal amplitude of the line after ice-shedding and the wind swing difference before and after ice-shedding are obtained according to the analysis on the numerical results. Based on the two linear relations, the simplified formulas for the jump height and horizontal amplitude of electric lines with odd number of multi-spans after ice-shedding are suggested for the design of the UHV Transmission lines. Moreover the method for minimum gap between the different phase conductor and/or between a conductor and a ground wire before or during the ice-shedding of conductor are also suggested for the design..