Abstract:
The dynamic tension generated during the icing and shedding process of a conductor can easily cause accidents such as wire breakage and tower collapse, thereby endangering power transmission. The maximum dynamic tension by ice shedding of a conductor is not only determined by the sudden release of the ice load, but may also be affected by wind actions, especially for the transmission lines in the windy area. This paper investigates coupling effects of wind action (including fluctuating horizontal and vertical wind load) and ice shedding on the dynamic tension of a conductor. The high frequency force balance wind tunnel tests were carried out to obtain aerodynamic force coefficients of an ice-accreted conductor with various crescent section thicknesses. Numerical simulation was applied to the dynamic response analysis of a real high voltage transmission lines by ice shedding, and to study the influences of wind attack angle, wind speed and ice thickness on the maximum dynamic tension of conductors. By considering the combined effect of ice and wind, the wind load amplification factor
μ for dynamic tension was proposed and the sensitivity of different parameters to it was analyzed. On this basis, the calculation formula of the maximum tension is given, which can be used in design applications. The study shows that ice shedding induced dynamic tension of a transmission conductor is largely dependent on wind attack angle, wind speed, and ice thickness. Regardless of coupling effects of fluctuating wind load and ice shedding, the conductor dynamic tension may be underestimated, especially under wind attack angles of 70°~150°. The amplification factor
μ proposed in this paper can take into account the influence of wind load on the dynamic tension by ice shedding, and make up for the lack of tension calculation in the existing specifications.