Characteristics of Rainfall in Wind Field of a Downburst and Its Effects on Motion of High-Voltage Transmission Line

Abstract

Despite most weather-related failures of high-voltage transmission lines (HVTLs) being attributed to the downbursts accompanied by heavy rainfall, research works mainly focused on the behaviors of the high-voltage transmission tower-line structures under dry downburst winds. This paper thus presents a preliminary study to discuss the characteristics of rainfall in the downbursts and their effects on responses of HVTLs. Based on Vicroy model, the velocities of raindrops and their loads and pressure ratios of downburst wind-driven rain and only downburst wind on the surface of HVTLs per unit length are obtained. A downburst wind-rain induced vibration model is established to calculate the effects of the rainfall intensity and wind velocities on the motions of HVTLs. To verify the feasibility and accuracy of the model, the model is applied to evaluate responses of HVTLs with measured aerodynamic coefficients. The responses of HVTLs from the evaluated (the model) and the field observation results are compared. The results indicated that the model is feasible and can capture main features of the rainfall acting on HVTLs in the downbursts. Furthermore, the effects of rainfall cannot be neglected, and more attention should be paid to the wet downbursts and their effects on aerodynamic property of HVTLs.