Numerical Simulation Research On Typhoon Wind Field Acting On Transmission Line Site In Eastern Coastal Mountainous Area

With the gradual deepening construction of the power grid system,the scope of transmission lines is also expanding,more and more transmission lines need to surpass a rough natural terrain.At the same time,due to the high structure flexiblity of the transmission line itself,it is a structure that is more sensitive to wind loads and is susceptible to extreme windy weather,especially typhoon disasters,which will cause great harm and damage to the transmission line.Also,The eastern coastal area is a typhoon-prone area,at the same time,the transmission lines in the eastern region often go over some local complex micro-topography mountainous area.Under the coupling action of typhoons and micro-topography mountainous areas,the wind field characteristics at the transmission line site are various and complex which requires indepth research.At present,the research on wind field characteristics of micro-topography mountainous area mainly adopts on-site measurement,numerical simulation and wind tunnel test methods.In view of the superiority of the numerical simulation method compared with other methods,this paper uses the numerical simulation method to study the wind field characteristics near the transmission line site in the coastal mountainous area of eastern China.This paper uses the large eddy simulation method to study the wind field characteristics of the local micro-topography area where the transmission tower is collapsed and broken due to the influence of the typhoon in the Xiaomen Island and Damen Island of Dongtou district.The main contents are as follows:（1）Using modeling software,a digital terrain model of the collapsed transmission tower accident area of Xiaomen Island,Damen Island was established,and a structured mesh was divided into the model.（2）The narrow-band synthesizing random flow generation method is used to generate the velocity entrance of the fluctuating wind field,and the generated fluctuating wind speed time history meets the needs of numerical simulation calculation and the turbulence characteristics of the atmospheric boundary layer wind field.（3）The time-varying average wind speed of the typhoon is extracted from the measured typhoon wind speed samples by the discrete wavelet transform method for the next simulation application.（4）The large eddy simulation method is used for numerical simulation of the above selected terrain,and the average wind field,fluctuating wind field and typhoon wind field are respectively used for the numerical simulation of the selected terrain,then the results are compared and analyzed.The following conclusions are obtained by analyzing the numerical simulation results:（1）From the simulation results of the average wind field,0° and 135° incoming wind direction angles are the main incoming wind direction angles in this area.Under the influence of micro-topography,the wind speed distributions obtained by different incoming flow are not the same.（2）Analyzing the numerical simulation results of the fluctuating wind field,it can be seen that the uplifting effect of the terrain and the narrow tube effect have a more obvious influence on the average wind speed.In addition,the role of local topography cannot be ignored.The local turning back topography at the monitoring point of Damen Island has a significant influence on the average wind speed and turbulence intensity.（3）For the typhoon wind field,due to the increase of the average wind speed,the average wind speed and turbulence intensity under the two inflow wind direction angles have a certain increase,and the coupling effect with the local topography makes the topography affect the wind field more seriously,it should be taken into consideration when designing the transmission tower line system.