# Analysis of Wind-Induced Vibration Response of Transmission Wire Under Crosswind in Canyon Terrain
## 1 Introduction  
Many mountains in China have complex terrains. The generation of local gates is closely related to micro-terrains. A micro-terrain area refers to a locally narrow range in a large topographic area [1]. When natural wind flows through mountainous terrain, the wind is blocked by the mountains and, therefore, flows around the sides of the mountains and the summits. Thus, the airflow has an accelerating effect. When the designs of transmission lines do not fully consider the complex wind field caused by local terrain, the transmission lines will swing under the wind force and the wind will exceed the limit load, leading to wire breakage [2, 3]. Unreasonable wire spacing arrangement can also lead to wind deviation tripping. Some high-altitude mountainous areas in China have dangerous terrains, inconvenient transportation, and a lack of operation and maintenance personnel. Once an accident occurs, it is difficult and costly to solve the problem [4]. Therefore, it is necessary to determine the carrying capacity of transmission lines under different wind loads by combining the local natural climatic conditions and the analysis of the wind field in micro-terrains. Most studies on the wind vibration response of transmission lines in mountainous terrain only consider the effect of wind force on the wires, unilaterally impose wind load on the wires, and ignore the multiple fluid-structure coupling effects between the wires and the wind during motion [5, 6, 7]. The design norms of wind load for overhead transmission lines differ in China and abroad, and considering different landforms is relatively simple. The accuracy and long-term applicability of the design norms for the wind prevention of transmission lines in China remain to be discussed [8]. The above factors cause a large deviation in the wind load on wires between the simulation calculation and the actualsituation. Moreover, the calculation results of the wind vibration response of the wires are inaccurate, which reduces the load design standards of the transmission lines in the terrain. This is not conducive to the safe operation of the wires. Chinese and foreign scholars have conducted few studies on the wind deflection characteristics of transmission lines in mountainous terrain. Most studies have focused on the boundary layer wind field in plain terrain or the wind vibration response of long-span overhead transmission lines [9; 10; 11; 12]. The authors of [13; 14; 15] used DEM to extract terrain elevation data to build a structured grid of the terrain to study the wind field. However, studies on wind fields in typical terrains are lacking. [PERSON] et al. [16] used CFD numerical simulation to study the three-dimensional average wind field and fluctuating wind field characteristics of typical single-mountain and double-mountain canyon terrains and compared the mountain terrain wind field parameters obtained using wind tunnel tests. The time domain method was used to study the influence of mountain wind field characteristics on the wind deflection response of transmission lines. The disadvantage was that the type of wind speed used in the study was relatively simple. The authors of [17] established coupled and uncoupled dynamic finite element models of a transmission tower line system composed of two towers, three spans of wires, and ground wires and modified the average wind profile of the windward slope, crosswind slope, and leeward slope. The wind load of the transmission line system was calculated according to the modified profile. However, only a single hill was used in the mountain model, which had a relatively simple topography. [PERSON] et al. [18] proposed a failure risk assessment method for transmission towers in a hurricane environment and studied the damage degree of the transmission tower system caused by downwind loads at different wind speeds and incidence angles. However, [PERSON] used the comprehensive wind field in a large area, and the specific wind field in the micro-terrain was not studied. [PERSON] et al.