With the continuous expansion of the capacity of electric power systems, the coverage of the high voltage transmission lines is also expanding. Therefore, in the micro-terrain area, wind bias may cause the insulation chain of the transmission line to tilt towards the tower, thus shortening the distance between the conductor and the tower. In open microterrain areas, linear winds often accompany thunderstorms and hail, resulting in upwind flashover. This results in more humid air when the wind is off, reducing the insulation strength of the power lines. Under strong winds, once the intermittent water line formed by rain is the same as the discharge flascent path, the gap discharge voltage will drop. According to the analysis of wind speed factors in the transmission line, it can be seen that the tower distance is generally about 3~400 meters. But for the small tower head, when the wind deviation occurs, the insulation chain is more likely to deviate from the wind direction, resulting in trigger failure. With the increase of tower height, the possibility of wind deflection increases. In order to reduce the possibility of wind deflection of high voltage transmission lines, the design scheme must be determined according to the weather conditions. However, due to the proximity of weather stations to the suburbs, it is very difficult to collect meteorological information about tornadoes and running wind, which leads to no accurate reference in the design of transmission lines. Therefore, once a tornado appears, the power supply will not be able to operate safely and stably.
Analysis of influencing factors of air deviation fault
1 Maximum designed wind speed
For transmission lines in mountain canyons, the cross-sectional obstruction of airflow is greatly reduced when air enters the open area of the canyons, and a truncation effect occurs. Due to natural conditions, air does not accumulate in the canyon and in this case, the air accelerates into the canyon, creating strong winds. When the airflow moves along the valley, the air in the flow area in the middle of the valley will be compressed, and the actual wind speed will be further strengthened, higher than the flat wind speed, resulting in the narrow tube effect. The deeper the valley is, the stronger the enhancement effect is. There is a certain difference between the meteorological data and the maximum wind speed at the canyon exit. In this case, the maximum designed wind speed of the line may be lower than the maximum instantaneous wind speed encountered by the actual line, resulting in a deviation distance smaller than the actual distance and stroke

2 Selection of tower
With the continuous deepening of research, technical means are constantly updated, the tower is also developing. At present, the typical tower design has been widely used, and the tower structure used in some new lines has been approved. In the circuit design, pay attention to the design of wind deflection, and determine the actual wind deflection bearing capacity. Before this, there was no unified standard for tower selection across the country, and some old lines with narrow transverse arms of tension towers were still in use. In windy weather, flexible connections could be twisted to shorten the distance between wires and towers. When the distance is smaller than the safe distance, it may cause an air deviation fault packet
3 Construction Technology
Transmission line erection project needs construction team, construction personnel quality, ability and responsibility are very different. For example, if the production specifications of the drainage lines are not up to standard and the acceptance personnel do not notice the problem, it can lead to the use of these non-standard drainage lines, which increases the possibility of wind deviation.
If the drain line is too large and the horizontal string is not installed, it will swing in windy weather, making the distance between the wire and the tower too small, resulting in displacement jumps: If the actual length of the jumper’s drain line is small, longer than the distance between the drain line and the boom, the bottom insulator may rise, which may cause the boom to discharge.