Wind-induced Coupling Effect Research Of High Voltage Transmission Tower-line System

High-voltage overhead transmission line system has the characteristics of large span, high and soft. Under the strong wind load, the wind-induced vibration response of the tower-line system would be more intense, and the strong winds cause the tower collapsed. So to ensure its safe operation is of great significance. Transmission line system is a complex coupling system. Under the strong wind, the coupling effect has great influence on the stress of the transmission tower. But the current specifications design tower and line respectively, without considering the negative impact of towerline coupling effect influencing on transmission tower. So it is of great importance to research deeply about the wind-induced coupling effect of tower-line system, and it can provide reference for circuit design.Firstly, this thesis establishes the finite element analysis model of high-voltage overhead transmission line system and simulates the wind speed time history effecting on the tower-line system. Secondly, it researches on the dynamic response of the tower-line system under the different wind speeds(U10=14m/s, U10=16m/s, U10=17m/s, U10=18m/s, U10=20m/s,U10=25.3m/s, U10 means wind speed at 10 meters) and wind angles( 90°、60°、45°、0°). Finally, it compares the time history response analysis results for transmission tower of tower-line system with the quasistatic analysis results of a single tower.In this paper, the concrete contents and conclusions are as follows:With 90° wind angle as an example, this thesis studies the dynamic response of the tower-line system under different wind speeds. Research results show that with the increase of wind speed, they are enhancing that the vibration of transmission line, insulators and transmission tower. The tower-line system’s coupling effect has certain effect on the vibration of transmission tower and component stress. If the ratio, that between the component stress of transmission tower in tower-line system and corresponding component quasi-static stress results of single tower, is defined as the coefficient δ. With 90° wind angle as an example, when the wind speed is in U10=14m/s and U10=18m/s range, stress increases significantly that caused by the coupling effect(corresponding δ is in between 1.19 and 1.48), but the absolute value of stress is still in the elastic range, the tower is still in the safe state, so we design it according to the current specification. When the wind speed is in U10=19m/s and U10=25.3m/s range, the absolute value of material component stress is larger that caused by the coupling effect(corresponding δ is in between 1.39 and 1.06), the stress has been approached or reached the material yield strength, but it is still in the elastic range that the absolute value of material component stress according to the traditional pseudo-static method, in this wind speed range, if we still design transmission tower according to the traditional pseudo-static method, we will get unsafe design results. The current specification designs the transmission tower using quasi static analysis results of the design wind speed, so this paper suggests using quasi static analysis results of the design wind speed multiplied by the corresponding δ to consider the negative effects of coupling effects on transmission tower.Then this thesis studies the dynamic response of the tower-line system under 60°,45°, 0° wind angles and different wind speeds. Research results show that with the increase of wind speed, they are enhancing that the vibration of transmission line, insulators and transmission tower. With the decrease of wind angle, they are reducing that tower-line system’s coupling effect and the vibration of transmission line, insulators, transmission tower. At 60°、45° wind angle and different wind speeds, to U10=25.3m/s, the transmission tower has broken down. At 0° wind angle and different wind speeds, to U10=25.3m/s, the transmission tower still has not been destroyed. At 60° wind angle, we also need to consider that the coupling effect influences on displacement of transmission tower. At 45°and 0°wind angle, we calculate the displacement of the transmission tower according to the current specification. Considering the different wind angles, in the actual engineering design, we can use pseudo-static method to calculate the stress of components; we calculate the main material internal force of transmission tower under the design wind speed, only according to 90° wind angle that is the most unfavorable angle; and we multiply internal force calculation results by δ of the design wind speed;we design component section according to the increased internal forces.