| Most transmission lines are built in the field,often passing through mountains and plains,and exposed to the external environment for a long time.They inevitably suffer from the continuous impact of the natural environment,including the effects of temperature changes,strong wind,freezing rain,icing and overhead line deadweight.The ice attached to the surface of the tower-line system will fall off uniformly or unevenly when it is subjected to external forces such as wind load,natural melting or artificial deicing,resulting in safety accidents.The angle tower can change the direction of transmission line because of its unique position in the line.Compared with the conventional transmission tower,the structure of the corner tower is complex and the force on the tower body is asymmetric.In this paper,the model of tower-line system is established,and the static and dynamic analysis of tower-line system under icing conditions is carried out.The following conclusions are obtained:(1)(1)The displacement and maximum stress of the midpoint of the guide line and the ground line increase significantly with the increase of ice thickness on the surface of the guide line.With the increase of conductor icing thickness and line angle,the force acting on the foundation of transmission tower on one side of tower foot changes from pressure to uplift force,and the pressure on the foundation on the other side increases.(2)The modal analysis of single tower,ice-covered transmission lines with different thickness,different line angles and different thickness of ice-covered tower-line system is carried out,and the vibration modes and frequency changes under different parameter combinations are compared.Through comparison,it is found that the frequency of tower-line system decreases with the increase of icing thickness and line rotation angle.(3)Due to the influence of ice shedding,the maximum stress of conductor and ground wire increases with the increase of ice thickness and wind speed.The lateral and vertical amplitudes of conductors and ground wires are larger when the conductors and ground wires are deiced due to the influence of wind vibration.The amplitudes of ground wires are smaller when the conductors and ground wires are not iced.With the increase of ice thickness,the maximum amplitude of ground wires increases,and the displacement of tower top increases with the increase of wind speed and ice thickness.When the wind speed is 27 m/s,the maximum displacement of the tower top has exceeded the allowable value of the tower top displacement when the icing thickness is 10 mm,20 mm and 30 mm.Under these conditions,the structure is unsafe. |
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