Experimental Study on the Influence of Transmission Lines on Tower-Line System Dynamics

Abstract

The line of large span transmission tower is heavy, which will have influence on system dynamics. The transmission tower-line rig was built. The influence of tower-line coupling effect, insulator connection state and line sag on system dynamics was tested by experimental modal analysis. Results show that the tower-line coupling effect influences the longitudinal bending and torsional modes mainly and has less effect on the lateral bending mode. There is a set of corresponding system frequencies near the tower’s modal frequency. For the tower-line system, modal frequency decrease and damping increases. The tower-line coupling effect is strong if the insulator and the tower are tightly connected. The coupling effect is weak under the loose connection state. If line’s sag is small, its constraint on the tower is large. The modal frequency is larger than that of system with large sag. Additionally, the greater the sag of the line, the greater the modal damping.