APPLICATION OF VIBRATION MODAL IDENTIFICATION IN DYNAMIC CHARACTERISTICS TESTS OF TRANSMISSION TOWERS AND CONDUCTORS

摘要

The transmission tower and conductor system is a 3- dimensional complicated tower-line coupled vibration system. Because of the softness of lines, most of its vibrations modes are local modes, that is, modes of lines. With the finite elements method program ANSYS, a three dimensional analysing mode of a 220kV combo steel tube tower with 120m height for large crossing transmission lines across Iron Pile Channel of Pear River at Guangzhou is analysed. Among the first 600 vibration modes, most lateral modes of the tower are basically coupled by lateral vibration of lines. And only the 323rd mode and 329th mode are longitudinal tower mode coupled by longitudinal vibration of lines. And these modes are very closed each other in their frequencies. In order to compare the in-situ experiments results to finite-element-method results, vibration modal identification technique is used to obtain the vibration mode of a tower coupled with lines. As an example, an environmental vibration test was carried out. The results showed a good accordance between them.