Dynamic behavior of power transmission line supports under wind influence

Строительная механика
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In this article, we give experimental research on the dynamic behavior of steel supports of overhead power lines (OHPL) under the action of wind loads. The methodology and scheme of the experiment were created in two stages on the corner dead-end and intermediate supports of OHPL 220 kV “TPP Zmiev – Zalyutino”. In the first stage, excitation of the support’s oscillations was achieved using wind exposure; in the second stage, there were recorded free oscillations of the system “support – current wires”, which were created by means of handmade resonance. There are presented graphs of stress variations in the structural elements of tower lattice supports under wind action along and across the OHPL. There were experimentally determined basic natural frequencies of steel supports, which are shown on the damping graphs of free oscillations. Analysis of the obtained spectra of longitudinal velocity wind pulsations allowed conclusions about the stationary nature of wind flow. There is a determination of the necessity of the frequency detuning of OHPL support from the natural frequency of 2.2 Hz because external action with the given frequency is possible at the current wire breakage in one of the phases. The first three natural frequencies of oscillations for overhead line support were determined experimentally. Frequencies below 0.75 Hz are associated with the effect of wind on current wires. Analysis of the results made it possible to clarify that the wind at angle of 90° to the overhead line route not only exerts maximum static pressure but is also almost twice as susceptible to the considered “support – wires” system in dynamics. The presented methodology makes it possible to study the dynamic properties and study the response of structures to wind influences not only of overhead line supports but also of wind power installations and antenna supports of radio relays and cellular communications.