Research On Dynamic Response Of UHV Guyed Single-mast Tower Under Strong Torsional Excitation

Unlike the free-standing transmission tower,the first-order vibration mode of the UHV guyed single-mast tower is torsional vibration.In the case of ice-shedding or cable-repture,strong torsional vibration may be produced in the guyed single-mast tower.Therefore,it is worthy to study the dynamic response of the UHV guyed single-mast tower under strong torsional excitation due to ice-shedding or cable-repture.The main contents of this paper are as follows:Firstly,a simplified finite element model of the tower-line system of the UHV guyed single-mast tower is established.By comparing the modal analysis with the fully accurate finite element model,the simplified model of the tower-line system is proved to be correct.The ice model was established on the basis of the model,and the accuracy of the model was verified by theoretical calculation.Secondly,the correctness of numerical simulation method for ice-shedding of power transmission line is verified by comparison with the ice-shedding test in the literature.The dynamic response characteristics of UHV guyed single-mast tower under strong torsional excitation are analyzed.Effect of initial stress on dynamic response of guyed single-mast tower under strong torsion excitation is analyzed.At last,the correctness of the numerical simulation method of the breakage of the transmission line is verified by the comparison with the cable-repture test in the literature.Under the three conditions of the ice-uncovered conductor broken,the ice-covered conductor broken and the ice-covered ground-wire broken,the dynamic response of the guyed single-mast tower is analyzed.The results show that under the action of strong torsional excitation due to ice-shedding and cable-repture,the main column above the hanging point of the cable has torsional deformation.The main column below the hanging point of the cable produces rigid body rotation with the cross-section of the hanging point of the cable.The dynamic response of the guyed single-mast tower under the ice-covered conductor broken condition is greater than that of the ice-uncovered conductor broken condition.The dynamic response of the guyed single-mast tower under conductor broken condition is larger than that of the ground broken condition.The deformation of the guyed single-mast tower and the peak stress of the main column's main member and diagonal member are small under ice-shedding condition,the guyed single-mast tower is still very safe.In the cable-repture condition,the dynamic response of the guyed single-mast tower is much greater than that of the ice-shedding condition,especially the peak stress of the diagonal member above the hanging point of the main column is larger than that of the main member.The disgonal member of the main column above the hanging point is in a more dangerous state.