Impact loads from the broken conductors are common for transmission lines, which can bring threaten to the safe operation of the transmission lines. Dynamic analysis of the conductors in transmission lines under broken load was carried out. A finite element model of seven span conductors in transmission line was established in general software ANSYS. The insulator and the phase spacer were considered in the FEA model. The broken load case can be realized by the birth-death element method in ANSYS. Stiffness of the broken conductor or insulator element was changed to be a near zero value in a very short time. Effect of the damping property of the conductors was considered by the Rayleigh damping method. Dynamic responses of displacements at the broken points and the reaction forces of the insulators were obtained. Dynamic responses for the broken conductors with different damping ratios and bundle numbers were compared.
The ZB1 cup-type steel tubular tower is the first single-circuit tower for UHV transmission line in heavy icing area. Except the ground supports, steel tubular are applied in whole tower. The plug-in boards and forging flanges are used in ZB1 tower,and the highest strength of tubular steel is Q345. Through the monographic study on the tower optimizationnode structuretowers Eiffel effect and bending moment at member end et., The design of ZB1 cup-type steel tubular tower is improved. The success of full-scale test verified the reliability in design and manufacture of cup-type steel tubular tower for UHV in heavy icing area. Research results of this paper can be applied in UHV transmission line projects.
Downbursts, which resulted from the flow downdraft in thunderstorms, have become one of the most destructive disasters to buildings including transmission towers, etc. This disaster has drawn researchers’ interests and progresses have been continuously made by employing test and numerical tools. Accounting for the grid validations in the numerical simulation of downbursts, eight grids with different grid point distributions are generated, and then their corresponding flow fields are calculated by solving Navier-Stokes equations. The numerical results are compared with test results to investigate the influence of grid distributions onto numerical results. The results indicate that, numerical fidelity could be improved by refining grids in the zone with strong horizontal wind; while local grid refinement at inlet boundary could deteriorate numerical accuracy when the grid point number is kept constant, hence uniform grid distribution is recommended at inlet boundary without any grid refinement.
Accounting for the disastrous phenomena of ice-accreted conductor galloping, wind tunnel tests of LGJ630/45 conductor accreted with crescent-shaped ice are conducted. Based on the test results, conductor galloping is simulated by employing the PCL language of ANSYS commercial software package and then the influences of span lengths as well as free-stream speeds on galloping characteristics are studied. The results indicate that, conductor galloping consists several different frequency components. With the increase of span length, galloping energy moves from low-frequency component to its high-frequency counterpart, and finally high-frequency component dominates the galloping phenomenon. And with the movement of energy, galloping traces transforms from ellipse to that similar to a butterfly. With the increase of span length, the maximum cable tension first increases, next decreases sharply, and then increases again.
Downburst is a kind of strong wind that resulted from the flow downdraft in thunderstorm, which could assert the most serious destruction in the zone nearby ground. Researches on downburst usually focusing on modeling and calculations of downburst wind profiles while the proposed nondimensional empirical models are dispersed for practical engineering applications. Accounting for this problem, diagram for of downburst wind profile calculation is cleared up by assuming jet impinging orthogonally and axisymmetrically to plane ground. Different empirical models, which include maximum horizontal velocity distributions at different radial locations, height distribution of half maximum horizontal velocity along radial direction, and horizontal velocity distributions at different heights with constant radial location, are presented and combined together to calculate dimensional radial wind profiles of horizontal velocity. The obtained wind profiles can be combined with atmosphere boundary layer wind profiles together for practical engineering applications.
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