| Ultra-High-Voltage Transmission Line Project has entered the stage of large-scale construction and service operation in our country.The research on the prevention and control of galloping for UHV transmission lines is one of the hot topics in this field in recent years.The dynamics and aerodynamic load properties of iced conductor with great rnumber of sub-conductors,large diameter and high-hanging point were studied.Meanwhile,taking solving the UHV engineering problems and satisfying demand as the starting point,and taking combination of theoretical analysis,numerical simulation and verification test as the overall technical route,in order to meet the practical engineering demand of establish the reasonable design,operation,maintenance and technical transformation principles,this paper showed the basic theory,key parameters and engineering design of the anti-galloping fittings for UHV transmission lines were all deeply studied and analyzed.Through the test of torsional stiffness and low-frequency self-damping,this two kinds of key parameters of the UHV and EHV conductors were compared and fond to be affected by the number of sub-conductors,type location and number of anti-galloping fittings.The test data showed that in the laboratory 140m test line,installation of RCS,Four Link damping heavy anti-galloping device,anti-galloping fittings' elastic deformation will decrease the split conductors' torsional stiffness,but their frictions at joints increase each degree of freedom's low-frequency self-damping;Iced UHV conductor galloping nonlinear dynamic equations was established,which was based on the curved beam theory and Dirac function to describe the distribution of anti-galloping fittings,and as well as considering the former test conclusion about torsional stiffness and low-frequency self-damping properties.By recording and comparing the forced vibration response of the 140m test line,the partial equations that belong to the conductor body were verified.Harmonic balance method was used to solve UHV conductors' icing galloping equations with two kinds of working cases,which were 1:1 internal resonance case for torsion and normal freedom,as well as non-internal-resonance case.The steady-state solutions and instability conditions were clear.The results show that the settings of initial ice angle was similar to that of Nigol.Compared with the common voltage lines,galloping critical wind speed in UHV conductor internal resonance case were more likely to occur in natural condition,non-internal-resonance case was not easy to appear.On this basis,the nonlinear internal resonance instability mechanism was proposed and the conditions and the basis for judging whether iced UHV conductors would gallop or not were both revealed;Considering the influence of wind speed gradient on the nonlinear dynamic performance of UHV long-span transmission lines,a new model was proposed.The theoretical analysis showed that because the traditional model didn't consider the factor of wind speed gradient,the possibility and severity of UHV long-span conductor's galloping disasters were artificially to be more serious,which lost the economy and practicability in UHV power grid design and construction;In order to apply research results on galloping mechanism of icing UHV conductor to engineering practice,protect conductors and fittings,prolong the service life of the UHV transmission line,and enhance the power grid overall anti-vibration ability,according to the characteristics of UHV transmission lines,Nonlinear Energy Sink theory and particle damping technology was introduced to design new type of anti-galloping absorber.At the same time,the absorber's design conditions,optimization method,installation quantity and distribution principle were researched and analyzed,which means particle-damping-dynamic-zero-natural-frequency absorber was proposed to be designed,and a series of in-depth research was carried out.The results showed that,through the optimization of critical parameters and structure design,the absorber had a large amplitude response and no obvious resonance peak in the frequency range from 0 to 2Hz.In practical engineering,comprehensive consideration of a variety of factors was necessary,such as single span conductor's common mode and carrying capacity,as well as absorber's target and costs,in order to determine the reasonable quantity and arrangement,which could help particle-damping-dynamic-zero-natural-frequency absorber to effectively play the role of vibration absorber.In summary,this paper revealed UHV conductor galloping mechanism,and at the same time,a new kind of anti-galloping device that was suitable for UHV transmission lines had been developed,optimized and evaluated.This paper provided the theoretical and engineering foundation for the UHV lines' construction,operation,maintenance and technical transformation,as well as for the application of Nonlinear Energy Sink theory and particle damping technology in anti-wind and anti-vibration fields of transmission line. |
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