Galloping Characteristics And Prevention Technology Of UHV Large-Section 8-bundle Conductors

With the development of national economic construction,UHV transmission project has been vigorously constructed by the State Grid,and its operation safety has been widely valued.Compared with others,UHV transmission lines have features like more conductor splits and large cross-sectional area,which make their galloping situation worse.Based on structural dynamics,the galloping characteristics of UHV large cross-section eight-split conductors are studied,the galloping prevention effect and effective range of UHV transmission projects are analyzed combined with the existing protection technology.The specific contents are as follows:(1)Flow field models of iced 8-bundled conductors are established by FLUENT software.The variation curves of aerodynamic coefficient with wind attack angle are numerically simulated to study the influence of conductor wake and bundle spacing on aerodynamic characteristics.The results show that aerodynamic characteristics of leeward side sub-conductor vary greatly in wake region of windward side sub-conductor compared with single-conductor.The smaller bundle-spacing relative to diameter of sub-conductor is,the smaller drag coefficient is.An equivalent galloping stability analysis method of bundled conductors is established to discuss the instability attack angle range of iced 8-bundled conductors.The results show that stability analysis provides an important basis for studying galloping mode and activation mechanism of transmission lines.(2)Based on numerical simulation method of conductor galloping,finite element models of UHV transmission line are established to simulate galloping process in ABAQUS.Galloping characteristics of isolated transmission line under different initial wind attack angle,wind speed and span length are studied.The results show that initial wind attack angle has significant effects on the galloping mode.With the increase of wind speed,galloping amplitude increases gradually.And galloping amplitude and form of different span length lines are changed.With the increase of span length,horizontal and torsional amplitudes increase.In addition,continuous transmission line galloping characteristics show that amplitude and mode change compared with isolated transmission line due to the mutual influence among spans,and vibration coupled so easily that excited large torsional motion.(3)The mechanism of double pendulum damper is discussed.Compared with the galloping characteristics of UHV transmission line,prevention effect and applicability of the anti-galloping device under different wind speeds,galloping modes,span lengths and continuous spans are studied.The results show that double pendulum damper can effectively suppress torsional vibration of transmission line,improve starting wind speed and reduce galloping amplitude.The galloping prevention effect decreases with the increase of span length.Double pendulum damper stabilizes galloping forms of continuous transmission line,avoids large torsional vibration,and slightly reduces galloping amplitude.(4)The mechanism and galloping prevention effect of dispersive conductor spacer,totally-rotary clamp conductor spacer and their combination with double pendulum damper on UHV transmission line are studied.The results show that,for the transmission line as research object,dispersive conductor spacer suppresses torsional vibration in a certain range of dispersed spacing.Its combination further improves starting wind speed of galloping.Totally-rotary clamp conductor spacer reduces starting wind speed,makes transmission line excited galloping more easily.Its combination is better to restrain vertical amplitude of galloping under partial wind speed.By quantitative evaluation,this paper perfects the analysis of the galloping characteristics and the anti-galloping effects of UHV transmission projects considered environmental conditions and line structures systematically,provides the necessary basic conditions for anti-galloping technology research,and provides reference for the design and operation of UHV transmission projects and the application of anti-galloping device.It has important theoretical significance and engineering value.