【摘要】：在覆冰狀態(tài)下，輸電導(dǎo)線會(huì)承受自重、冰載、風(fēng)壓及由大幅舞動(dòng)所產(chǎn)生的動(dòng)載荷的綜合作用。導(dǎo)線在該作用影響下所引起的內(nèi)部張力一旦達(dá)到或超過設(shè)計(jì)載荷，便會(huì)很容易出現(xiàn)導(dǎo)線斷裂、桿塔倒塌等嚴(yán)重災(zāi)害。頻繁出現(xiàn)的覆冰導(dǎo)線舞動(dòng)使電力系統(tǒng)面臨更加嚴(yán)重的威脅，因此，國內(nèi)外的學(xué)者們正致力于解決這一工程實(shí)際問題。目前，關(guān)于覆冰導(dǎo)線舞動(dòng)的理論模型基本都是建立在單自由度或多自由度耦合的集中參數(shù)模型基礎(chǔ)上；基于非線性動(dòng)力系統(tǒng)理論開展的導(dǎo)線舞動(dòng)研究也十分有限。針對(duì)這些問題，本文的研究主要從以下幾個(gè)方面展開： (1)為了充分體現(xiàn)導(dǎo)線所具有的垂度和柔性，本課題依據(jù)彈性力學(xué)和氣動(dòng)彈性理論，建立了覆冰四分裂導(dǎo)線垂直、水平及扭轉(zhuǎn)振動(dòng)耦合的三維連續(xù)體動(dòng)力學(xué)偏微分方程。采用模態(tài)假設(shè)，運(yùn)用Galerkin離散法將其轉(zhuǎn)化為常微分方程，分析了結(jié)構(gòu)參數(shù)對(duì)各階模態(tài)線性固有頻率的影響。應(yīng)用數(shù)值模擬研究了不同檔距覆冰四分裂導(dǎo)線在不同風(fēng)速下的振動(dòng)特性，所得模擬結(jié)果與非線性有限元模型動(dòng)力分析結(jié)果基本一致。 (2).本課題確定了在不同跨度的工況下，具有幾何強(qiáng)非線性特性的導(dǎo)線垂直振動(dòng)水平張力的范圍。以具有典型強(qiáng)非線性振動(dòng)特性的覆冰導(dǎo)線振動(dòng)系統(tǒng)為基礎(chǔ)，通過研究各種因素對(duì)舞動(dòng)的影響，揭示了覆冰導(dǎo)線舞動(dòng)的內(nèi)在機(jī)理，發(fā)現(xiàn)了舞動(dòng)導(dǎo)線系統(tǒng)中豐富的非線性動(dòng)力學(xué)現(xiàn)象，發(fā)展了現(xiàn)有的舞動(dòng)機(jī)理。研究結(jié)果表明由輸電線的柔性和大振幅所造成的幾何強(qiáng)非線性特性在不同檔距內(nèi)普遍存在。 (3).根據(jù)規(guī)范形理論，應(yīng)用適用于強(qiáng)非線性振動(dòng)系統(tǒng)的待定固有頻率法并借助于符號(hào)運(yùn)算語言Mathematica編制的通用程序計(jì)算了系統(tǒng)的規(guī)范形，得到導(dǎo)線在前3階模態(tài)坐標(biāo)下垂直振動(dòng)的振幅和振動(dòng)頻率。分析結(jié)果表明各階模態(tài)振幅均隨風(fēng)速均增加而增大，1階模態(tài)振動(dòng)頻率偏離固有頻率隨振幅增加而減小，2、3階模態(tài)振動(dòng)頻率偏離固有頻率隨振幅增加而增大，各階模態(tài)振動(dòng)頻率隨幅值的變化規(guī)律與動(dòng)力學(xué)方程中二次或三次非線性項(xiàng)有關(guān)。 (4).以初始攻角作為分岔參數(shù)，分析了系統(tǒng)的動(dòng)力學(xué)穩(wěn)定性。應(yīng)用程序計(jì)算了垂直與扭轉(zhuǎn)振動(dòng)耦合系統(tǒng)的中心流形，，得到在極坐標(biāo)下前9階Hopf分岔A規(guī)范形。確定了使系統(tǒng)動(dòng)力失穩(wěn)并致舞動(dòng)的初始攻角等參數(shù)范圍值，研究結(jié)果表明初始攻角是控制舞動(dòng)發(fā)生及舞動(dòng)幅值的主要結(jié)構(gòu)因素。該研究為工程實(shí)際中導(dǎo)線防舞、減輕甚至消除舞動(dòng)帶來的危害提供了理論依據(jù)。
[Abstract]:Under the condition of icing, the transmission line will bear the combined effects of self weight, ice load, wind pressure and dynamic load caused by large galloping. Once the internal tension caused by the action of wire reaches or exceeds the design load, it is easy to cause serious disasters such as wire fracture, tower collapse and so on. The frequent ice conductor galloping makes the power system face more serious threat. Therefore, scholars at home and abroad are devoting themselves to solve the practical problem of this project. At present, the theoretical models of icing conductor galloping are based on the single degree of freedom (DOF) or multi-degree-of-freedom (DOF) coupling model, and the research on conductor galloping based on nonlinear dynamic system theory is also very limited. In order to fully reflect the sag and flexibility of conductors, this thesis is based on the theory of elasticity and Aeroelasticity. A partial differential equation of three-dimensional continuum dynamics with vertical, horizontal and torsional vibration coupling is established. The modal assumption and Galerkin discretization method are used to transform it into ordinary differential equations, and the influence of structural parameters on the natural frequencies of various modes is analyzed. Numerical simulation is used to study the vibration characteristics of ice-coated four-splitting conductors with different spacing at different wind speeds. The simulated results are in good agreement with the dynamic analysis results of nonlinear finite element model. (2) In this paper, the range of horizontal tension of vertical vibration of conductors with strong geometric nonlinearity under different span conditions is determined. Based on the ice-covered wire vibration system with typical strong nonlinear vibration characteristics, the internal mechanism of the ice conductor galloping is revealed by studying the influence of various factors on the galloping. The abundant nonlinear dynamic phenomena in the galloping conductor system are found, and the existing galloping mechanism is developed. The results show that the strong geometric nonlinearity caused by the flexibility and large amplitude of transmission lines exists in different spacing. (3). According to the normal form theory, the undetermined natural frequency method suitable for strong nonlinear vibration system and the general program of symbolic operation language Mathematica are used to calculate the normal form of the system. The amplitude and frequency of the vertical vibration of the conductor in the first three modal coordinates are obtained. The results show that the amplitude of each mode increases with the increase of wind speed, and the frequency deviation from the natural frequency of the first-order modal vibration decreases with the increase of the amplitude, and the deviation frequency of the third-order mode vibration frequency increases with the increase of the amplitude. The variation of vibration frequency with amplitude is related to the quadratic or cubic nonlinear terms in the dynamic equation. (4). The dynamic stability of the system is analyzed with the initial angle of attack as the bifurcation parameter. The central manifold of the coupled system of vertical and torsional vibration is calculated by the program, and the A-normal form of the first nine Hopf bifurcation is obtained in polar coordinates. The range of parameters such as the initial angle of attack which causes the dynamic instability and galloping of the system is determined. The results show that the initial angle of attack is the main structural factor controlling the occurrence and amplitude of the galloping. The research provides a theoretical basis for the engineering practice to prevent wire from dancing and to reduce or even eliminate the harm caused by galloping.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM75;O322

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