【作者】 陈元坤；

【导师】 李黎；

【作者基本信息】 华中科技大学 ， 结构工程， 2011， 博士

【摘要】 随着我国电力输送容量的迅速增长,选择多分裂、大容量、远距离的输电线路已成为必然。而微风振动与次档距振荡对电力会具和导线的安全运行有着极大的威胁,且两种振动危害的发生频率在我国又非常高。作为重要生命线工程,输电系统的破坏会引起巨大的社会经济损失和其它次生灾害。但是目前工程界对分裂导线的设计主要采用的是依赖经验的折减系数法,该方法在我国尚缺乏理论研究的技术支撑,因此急需在此领域进行深入的理论与试验研究以确保大容量输电线路安全运行。本文利用计算流体动力学(CFD)对分裂导线绕流的数值仿真,研究分裂导线的微风振动特性、分裂导线的风能输入功率以及分裂导线平均气动力特性；通过对能量平衡法改进研究,提高分裂导线微风振动的计算分析的精度；通过对导线振动试验研究,弄清间隔棒、防振锤等金具的消能减振特性；利用分裂导线平均气动特性的仿真结果,结合稳定性理论、非线性振动理论以及非线性有限元法,研究次档距振荡的机理与计算方法。具体研究内容如下：(1)首先利用计算流体动力学对固定单导线与分裂导线的绕流现象进行了数值仿真,验证了计算模型与求解模式的可靠性,并考虑了三维效应的影响。其次利用动网格技术研究了单导线与分裂导线的微风振动特性,分析了两者的异同点。再次在验证了单导线风能输入功率有效的基础上,通过对分裂导线中振动子导线绕流的数值模拟,得到了分裂导线中各子导线的风能输入功率Pw，并研究了子导线间的水平间距L、分裂导线倾角β以及湍流强度Iw等因素对Pw的影响。最后拟合得到了风能输入功率Pw的解析表达式,为分裂导线的微风振动响应的求解提供基础。(2)依据IEEE微风振动试验标准,分别进行了单导线的振动试验与分裂导线的微风振动试验。通过单导线微风振动试验研究了导线的自阻尼特性与防振锤的耗能特性。通过双分裂导线、四分裂导线微风振动试验研究了分裂导线的振动特性,以及防振锤、阻尼线、间隔棒等防振会具对分裂导线的消振性能。(3)利用传递矩阵法计算得到了分裂导线的振动频率与振型,并结合导线自阻尼功率、防振锤耗能功率计算方法以及数值仿真得到的多分裂导线风能输入功率,建立了精细计算分裂导线微风振动的改进能量平衡法。(4)通过对分裂导线的CFD数值仿真获得了分裂导线的平均气动力系数曲线。基于准定常理论,分别建立了分裂导线次档距振荡的二自由度与四自由度的振子模型,对两种振子模型进行了稳定性分析,得到了次档距振荡发生的临界条件,分析了临界条件的各种影响因素。利用数值求解与平均法对两种振子模型的振动方程进行求解,得到了导线次档距振动响应,并两种振子模型的计算结果进行了比较,讨论了上游子导线振动自由度对次档距振荡的影响。(5)建立了次档距振荡仿真分析的有限元模型,运用Newton-Raphson迭代法确定其动力分析的初始静力构形。根据分裂导线平均气动力系数曲线建立了分裂导线的气动力模型,利用Runge-Kutta显示积分法对动力方程的求解实现了对分裂导线次档距振荡的有限元仿真分析。最后计算研究了分裂导线倾角、间隔棒布置、风速等因素对次档距振荡响应的影响。分裂导线的微风振动与次档距振荡研究的既有其重要的理论意义,又有其重要的经济价值。本文的研究能为分裂导线两种振动的防振设计提供有效的理论依据与合理的建议,为以后更深入研究提供基础。更多还原

【Abstract】 With the rapid growth of electricity transmission capacity, the adoption of bundle conductor, high-capacity and long-distance transmission lines have become inevitable. Aeolian vibration and subspan oscillation can easily cause damage of the bundle conductor and electric power fittings, which have a serious threat to the safe and reliable operation of transmission lines. As an important lifeline facility, the damage of transmission line system can lead to the paralysis of power supply system and cause huge economic losses and other secondary disasters. However, the existing methods are difficult to meet the design requirements. In order to ensure the safe operation of transmission line system, it is necessary to make further research in this field.In this dissertation, the numerical simulation on bundle conductor in a cross-flow is implemented by using computational fluid dynamic (CFD) method to study the aeolian vibration mechanism, wind power input, and the average aerodynamic characteristics of bundle conductor. The calculation precision of bundle conductor’s aeolian vibration is improved through the modified study of energy balance pricinple. The conductor vibration test is adopted to study the energy dissipation characteristics of stockbridge damper, wire damper, spacer damper. Using the numerical simulation results of average aerodynamic characteristics of bundle conductor and combined with stability theory, nonlinear oscillation theory and nonlinear finite element method, the mechanism of subspan oscillation is studied and the calculation methods are presented. The specific contents are as follows:(1) Firstly, CFD numerical simulation of the flow around the fixed single conductor and bundle conductor is carried out to verify the reliability of solution method. The three-dimensional effect is also considered. By means of the dynamic mesh method, the aeolian vibration mechanism and properties of single conductor and bundle conductor are studied. Moreover, the differences of the two cases are analysised and discussed. The wind power input of single conductor is numerically obtained through the simulation of the flow around a vibrating conductor. The numerical value of wind power input has a good agreement with the experimental value by the researches in wind tunnel tests. It’s confirmed that the numerical method is feasible. The subconductors of the bundle conductor are also obtained throuth the CFD numerical simulation. Meanwhile, the influences of subconductor horizontal spacing, inclination angle, turbulence intensity were discussed. And the analytical expressions of wind power input for bundle conductor are gained through the curve-fitting of numerical results. This can provide a basis for the solving the aeolian vibration response of bundle conductor.(2) According to IEEE standards, the vibration test of single and bundle conductor are designed and carried out. Through the single conductor test, the self-damping characteristic of conductor and the anti-vibration property of stockbridge dampers are investigated. Based on the theory of wave propagation, the calculation method for the energy dissipation of stockbridge damper, considering the damper’s installation posisiton, is established. And the method is validated by the corresponding vibration test. The vibration characteristic of the bundle conductor and the energy dissipation characteristics of spacer damper, wire damper, stockbridge damper are studied through the bundle conductor vibration test.(3) The modified energy balanced method is established to analysis the aeolian vibration of bundle conductor, which is different from the traditional reduction factor method. The transfer matrix method is used to calculate the vibration frequency and mode of the bundle conductor. Combined with the wind power input of bundle conductor by means of CFD simulation and the energy dissipation calculation method for conductor self-damping and stockbridge damper, the modified energy balanced method is established to calculate the response of the aeolian vibration of bundle conductor. Compared with the reduction factor, the modified energy balanced method is more reasonable and effective.(4) The average aerodynamic characteristics of bundle conductor is obtained by the CFD numerical simulation. Moreover, the influences of the conductor spacing, turbulence intensity, Reynold number effect are discussed. On the basis of the quasi-static aerodynamic theory, the oscillator models of two-degree-of-freedom motion and four-degree-of-freedom motion are built. Through the instability analysis of the two oscillator models, the critical conditions for the occurrence of subspan oscillation are investigated. By means of numerical solution and the average method, the dynamic response of subspan oscillation is calculated. Meanwhile, the investigation is made to study the influence of wind velocity, the damp of bundle conductor system, the frequency ratio on the subspan oscillation. The results of the two oscillator models are compared and analysed to discuss the influence of the windward’s oscillation freedom.(5) The finite element model of bundle for subspan oscillation analysis is established. In addition, the aerodynamic coefficients of bundle conductor with different conductor spacing and inclination angle are obtained through computational fluid dynamics method. The Newton-Raphson iteration method is employed to determine the initial configuration of the bundle conductor and the Runge-Kutta method is applied to carry out nonlinear numerical simulation. Through that, the subspan oscillation response is obtained. Finally, the impact of conductor spacing, inclination angle and spacer arrangement on subspan oscillation are investigated with the FEM simulation.The studies of aeolian vibration and subspan oscillation of bundle conductor have important theoretical significance and economic value. This dissertation provides an effective theoretical basis and reasonable references for the anti-vibration design and further study of the two kinds of wind-induced vibration.更多还原