共查询到20条相似文献，搜索用时 31 毫秒
1.
Long span ultra-high voltage （UHV） transmission lines have serious aeolian vibration problems. To control these vibrations, we improved the energy balance method in the following aspects： the wind power input, the conductor self-damping, and the damper dissipated power. Meanwhile, we built a theoretical mechanical model of β wire dampers and derived energy dissipation calculation formulae. This permits the vibration energy dissipated by β wire dampers can be considered in the energy balance method. Then, we developed a computer program based on the improved energy balance method using Matlab, and analyzed UHV long span ground wires of the Han River long span project in P. R. China. The results show that the combination of β wire dampers and Stockbridge dampers can reduce vibration of UHV long span transmission lines, which provides a reference for research and construction of UHV engineering projects. 相似文献
2.
张伟丽 《杨凌职业技术学院学报》2014,(4):40-43
基于某220kV羊角输电塔线体系,采用线性滤波法中的自回归（AR）模型,考虑结构节点间的风速时程相关性,利用MATLAB与VISUAL C＋＋语言的混合编程技术,建立了输电塔线体系的三维空间分析模型,并对输电塔线体系的风振反应进行分析。计算结果表明：该方法具有良好的稳定性和计算效率。对于同风向下的单塔和塔线体系而言,塔线体系的风振响应较弱。通过对比分析单塔、塔线体系及两种规范的风振系数差异,说明采用规范计算风振系数值是偏于保守的。 相似文献
3.
Dynamic characteristics analysis of a misaligned rotor-bearing system with squeeze film dampers 总被引：1，自引：0，他引：1
In this paper, a dynamic model is established for a two-stage rotor system connected by a gear coupling and supported on ball bearings with squeeze film dampers (SFDs). The nonlinear dynamic behavior of the rotor system is studied under misalignment fault condition. The meshing force of the gear coupling is calculated considering the deformation of the tooth caused by torque transmission and dynamic vibration. The contact force between the ball and race is computed based on the Hertzian elastic contact deformation theory and the elastohydrodynamic lubrication theory. The supported force of SFD is simulated by integrating the pressure distribution derived from Reynolds’s equation. The equations of motion are rewritten in non-dimensional differential form, and the fourth-order Runge-Kutta method is employed to solve the nonlinear dynamic equilibrium equations iteratively. To verify the validity of the dynamic model and the correctness of the numerical solution method, the experimental power spectra of the rotor system under various misalignment degrees are compared with the analytical results. The effects of several important parameters, such as the lubrication of the ball bearing, the centralizing spring stiffness, the radial clearance of SFD, and the misalignment of gear coupling, on the dynamic characteristics of the rotor system are investigated and discussed mainly focusing on the system stability. The response spectra, bifurcation diagrams, and Pointcaré maps are analyzed accordingly. These parametric analyses are very helpful in the development of a high-speed rotor system and provide a theoretical reference for the vibration control and optimal design of rotating machinery. 相似文献
4.
We investigated wind-induced vibration control of long-span power transmission towers based on a case study of the Jingdongnan-Nanyang-Jingmen 1 000 kV transmission line project in P. R. China. The height of the cup tower is 181 m with a ground elevation of 47 m, which makes it a super flexible and wind-sensitive structure. Therefore, we should analyze the wind- resistant capacity of the system. We simulated applicable transverse fluctuating wind velocity field, developed a lead-rubber damper （LRD） for controlling wind-induced vibration of long-span transmission towers, deduced LRD calculation model parameter, and researched the best layout scheme and installation method of LRD. To calculate the wind-induced response of tower-line coupling system in seven layout schemes, we used the time history analysis method, and obtained the efficiencies of wind-induced vibration control. LRD deformation research proved that the damp of all LRDs was efficient under the designed wind velocity when they were laid along the edge of tower heads. We studied the controlling efficiency resulting fTom only applying stiffness to the tower polos where the dampers used to be laid under the designed wind velocity. The results show that the controlling efficiency was not ideal when the stiffness is increased on the poles only. Therefore, LRD should conlxibute to both the stiffness and damp of a structure to effectively reduce the dynamic response of a tower-line coupling system under strong winds. We also discussed the controlling efficiency of LRD under static winds. The results show that there was little difference between displacements derived by the finite clement time history method and those obtained by static wind method conducted by a design institute. This means the simulation on space relevant wind velocity field was accurate and reasonable. 相似文献
5.
拱型波纹屋盖风荷载数值模拟研究 总被引：1，自引：0，他引：1
基于谐波叠加法的基本原理,结合快速傅立叶变换,利用MATLAB编写了拱型波纹屋盖多点互相关的脉动风速程序.程序运行结果表明,结构各点模拟脉动风速时程的功率谱密度函数与目标函数、风速时程的自相关函数与目标自相关函数较为一致;相邻两点之间距离越近,互相关性越强,反之,则越弱.该研究结果对进一步研究拱型波纹屋盖结构风致振动时域分析具有重要意义. 相似文献
6.
Based on phase-plane orbit analysis, the mathematical model of piecewise-smooth systems of multidegree-of-freedom under the mode coordinate is established. Approximate analytical solution under the physical coordinate of multi-degree-of-freedom self-excited vibration induced by dry friction of piecewise-smooth nonlinear systems is derived by means of average method, the results of which agree with those of the numerical solution. An effective and reliable analytical method investigating piecewise-smooth nonlinear systems of multi-degree-of-freedom has been given. Furthermore, this paper qualitatively analyses the curves about stationary amplitude versus rubbing velocity of hands and versus natural frequency of hands, and about angular frequency versus rubbing velocity of hands. The results provide a theoretical basis for identifying parameters of the system and the analysis of steady region. 相似文献
7.
8.
On maximum power point tracking control strategy for variable speed constant frequency wind power generation 总被引：1，自引：0，他引：1
WU Guo-qing NI Hong-jun WU Guo-xiang ZHOU Jing-ling Zhu Wei-nan MAO Jing-feng CAO Yang 《重庆大学学报(英文版)》2010,9(1):21-28
Based on the characteristic of AC-excited variable speed constant frequency （VSCF） wind power generation, the vector control technique was applied in a doubly fed induction generator （DFIG）. Maximum wind energy or maximum output power point can be tracked by decoupling control of active power and reactive power. The research result shows that the net power of generation system delivered to grid in maximum wind energy tracking mode is not the most. We presented a novel maximum power point tracking （MPPT） control strategy by analyzing the DFIG mathematic model and power relations which delivered the maximum power to the grid. The maximum power point could be tracked automatically without measuring wind speed in the control strategy and the control was independent of optimal turbine power curve, which had excellent dynamic and static performances and robustness. Simulation and experimental results testify the accuracy and validity of the control strategy. 相似文献
9.
WANG Yong HUANG Qi-bai ZHOU Ming-gang XIE Shou-yong 《重庆大学学报(英文版)》2006,5(3):125-130
1 Introduction ? Low frequency vibration has an important effect on body comfort and on the fatigue of a vibrating system. Nearly all actual vibrating systems are nonlinear. However, nonlinear behaviors are not always observed in the system dynamics. Thus… 相似文献
10.
韩小卫 《西安文理学院学报》2008,11(3):49-51
利用多模压缩态理论,对介质中两态叠加多模叠加态光场｜ψ^（α）〉q的不等幂次Nj次方和压缩特性进行了详细的研究．结果发现当各模压缩幂次数之和为偶数时,介质中多模叠加态光场｜ψ^（α）〉q恒处于不等幂次Nj最不测不准态;而当各模压缩幂次数之和为奇数时,多模叠加态光场｜ψ^（α）〉q在一定条件下呈现出周期性变化的Nj次方和压缩效应． 相似文献
11.
方小兵 《五邑大学学报(社会科学版)》1992,(1)
本文采用矩阵传递法分析了调频质量阻尼器(TMD)被动控制高层建筑风振反应,导出了结构顶层位移、加速度和基底剪力频域内统计特征公式。最后通过实例的结果说明,经过控制后能显著地降低风振反应。 相似文献
12.
针对目前煤矿使用的信息传输系统,提出以煤矿井下铺设好的低压电力线作为通讯介质而建立的信息传输系统,通过对通讯技术、电力线特性及煤矿井下特殊环境的分析和研究,采用了基于Lonworks总线技术的电力线载波通信方式,完成了煤矿井下电力线通讯系统的设计和研发,经实际测试实现了载波通讯,为产品的开发奠定了基础。 相似文献
13.
In this study, ground vibrations due to dynamic loadings from trains moving in subway tunnels were investigated using a 2.5D finite element model of an underground tunnel and surrounding soil interactions. In our model, wave propagation in the infinitely extended ground is dealt with using a simple, yet efficient gradually damped artificial boundary. Based on the assumption of invariant geometry and material distribution in the tunnel??s direction, the Fourier transform of the spatial dimension in this direction is applied to represent the waves in terms of the wave-number. Finite element discretization is employed in the cross-section perpendicular to the tunnel direction and the governing equations are solved for every discrete wave-number. The 3D ground responses are calculated from the wave-number expansion by employing the inverse Fourier transform. The accuracy of the proposed analysis method is verified by a semi-analytical solution of a rectangular load moving inside a soil stratum. A case study of subway train induced ground vibration is presented and the dependency of wave attenuation at the ground surface on the vibration frequency of the moving load is discussed. 相似文献
14.
随着建筑形式的多样化以及结构高度、跨度的增大,结构在地震和风等动力荷载作用下的振动问题也日益突出,单纯通过结构设计中增大构件截面或者增强刚度的方法越来越显示出其不合理性,与此同时,智能材料的研究与应用给结构振动控制技术开辟了新的天地,已成为结构工程领域最具有前沿性的发展方向之一。本文根据主动控制力学模型,进行了压电主动杆件位置优化的推导分析,并介绍了优化布置的实现方法,结合一个七层框架结构进行了仿真模拟,可以看到,对结构进行智能控制之后效果显著,并且压电主动杆的控制效果不因输入地震波的不同而不同,同时与结构自身参数有很大关系,通过布置位置的优化,可以实现在布置较少主动杆的同时达到良好控制效果的目标。最后通过一个三层框架结构试验验证了优化方法,较好的实现了主动控制。 相似文献
15.
风能、太阳能作为无污染的绿色能源具有广阔的发展前景,但是其随机性和不稳定性是风光互补发电系统中应尽可能克服的问题。本文介绍了以ATMEGA8单片机为核心组成风机和太阳能发电的功率跟随技术,以最大限度的利用风能和太阳能。 相似文献
16.
Combining lubrication theory and CFD technology, a finite element model is established to simulate the rain-wind-induced vibration (RWIV). Based on Spalart-Allmaras(S-A)turbulence type, COMSOL software is adopted to calculate the wind pressure coefficient and wind friction coefficient that vary with the location and time. To verify the veracity and rationality of this method, the formation and evolution of rivulets at different wind speeds are studied and compared with the existing experimental results. Furthermore, the time, location, height and width of the initial formation of rivulets are analyzed at different wind speeds, cable inclination angles and wind yaw angles. The results show that the three influencing factors mentioned above have great effect on the formation of rivulet, and the influencing tendency, range and degree are different from each other. 相似文献
17.
Hao WANG Tian-you TAO Huai-yu CHENG Ai-qun LI 《浙江大学学报(A卷英文版)》2014,(10):798-812
研究目的：为超大跨度斜拉桥抗风设计与抖振控制提供参考。研究方法：基于ANSYS建立了苏通大桥三维有限元模型,并在MATLAB平台模拟了苏通大桥三维脉动风场。考虑主梁断面气动自激力,进行了苏通大桥抖振时域分析。根据苏通大桥动力特性和抖振时域分析结果,重点分析了多重调谐质量阻尼器（MTMD）用于抖振控制的参数敏感性。考虑MTMD的控制效果、建造费用、施工难度及鲁棒性等因素建立了关于MTMD设计参数的目标函数,并基于一阶优化算法进行目标函数最优解的非线性搜索,据此获得了MTMD在约束条件下的最优设计参数。重要结论：1.苏通大桥侧向抖振位移主要由第一阶侧弯振型控制,竖向抖振位移主要由第一阶竖弯振型控制;2.MTMD的控制效果对设计参数的变化十分敏感,其中质量比和频带宽敏感性更强;3.MTMD的最优设计参数可以通过一阶优化算法获得,并可通过零阶优化算法对优化结果进行验证;4.采用优化后的MTMD设计参数,苏通大桥的抖振响应可以得到明显抑制,且侧向抖振控制效果更加明显。 相似文献
18.
INTRODUCTIONWindenergyofabout2.531011Wavailableeverywhere,especiallyincoastalregions,deserts,grasslandsandcountrysideareasinChina,ispol-lutionfreeandrenewable(Xueetal.,2001).Useofwindenergycanimprovethelivingandworkingconditionsofpeople.Themanyelectricitygen-eratorsdrivenbywindpowerallovertheworldefficientlyextractwindenergyforconversionintoelectricalenergy.Manyregions,suchascountry-sideandruralareashavehighdensityofwindpower,buttheconditionsarenotgoodenoughforestablishingahighelectricpo… 相似文献
19.
建筑物风环境CFD模拟方法综述 总被引：1，自引：0，他引：1
结合通用CFD软件包的特点,介绍了计算机流体力学（CFD）的模拟方法,探讨了各类公式以及参数设置的基本模式,为建筑物环境风数值模拟总结出理论依据。 相似文献
20.
Wind energy is a pollution free and renewable resource widely distributed over China. Aimed at protecting the environment and enlarging application of wind energy, a new approach to application of wind energy by using compressed air power to some extent instead of electricity put forward. This includes: explaining the working principles and characteristics of the wind energy-compressed air power system; discussing the compatibility of wind energy and compressor capacity; presenting the theoretical model and computational simulation of the system. The obtained compressor capacity vs wind power relationship in certain wind velocity range can be helpful in the designing of the wind power-compressed air system. Results of investigations on the application of high-pressure compressed air for pressure reduction led to conclusion that pressure reduction with expander is better than the throttle regulator in energy saving. 相似文献