Non-singular fictitious boundary integral equations for orthotropic elastic plane problems were deduced according to boundary conditions by the techniques of singular-points-outside-domain. Then the unknown fictitious...Non-singular fictitious boundary integral equations for orthotropic elastic plane problems were deduced according to boundary conditions by the techniques of singular-points-outside-domain. Then the unknown fictitious load functions along the fictitious boundary were expressed in terms of basic spline functions, and the boundary-segment-least-squares method was proposed to eliminate the boundary residues obtained. By the above steps, numerical solutions to the integral equations can be achieved. Numerical examples are given to show the accuracy and efficiency of the proposed method.展开更多
In the paper an important issue of vibrations of the transmission line in real conditions was analyzed.Such research was carried out by the authors of this paper taking into account the cross-section of the cable bein...In the paper an important issue of vibrations of the transmission line in real conditions was analyzed.Such research was carried out by the authors of this paper taking into account the cross-section of the cable being in use on the transmission line.Analysis was performed for the modern ACSR high voltage transmission line with span of 213.0 m.The purpose of the investigation was to analyze the vibrations of the power transmission line in the natural environment and compare with the results obtained in the numerical simulations.Analysis was performed for natural and wind excited vibrations.The numerical model was made using the Spectral Element Method.In the spectral model,for various parameters of stiffness,damping and tension force,the system response was checked and compared with the results of the accelerations obtained in the situ measurements.A frequency response functions(FRF)were calculated.The credibility of the model was assessed through a validation process carried out by comparing graphical plots of FRF functions and numerical values expressing differences in acceleration amplitude(MSG),phase angle differences(PSG)and differences in acceleration and phase angle total(CSG)values.Particular attention was paid to the hysteretic damping analysis.Sensitivity of the wave number was performed for changing of the tension force and section area of the cable.The next aspect constituting the purpose of this paper was to present the wide possibilities of modelling and simulation of slender conductors using the Spectral Element Method.The obtained results show very good accuracy in the range of both experimental measurements as well as simulation analysis.The paper emphasizes the ease with which the sensitivity of the conductor and its response to changes in density of spectral mesh division,cable cross-section,tensile strength or material damping can be studied.展开更多
高压直流(high voltage direct current,HVDC)输电线路两端的平波电抗器和直流滤波器构成现实的边界元件,对暂态电压高频分量呈带阻传变特性,来自直流线路区外的高频电压信号通过平波电抗器和直流滤波器后被衰减,其能量显著减小,不同频...高压直流(high voltage direct current,HVDC)输电线路两端的平波电抗器和直流滤波器构成现实的边界元件,对暂态电压高频分量呈带阻传变特性,来自直流线路区外的高频电压信号通过平波电抗器和直流滤波器后被衰减,其能量显著减小,不同频带的高频电压信号小波能量可应用小波变换求得。利用区内、外故障时于保护安装处获得的暂态电压小波能量的显著差异来构造直流输电线路区内、外故障判据;利用故障暂态电压小波变换模极大值,构造启动判据;利用正极和负极暂态电压分别与+800和-800kV的相关系数,构造雷击干扰识别判据;利用两极线极波,构造故障选极判据。给出了特高压直流(ultra high voltage direct current,UHVDC)输电线路单端电气量暂态保护方案。对该保护进行了大量仿真分析,计及了雷击干扰、边界上避雷器动作、不同过渡电阻、换相失败故障等因素的影响。仿真结果表明,该保护具有绝对选择性,能可靠有效地保护直流线路全长。展开更多
文摘Non-singular fictitious boundary integral equations for orthotropic elastic plane problems were deduced according to boundary conditions by the techniques of singular-points-outside-domain. Then the unknown fictitious load functions along the fictitious boundary were expressed in terms of basic spline functions, and the boundary-segment-least-squares method was proposed to eliminate the boundary residues obtained. By the above steps, numerical solutions to the integral equations can be achieved. Numerical examples are given to show the accuracy and efficiency of the proposed method.
文摘In the paper an important issue of vibrations of the transmission line in real conditions was analyzed.Such research was carried out by the authors of this paper taking into account the cross-section of the cable being in use on the transmission line.Analysis was performed for the modern ACSR high voltage transmission line with span of 213.0 m.The purpose of the investigation was to analyze the vibrations of the power transmission line in the natural environment and compare with the results obtained in the numerical simulations.Analysis was performed for natural and wind excited vibrations.The numerical model was made using the Spectral Element Method.In the spectral model,for various parameters of stiffness,damping and tension force,the system response was checked and compared with the results of the accelerations obtained in the situ measurements.A frequency response functions(FRF)were calculated.The credibility of the model was assessed through a validation process carried out by comparing graphical plots of FRF functions and numerical values expressing differences in acceleration amplitude(MSG),phase angle differences(PSG)and differences in acceleration and phase angle total(CSG)values.Particular attention was paid to the hysteretic damping analysis.Sensitivity of the wave number was performed for changing of the tension force and section area of the cable.The next aspect constituting the purpose of this paper was to present the wide possibilities of modelling and simulation of slender conductors using the Spectral Element Method.The obtained results show very good accuracy in the range of both experimental measurements as well as simulation analysis.The paper emphasizes the ease with which the sensitivity of the conductor and its response to changes in density of spectral mesh division,cable cross-section,tensile strength or material damping can be studied.
文摘高压直流(high voltage direct current,HVDC)输电线路两端的平波电抗器和直流滤波器构成现实的边界元件,对暂态电压高频分量呈带阻传变特性,来自直流线路区外的高频电压信号通过平波电抗器和直流滤波器后被衰减,其能量显著减小,不同频带的高频电压信号小波能量可应用小波变换求得。利用区内、外故障时于保护安装处获得的暂态电压小波能量的显著差异来构造直流输电线路区内、外故障判据;利用故障暂态电压小波变换模极大值,构造启动判据;利用正极和负极暂态电压分别与+800和-800kV的相关系数,构造雷击干扰识别判据;利用两极线极波,构造故障选极判据。给出了特高压直流(ultra high voltage direct current,UHVDC)输电线路单端电气量暂态保护方案。对该保护进行了大量仿真分析,计及了雷击干扰、边界上避雷器动作、不同过渡电阻、换相失败故障等因素的影响。仿真结果表明,该保护具有绝对选择性,能可靠有效地保护直流线路全长。
