软导线互连电气设备回路抗震试验研究

复合材料电气设备由于其材料质轻高强、绝缘性能好的特点,在电网工程中得到了推广应用。为研究特高压复合材料电气设备在软导线连接回路中的抗震性能,采用地震模拟振动台试验,研究5种不同软导线冗余长度的回路系统,在不同地震波波形、加速度峰值和激振力方向影响下设备的加速度和应力变化趋势。试验结果表明:互连回路中在导线连接方向上,刚度大的设备频率降低、刚度小的设备频率增大;地震作用下回路中两设备最大应力均出现在底部绝缘子根部,应力响应基本与加速度峰值呈线性变化关系,竖向地震组合的地震影响系数可按1.40考虑;回路导线冗余长度变化,对小震中设备地震响应影响较大。试验得到的软导线连接回路在地震作用下的响应规律,可为变电站或换流站回路系统抗震设计提供借鉴和参考。     

加载频率对铅合金减震器动力特性的影响

铅合金减震器是一种适用于电瓷型电气设备的新型减震器,其动力特性对减震效果有重要影响.根据断路器等电气设备的特点,定制了相应的铅合金减震器.通过铅合金减震器滞回特性试验,研究了加载频率对其动力特性的影响.同时以不同加载频率下得到的骨架曲线作为材料的本构关系,研究了加载频率对单自由度体系弹塑性地震反应的影响.研究表明:在相同输入下,采用不同本构关系的单自由度体系,其相对位移峰值、永久位移及塑性耗能均有较大差异,应重视加载频率对铅合金减震器动力特性的影响.     

基于MRTMD的瓷柱型电气设备减震技术研究

瓷柱型电气设备由于结构高耸、阻尼小等特点在地震中极易发生破坏。现有瓷柱型电气设备的加固措施均不能充分保证该类设备在地震发生时的安全运行。本文基于调谐质量阻尼器原理,结合瓷柱型电气设备中心对称的结构特点,提出了多重环式调谐质量阻尼器(MRTMD)的概念并设计了相应的三重调谐质量阻尼器减震装置,推导了对应的减震方程。文中以2个不同型号的电压互感器为例,通过有限元模拟,对比了该设备有控和无控时的动力响应。此外,考虑到导线及裹冰荷载的影响,本文研究了MRTMD控制频率偏移最佳控制频率时的减震效果。结果表明:MRTMD可以明显增强瓷柱型电气设备的抗震性能,实现任意方向的地震动减震;MRTMD对于不同类型的地震动均具有良好的鲁棒性;当控制频率发生50%偏移时,MRTMD仍然可以保持稳定的减震效果。     

不同垂度导线连接变电站实体耦联设备振动台试验研究

为了对地震作用下柔性导线连接的变电站电气设备间的相互作用进行研究,本文进行了不同垂度下柔性双分裂导线连接实体隔离开关和断路器的地震模拟振动台试验.振动台试验中采用无导线连接的单体设备以及三种不同松弛度导线连接设备体系,在不同强度的三种地震动输入下对耦联体系的动力响应进行了试验研究.试验结果表明:导线的存在使得耦联设备间...     

立式储罐与地基相互作用地震反应分析

在考虑地基与储罐相互作用的情况下,采用有限元法对储罐住水平地震荷载作用下的反应进行了计算。推导了系统刚度矩阵及质量矩阵的计算过程。通过对四种场地条件下的地震响应分析,得出了储罐各种参数对地震反应的影响。分析表明：不同的地震激励对储罐系统的反应是不同的;地基刚度对系统的动力响应的影响也很大：即地基越“柔”,基底弯矩、罐壁轴向应力越小,但环向应力和底板变形却在增加。     

特高压输电线路塔线耦联体系非线性振动响应振动台试验研究

为了研究地震作用下特高压塔线耦联体系导线、地线的非线性振动响应,文中以单向和双向一致激励为主,通过输入不同加速度幅值的El Centro波、Taft波、Pasadena波及上海人工波,对某型特高压输电塔线耦联体系进行了缩尺模型振动台试验.试验主要分2种工况:将导线作为集中质量进行计算的方法以及挂有实际分裂导线模型的方法.试验结果表明:两种体系中塔体结构动力特性存在差别;地震作用下,挂线单塔各项动力反应峰值比相应的单塔悬挂集中质量有不同程度的降低,8度罕遇地震时较为显著,导线的非线性振动效应有利于该型输电塔动力反应幅值的降低.挂线单塔与挂集中质量单塔不同方向的加速度能量谱分布规律存在较大差异.     

复合外套型特高压交流CVT抗震与减震试验研究

为研究复合外套型电气设备的抗震性能与安装减震装置后的减震效果,对其进行特高压交流CVT地震模拟振动台试验研究,分析设备的动力特性与地震响应。白噪声试验结果表明试验设备安装减震器后其结构第一阶频率由1.07Hz略降低至1.04Hz,即减震装置对结构的整体刚度影响较小;人工波试验中原结构在地震动峰值加速度0.2g(PAG=0.2g)抗震试验中设备最大应力与位移响应为46.33 MPa与349.12mm,减震结构在PAG=0.5g抗震试验中,设备最大应力与位移响应为27.64 MPa与330.06mm,设备安装减震装置后抗震性能得到显著提升。试验研究结果可为复合材料电气设备抗震性能研究与减震装置应用提供参数数据。     

隧道-土-隧道轴向动力相互作用的一个解析解

本文采用波函数展开法给出弹性半空间中隧道-土-隧道轴向动力相互作用的一个解析解,并通过对地表位移残差的收敛性分析对解析解的精度进行了验证。研究了隧道埋深、隧道质量、隧道间距、波入射频率和入射角度等参数对隧道轴向动力响应的影响。研究表明,隧道埋深越小,隧道动力响应越大;隧道质量越大,隧道动力响应越大;隧道间距越小,隧道动力响应越大,但隧道间距的影响并不是单调变化,与波入射频率密切相关,两个隧道情况动力响应幅值可达单隧道情况的2.7倍。当隧道间距较小时,地下隧道的抗震设计需要考虑隧道之间的影响。     

地震作用下附建式变电站电气设备动力响应

附建式变电站通常会对电气设备采取隔振措施以减小设备振动及噪声通过结构传播扰民。然而,目前常用的隔振装置系统的自振频率通常位于2～10 Hz之间,与地震动卓越频率相近。因此,这类隔振装置在地震发生时,往往无法发挥隔震效果,反而可能会放大地震的作用,导致采用了隔振措施的电气设备更容易受到损坏。通过有限元模拟的方法,旨在研究不同周期类型的地震动激励下,采用常规隔振方案的电气设备的动力响应。结果表明,采用普通隔振装置后,电气设备所受的竖向地震作用响应相较楼板处有不同程度的放大。这一发现对电气设备的抗震设计提出了重要的警示,需要更加谨慎地考虑隔振装置的选用,以确保设备在地震发生时能够有效地减小振动,降低损坏风险。     

电流互感器抗震性能及减震振动台试验

瓷柱型电气设备是电力系统的重要组成部分,其抗震能力较差,在历次强震中破坏严重。根据地震中电流互感器的实际破坏情况,选用了2个不同型号的电流互感器,进行了地震模拟振动台试验,试验中测试了瓷柱型电气设备在不同地震动作用下的加速度、位移及应变响应,分析了该类设备的动力特性及抗震性能。基于调谐质量阻尼器原理设计了减震装置并进行了振动台试验。结果表明:地震作用时瓷柱型电气设备反应放大明显,抗震能力较差,绝缘子根部属于该类设备的薄弱环节,220kV电流互感器在峰值0.5g的正弦拍振作用时绝缘子根部拉裂和漏油。减震装置有效,可以降低瓷柱型电气设备的动力响应。     

Response evaluation of interconnected electrical substation equipment using real‐time hybrid simulation on multiple shaking tables

In an attempt to quantify the conductor cable effect on substation electrical equipment, real‐time hybrid simulation (RTHS) is conducted on interconnected equipment using two shaking tables. For this purpose, the existing RTHS system with advanced control capabilities at the Pacific Earthquake Engineering Research Center structural laboratory is enhanced to accommodate the simultaneous use of two shaking tables. An experimental parametric study is conducted to investigate the conductor cable effect using this system with a two‐table RTHS setup. Post insulators of disconnect switches, important components of substations that are usually tested with conventional methods for evaluating their seismic performance, are utilized as experimental substructures for realistic representation of the electrical equipment. Various global and local response parameters, including accelerations, forces, displacements, and strains, are considered to evaluate the effect of the tested conductor cable configuration for a wide range of support structure configurations, which are modeled in the computer as analytical substructures. The experimental parametric study results indicate that the conductor cable has a significant effect on the response of the interconnected equipment over the whole range of investigated support structures and needs to be explicitly considered for seismic testing of electrical equipment. Copyright © 2016 John Wiley & Sons, Ltd.     

Seismic interaction in linearly connected electrical substation equipment

An electrical substation consists of a complex set of equipment items that are interconnected through conductor buses or cables. If the connections are not sufficiently flexible, significant dynamic interaction may occur between the connected equipment items during a seismic excitation. This interaction is believed to be responsible for some of the observed substation equipment damage in recent earthquakes. This paper investigates the interaction between two equipment items connected by a linear spring‐dashpot or spring‐dashpot‐mass element representing a conductor bus. It is found that the interaction between the two equipment items may significantly amplify the response of the higher‐frequency equipment item. The influences of various key parameters on the interaction effect are quantified. Means for reducing the adverse interaction effect are described. Copyright © 2001 John Wiley & Sons, Ltd.     

二维地质体的瞬变电磁场响应特征

直接从时间域出发 ,应用时域有限差分方法 (FDTD)分析地下和地面的瞬变响应。由于二维情况便于图形表示 ,采取了线源二维地电模型。通过对二层均匀地电结构和含二维低阻体时地面垂直感生电动势曲线的计算 ,说明瞬变场响应有滞后现象 ,即异常地质体一旦引起瞬变响应 ,就会往后延时 ,并使响应延续较长时间。在实际的工程勘察中 ,曾用 3～ 5ms以后的延迟时间探测过较浅的异常体 ,如 2 0m至 150m深度范围内的地下老窑采空区 ,并取得了较好的探测效果 ,上述数字模拟结果为以往的实践提供了理论依据     

Electrical properties and geochemistry of carbonate rocks from the Qasr El‐Sagha Formation,El‐Faiyum,Egypt

Understanding petrographical, geochemical and electrical properties of rocks is essential for investigating minerals. This paper presents a study of the petrographical, geochemical and A.C. electrical properties of carbonate rock samples. The samples collected show six lithostratigraphic rock units. Electrical properties were measured using a non‐polarizing electrode at room temperature (～20°C) and a relative atmospheric humidity of ～50% by weight in the frequency range from 42 Hz to 5 MHz. The difference in electrical properties between the samples was attributed to the change in composition and texture between the samples. Electrical properties generally change with many factors (grain size, chemical composition, grain shape and facies). The dielectric constant decreases with frequency and increases with conductor composition. The conductivity increases with the increase of conductor paths between electrodes. Many parameters can contribute to the same result of the electrical properties. The main objective of the present study is to shed more light on the relation between the texture and geochemical composition of measured samples (carbonates that contain clays and quartz grains) through electrical laboratory measurements (conductivity and dielectric constant as a function of frequency).     

Analysis of the earth resistivity response of buried cables

Current flow in homogeneous and layered conducting media is analyzed for the case where an axial conductor or cable is present. The cable is characterized by a specified axial impedance and is assumed to be infinite in length. Various configurations are chosen such as a current point source in an infinite, semi-infinite, and layered region where the cable is taken parallel to the interface(s). The resulting formulas for the potentials reduce to known cases in the absence of the cable. Using these formulations, we present some concrete calculated examples that are relevant to resistivity probing of perturbed homogeneous and layered structures. Only the two-electrode array is treated, but various cable orientations are considered. In general, it is found that a long axial conductor such as a bare cable will distort the potential distribution of the current in a major way. This leads to profound departures from the apparent resistivity curves calculated for idealized homogeneous and layered structures.U.S. Government Work not subject to U.S. copyright.     

勘查天然气水合物资源的海洋可控源电磁发射系统

海洋可控源电磁探测(MCSEM)是勘查天然气水合物资源的有效方法之一.海洋可控源电磁发射系统是实现MCSEM的重要硬件组成部分.本文以天然气水合物在海底的一维地电模型为例,研究电偶源发射频率、发射偶极侧向漂移、源偶极矩大小对电场响应的影响,进而指导发射系统研制.该系统包括:甲板升压控制单元,可将船载大功率电能升为高压并通过万米光电复合缆输送至海底的发射机;水下变压器,可将深拖缆中的大功率高压转换为低压;拖曳式大功率电磁发射机,其内部的控制电路硬件和嵌入式驱动软件可将水下变压器输出的电能逆变为大功率矩形脉冲,并通过发射偶极将脉冲发送至海水介质中;借助水动力学设计的发射机拖体,用于装载发射系统水下部件和保持拖曳过程中的平衡与稳定;甲板端上位机监控单元,利用万米光电复合缆中的光纤实现船上计算机与海底发射机的远程数据通信.2012年5月和2013年5月海洋试验的结果均表明,所研制的发射系统可作为天然气水合物资源勘探的有效激励场源.     

Frequency dependent electrical properties of minerals and partial-melts

The resistance to current flow of minerals and partial-melts is a frequency dependent electrical property. Measurements of the frequency dependent electrical impedance of single crystal olivine, polycrystalline olivine, dunites, metapelites, and partial-melts, between 10^–4 and 10⁵ Hz, when plotted in the complex impedance plane, reveal arcs that correspond to different conduction mechanisms in the material being studied. In polycrystalline materials, two impedance arcs related to material properties (as opposed to electrode properties or electrode-sample interactions) are observed. Each impedance arc is activated over a distinct range of frequency, that is, the mechanisms occur in series. Based on experiments comparing single and polycrystalline impedance spectra, experiments on samples with different electrode configurations, and on samples of varying dimension, the mechanisms responsible for these impedance arcs are interpreted as grain interior conduction ( _gi ), grain boundary conduction (in polycrystalline materials; _gb ), and sample-electrode interface effects, from highest to lowest frequency, respectively. Impedance spectra of natural dunitic rocks reveal analogous behavior, that is, _gb and _gi add in series. The grain boundaries do not enhance the conductivity of any of the materials studied (a direct result of the observed series electrical behavior) and, under certain conditions, limit the total conductivity of the grain interior-grain boundary system. By examining the frequency dependence of the electrical properties of partial-melts, it is possible to gain information about microstructure and the distribution of the melt phase and to determine the conditions under which the presence of melt enhances the total conductivity. Impedance spectra of olivine-basalt partial-melts indicate that at least two conduction mechanisms occur in series over the frequency range 10^–4-10⁵ Hz, similar to the observed electrical response of melt-absent polycrystalline materials. In a sample containing isolated melt pockets the intermediate frequency grain boundary impedance arc is modified by the presence of melt indicating series conduction behavior. In a sample with an interconnected melt phase the high frequency grain interior impedance arc is modified by the melt phase, indicating the initiation of parallel conduction behavior. Because field EM response versus frequency curves are used to derive conductivity versus depth profiles, it is important to perform laboratory experiments to understand the frequency-dependent electrical behavior of Earth materials. Activation energies determined from studies that measure conductivity at a single frequency may be erroneous because of the shift of the dominant conduction mechanism with frequency as temperature is varied.     

Modeling of cable vibration effects of cable-stayed bridges

The analysis of dynamic responses of cable-stayed bridges subjected to wind and earthquake loads generally considers only the motions of the bridge deck and pylons. The influence of the stay cable vibration on the responses of the bridge is either ignored or considered by approximate procedures. The transverse vibration of the stay cables, which can be significant in some cases, are usually neglected in previous research. In the present study, a new three-node cable element has been developed to model the transverse motions of the cables. The interactions between the cable behavior and the other parts of the bridge superstructure are considered by the concept of dynamic stiffness. The nonlinear effect of the cable caused by its self-weight is included in the formulation. Numerical examples are presented to demonstrate the accuracy and efficiency of the proposed model. The impact of cable vibration behavior on the dynamic characteristics of cable-stayed bridges is discussed. Supported by: Natural Science and Engineering Research Council of Canada     

Nonlinear finite element analysis of three‐dimensional free and harmonically forced vibrations of stranded conductor cables

The 3D finite deformation beam model originally developed by Simo is appropriately modified to derive a finite element formulation for the static and dynamic analysis of flexible electrical conductors. In contrast to what is currently carried out in the literature, a linear viscoelastic constitutive equation and an additional mass proportional damping mechanism are introduced to account for energy dissipation in a physically consistent way. The model is used for simulation of free and forced vibration tests performed on an actual electrical conductor. Energy balance calculations illustrate the reliability of the computations. The experiments reveal amplitude dependence of both stiffness and damping, pointing out the presence of material nonlinearity in the cable. The development of numerical models that can account for the amplitude dependence of bending stiffness and energy dissipation capacity is subject of current computational and experimental work. Copyright © 2014 John Wiley & Sons, Ltd.