An Improved On-line Contingency Screening for Power System Transient Stability Assessment

This paper presents a contingency screening method and a framework for its on-line implementation. The proposed method carries out contingency screening and on-line stability assessment with respect to first-swing transient stability. For that purpose, it utilizes the single machine equivalent method and aims at improving the prior developed contingency screening approaches. In order to determine vulnerability of the system with respect to a particular contingency, only one time-domain simulation needs to be performed. An early stop criteria is proposed so that in a majority of the cases the simulation can be terminated after a few hundred milliseconds of simulated system response. The method’s outcome is an assessment of the system’s stability and a classification of each considered contingency. The contingencies are categorized by exploiting parameters of an equivalent one machine infinite bus system. A novel island detection approach, appropriate for an on-line application since it utilizes efficient algorithms from graph theory and enables stability assessment of individual islands, is also introduced. The New England and New York system as well as the large-scale model of the Continental-European interconnected system are used to test the proposed method with respect to assessment accuracy and computation time.     

某超深矿山竖井修复及加固方案的论证分析

某水泥厂矿山竖井发生严重垮塌导致无法使用。通过综合分析对比,并基于二维有限元数值模拟,确定了钢模板+钢筋混凝土衬砌(内模法)+锚杆(土钉封堵法)+锰钢护筒(护筒跟进法)的修复及加固方案。该方案的成功实施验证了其可行性,可作为矿山竖井修复、加固工程中的成功案例。     

大型水轮发电机通风模拟试验台新型测控系统设计与实现

针对大型水轮发电机通风模拟试验要求,设计并提供了一种基于远程控制技术、虚拟仪器技术、PXI技术的先进的、功能完善的测控系统,并在文中论述了该测控系统的设计方案及其实现方法。该测控系统实现了大型水轮发电机通风模拟试验的自动控制与测量,试验结果表明,该系统具有测量与控制精度高、实时性、稳定性高以及抗干扰能力强等优点。     

Bearing behavior and failure mechanism of squeezed branch piles

The current practice for the design of squeezed branch piles is mainly based on the calculated bearing capacity of circular piles. Insufficient considerations of the load-transfer mechanism, branch effect and failure mechanism, as well as overreliance on pile load tests, have led to conservative designs and limited application. This study performs full-scale field load tests on instrumented squeezed branch piles and shows that the shaft force curves have obvious drop steps at the branch position, indicating that the branches can effectively share the pile top load. The effects of branch position, spacing, number and diameter on the pile bearing capacity are analyzed numerically. The numerical results indicate that the squeezed branch piles have two types of failure mechanisms, i.e. individual branch failure mechanism and cylindrical failure mechanism. Further research should focus on the development of the calculation method to determine the bearing capacities of squeezed branch piles considering these two failure mechanisms.     

严寒地区多层住宅体型系数的研究--以内蒙古巴彦淖尔市为例

本文以内蒙古巴彦淖尔市五原县新建项目——鼎盛花园中两栋多层住宅户型为例,通过清华斯维尔软件模拟不同的层高、体量与体型系数的关系,在得出不同条件下体型系数变化的同时,还验证了该项目的节能设计的合理性。     

双排桩及搅拌桩联合支护基坑的应用探讨

以一实际基坑支护工程为研究背景,该基坑工程的支护形式为双排桩结合深层搅拌桩,分析了现场监测资料如基坑变形、桩体变形等.结果表明,这种支护形式能够确保基坑的稳定性.最后以实测数据为依据,运用数值模拟软件对这种支护形式进行模拟实验,分析了深层搅拌桩和双排桩联合支护结构的变形特征和受力机理,并且对深层搅拌桩及双排桩的位置关系进行了探讨.本文的实例分析可以为类似工程提供必要的参考.     

抗震混合试验中预测-校正加载控制方法研究

为使抗震混合试验中电液伺服作动器加载与有限元分析同步进行,国外研究者将预测-校正加载控制方法引入该试验中,但在高频率模态或远离区间左端点处作动器命令信号的精确性不高。为提高该技术的精确性,本文对采样时间间隔内加速度变化规律的假设,以当前步的位移和速度为初始值,对加速度进行二次积分且以五阶精度的一、二阶导数作为速度、加速度,得到预测-校正表达式(PCVA-β),运用绝对误差限判断各种算法的精确性。使用Matlab/Simulink编程仿真模拟,结果表明:在较高阶频率且远离区间左端点处,这种方法不仅精确性较好且作动器能够连续平稳的运行。     

深部基岩地面预注浆模型试验及数值计算分析

依托深部基岩地面预注浆工程,研究了注浆质量控制方法,通过模型试验,对影响注浆的因子进行了试验分析,得出浆液扩散半径和注浆后的结石体抗压强度的影响规律及应用有限元软件分析试验规律的适用条件。     

超高层钢结构转换层施工技术

广州珠江新城J2-2地块项目超高层钢结构转换层施工技术,采取厂内实体卧拼和计算机模拟预拼互验规则;优化后,可直接采用计算机模拟验收。桁架层超重构件吊装、定位、焊接等关键施工工段,采取相应的施工措施,保证施工质量及精度。为超高层钢结构转换层施工积累了宝贵的经验。