同步发电机三阻抗元件失步保护原理的改进

对目前现场广泛应用的同步发电机三阻抗元件失步保护原理进行了分析和评价 ,在此基础上提出了具有多重启动元件、可根据频率变化量自动调节失步保护与预测启动角、并利用最小二乘法预测功角变化轨迹的改进方案。改进后的失步保护方案能够区分故障、静稳破坏以及动稳失步等情况 ,并实现发电机的失步预测功能 ,提高了失步保护的性能。对振荡中心在发电机 -变压器组外部与内部等情况进行了发电机失步预测试验 ,试验结果验证了改进方案的正确性与可行性。     

利用局部量进行多机系统失步快速预测原理的探讨

本文研究多机电力系统遭受大扰动后系统首次摇摆暂态不稳定性的在线实时预测方法.导出了使用局部状态量的多机系统失步快速预测判椐及一系列计算公式,给出了失步预测与控制系统的初步构成方案.经多种故障条件下模拟计算,结果表明失步预测装置给出的稳定边界与使用全部状态量离线计算所得稳定边界相当吻合.     

轨迹凸凹性判据在不健全广域信息条件下的可靠性研究

基于局部惯性中心轨迹的几何特征，提出了一种识别系统暂态不稳定性的判据以及相应的多机系统暂态不稳定性识别方案，并在系统局部惯性中心参考坐标下基于广义势能函数推导了判据的离散表达形式．该方案摆脱了因求取全局惯性中心导致的不稳定性识别方法在实际应用时的限制，能够准确地识别出系统中具有局部广域信息条件区域内的不稳定性．IEEE50机145节点系统仿真结果表明：当失步机组具有观测条件时，使用该判据仍然能够正确判别出系统的稳定性，全系统轨迹信息的不健全程度只会导致不稳定性识别时间的不同，相对于传统时域仿真方法，该方法能够提前0．3～1S识别出系统失稳．     

变电站电压稳定性的实用判据

给出了基于变电站实时信息和电网准实时信息的电压稳定性实用判据。利用该判据能有效地预测节点电压稳定裕度，并用ＩＥＥＥ－１４节点系统对判据进行了验证。     

一种寻找正确相关不稳定平衡点的基准方法

在电力系统暂态稳定性分析的能量函数方法中，求解正确的相关不稳定平衡点是这类方法中十分关键的一步。为此，提出一种方法作为评价不同Ｃｏｎｒｔｒｏｌｌｉｎｇ ＵＥＰ求解方法可靠性的工具，可在能量函数方法的发展过程中发挥作用。     

基于振荡能量的失步振荡中心定位

失步解列在保护电力系统的稳定运行方面发挥着重要作用。然而,如果缺少失步振荡中心的位置信息,失步解列策略将无法得到有效实施。由于传统失步解列判据不能有效定位失步振荡中心,从振荡能量的角度阐释电力系统失步振荡过程,并创新性地提出了一个基于振荡能量的失步振荡中心定位方法。仿真算例验证了所提方法的有效性。     

基于振荡能量的失步振荡中心定位研究

失步解列在保护电力系统的稳定运行方面发挥着重要作用。然而,如果缺少失步振荡中心的位置信息,失步解列策略将无法得到有效实施。由于传统失步解列判据不能有效定位失步振荡中心,本文从振荡能量的角度阐释电力系统失步振荡过程,并创新性地提出了一个基于振荡能量的失步振荡中心定位方法。仿真算例验证了所提方法的有效性。     

基于实测响应轨迹稳定边界的电力系统暂态不稳定识别

为充分利用广域测量系统WAMS(wide area measurement system)信息实现电力系统暂态稳定性快速在线识别,提出一种基于实测响应轨迹稳定边界的暂态不稳定识别方法.根据单机"位能脊"推导了单机-无穷大系统在相平面上的暂态稳定边界;证明单机无穷大系统任意比例剖分点处,由扰动能与电压相角构成的平面上的轨迹与相平面轨迹具有相似的几何特征,为间接利用发电机端口外网络测量信息识别电力系统暂态不稳定性提供了依据;证明了临界机组对的相轨迹上二阶导数等于零的点构成了系统的不返回边界,提出用临界机组对的相轨迹几何特征来识别系统暂态稳定性.为避免判据在线应用时受参数及不确定性干扰可能造成误判,对判据进行了实用性改进.利用PSASP 6.28 WEPRI 36节点仿真算例验证了所提判据的有效性.     

中国供给侧结构性改革的宏观经济含义

为充分利用广域测量系统WAMS（wide area measurement system）信息实现电力系统暂态稳定性快速在线识别,提出一种基于实测响应轨迹稳定边界的暂态不稳定识别方法.根据单机"位能脊"推导了单机-无穷大系统在相平面上的暂态稳定边界;证明单机无穷大系统任意比例剖分点处,由扰动能与电压相角构成的平面上的轨迹与相平面轨迹具有相似的几何特征,为间接利用发电机端口外网络测量信息识别电力系统暂态不稳定性提供了依据;证明了临界机组对的相轨迹上二阶导数等于零的点构成了系统的不返回边界,提出用临界机组对的相轨迹几何特征来识别系统暂态稳定性.为避免判据在线应用时受参数及不确定性干扰可能造成误判,对判据进行了实用性改进.利用PSASP 6.28 WEPRI 36节点仿真算例验证了所提判据的有效性.     

发电机临界失步电势与有功功率的关系分析及其在失磁保护中的应用

本文主要分析和论证了以静态稳定极限为主要判据(定子判据)和转子低电压闭锁(转子判据)构成的低励磁失步保护的准确的整定计算方法。在对转子判据的分析中,着重论证了水轮发电机以不同的有功功率失磁达临界失步时的同步电势极限值E_(di)的计算公式;利用该公式,提出了转子低电压继电器新的动作条件,作为研制新的转子判据电路继电器的理论基础,从而进一步完善现有失磁保护的性能。     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.