Adaptive relay co-ordination using a busbar splitting approach for a system integrity protection scheme

Power system faults can often result in excessively high currents. If sustained for a long time, such high currents can damage system equipment. Thus, it is desirable to operate the relays in the minimum possible time. In this paper, a busbar splitting approach is used for adaptive relay setting and co-ordination purposes for a system integrity protection scheme (SIPS). Whenever a fault occurs, the busbar splitting scheme splits a bus to convert a loop into a radial structure. The splitting schemes are chosen such that the net fault current is also reduced. Busbar splitting eliminates the dependency upon minimum breakpoints set (MBPS) and reduces the relay operating time, thus making it adaptive. The proposed methodology is incorporated into the IEEE 14-bus and IEEE 30-bus systems with single and multiple fault conditions. The modeling and simulation carried out in ETAP, and the results of the proposed busbar splitting-based relay co-ordination are compared with the MBPS splitting-based relay co-ordination.     

Design for the Future: Educational Institutions in the Gulf

Despite a distinguished heritage of learning in the Middle East, the expansion of provision for higher education is currently at an unprecedented scale. The Gulf States, in particular, are seeking to keep up with accelerated population growth and a demographic ‘youth bulge’. Guest-Editor Kevin Mitchell describes the architectural approaches employed in the design of institutions in the region from the first universities in Saudi Arabia to Foster + Partners's ground-breaking sustainable design for the Masdar Institute in Abu Dhabi and future projects.     

基于复杂网络聚类的提升机主轴系统故障诊断

针对摩擦提升机主轴系统故障耦合、特征微弱且故障样本不易获得的问题,提出一种基于复杂网络聚类的故障诊断方法。该方法从故障数据表现出社团结构的本质出发,以各数据样本为节点,样本间相似度为有权边,构建加权无向复杂网络模型。将欧氏空间的距离概念推广到样本的相似性度量上提出广义Ward距离,并以此为划分准则,采用凝聚型合并过程实现网络模型中社团的聚类,即故障样本的模式识别。对主轴系统过载、滚动轴承元件故障及减速器齿轮磨损的分析结果表明,该方法能准确对已知故障类型数据进行聚类,且在过程中不预设类别数,为收集异常数据以便未知故障的发现与诊断提供了数据支持。与多元支持向量机与快速Newman算法的对比结果表明,该方法具有更高的识别精度与效率。     

Method to evaluate UV dose of upper-room UVGI system using the concept of ventilation efficiency

Several countermeasures against the prevalence of infectious diseases have recently been issued, and one of them, the ultraviolet germicidal irradiation (UVGI) system, has been carefully considered for building environments especially. Besides experimental methods to evaluate the germicidal performance of upper air UVGI systems, this research introduces two numerical methods using the concept of ventilation performance, and illustrates the methods with a ward model. The first calculates the average residence time of air using the concept of local purging flow rate (L-PFR) which is multiplied by the average UV intensity of the upper area to obtain a UV dose. The other calculates the UV dose with the distributional UV intensity and deals with UV intensities as contaminant sources. The results of the illustrative cases with a ward model show that the method using the L-PFR concept could not clearly identify the difference in UV doses for each case with different exhaust opening setups, although the other could. The results from the method using the distributional UV intensity indicated the layout of ventilation openings and upper-room UVGI systems are important to optimize the germicidal performance.     

Samuel Palmer and the Pastoral Vision

Colin Harrison , Senior Curator of European Art at the Ashmolean Museum in Oxford, describes how the English 19th-century artist Samuel Palmer was deeply influenced by the poet and painter William Blake. Palmer's sublime paintings of the 1820s placed a new emphasis on the harmony of nature, reinterpreting traditional subjects entirely afresh, placing the Holy Family not in the Holy Land, but in the English countryside.     

广东省地区电网外网等值自动生成系统设计

为了使地区电网能量管理系统(EMS)计算准确,需要省级电网调度中心自动计算并发送外网等值信息。为此,设计了便于地区电网应用的外网等值参数自动生成系统框架。该系统实时反映网络拓扑的变化,并与动态等值计算参数相配合,以公用对象请求代理程序结构(CORBA)规范完成数据通信平台,按公用信息模型(CIM)标准完成从SCADA／EMS的模型转化,随时为地区电网实时网络分析提供开放、灵活、方便的外网等值模型,大大减少了地区电网EMS的维护工作量,提高了计算精度。     

基于功率传输转移分布因子的简化电网潮流计算方法

为了减少大型电力系统的潮流计算时间,研究简化电网的潮流计算方法具有重要意义。现有方法将传统Ward等值技术用于电网简化后,简化电网却产生与原始电网不同的潮流结果。针对这种情况,提出了一种改进的简化电网的直流潮流计算方法。在已有研究的基础上,给出了基于功率转移分布因子的直流潮流算法以及使用Ward技术对电网的简化方法。结合上述两部分,给出了基于功率转移分布因子的简化电网潮流计算方法。通过仿真算例表明,所得的结果具有较高的精度,可用于简化大型电网的潮流计算、潮流预报等应用中。     

一种基于SFS方法的含高光表面三维重构系统

针对含高光表面三维形状重构的需求,设计了一种基于从明暗恢复形状(SFS)方法的三维重构系统。在正交投影条件下由CCD相机获取点光源照射下的物体表面图像,使用Ward反射模型描述含高光表面的反射特性,建立物体表面图像辐照度方程。系统软件将该方程转化为包含物体高度信息的H-J偏微分方程,并计算此偏微分方程的解,得到物体的高度函数,进而恢复出物体的表面形状。实验表明,该系统可以有效地重构含高光表面的三维形状。     

The Unified Project

Albert Pope argues that a unified architectural and urban project is not possible without addressing the conceptual divide that exists between building and infrastructure. It is a split that was first set in motion by the breakdown of Modernism in the 1960s and was reaffirmed by the rise of Postmodernism. Since then, architectural form and urban infrastructure have not only remained disjointed, but have been overtly celebrated by the collages and juxtapositions of the contemporary and the historic in our cities.