掏挖式基础受力机理试验研究

掏挖式基础是近年来在我国输电线路建设中广泛采用的一种基础型式, 具有充分利用原状土的承载力、减少开挖量等优点。为进一步研究掏挖基础的工作机理以及抗拔设计中存在的问题, 针对掏挖基础进行了原位真型基础载荷试验, 原位测试各种试验工况下基础的变形性状和承载能力。根据试验结果着重对抗拔计算及地基基础间的作用特性进行了分析, 为掏挖基础在浙江地区输电线路工程中的应用和设计提供依据。     

输电线路铁塔基础选型分析

输电线路铁塔基础部分的施工周期及造价占整个工程的比例较大,介绍国内架空输电线路设计中几种常见基础型式及其适用性,对相同塔型不同基础型式进行技术经济分析,提出直线塔和转角塔优先选用掏挖基础,针对不同影响因素和基础型式的特点,结合工程实际情况,合理选择基础型式的建议。     

750 kV 输电线路戈壁碎石土地基直柱掏挖基础试验

戈壁碎石土地基是我国西北750 kV输电线路建设中的典型地质条件。为了减少开挖回填基础的工程应用,充分利用戈壁碎石土地基的良好胶结性能和抗剪强度,减少工程材料消耗量,提出了戈壁碎石土地基直柱掏挖基础型式。选择3 个典型地质条件完成了12个直柱掏挖基础的现场施工和静载荷试验,给出了相应的设计方法和计算参数。结果表明：戈壁碎石土地基中应用的直柱掏挖基础具有良好的抗拔承载性能,其施工安全性高,经济环保,能够满足750 kV输电线路杆塔基础荷载要求,可以在该地区750 kV输电线路铁塔基础中使用。     

掏挖基础机械成孔设计研究及在向上线工程中的应用

结合向家坝—上海±800 kV特高压直流输电线路工程基础设计特点,开发研制了输电铁塔掏挖基础机械成孔的旋挖钻机专用设备,并选择具有典型地质条件的BN157和BN162塔位进行了现场基础真型试验和工程应用。通过与人工掏挖基础相比较,掏挖基础机械成孔设备避免了人工掏挖基础的安全风险,具有较好的经济效益和社会效益,值得在输电线路工程基础施工中推广应用。     

输电线路典型基础机械化施工设计技术探讨及经济分析

正输电线路基础一般为大开挖板式基础、原状土掏挖基础及桩基础等,长期以来,基础施工主要以人力为主,施工作业人员安全风险较大,人力成本亦逐年增加。随着电网发展及工业技术的进步,输电线路基础机械化施工要求日益迫切。本文结合工程实例,探讨适合输电线路基础机械化施工的设计技术要点,并与常规基础型式进行技术对比及经济分析,为输电线路基础机械化设计和施工提供借鉴。     

新型斜柱挖孔桩基础竖向抗压及水平承载力试验研究

斜柱挖孔桩基础在国外线路工程中已有应用,在国内仍是一种新的基础结构型式。通过对斜柱挖孔桩基础进行真型试验,采用模拟送电线路直线塔受压时实际工作条件的试验方法,验证了桩基础竖向抗压及水平承载力的设计理论、方法以及设计参数取值的合理性、可靠性。试验结果表明：该基础型式在设计荷载范围内,结构是稳定、安全的。     

750kV交流输电线路工程承压水地区基础选型及施工方法研究

目前,越来越多的输电线路需要途经承压水地区,而承压水对输电线路塔基工程的设计及施工有重要影响。以新疆地区750 kV交流超高压输电线路悬垂塔的基础设计为例,对其基础选型和施工方法进行了对比论证,推荐了承压水地区输电线路的基础型式和施工方法,为承压水地区输电线路的基础设计和施工提供了一定参考。     

斜插式挖孔桩基础的三维仿真分析

斜插式挖孔桩基础是近年来开发的输电线路中新型基础型式,方形斜柱与圆形挖孔桩相连处是这种结构的设计关键。这里以某工程的斜插式挖孔桩基础的设计为实例,用大型有限元软件ANSYS进行三维仿真分析,得到的截面变刚度处的位移和应力分布,符合理论分析和实际情况,可作为今后设计和工程实践参考。     

浅谈掏挖式基础在输电线路上的运用

提出了一种新的输电线路基础型式－掏挖式基础,讨论了该基础型式的受力特点,并与传统的板式基础和阶梯式基础比较,得出：基于广东省的地质条件,掏挖式基础适于广东省大多数输电线路的塔基,工结构合理,可减少基础土石方开挖工程量,节省钢筋和混凝土的,降低工程造价。广东省５００ｋＶ蓄增Ⅱ输电线路的部分塔基首次采用了掏挖式基础,线路已投运一年多,运行稳定。     

新疆戈壁地区输电线路铁塔掏挖基础的设计与应用

戈壁碎石土是一种特殊土体,为充分发挥其工程力学特性,输电线路基础工程在该类地区通常采用掏挖基础形式。针对新疆戈壁土地区铁塔掏挖基础的选型和设计问题,根据掏挖基础和戈壁碎石土地基的特点,分析了多个碎石土场地掏挖基础的载荷试验结果,研究了该基础在新疆戈壁地区的适用性,提出了基础稳定性的分析方法及设计条件,并在新疆地区依托工程中进行了设计应用,取得了良好的经济和社会效益。     

Safety practices in electrolytic cell line working zones: 1994changes

In 1974 the Electrical Cell Line Working Group of the Chemical Industry Committee prepared a trial-use standard for Electrical Safety Practices in Electrolytic Cell Line Working Zones. Comments on the trial-use standard were incorporated into a full-status standard and published as IEEE Std 463-1977, IEEE Standard for Electrical Safety Practices in Electrolytic Cell Line Working Zones. IEEE Std 463-1977 was reaffirmed in 1987. IEEE Std 463 was used as a source document for Article 668, Electrolytic Cells, of the National Electrical Code (ANSI/NFPA 70); Part 1, Chapter 4H, Specific Purpose Equipment and Installations-Electrolytic Cells of the Standard for Electrical Safety Requirements for Employee Work Places (NFPA 70B-1988); and OSHA 1910.306(h), Electrolytic Cells. In 1991 a working group was formed to review and update IEEE Std 463. The purpose of this article is to describe the current update to IEEE Std 463. The current application of IEEE Std 463 in relation to NFPA 70; NFPA 70E, Parts 1 and 2; and OSHA 1910 Subpart S-Electrical are discussed     

美国《变电站抗震设计推荐规程》评介

简要介绍了美国《变电站抗震设计推荐规程》(IEEE Std693-2005)的基本情况,详细讨论了变电站电气设备抗震性能标准,并与我国《电力设施抗震设计规范》进行了比较。介绍了IEEE Std693-2005规范对变电站电气设备振动台试验输入时程的规定,并给出了满足IEEE Std693-2005要求的推荐输入时程。以断路器为例,简要介绍IEEE Std693-2005抗震性能的评定方法和评定步骤。结合我国情况,提出了建立变电站电气设备抗震性能检测标准的建议。     

故障录波仪在核电站应急柴油机上的在线监测

根据美国电子电气工程师协会标准IEEE 387- 1995中的规定 ,核用柴油发电机启动成功率要求 >99% ,运行故障率 <6 0× 10 - 3,为了保证柴油发电机运行的可靠性与稳定性 ,除了在设备建造、安装、调试阶段严格遵守质量保证大纲与质量控制程序外 ,在运行阶段引入切实可靠的探测及判断故障的手段与措施也是非常重要的。这样一旦发生故障 ,便可及时排除。而故障录波仪以其探测故障及时、测量精度高、判断故障点准确、处理速度快、存储数据容量大等特点被广泛用在柴油发电机组上进行在线监测、故障诊断及数据处理     

超高压发电机短路特性和参数计算

超高压发电机是一种不需要升压变压器可直接与电网相连的结构全新的发电机。本文采用场路耦合时步有限元方法对超高压发电机的对称和非对称空载短路瞬态过程进行仿真分析。给出超高压发电机三相短路和两相短路时电枢电流的最大值。根据IEEE-115-2002标准,由空载三相和两相突然短路的电枢电流曲线计算了瞬变电抗、超瞬变电抗和时间常数及负序电抗。     

大容量发电机出口断路器选择

针对大容量发电机出口断路器的选择问题,依据GB/T 14824-2008、IEEE Std C37.013-1997和IEC 60909-0-2001中的计算方法,并结合发电机出口断路器型式试验报告的有关数据,以某百万千瓦级发电机组为例进行了比较计算,分析计算结果,提出了对发电机出口短路器短路电流开断能力不能采用百分比...     

Determination of IPFC operating constraints in power flow analysis

In recent years, the Flexible AC Transmission System (FACTS) controllers have been widely used to enhance the controllability, security and flexibility in power transmission networks. Interline power flow controller (IPFC) is a versatile member of FACTS devices that can be used to control the power flow in multiple lines in network. Modeling of IPFC with handling its operating constraints is an important issue to determine the practical capabilities of this device. This paper presents a simple modeling with strategies for handling all operating constrains of IPFC in Newton–Raphson (NR) load flow algorithm. The various operating constraints such as; the injected series voltages, injected line currents passing through the converters and exchanged powers among the series converters are investigated. The developed IPFC model with these constraints is validated using standard IEEE 30-bus and IEEE 118-bus test systems.     

光纤复合相线的架设和接续

光纤复合相线(OPPC)的架设基本上同OPGW类似,也是依据IEEE Std 1138-1994、IEEEStd 524-1992等电力部门架空线安装安全管理规程和操作技术,但OPPC的接续涉及到光纤接续和光电分离技术,对接续的技术、高压绝缘有严格要求。文章简单介绍了OPPC的结构、主要技术参数、架设和预绞丝电力金具的配置,重点介绍了OPPC独特的接头盒和接续技术。     

A comparison between different windows in spectral and cross spectral analysis techniques with Kalman filtering for estimating power quality indices

Fourier based methods are still popular for calculating power quality indices (PQIs) in the technical community such as IEC and IEEE. They are robust towards noise and can be calculated efficiently using the fast Fourier transform (FFT) method. IEEE Std 1459-2010 provides formulations for calculating important PQI for single and three phase systems. The aim of this paper is to present the theory for estimating PQIs using the Welch spectral and cross spectral analysis techniques, and show experimentally the accuracy of the proposed methods when calculating the PQIs. Further it provides a comparison on the windowing techniques (WTs) that accompany the PQI estimations when using FFT based methods. This information has not been documented extensively in the technical literature when trying to calculate the PQI as specified by IEEE Std 1459-2010. Further we present a virtual instrument (VI) with a Kalman filter (KF) to estimate the PQIs. The KF is used to reduce the variance in measurements for the PQI estimation. We also compare experimentally the accuracy of the VI without the KF with the VI using the KF. Specifically we propose good and bad WTs to estimate such PQIs.     

Non-fundamental effective apparent power defined through an instantaneous power approach

This paper proposes a new definition of non-fundamental effective apparent power based on an analysis of instantaneous power flows. This new instantaneous power approach for the calculation of the non-fundamental effective apparent power extends, and adapts for new electrical conditions, the procedure applied by IEEE Std. 1459 for the quantification of active and reactive power in single-phase systems.This proposed approach is based on the analysis of per-phase and three-phase instantaneous power flows when a three-phase four-wire balanced non-linear load is connected to an ideal power network that supplies a set of positive-sequence fundamental voltages. The per-phase and three-phase instantaneous power flows caused by positive-, negative-, and zero-sequence harmonic load currents are analyzed. The results obtained for the load zero-sequence harmonic currents disagree with the results obtained when applying IEEE Std. 1459. As a consequence, a new definition of the effective quantities is proposed. A comparison between the new definitions and IEEE Std. 1459 definitions is made in the paper.     

IEEE 841- 1994 versus IEEE 841 - 2001

IEEE 841 has been widely accepted throughout various process industries as a simple way to specify and purchase a reliable energy-efficient severe-duty motor off the shelf. During the next standard revision cycle, IEEE 841 should be made more user-friendly and provide more consistency between suppliers, as the specification was originally intended. This article will discuss the basic differences between IEEE 841-1994 and IEEE 841-2001 revisions. The features added to the 2001 revision were intended to improve motor reliability and life.