变压器新差动保护技术研究

变压器保护主要有瓦斯保护和纵联差动保护,纵差动是变压器必须采用的保护原理。可以反映变压器的各种内部相间和接地故障。文章提出了一种不受空投时励磁涌流影响的新方法,用阻抗继电器反应空投于内部故障．这种保护配置方式在内部故障时有很高的灵敏度,在外部故障时又有很强的制动作用,不反映空投时的励磁涌流．却能反映变压器空载合闸时有故障的情况．解决了变压器差动保护的难题。     

升压变压器低阻抗保护的原理及测试方法

升压变低阻抗保护主要作为发电机—变压器组相间短路的后备保护,逻辑判据中包含相间阻抗、相电流及负序电流三个变量参数,在测试过程中有一定的难度。通过对国电南京自动化股份有限公司生产的GDGT801型数字式发变组保护A柜变压器低阻抗保护的调试和检测,总结出该保护的调试技巧及测试方法,对有类似微机保护装置的发电厂、变电站、电力职业院校及电力培训中心也有一定借鉴意义。     

继电保护技术在变压器故障中的应用

阐述变压器设备和继电保护的配置方法,包括过负荷保护与过电流保护、瓦斯保护、差动保护、后备保护,探讨继电保护技术在变压器故障维修中的应用策略,从而解决盲区故障。     

变压器差动保护分析

一 概述 电力变压器是电力系统中十分重要的设备,如果出现故障将对供电可靠性和系统的正常运行带来严重的影响,特别是大型电力变压器,更是很贵重的设备.为了避免变压器事故的扩大,要求变压器内部发生故障时应迅速切断电源,使变压器退出运行.由于变压器的过流保护、速断保护还存在一定的死区,所以规定对于大容量变压器应装设电流差动保护. 变压器的纵联差动保护,是将变压器的一次侧和二次侧电流的数值和相位进行比较而构成保护装置,是变压器的主保护之一;变压器的差动保护主要用来保护变压器绕组南部及其引出线上的相间短路,同时也可以保护变压器单相匝间短路和接地短路.     

500kV三相共体变压器低压侧后备保护二次接线设计

执行国网公司标准化设计规范时,对于500kV三相共体变压器,其低压侧后备保护二次接线设计易出现差错.本文通过分析对比三相共体变压器和三相分体变压器一次接线的区别,并结合变压器保护装置技术说明及定值清单分析,介绍了三相共体变压器低压侧后备保护正确的二次接线设计和保护定值下达中应注意的问题.     

数字智能变电站变压器保护方案的探讨

十二五规划以来,智能电网越来越受到国家的重视,数字智能变电站作为智能电网的重要组成部分,赋予了传统变电站新的活力。从变压器保护的可靠性出发,首先对变电站变压器保护系统进行简单介绍。列出了匝间短路和漏感两种变压器故障,对其进行诊断分析。随后对变压器继电保护系统进行了探讨,讨论了数字智能变电站变压器的主保护、后备保护和现场调试,为今后变压器保护方案的确定提供了理论基础。     

线路距离保护Ⅲ段作变压器低压侧故障远后备存在的问题分析及解决方案探讨

按照电力行业标准的要求,分析了距离Ⅲ段作为变压器低压侧远后备保护的必要性,通过分析说明了距离保护做远后备时不同动作特性反应故障的能力以及出现的问题,结合我局目前保护配置现状,提出了面对保证灵敏度和躲负荷阻抗之间矛盾的解决方案。     

110kV金泉变1号主变间隔典型相间短路故障分析

由于变压器元件的工作原理及电气接线方式比起线路、母线等一次设备更为复杂,当发生故障,在进行故障分析时不是很直观,难度也比较大。结合我局110kV金泉变1号主变间隔故障情况,通过对保护相关故障波形的分析,给出主变典型相间故障的分析方法。     

浅谈变压器重瓦斯保护动作跳闸的处理办法

变压器油浸式结构简介变压器内部故障类型有相间短路单相匝间短路单相接地短路等。上述短路故障电路将产生电弧,会烧坏线圈的绝缘和变压器的铁芯,甚至引起绝缘材料变压器油的强烈气化,而导致油相爆炸等严重后果。     

浅谈变压器差动保护

变压器在现在电力系统中是一个必不可少的设备。如果在运行中出现故障,不能在极短的时间内切除故障,将会给电力系统的正常运行以及安全供电造成不可估量的损失,因此,差动保护作为变压器主保护的正确动作十分重要。为保证差动保护可靠动作,我们要总结工作中遇到有关变压器差动保护出现的问题,并有针对性地提出改进措施,提高电网的安全可靠性。     

变压器后故障方向继电器的动作行为分析

分析了电力系统Y/△-11联接组别变压器两侧发生两相非金属性短路时,当故障点过渡电阻R由0变化到∞时,故障点以及保护安装处的各相电压、电流的变化规律及特点,由此分析出变压器各相电流保护接线的功率方向继电器的动作情况.     

核心链路感知的可生存虚拟网络链路保护方法

针对现有可生存虚拟网络链路保护方法无差别对待所有虚拟链路、备份资源消耗多且故障后网络恢复时延长的问题,该文提出一种核心链路感知的可生存虚拟网络链路保护(CLA-SVNLP)方法。首先,综合考虑虚拟链路动态和静态两方面因素构建虚拟链路核心度度量模型,依据虚拟网络生存性需求,对核心度较高的虚拟链路进行备份保护;其次,将p圈引入可生存虚拟网络链路保护,依据虚拟网络特点构建p圈,为核心虚拟链路提供1:N保护,即每条核心虚拟链路平均消耗1/N条的备份链路带宽资源以减少备份链路资源消耗,并将单物理链路保护问题转化为多个p圈内的单虚拟链路保护问题;最后网络编码技术与p圈结合,将备份链路对核心虚拟链路提供的1:N保护转化为1+N保护,避免了故障后定位、检测及数据重传。仿真结果表明,该方法提高了备份资源利用率且缩短了故障后的网络恢复时延。     

Clustering-based multi-hop protection scheme for long-reach passive optical network against single shared-risk link group failure

The next-generation passive optical networks (NG-PONs) are expected to offer very high data rate to large number of users. Long-reach passive optical network (LR-PON) is considered to be one of the most promising solutions for NG-PONs. Since providing full protection (i.e., 100 % reliability) to each user in LR-PON is complex and cost-prohibitive, we propose in this study a novel heuristic scheme against single shared-risk link group (SRLG) failure to ensure certain degree of reliability (as determined by the network operator) to the users. In the proposed scheme (referred to as clustering-based multi-hop protection or CMHP scheme), we allocate residual capacity of backup optical network units (ONUs) among the ONUs that require protection by using bypass-based multi-hop traffic transmission strategy through backup fibers. CMHP scheme reduces the total length of backup fibers to be deployed between the ONUs (that require protection) and the respective backup ONUs through sharing of the backup fibers. In this study, we evaluate the total required length of backup fiber for a given network setting and different reliability requirements (viz. 75, 85 and 95 %). With the help of exhaustive simulations, we show that CMHP scheme significantly reduces the total length of backup fiber with reference to existing scheme to protect against single SRLG failure. We also explore a heuristic scheme referred to as clustering-based multi-hop protection with consideration of street layout (i.e., CMHP-SL) to implement CMHP scheme in practical scenario with due consideration of the street layout. CMHP-SL scheme provides protection to ONUs following a cost-efficient approach based on the existing fiber infrastructure in the distribution section.     

Multiple link failure recovery in survivable optical networks

Survivability is of critical importance in high-speed optical communication networks. A typical approach to the design of survivable networks is through a protection scheme that pre-determines and reserves backup bandwidth considering single/double link failure scenarios. In this article, a greedy algorithm is presented to reserve backup bandwidth considering multiple (F > 2) link (SRLG) failure scenarios. A bandwidth-saving joint selection scheme of working and protection paths is presented for protection against random multiple-link failures under dynamic traffic. Simulation shows that the algorithm can achieve maximum sharing of backup bandwidth for protection against random multiple-link failure with significant amount of bandwidth saving.     

iOS备份机制中隐私威胁问题的分析

目前,iOS安全研究主要在应用程序安全性检测、安全模型剖析、漏洞和数据保护机制分析等方面,对于iOS备份机制的安全性缺乏深入系统地研究。备份是iOS系统中惟一合法获得设备内部数据的渠道,但是备份数据缺少必要防护措施,用户数据安全和隐私受到潜在威胁。通过描述备份分析的方法,进而对备份存储数据进行深入理解,发现其存在严重隐私威胁,忽视对第三方应用程序数据信息的保护,最后评估了备份机制潜在的安全影响并给出提高备份安全性的建议。     

智能光网备份路径恢复问题研究

提出了智能光网中的备份路径的本地恢复、全局恢复和更为合理的两阶段恢复方案,并在GMPLs控制平面内设计了若干信令协议用于实现备份路径的建立与故障通知和恢复过程。该方案充分考虑了备份路径保护,能够提高预建立备份路径保护方案的可靠性。     

A hybrid protection strategy based on node-disjointness against double failures in optical mesh networks

As the size and the complexity of optical mesh networks are continuing to grow and the severe natural disasters are occurring more frequently in recent years, multiple failures (link failures or node failures) become increasing probable. Protection strategies against these failures generally provision backup paths for working paths based on link-disjointness or node-disjointness. Compared with link-disjoint protection, node-disjoint protection means higher degree of risk isolation and can accommodate both link failures and node failures. This motivates us to propose a hybrid node-disjoint protection, named Segment and Path Shared Protection (SPSP), to provide 100% protection against arbitrary simultaneous double-node failures (the worst double-failure case). For each service connection request, SPSP first provisions backup segments for the working segments, respectively, as the primary backup resources, then provisions a single backup path for the whole working path as the second backup resource. In addition to its complete protection capability and flexible scalability for double failures, SPSP can also obtain better network load balance and resource sharing degree by dynamic link-cost adjustment and reserved backup resource sharing. Simulation results show that SPSP can achieve a shorter average recovery time than path shared protection (PSP) and higher resource utilization and lower blocking probability than segment shared protection (SSP).     

Genetic algorithm based dynamic combination of polyhedron structures against multiple link failures

Polyhedron protection realizes link protection by constructing a pre-assigned structure and allocates backup resources on a fixed polyhedron structure based on the maximum number of working resources. Taking into account both protection success rate and resource redundancy, this paper dynamically combines different polyhedron structures to allocate backup resources according to the link load, and proposes a genetic algorithm based dynamic combination of polyhedron structures (GA-DCPS) to reduce the resource consumption in the network while ensuring the protection success rate. GA-DCPS aims to minimize the consumption of wavelength resources, and uses the genetic strategy to find the polyhedron combination with the least redundancy to allocate backup resources while ensuring the success rate of service protection. Compared to using the fixed polyhedron structure with 1:m backup resource allocation, GA-DCPS can reduce resource redundancy by about 15% while ensuring complete protection against double-link failures.     

基于波形相似度的水电站电流饱和变压器保护装置设计

为解决传统水电站电流饱和变压器保护装置保护及时率低的问题,基于波形相似度设计水电站电流饱和变压器保护装置。计算水电站电流饱和变压器保护运维动态基线,补偿水电站电流饱和变压器保护功率因数,基于波形相似度,分析水电站电流饱和变压器保护信号,采用NBC叠片式弹片,设定水电站电流饱和变压器保护装置额定电压,实现水电站电流饱和变压器保护装置设计。设计实例分析,结果表明,设计的保护装置保护及时率明显高于对照组,能够解决传统保护装置保护及时率低的问题。