基于开关变位信息的电网可疑故障元件集识别方法

根据现有的电网故障诊断过程,提出在建立系统元件的开关变位次序图的基础上,采用变位开关附近的改进深度优先搜索法确定停电区域。通过计算变位开关的拒动级别将可疑故障元件依故障概率的大小按顺序排列,进一步提高了故障诊断速度。对开关变位信息在传输过程中发生畸变的情况进行了分析,给出了相应的停电区域搜索步骤。对于电网的单一故障、多重故障以及存在保护和开关多次不正确动作的严重故障,该方法均能快速准确地定位停电区域,并给出精简后的可疑故障元件集。     

桥式双断点塑料外壳式断路器磁场分析

利用三维有限元方法对4种不同结构的桥式双断点塑料外壳式断路器进行了磁场分析,比较了4种结构触头间的电动斥力、吹弧磁场分布以及电弧受到的磁吹力。研究结果可为桥式双断点塑料外壳式断路器的设计和优化提供参考。     

断路器运行在线自动监测

断路器在电力系统中非常重要,用它来切换其他设备在工作与停止两种状态。断路器的可靠运行对重新配置电力系统的能力至关重要,并且可靠性可以通过定期检查和维护来保证。现在可以采用一种自动断路器监测系统来监测断路器的控制电路。系统包括一套新的断路器监测数据采集智能电子设备,它位于断路器上,用于获得关于实时运行的详细信息。本文也论...     

变压器励磁涌流抑制器工程应用及探讨

介绍了一种从根本上抑制和消除励磁涌流的新方法。论述了励磁涌流产生的机理,指出抑制励磁涌流的根本办法是防止磁通饱和。根据铁磁材料的时效特性指出剩磁不会自行衰减消失。利用分闸时刻电压角度计算出剩磁角度,然后通过控制下次合闸电压角度,控制合闸时刻偏磁与剩磁相位相反互相抵消,从而控制合闸总磁通不饱和,避免励磁涌流的产生。指出该方法不仅适用于单相断路器,同样也适用于三相断路器。介绍了涌流抑制器的2例工程应用实例,现场实测结果表明该抑制器可将励磁涌流有效抑制在变压器额定电流以下。     

On the computation of high-speed d.c. circuit breakers arc chute

Contents The paper refers to the design of high-speed d.c. circuit breakers arc chutes. The magnetic blowing effect is computed for a plane parallel system, which reproduces partially the conditions from an arc chute with magnetic field concentrators. The static case is analysed. A second kind Fredholm integral form of the magnetic vector potential is used. Results obtained by the numerical approximation of the integral equation on the boundary of the ferromagnetic bodies are presented.

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Über die Berechnung der Löschkammer des Gleichstromschnellschalters

Übersicht Diese Arbeit befaßt sich mit der Dimensionierung der Gleichstromschnellschalter-Löschkammer. Es wird die magnetische Beblasung für ein planparalleles System berechnet, das die reale Löschkammer mit Magnetfeldkonzentratoren modelliert. Dabei wird der statische Fall untersucht. Für die Berechnung des magnetischen Vektorpotentials werden Fredholm'sche Ansätze verwendet. Die Ergebnisse werden über die Integral-Gleichung am Rande der ferromagnetischen Magnetfeldkonzentratoren gewonnen.

     

变电站直流系统常用断路器及熔断器动作特性分析

变电站直流系统中存在着大量的直流断路器、熔断器,但是有关它们动作(熔断)特性的安-秒特性数据在厂家说明书中提供较少,现场用户对直流保护级差配合的动作特性认知较为模糊,在一定程度上影响到了变电站电气成套设备有关直流保护元件的参数选型。为了准确把握变电站常见直流保护控制元件的动作(熔断)特性,通过设计合理的试验方案,选取现场主流配置的直流断路器、熔断器进行安-秒特性试验。通过上千次试验,从准确的试验数据中发现了问题,为讨论变电站直流保护级差配合提供了依据。     

Pressure estimation in vacuum circuit breakers

The pressure of vacuum switching elements after production is checked normally by Penning or magnetron methods (combined electrical and magnetic field). Vacuum in the range of 10^-1 to 10^-4 Pa can be measured in this way. After assembly into circuit breakers however, these methods are not applicable. HF interruption performance during the make operation was proposed earlier as a possible alternative. Further investigations show that differences in the number of HF prestrike current loops can be found in the pressure range of 10 ^-1 to 10⁵ Pa. Current chopping of dc arcs between 5 and 30 A during the opening operation may be another option for determination of the pressure range by measuring the lifetime of the arc, but the resolution in the vacuum range <10^-1 Pa is too poor     

基于停电区域的电力系统故障诊断的一种新模型

提出了基于停电区域的电力系统故障诊断的一种新方法.主要包括三个方面的工作:(1)提出了应用无源信息识别停电区域的方法,有效地把故障诊断问题局限于某个或某些小的局部网络中;(2)在停电区域中,根据停电元件、断路器和保护动作信息构造了新的只在停电区域中识别故障元件的0-1规划模型.该模型简单、求解速度快,大大提高了故障诊断的速度;(3)采用了贪婪算法对该故障诊断模型进行求解.经算例计算表明,所提出的故障诊断的数学模型是正确的.     

基于IEC 61850的电网故障诊断完全解析化建模

电网故障诊断完全解析模型在对故障诊断规则进行解析的过程中,完整保留了电网元件、保护动作和断路器跳闸之间的逻辑关系,有很好的容错能力和应用前景。文中基于IEC 61850标准,提出一种利用变电站系统配置描述文件(SCD)构建电网故障诊断完全解析模型的方法。该方法通过解析变电站系统配置描述文件,获取系统元件的保护配置信息和保护动作与断路器跳闸的逻辑关系,再结合电网拓扑信息,可在线生成电网故障诊断的完全解析模型。最后,通过一个复杂故障的诊断算例证明了该建模方法的可行性,可望用于在线故障诊断。     

Three-dimensional magnetic field analysis of electrodes for VCBs[vacuum circuit breakers]

This paper describes the application of three-dimensional magnetic field analysis, including eddy current effects on the axial magnetic field electrodes of vacuum circuit breakers. The accuracy of the analysis is verified with both basic and full models of the electrodes. The analytical results were compared with measured values obtained by a Hall sensor system. The effect of the electrode slit length and the electrical conductivity of the contact on the magnetic flux density and phase difference was analyzed with the full model. The magnetic field in the gap was simulated when the arc ignites between the electrodes. These results demonstrated that the magnetic design of the electrodes can be carried out on an engineering workstation     

Comparing test requirements for low-voltage circuit breakers

Low-voltage circuit protective devices include low-voltage power circuit breakers, insulated case circuit breakers, and molded case circuit breakers. Each of these circuit breaker types is used for particular applications, and is tested against standards that relate to those applications. In North America, low-voltage power circuit breakers are designed and tested in accordance with ANSI/UL standard 1066, which in turn refers to the series of applicable ANSI C37 standards. Insulated case circuit breakers and molded case circuit breakers are designed and tested in accordance with the UL standard 489. In this paper the standards are compared by means of tables. The standards for low-voltage power circuit breaker and the molded case circuit breaker have many common elements. As a consequence, either type of circuit breaker could be used for some applications. However, there are several significant performance differences that relate to the application of these circuit breakers. Specifically, the low-voltage power circuit breaker is normally applied upstream of the molded case circuit breakers     

Total Motor Branch Circuit Protection with Instantaneous Trip Type Circuit Breakers and High Fault Circuit Protectors (HFCP)

Instantaneous trip type circuit breakers can protect controllers against damage due to overcurrents above six and up to 13 times full load motor currents (FLMC). They may be used for full protection if the starter and wire are self-protected up to 13 times FLMC. Molded case circuit breakers take at least 1/2 to 1 cycle to interrupt. An interrupting time of 1 cycle is too long at high let-through currents to protect contactors from being damaged and, in many cases, to protect heaters from being burned out. A line of high fault circuit protectors is described that protect all branch circuit components in case the available short circuit current is so high that the let-through current would, without protectors, be higher than a current that the branch circuit elements could with-stand for at least 1 cycle. A system is described that insures tripping of the circuit breaker whenever a high fault circuit protector opens. Tests, physical arrangements, coordinated system selections, and applications are described.     

分频输电系统中真空断路器的开断性能

风能作为可再生的绿色能源,将成为以分布式发电为特征的智能电网的重要组成部分.然而现有电力系统抗风电扰动能力差是影响风电产业发展的关键性制约.采用分频输电技术可解决上述风电并网问题,而分频输电会造成断路器开断短路电流时有较长的燃弧时间,从而引起断路器的开断能力降低.笔者综述了分频输电对真空断路器开断能力的影响.Slade...     

多端直流系统分区协调保护策略

针对多端直流系统的故障保护问题,首先分析了直流故障特性及多端直流系统保护难点,总结了现有多端直流系统故障保护方法。然后,基于一种典型的多端直流系统拓扑结构,以使用最少数量直流断路器为目标,提出了多端直流系统区域保护划分原则和分区保护策略。该方法将直流故障区域通过直流断路器与非故障区域进行隔离,从而使非故障区域可以继续维持正常运行,而故障区域则通过换流站交流侧断路器和直流侧开关进行保护和隔离。最后,通过MATLAB/Simulink仿真平台建模及仿真分析,验证了多端直流系统分区保护的有效性和经济性。     

能谱熵向量法及粒子群优化的RBF神经网络在高压断路器机械故障诊断中的应用

高压真空断路器是电力系统开关设备中极其重要的一种高压电器,而高压断路器故障中80%是由于机械特性不良造成,为此通过小波包变换对高压断路器机械振动信号进行了分析,以信号的能谱熵作为特征输入向量,建立了粒子群优化(PSO)径向基函数(RBF)神经网络的高压断路器故障识别系统模型,最后对实际高压断路器振动信号进行获取分析并得到结果。实验结果表明,高压断路器正常信号能谱熵向量各元素分布比较均匀;而故障信号所得能谱熵向量各元素变化较大且有一定变化规律;粒子群优化后的RBF网络模型在正确率、精度等方面高于传统神经网络模型。实验结果表明该方法用于高压断路器的故障诊断是可行的,并且可以为断路器的故障诊断提供更好的理论依据。     

Fault Section Estimation of Power System Using Colored and Timed Petri Nets

A correct and rapid inference is required for practical use of expert system for fault section estimation in power systems. This paper proposes a new model-based expert system for fault section estimation using colored and timed Petri nets. The Petri nets simplify the inference procedure greatly because it can represent the causalities among faults of power system components, protective actions of relays and circuit breakers. They can also represent the operating states of these protective devices explicitly, or, more precisely, whether a relay has been actuated correctly or falsely, etc. In addition, time sequence information on actuated relays and tripped circuit breakers can be handled by using the colored and timed Petri nets. Therefore, the operating states of relays and circuit breakers can be inferred more correctly. Petri nets are suited for parallel processing so well that there is a possibility of reducing the inference time considerably. In the proposed system, the inference is executed by setting the initial states in the Petri nets using the information on the actuated relays and the tripped circuit breakers and then operating the Petri nets. There have been several test cases which used a prototype system on the Macintosh computer employing Object Common Lisp, and good results have been obtained.     

A new neural networks approach to on-line fault section estimationusing information of protective relays and circuit breakers

This paper proposes a new neural network diagnostic system for online power system fault section estimation using information of relays and circuit breakers. This system has a similar profile of an expert system, but can be constructed much more easily from elemental samples. These samples associate fault section with its primary, local and/or remote protective relays and breakers. The diagnostic system can be applicable to the power system control center for single or multiple fault sections estimation, even in the cases of failure operation of relays and breakers, or error-existent data transmission. The proposed approach has been practically verified by testing on a model power system. The test results, although preliminary, suggest this system can be implemented by various electric utilities with relatively low customization effort     

Reducing Interrupting Duties of High-Voltage Circuit Breakers by Increasing Contact Parting Time

The interrupting duty of high-voltage circuit breakers can be reduced by increasing the contact parting time, which is the sum of tripping delay and the circuit breaker opening time. The contact parting time is fixed; however, the tripping delay can be increased. Although this method is not discussed in current technical literature, it is valid according to the ANSI/IEEE standards. Immediate replacement of the circuit breakers or other alternatives to reduce interrupting duties can be avoided, resulting in large cost savings and process downtime. The problem occurred in a large paper mill distribution system, where the circuit breakers were applied well within their close and latch ratings but the interrupting duty exceeded by 6%. By introducing an additional tripping delay of one cycle, the interrupting duty is reduced and the existing breakers are retained in service. This paper demonstrates these calculations.      

同轴式磁力齿轮试验样机的参数优化与设计改进

针对一台传动比为-15/7的同轴式磁力齿轮试验样机存在转矩密度偏低的问题,运用二维有限元法分析调磁极片的径向齿高、相对齿宽、连接桥位置及内外磁体充磁方式、磁体体积对转矩密度的影响,从而来寻找提升转矩密度的措施。结果表明,在不增加制造成本的前提下,通过改进调磁极片和磁体的相关参数使转矩密度提升43%,磁力齿轮外径缩小7.5mm。     

小型断路器灭弧室的仿真与实验分析

针对某小型断路器产品的灭弧室,建立了三维电弧仿真模型并进行了动态特性仿真,仿真结果揭示了灭弧室内电弧的运动规律,电弧弧根从动触头到跑弧道的转移,电弧沿跑弧道向栅片运动并被铁质栅片切割的过程。在此过程中,电弧多次出现背后击穿,电弧在跑弧道拐点长时间停滞,使该位置的电极被强烈烧蚀。此现象得到了实验的验证,同时仿真得到的电弧电压和电流与实验结果较为一致。