多相多边形无刷励磁机及旋转整流系统的运行状态分析

多相多边形无刷励磁机由于其固有的一些技术特点在一些大容量常规火电站和核电站中得到应用,对该励磁机整流系统运行状态的分析是研究其电气原理和特性的关键。基于多相多边形无刷励磁机电枢实际的空间分布与连接,得到了二极管的理想导通规律;进一步地,考虑换相过程中各阶段的二极管导通数量及等值电路,解析了各状态的电气量波形,获得了各导通状态所满足的临界条件;对一台十一相动模样机进行了实验研究,将实验结果与通过理论解析得到的二极管电流进行了对比,验证了理论分析的准确性。从而完整地揭示了多相多边形无刷励磁机及旋转整流系统的导通换相规律,为该系统的设计提供了理论依据。     

基于IEC61850的断路器剩余电寿命监测系统设计

基于触头相对电磨损与相对电寿命法研究断路器剩余电寿命监测功能,并依据IEC61850标准构建数学模型。通过实时监测分/合闸电流及次数实现对电磨损量的监测折算,在此基础上构建适应IEC61850要求的电寿命监测分析系统。该系统可实现采样值的数字化传输与逻辑节点的无缝衔接,确保电流采样和分合闸位置监测数据并行传输时的传输实时性与一致性。实例分析表明,该断路器剩余电寿命监测系统稳定可靠,具有工程应用价值。     

串联电池组接触电阻故障诊断分析

开发资源节约型、环境友好型的电动汽车是当前全球汽车技术革命和产业转型的前沿阵地和技术制高点。为确保电动汽车行驶过程中的安全,避免电池发生功率衰退故障,采用一阶RC等效电路模型分析电池组的接触故障,并利用最小二乘法对模型参数进行识别,研究模型参数随电池荷电状态的变化规律。然后,在Simscape仿真模拟电池故障现象的基础上,分析出现电池电压变化异常的电池故障,得知其原因为接触电阻故障或内阻异常增加。最后,通过实验对比故障前后单体电池的电压、电流和内阻,总结得到电池发生接触故障的方法。     

新型触头材料电接触行为测试技术及试验研究

为研究微机电系统（MEMS）开关的失效机理,设计了一种以压电陶瓷电动机为核心的新型超低速致动形式的触点材料电接触行为测试分析系统。应用该系统对典型触头材料在闭合和分断过程中的接触力特性、滞回特性、接触电压特性和电弧特性进行了初步观测和物理解释。     

数字化电气监控管理系统的探讨

电气系统设备的运行管理水平,将直接关系到发电厂运行的安全经济性,影响发电厂在发电市场上的竞争能力。针对电气纳入分散控制系统DCS(Distdbuted Control System)所存在的不足,阐述了实施发电厂电气监控管理系统的必要性和可行性,探讨了应用数字化技术将电气接入DCS,实现发电厂电气监控管理的可行方案。     

ETI载波机告警系统的分析与监测点的选取

对ETI复用载波机的告警系统进行了分析,指出了可选作计算机监控系统的监测点,以及监测点的接线益和继电器接点的状态。分析了告警电路产生告警的条件及告警电路所能监视的范围。并选取了部分具有代表性的模拟信号作为监测信号。     

Cathodic protection

Cathodic protection is the electrical solution to the corrosion problem. In this article, the history of cathodic protection (CP) is traced, and the design fundamentals are developed, including the three components of a corrosion system, the three elements of an electric circuit, and the three configurations causing potential difference. CP is the process of forcing a metal to be more negative (cathodic) than the natural state. Corrosion of metal equipment in contact with the earth is a natural phenomenon. To control this corrosion, CP systems intentionally sacrifice one material to protect another. For this system to work, there must be a complete electric path from a negative source, to the protected structure, through the electrolyte, via the ground bed, to the positive side of the source. Some more methods are also handled to control corrosion that is discussed.     

SPD“3+1”接线模式及间接触电防护分析

介绍了TT系统中SPD的"3+1"保护模式。重点分析采用"3+1"接线模式时,其N-PE放电间隙的失效短路使TT系统暂时成为局部TN系统运行,电气设备外露导电部分可能出现的危险对地故障电压。并指出,为满足间接触电防护要求、避免电击事故的发生,应尽量降低电源端系统中性点接地电阻。     

电动汽车用直流接触器的设计

电动汽车用直流接触器的特点是工作电压高,比汽车电器常用的24 V要高出近20倍,当分断工作电压高出250 V的直流电路时,灭弧较困难。在分析传统产品触头系统发生接触故障和电磁机械系统发生动作故障的原因后,运用可靠性设计理念,降低触头系统工作时的失效率,提高电磁机械系统的动作与复位可靠性。最后提出了设计具有永久磁吹灭弧性能的主触头系统等重要零部件的设计要点,以期达到体积小、运行可靠性高的电动汽车用直流接触器需求。     

Investigations on the failure modes of XLPE cables and joints

The work reported in this paper pertains to the investigations on the cross-linked polyethylene (XPLE) cable systems in the presence of water and other electrolytes in contact with the conductor. In this connection, several diagnostic test procedures have been instituted which reveal the status of the dielectric at any point of time. While evaluating different types of joints, it has been observed that two modes of failure are operative, while one is due to electrical effect, the other is essentially due to mechanical effect     

Reducing unscheduled plant maintenance delays-field test of a newmethod to predict electric motor failure

Most electric motor predictive maintenance methods have drawbacks that limit their effectiveness in the mining environment. The US Bureau of Mines (USBM) is developing an alternative approach to detect winding insulation breakdown in advance of complete motor failure. In order to evaluate the analysis algorithms necessary for this approach, the USBM has designed and installed a system to monitor 120 electric motors in a coal preparation plant. The computer-based experimental system continuously gathers, stores, and analyzes electrical parameters for each motor. The results are then correlated to data from conventional motor maintenance methods and in-service failures to determine if the analysis algorithms can detect signs of insulation deterioration and impending failure. This paper explains the online testing approach used in this research, and describes monitoring system design and implementation. At this writing, data analysis is underway, but conclusive results are not yet available     

基于端点聚合的企业电力系统离线网络拓扑分析及应用

电力网络拓扑分析是对实际电力网络复杂电气接线的简化过程,是进行计算分析的基础。根据企业电力系统离线应用的特点,在CIM模型基础上,引入触点的概念,建立了适用于企业电力系统图形化电网建模的电气连接模型,提出了详细描述电气设备实际连接关系的连接线表示法。将所有电气上零阻抗连接的设备（或端点）聚合在一起,形成拓扑节点;然后利用拓扑节点与设备的关联关系,将所有电气上连通的设备（或端点）聚合在一起,形成拓扑岛。结合企业内部电力系统与外部电网的不同接入方式,分析了该方法在企业电力系统离线分析中的典型应用。算法分析和算例表明,该方法逻辑简单、结构清晰、结果信息丰富,适用于企业电力系统离线应用。     

电器设备组件特别是接线端子容许温升的导则--IEC60943技术报告(三)

IEC60943技术报告是由IEC32熔断器技术委员会编制，并于1998年发布的。技术报告旨在指导评估稳定状态下载流电器设备组件的温升容许值。技术报告提供了触头接触电阻的计算和基本老化机理；触头和接线端子的温度和温升计算；不同组件，特别是触头，接线端子和连接它们的导体的最大容许温度和温升；IEC各产品委员会确定最大容许温度和温升必须遵守的主要程序。     

电器设备组件特别是接线端子容许温升的导则-IEC60943技术报告(二)

IEC60943技术报告是由IEC32熔断器技术委员会编制,并于1998年发布的.技术报告旨在指导评估稳定状态下载流电器设备组件的温升容许值.技术报告提供了触头接触电阻的计算和基本老化机理;触头和接线端子的温度和温升计算;不同组件,特别是触头,接线端子和连接它们的导体的最大容许温度和温升;IEC各产品委员会确定最大容许温度和温升必须遵守的主要程序.     

电器设备组件特别是接线端子容许温升的导则--IEC60943技术报告(一)

IEC60943技术报告是由IEC32熔断器技术委员会编制，并于1998年发布的。技术报告旨在指导评估稳定状态下载流电器设备组件的温升容许值。技术报告提供了触头接触电阻的计算和基本老化机理；触头和接线端予的温度和温升计算；不同组件，特别是触头，接线端子和连接它们的导体的最大容许温度和温升；IEC各产品委员会确定最大容许温度和温升必须遵守的主要程序。     

Simulation Model of a Direct-Current Electric Locomotive with Commutator Traction Motors

A dc electric locomotive simulation model is considered that makes it possible to study transient and steady processes and may serve as a basis for the notion of a “digital locomotive” being implemented within the “Digital Railway” project. One of the most popular electric locomotives is selected, which is designed for pulling freight trains along long-distance railways electrified with direct current with a voltage of 3000 V. The electric locomotive model is based on a mathematical model of a collector traction engine. The model takes into account the nonlinearity of the main pole’s magnetic characteristic, as well as the effect of eddy currents in solid magnetic circuit sections on the magnetic flux variation. The model provides a mechanism for regulating motors in the course of investigations in accordance with operating conditions. The processes of resistor starting and voltage regulation by connection to resistors by means of transposition, as well as motor regulation by changing the magnetic flux, are taken into account. The possibility of using the developed model to study the traction substation–traction network–electric rolling stock system, which is determined by different operating modes of the traction network in the process of converting electrical energy into mechanical, is shown. Calculations of various locomotive operating modes in the event of failure in the contact network are carried out.     

基于故障树的电气主接线可靠性及薄弱环节分析

针对电力系统规划、设备选型、故障诊断等问题进行研究,提出一种基于故障树和重要度分析的电气主接线可靠性评估新方法。运用故障树分析法将系统拓扑结构转换为元件逻辑关系,简单直观的反映出系统故障根本原因,选取可靠性基本特征量,结合元件的结构重要度、概率重要度、关键重要度对比分析找出系统薄弱环节,实现了电气主接线可靠性的定性和定量评估。通过桥式接线案例分析,计算出基本电气元件三种重要度并进行排序,探讨了元件合并对评估结果的影响,同时验证了该方法的合理性。     

三菱触摸屏在某发动机试车台电气操纵控制系统的应用

触摸屏与PLC组成的电气操纵控制系统不仅使该系统操纵控制功能强大、容易扩展、改造而且省去了很多硬接线的麻烦,简化了操纵控制系统结构;各种工艺参数的设定,实时数据显示,故障报警等都可以在触摸屏上直接操作,真正体现了人机交互功能。本文通过三菱触摸屏在某发动机试车台电气操纵控制系统应用的工程实践,着重介绍了触摸屏通信、操纵控制功能的设计并给出了某型发动机操纵屏、发动机辅助用电设备操纵屏画面设计图。为触摸屏在其它电气操纵控制系统的应用提供了参考和借鉴。     

Sensorless control of a linear reciprocating switched-reluctance electric machine

It is proposed to use a simple switched-reluctance electric machine that does not have windings or permanent magnets on a movable part to develop a linear reciprocating electric machine intended for use as an electric generator together with a free-piston internal-combustion engine. It is noted that one of the most difficult problems in the development of such a linear electric machine is the development of a control system. A sensorless control algorithm is considered. Information on the stator-phase inductance of the electric machine and its variation is used to determine the position of the movable part. For its estimation, probing voltage pulses of known duration are applied to the phase. The amplitude of the current pulses caused by them will be proportional to the phase inductance. A mathematical model of electromagnetic processes is used to test the efficiency of the proposed control algorithm and determine appropriate control parameters. Since stator phases have separate magnetic circuits and are not magnetically connected, the electromagnetic processes in each phase are considered independently. Model parameters are determined experimentally using an experimental prototype of the considered electric machine, for which the dependences of the phase flux linkage and the generated force on the phase current for different positions of the movable part are obtained. The results of the investigation of processes in the considered electric machine at different frequencies of the movable part are given. It is found that, at frequencies of the movable part close to the nominal frequency, the phase should be connected to the power supply even before the movable part reaches the extreme position. Control using probing pulses applied to the operating phase is impossible, because the level of these pulses does not reach the maximum value until the phase is switched on. In this case, it is necessary to use the probing pulses of another, nonoperating phase to determine the position of the movable part. Such an algorithm makes it possible to control a linear reciprocating switched-reluctance electric machine at both low and high frequencies of the movable part. The obtained results confirmed the correctness of the adopted approaches to the development of a sensorless control algorithm.     

线圈电流零相位分断下交流接触器电寿命预测

交流接触器电寿命受多种因素影响,其线圈控制方式是主要影响因素之一。线圈电流零相位分断方式是控制交流接触器分断的常见方式之一,其分断方式会严重影响交流接触器电寿命。首先,分析了线圈电流零相位分断方式下交流接触器动作特点,发现其三相触头磨损不均匀,某相触头磨损最大;其次,提出利用交流接触器首熄弧相的分布均匀度来判别触头磨损最大相的方法,并根据触头磨损最大相最先失效理论建立了交流接触器电寿命预测模型;最后,采用交流固态继电器对线圈进行控制并进行交流接触器电寿命试验,通过对试验数据进行分析,验证了文中建立寿命预测模型的有效性。