电力电缆故障冲闪测试放电回路建模

对电力电缆故障冲击高压闪络测试(简称冲闪测试)系统的放电响应进行了研究.在只考虑暂态低频分量信号的条件下,利用电缆的均匀传输线T型等效网络,建立了冲闪测试放电回路的集中参数电路模型.根据电缆的结构和材料参数.以及电缆集中参数与其分布参数之间的关系,推导了模型的电流、电压响应近似表达式.以及电流响应的衰减系数和振荡频率表...     

Development of a fault locator for a branch line

Formerly, only pulse radar and the Murray loop bridge could be utilized in a cable fault location method that is applicable to branch lines. Those methods need a terminal connection at the far end. Therefore, it is difficult in fault location involving branch lines. Pulse radar is applicable only for high‐resistance ground faults and the Murray loop bridge is applicable only for low‐resistance ground faults. We have developed current‐detection pulse radar and tested it. In high‐resistance ground fault location, the measured result includes discharge delay error. Therefore, we have proposed an error correction method and confirmed it. In addition, we have designed a new cable fault location method of pulse radar and tested it. © 2000 Scripta Technica, Electr Eng Jpn, 134(2): 19–28, 2001     

电力电缆脉冲电流测距法的改进

提出了一种改进的电力电缆故障脉冲电流测距法.通过在高压回路里串联电感和电阻,限制电缆中冲击电压的上升速度,延迟故障点击穿放电的时间,使得加入冲击电压产生的暂态过程和故障点放电产生的暂态过程具有明显的时间差,避免两个暂态过程的脉冲电流波形产生混叠,解决了故障点反射脉冲难以识别的问题.数字仿真与现场试验结果证明了所提出的对脉冲电流测距法的改进是正确、可行的.     

基于虚拟仪器的接触网故障测距装置

微机接触网故障测距装置能在电气化铁路接触网发生各种短路故障后自动进行故障诊断和故障点精确定位，介绍了利用故障电压和故障电流计算故障回路电抗值的电抗法故障点定位的原理，装置采用软件替代硬件，使用NI公司的虚拟仪器开发平台Labwindows CVI和数据采集卡完成了系统功能，简单介绍了基于虚拟仪器的故障测距装置的软件设计。     

基于泄漏电流的高压电缆线路故障测距方法

为实现高压电缆线路短路故障发生后准确故障定位,提出一种利用故障通道泄漏电流的离线故障测距方法。该方法在短路故障发生后于电缆终端加直流电压,泄漏电流主要通过故障击穿通道沿金属护层流入两端接地点,在线路两端接地点检测护层电压,通过单位长度金属护层阻抗与泄漏电流和护层电压的关系,可计算出故障点位置。仿真结果表明,该方法能够有效的定位故障点位置,其相对误差不超过8%,绝对误差不超过50 m。     

基于差分方向行波的脉冲电流电缆故障测距方法

针对脉冲电流电缆故障测距法测试波形复杂、数据分析自动化尚未实现的问题,构建差分方向行波对,提出以相关分析提取行波往返时间的方法,实现脉冲电流法测试数据自动分析.基于行波信号在电缆中的传播特性,分析了传播畸变中衰减畸变和色散畸变对相关分析峰值位置的影响,推得低频频带的色散畸变是影响相关分析准确性的主要因素.提出了利用导引...     

一种新原理在超高压输电线路故障定位装置中的应用

小波分析是分析非平稳信号的一种非常有效的方法,快速小波变换使得小波分析的广泛应用成为现实,高速数字信号处理芯片(DSP)为其在行波测距中的实现提供了硬件支持.论述了装置的实现原理,通过EMTP仿真,证明了算法的有效性及其实现的实时性.     

一种新原理在超高压输电线路故障定位装置中的应用

小波分析是分析非平稳信号的一种非常有效的方法 ,快速小波变换使得小波分析的广泛应用成为现实 ,高速数字信号处理芯片 (DSP)为其在行波测距中的实现提供了硬件支持。论述了装置的实现原理 ,通过EMTP仿真 ,证明了算法的有效性及其实现的实时性。     

Bearing fault detection via autoregressive stator current modeling

This paper proposes a method for detecting developing bearing faults via stator current. Current-based condition monitoring offers significant economic savings and implementation advantages over vibration-based techniques. This method begins by filtering the stator current to remove most of the significant frequency content unrelated to bearing faults. Afterwards, the filtered stator current is used to train an autoregressive signal model. This model is first trained while the bearings are healthy, and a baseline spectrum is computed. As bearing health degrades, the modeled spectrum deviates from its baseline value; the mean spectral deviation is then used as the fault index. This fault index is able to track changes in machine vibration due to developing bearing faults. Due to the initial filtering process, this method is robust to many influences including variations in supply voltage, cyclical load torque variations, and other (nonbearing) fault sources. Experimental results from ten different bearings are used to verify the proficiency of this method.     

双端行波故障测距装置性能测试方法

在介绍双端行波故障测距装置工作原理的基础上,分析了影响故障测距精度的主要因素。基于此,设计了双端行波故障测距装置性能测试方案,研究了测试系统、测试内容以及所用的仿真模型,并重点分析了线路和二次回路的模型。按照设计的方案对双端行波故障测距装置进行了实际测试,验证了所提方案的合理性和有效性。     

预防电缆沟起火的小电流接地系统单相接地故障处理

为避免小电流接地系统单相接地故障引发的电缆沟起火事故,采用火灾动态仿真分析方法得到了接地故障电弧导致电缆沟引燃的时间与空间阈值。在此基础上阐述了预防电缆沟起火的综合治理措施。论述了兼具相控消弧线圈和预调式消弧线圈优点的相控预调式消弧线圈的实现方式及其实验测试数据。阐述了跨线相继接地故障的处理方法,包含以暂态量法为主的连续检测过程及以稳态量法为主的增补处理过程。给出了单相接地保护跳闸延时的整定依据及间断性接地故障的处理方法。针对城区和郊区配电线路分别论述了集中智能容错单相接地故障处理方法和基于合闸速断的分布智能单相接地故障处理方法。介绍了在陕西全省172座110 kV变电站供电区域范围内配电网的整体应用成效,表明所论述的技术措施的有效性。     

海底光缆无源探测技术及其实现

介绍了海底光缆的无源探测技术,着重分析了其关键电路——线圈探测电路的工作原理及其实现方法,对其中的开关电路的电路结构、元件值、工作原理作了较详细的介绍。     

一种新型超导直流故障限流器

与用于交流系统或双极直流系统的限流器不同,用于多端柔性直流系统的故障限流装置应能够在短路故障发生初期有效抑制故障电流的快速上升,避免在线路断路器动作之前换流器桥臂闭锁。针对这一性能要求提出了一种专门用于多端柔性直流电网中的新型超导故障限流器的基本结构和工作原理,并制作了原理验证样机。通过对原理验证样机开展的一系列实验,证明了设计结构与原理的可行性。实验结果也充分展示了这类限流器的功能特性,如其能充分利用铁芯的最大磁导率在短路故障发生的几个毫秒内实现最大限流感抗,从而有效抑制故障早期的短路电流上升率。此外,可以通过对超导隔离环组数量的调整,设定限流器的限流阈值,灵活适应不同直流系统的限流需求。     

串联谐振式限流器的仿真研究

串联谐振式限流器具有工作原理、拓扑结构简单等优点,且对于高压系统,其一次回路参数能够做到合理配置;但在电网发生短路故障进入短路限流工况过程中,其电容器及并联转换开关将工作在相当恶劣的条件下.应用Matlab软件对上述情况进行了建模仿真研究,得出如下结论:①闭合转换开关短接电容器使限流器从正常运行模式切换到短路限流模式过程中,将在电容与转换开关之间产生电压(电流)的高频振荡,且振荡电压(电流)的幅值与转换开关的动作速度成振荡增幅关系;②当转换开关采用功率半导体器件构成时,要求控制系统快速响应短路故障闭合转换开关,否则极易因振荡过流(过压)而损坏;③在限流器进入短路限流模式但继电保护尚未动作于断路器切断故障回路期间,转换开关将承受全部短路电流以及振荡电流,采用电力电子型转换开关时,其功率半导体器件的容量必须按这种工况进行选择.     

基于沿线电流故障分量差值的交叉互联电缆故障测距

为解决长距离高压电缆采用交叉互联接地方式时故障测距较为复杂的问题,提出基于沿线电流故障分量差值分布的交叉互联电缆故障测距方法。首先,通过故障发生前后护层环流判断电缆故障区段。其次,考虑线芯与护层之间的耦合关系,基于双π模型推导电缆不同区段发生故障时的沿线电压、电流方程。在此基础上,通过求解电流故障分量差值函数零点得到故障距离,并结合切线方程对所得故障距离进行修正。最后,搭建电缆故障模型对测距方法进行仿真验证。结果表明,所提方法测距误差为1%左右,具有较高的准确性,对采用交叉互联接地方式的电缆实现故障测距具有一定的参考意义。     

Efficient reduction of fault current through the grounding grid ofsubstation supplied by cable line

The paper presents an analytical procedure suitable for the determination of the part of the ground fault current emanating from the substation grounding grid in the conditions when a particular measure has been taken to reduce it. The practical realization of this measure can be simply described as burying one bare copper wire of a certain length in the same trench as the cable feeding line. In the case of an overhead feeding line, the similar measure is denoted in the expert literature as the “counterpoise”. The presented method enables a quick and, for practical purposes, sufficiently accurate evaluation of the copper wire length providing the maximum possible reduction of the substation grid current. The conveniences of the method result from the simplicity of the formulae for the determination of the realized grid current reduction at the effective copper wire length     

Novel leak detection system for pipe type cable installations

This paper presents a new application of modern numerical algorithms, such as neural and probabilistic networks, for monitoring pressure system installations. Theoretical background as well as custom implementation of the algorithms is presented, and a complete system for monitoring high-pressure, fluid-filled (HPFF) cables is described.     

基于LCL故障电流控制器的故障快速检测

相较于交流配电网,直流配电网存在故障电流限流、阻断和电能质量治理等多种问题。为减少直流系统中设备的数量,文中提出了一种基于LCL型多功能故障电流控制器拓扑结构,使其同时具备故障限流、故障阻断和电压调节功能。首先针对该拓扑结构,研究其在限流、阻断和电压调节等不同工作目标下的运行工作原理,分析LCL结构的滤波和限流复用过程,提出故障电流的快速检测方法。然后,通过对限流器件不同位置电压变化率和电流变化率的阈值匹配,实现双极故障、单极故障和高阻故障等多类型故障的快速判断。最后,搭建系统仿真模型,验证了该故障电流控制器拓扑同时具备调压、限流和阻断等功能,且能够快速检测故障电流。     

A transformer type fault current limiter with spark gap

A novel fault current limiter (FCL) is proposed in this paper. The FCL consists of a capacitor, a transformer and a spark gap. The spark gap is used to control the inductive reactance of the transformer for matching the capacitive reactance of the capacitor. During the short-circuit faults, the FCL resonantly produces a high impedance in the fault circuit after the breakdown of the spark gap, which enables the fault currents to be reduced. A steady-state analysis is made for investigating the current-limiting operation condition of the FCL. Laboratory test and Alternative Transients Program (ATP) are also employed to examine the current-limiting effect of the FCL. The results obtained from measurement and ATP-simulation show that the FCL has the capability of limiting the fault currents to lower levels.