中性点不接地或高阻接地系统接地故障定位方法探究

本文提出了一种中性点不接地或高阻接地系统接地故障定位的新方法，该方法采用相对电压算法原理，将数字继电器、零序信号发生器和远距离接地故障指示器相结合。能处理间歇性故障和多重故障的问题，能识别反向接地故障。     

中性点非直接接地方式故障处理及接地信号检测

为了在35kV及以下电网中发生接地故障时能快速找到故障点,文章对非直接接地电网和接地故障处理过程进行分析,通过接地信号检测方式来缩短接地时间,快速隔离故障点,减少经济损失,提高供电可靠性。     

中性点有效接地配电网高阻接地故障特征分析及检测

中性点经小电阻等有效接地方式能有效地克服配电系统单相接地故障暂态过电压超标及故障选线不灵敏等问题,逐渐在城市配电网、大型厂矿企业电网中得到了推广应用;但这种运行方式仍然存在弧光接地等高阻接地故障正确动作率较低的问题。针对该问题,文中分析了高阻接地故障的特征,给出并验证了适用于配电网高阻故障检测的故障点电弧模型。针对现有方法中主要利用频域特征来检测高阻接地故障导致成功率低的缺点,提出了一种基于零序电流波形畸变凹凸性的高阻接地故障检测方法,仿真实验与现场试验数据验证了该算法的灵敏性和可靠性。     

基于Gradient-Closing变换的接地故障识别

无论陆地配电网或是船舶电网中,单相接地所占故障的比例最大.当前采用高电阻接地方式的电网,在发生金属性接地或电缆单次放电时,接地电阻不但不能抑制过电压,反而使故障点电流增加.从单相接地实验出发,提出一种利用数学形态学中的Gradient变换和Closing变换级联的方式识别接地故障类型的方法.该方法能将金属性接地和间歇性接地区分开,并且忽略掉单次放电的情况.通过大量实验和仿真对该方法进行验证,该方法在不同条件下均有良好的故障识别能力.     

间隙性接地故障保护原理

Siemens根据间隙性接地故障时电网中电力电缆电压电流的变化特点,利用零序电流作为间隙性接地故障发生标识,累积间隙性接地故障的持续时间,建立起热负荷模型,从而实现间隙性接地故障保护灵敏性,准确性。该方法不受电网中性点和接地电阻大小的影响,适用范围广,对各种复杂的电网中的间隙性接地故障同样有效。     

可控接地电阻系统在接地故障处理中的原理及应用

配电网接地故障处理是电网运维的一项重要内容。针对当前普遍采用的消弧接地模式的不足,提出一种基于可控接地电阻系统的接地故障全自动全过程处理方案。该方案充分结合了传统低阻接地和消弧线圈接地优点,完整实现了接地故障类型智能识别、与配网智能终端FTU协调配合及故障自动隔离等功能,避免了人工干预,大幅提高了系统供电的安全可靠性。     

基于Gradient-Closing变换的接地故障识别

无论陆地配电网或是船舶电网中,单相接地所占故障的比例最大。当前采用高电阻接地方式的电网,在发生金属性接地或电缆单次放电时,接地电阻不但不能抑制过电压,反而使故障点电流增加。从单相接地实验出发,提出一种利用数学形态学中的Gradient变换和Closing变换级联的方式识别接地故障类型的方法。该方法能将金属性接地和间歇性接地区分开,并且忽略掉单次放电的情况。通过大量实验和仿真对该方法进行验证,该方法在不同条件下均有良好的故障识别能力。     

带人为接地分流装置配电网的小电流接地选线

分析了带人为接地分流装置的小电流接地电网发生单相接地故障时的零序导纳分布情况,提出了一种新颖有效的小电流接地选线方法。该方法不仅可以单独使用而且可以作为其他选线方法的有效补充,对于中性点不接地和中性点经消弧线圈并（串）电阻接地电网均可有效选线。     

小电流接地故障选线技术探讨

我国配网的中性点广泛采用不接地与经消弧线圈接地这两种方式，习惯上称为小电流接地系统。当小电流接地电网发生单相接地故障时，因故障电流很小，故称为小电流接地故障。由于小电流接地故障对系统影响不大，所以可以运行一段时间，以确保对用户的供电。但小电流接地系统发生单相接地故障时，非故障相对地电压将有不同程度的升高，而且间歇性弧光接地可能引起电弧接地过电压，对系统绝缘造成威胁，容易扩大为相间短路，因此需要尽快排除。传统的处理方式是逐条拉线路，     

小电流接地电网改进能量法接地选线原理

根据小电流接地电网单相接地故障时电压电流的变化特点,利用中性点电压、故障相电压和零序电流构造的能量曲线的斜率来进行故障选线.该方法不受电网平衡情况和接地电阻大小的影响,对复杂的间歇性电弧接地故障同样有效.MATLAB仿真证明了本文的结论是正确的.     

矿山电网漏电保护的研究

分析了矿山电网供电的特点 ,给出了附加直流电源的电流与系统绝缘电阻的关系 ,系统正常运行与漏电故障时导纳的变化。提出了基于附加直流电源和导纳 (有功导纳 )增量原理的漏电保护新判据。介绍了基于这些原理的微机漏电保护装置 ,经现场运行表明选线准确、可靠。     

基于故障录波分析的小电流接地选线保护装置

分析了小电流接地系统单相接地故障选线困难的主要原因,在对单相接地故障暂态与稳态过程仿真的基础上,提出了基于故障录波分析的接地选线保护原理.介绍了一种基于ARM DSP双CPU硬件结构的新型小电流接地选线装置,并给出了其实现原理和组成结构.实验结果表明,该装置反应速度快、选线精度高.     

闭环微电网快速接地保护实用化方案

微电源以微电网形式接入配电网,使其单向潮流、辐射供电方式转变为双向潮流、环网供电方式;并网运行发生接地故障时,因微电源并网逆变器所产生的方向性助增故障电流或外汲故障电流,可能导致传统继电保护装置拒动或误动。针对这一问题,文中提出一种适用于闭式环网的微电网接地保护方案。该方案需将辐射、树干式配电线路改造成闭式环形配电线路,每段线路按需配置第1类保护器和第2类加速保护器。第1类保护器以单端工频正序故障分量相位判定正向故障,2个保护器同时为正向故障时,实现故障区域定位;第2类加速保护器在加速时段内根据对端保护器动作情况,检测故障分量比值,实现故障区域快速隔离。通过理论分析和系统仿真验证了该保护方案的有效性与可行性。     

中性点经消弧线圈瞬时并联小电阻接地研究

从配电网供电的安全可靠性、电气设备和线路的绝缘水平、继电保护的选择性和灵敏性以及对通信系统的干扰等方面,综合说明了采用中性点经消弧线圈瞬时并联小电阻的接地方式可充分发挥消弧线圈和小电阻接地方式的优点,建议在配电网中采用中性点经消弧线圈瞬时并联小电阻的接地方式。     

基于数学形态谱和人工神经网络的高压输电线接地故障类型识别方法

高压输电线接地故障的正确、快速识别是处理故障的前提之一。该文提出了一种基于数学形态谱和人工神经网络识别高压输电线路接地故障类型的新方法。数学形态学颗粒分析是一种用来处理图像的粒度和形状特征的图像处理工具。该方法通过对故障电流进行相模变换后,用数学形态学颗粒分析方法提取序电流分量的形态谱,并作为神经网络的输入,实现对接地故障类型的识别。仿真表明,该方法具有较高是识别率。     

System grounding and ground-fault protection in the petrochemical industry: a need for a better understanding

This paper provides an in-depth discussion of system grounding and ground fault protection on systems from 480 V and above. The paper also discusses modeling of ground faults, the proper design for ground-fault protection, and common problems associated with ground-fault protection. The paper address many real-life problems associated with system grounding and ground-fault protection, including safety issues and how to avoid those problems. The topics included in the paper include low-voltage systems, under 600 V, through high-voltage transmission systems.     

A new digital ground-fault protection system for generator–transformer unit

Ground faults are one of most often reasons of damages in stator windings of large generators. Under certain conditions, as a result of ground-fault protection systems maloperation, ground faults convert into high-current faults, causing severe failures in power system. Numerous publications in renowned journals and magazines testify about ground-fault matter importance and problems reported by exploitators confirm opinions, that some issues concerning ground-fault protection of large generators have not been solved yet or have been solved insufficiently. In this paper a new conception of a digital ground-fault protection system for stator winding of large generator was proposed. The process of intermittent arc ground fault in stator winding has been briefly discussed and actual ground-fault voltage waveforms were presented. A new relaying algorithm, based on third harmonic voltage measurement was also drawn and the methods of its implementation and testing were described.     

Development of cable fault location method using fiber optic distributed temperature sensor

When ground-fault problems occur on a cable line, immediate fault location and restoration are required. Therefore, various new methods to locate the fault point instantaneously have been investigated to replace such conventional methods as the Murray loop method and the pulse radar method [1]. These methods require a long time to locate the fault point. One possible fault location method is to sense the temperature rise following a ground fault using a fiber optic distributed temperature sensor. Application of this method was found feasible through sensing the temperature rise at a ground-fault test using a thermocouple as a temperature sensor with test cables [4]. A power/optical composite cable was prepared experimentally and after verifying its thermal mechanical performance, the temperature rise at an incidence of a fault was determined and the anticipated performance was demonstrated in a ground-fault test. This article describes the outline of the test.     

Directional ground-fault indicator for high-resistance grounded systems

Locating ground faults is a difficult and challenging problem for low-voltage power systems that are ungrounded or have high-impedance grounding. Recent work in pilot signals has renewed efforts in developing fault location methodologies. This paper presents a method for directional ground-fault indication that utilizes the fundamental frequency voltages and currents. Although the ground-fault current is small and usually less than the load currents, the fault has zero-sequence components that distinguish it from the load. Signal processing techniques are used to identify and compare the fault signals to determine the fault direction. The process takes advantage of the currents flowing from the distributed grounding capacitance. An experimental microprocessor-based directional indicator unit is tested in an industrial power distribution system. Directional indication of ground faults is applied near tap-off branch circuit connections. Promising results from field test conducted in a harmonic-noisy setting are presented. Directional indicator units simplify the search process on large networks, thus reducing the time and effort necessary to locate and remove the fault, and thereby significantly reduces the probability of a second ground fault with its destructive currents.     

基于特征频带小波包分析的小电流接地故障选线研究

分析了小电流接地系统单相接地故障时基波稳态零序电流、暂态零序电流和谐波零序电流的故障特征,并在此基础上确定了在进行小电流接地故障选线时应从零序电流暂态信号中提取故障特征量,提出了基于故障暂态电流特征频带小波包极性的选线算法,结合PSCAD仿真试验数据对选线算法进行了算例分析,并验证了算法的准确性。