Artificial neural network based fault diagnostic system for electric power distribution feeders

This paper describes the development of a fast, efficient, artificial neural network (ANN) based fault diagnostic system (FDS) for distribution feeders. The principal functions of this diagnostic system are: (i) detection of fault occurrence, (ii) identification of faulted sections, and (iii) classification of faults into types, e.g. HIFs (high impedance faults) or LIFs (low impedance faults). This has been achieved through a cascaded, multilayer ANN structure using the back-propagation (BP) learning algorithm. This paper shows that the FDS accurately identifies HIFs, which are relatively difficult to identify with other methods. Test results are generated using the Manitoba Hydro 24 kV distribution feeder. These results amply demonstrate the capacibility of the FDS in terms of accuracy and speed with respect to detection, localization, and classification of distribution feeder faults.     

Broken conductors protection system using carrier communication

This paper presents a detection and signaling system designed to identify and locate high impedance faults caused by broken conductors on distribution primary feeders. Unlike conventional protection systems, which perform current sensing, the working principle of the proposed system consists on monitoring the voltage unbalance along a feeder. This allows the system to detect a fault occurrence even in cases when the conductor touches a high impedance earth surface (for instance asphalt). This system has an additional advantage of giving an indication of the location of a fault since it involves measurements at multiple points on a feeder. In order to detect the voltage unbalance produced by a broken conductor, a new sensor was developed which is sensitive to the electric field generated by primary feeders. A carrier communication channel is associated to each sensor allowing the high impedance fault occurrence information to reach the protection equipment located closer to or at the substation     

电力系统的集成保护

通过介绍一种新颖的配电网保护方案来阐述集成保护的优越性。这个基于暂态极性方向比较的保护方案以伴随故障出现的暂态电流信号的检测和处理为基础,在配电网的各个变电站安装有专门设计的保护继电器,继电器的暂态检测单元检测故障生成的故障分量电信号,并将暂态极性识别算法应用于叠加故障分量信号上,判断信号的极性。通过对来自连接到变电站的所有线路的信号极性进行比较,可以确定出故障的方向。通过处理来自各变电站的方向信息,判别出实际的故障线路,从而实现电网的集成保护。     

配电网馈线自动化系统分析及技术实施要点

分析了现阶段配电网自动化系统结构及配电网馈线自动化技术。说明了实施馈线自动化的技术原则．将故障诊断流程归纳为以配电终端为基础的故障检测、以配电网子站为中心的区域控制和以主站为管理中心的高层全局控制．并提供了线路相间短路及单相接地故障的识别策略。阐述了馈线自动化处理过程,包括馈线终端装置（FTU）／开闭所终端装置（DTU）、配电网子站、主站以及架空线路的故障处理,将故障处理时间划分为永久性故障判别时间、子站故障信息收集时间、子站故障定位时间、子站执行故障隔离时间、主站处理时间、主站执行故障恢复时间。最后描述了配电网自动化的发展方向．     

A microcomputer-based unique digital fault diagnosis scheme of radial transformer feeders

This investigation aims to develop a comprehensive microcomputer based fault protection scheme for indicating various types of faults in a radial transformer feeder in subtransmission or distribution circuits and its protection against those faults. The type of fault in the feeder can also be determined by observing the phase angles of the primary currents of the transformer with which the feeder is connected at its secondary. This method dispenses off conventional electromagnetic relays and HRC fuses in feeder protection schemes. The developed system provides necessary information regarding the faulted phase and displays appropriate symbols on the display screen of the microcomputer about the type of fault.     

小电流接地故障暂态监测新技术

介绍了小电流接地故障暂态信号频域特征，基于暂态零序电流特征频段(SFB)分量幅值、极性和无功功率流向关系的故障线路选择算法，以及在此基础上研制的XJ-100小电流接地故障选线及监测系统。该系统结构合理、功能完善，检测灵敏度、可靠性高，不受消弧线圈、不稳定电弧影响，可适用于配网自动化系统和变电站综合自动化系统，并可利用瞬时接地故障信息对线路绝缘监测提出预警。     

Development of automatic fault point locating and sectional isolating system for power distribution line

This paper describes the development of the Automatic Fault Point Locating and Sectional Isolating System. This system locates a single-line-to-ground fault point at each pole by using ground-current sensors, and isolates the faulted section by controlling pole switches with no outage of unfaulted sections. The ground-current sensor is connected to the line between allied ground terminals of pole devices and grounded conductor. It detects a ground fault current of more than 0.64 amperes that is determined so as to avoid an unexpected operation by stray current, but to detect the fault current accurately, and sends out an emergency signal with time delay of 0.1 s. Sectional isolation starts when both the emergency signal from the sensor and relay operation signals from a substation are received and ends within a feeder circuit-breaker tripping time of 1.5 s.     

IEC 61850应用于分布式馈线自动化系统的模型

远传型故障指示器或功能模块可以检测配电线路各区段的故障并上传检测结果,从而为分布式馈线自动化(FA)进行故障区间定位提供判断依据。以IEC 61580-90-6技术报告所提出的故障指示功能为基础,构建基于IEC 61850的分布式馈线自动化的系统模型,提出了分布式故障区间定位、隔离和供电恢复的逻辑节点。扩展现有的IEC 61850系统配置语言(SCL)模型以描述配电网的一次拓扑和逻辑功能配置。给出IEC 61850应用于馈线自动化系统的通信服务映射。最后,提出了变电站自动化和馈线自动化系统进行数据交换的配置流程。通过应用示例表明,所提出的IEC 61850信息模型可以支持分布式馈线自动化功能和终端之间的互操作。     

基于故障电阻测量的小电流接地系统保护方法

为解决小电流接地系统高阻接地故障检测的难题,分析了单相接地故障前后相电流变化特征:故障线路的故障相与非故障相电流变化量之差等于接地故障电流,非故障线路的故障相与非故障相电流变化量相等;并由故障相电压与故障电流之比计算出接地故障电阻,发明了基于接地故障电阻测量的高阻接地保护方法。EMTP仿真分析和动模实验测试结果表明,该保护方法能够保护各种高阻接地故障,具有较高的保护精度和可靠性,适合在配电自动化终端单元(FTU)上就地实现。     

Fault diagnosis system for tapped power transmission lines

This paper presents a design for a fault diagnosis system (FDS) for tapped HV/EHV power transmission lines. These lines have two different protection zones. The proposed approach reduces the cost and the complexity of the FDS for these types of lines. The FDS consists basically of fifteen artificial neural networks (ANNs). The FDS basic objectives are mainly: (1) the detection of the system fault; (2) the localization of the faulted zone; (3) the classification of the fault type; and finally (4) the identification of the faulted phase. This FDS is structured in a three hierarchical levels. In the first level, a preprocessing unit to the input data is performed. An ANN, in the second level, is designed in order to detect and zone localize the line faults. In the third level, two zone diagnosis systems (ZDS) are designed. Each ZDS is dedicated to one zone and consists of seven parallel-cascaded ANN's. Four-parallel ANN's are designed in order to achieve the fault type classification. While, the other three cascaded ANN's are designed mainly for the selection of the faulted phase. A smoothing unit is also configured to smooth out the output response of the proposed FDS.     

新型智能重合控制器及其应用

提出一种用于中压馈线自动化的户外柱上型智能重合控制器实现方案。以工业级微控制器Intel 87C196KC为核心,应用现场总线和智能化技术将测量、控制、保护、计量、远动和故障诊断等综合自动化、配电自动化功能就地分散到开关安装处,采用CAN总线构造户外智能化设备的全分布式对称型多主网络。现场运行结果表明该方案具有可靠性高、运行稳定、成本低等优点,还能与目前广泛应用的变电站综合自动化、调度自动化系统相配合,为今后的配电自动化打下了基础。     

小电流接地系统故障检测选线的一种新算法

提出了一种新的基于暂态零模量电流差分算法的接地系统故障检测方法,适用于中性点不接地或非直接接地的配电系统。该方法是计算每一路馈线的暂态电流零模量值,然后利用其差分比率,实现接地系统故障的检测。利用Matlab/Simulink进行仿真,模拟了3种不同故障条件下的仿真过程,验证了该方法的可行性。     

Required limiting impedance and capacity of fault current limiter installed in customer system with synchronous generator

We investigated the required limiting impedance and capacity of a fault current limiter (FCL) installed at an incoming feeder of a customer system with a synchronous generator in a utility distribution system. It was assumed that two types of FCL were installed, i.e. a resistive type (R‐type) FCL and an inductive type (L‐type) FCL. A fault current out of the customer system and a voltage in the customer system were calculated following a three‐phase, short‐circuit fault occurrence. It was found that the required type of FCL and the required limiting impedance depended on the rated capacity of the generator in order to obtain the suppression of the fault current under 0.1 kA_S and to maintain of customer voltage between 85 and 100% of the nominal voltage (6.6 kV). The capacity of FCL consisting of the smallest limiting impedance is discussed. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于KL散度的配电网高阻抗故障检测研究

高阻抗故障（HIF）主要与电弧现象有关,具有低电流、随机性、非线性和不对称性特征。配电网过流保护系统需要考虑HIF的低故障电流,检测功率损失、潜在火灾危险和电击风险。提出了一种基于变电站电流波形的时域HIF检测算法,利用Kullback-Leibler散度相似性度量,量化了电流波形两个故障后半周期的非线性和不对称性特征作为HIF检测的判据,此判据也被用来区分HIF与负荷、电容器、馈线和分布式能源投切事件以及电压骤降和浪涌事件。利用IEEE13节点和IEEE34节点测试系统进行了大量的时域仿真,验证了所提HIF检测算法的优越性。     

基于可辨识矩阵的单相接地故障选线新方法

配电网单相接地故障时的故障电气量微弱,必须设法突出故障电气量才有助于提高选线的准确率。针对电气量的幅值比较选线原理,提出了基于可辨识矩阵的幅值比较选线判据。构造了幅值特征量的可辨识矩阵,可辨识矩阵中的元素为各线路中每2条线路幅值特征量的差,使各线路的幅值特征量作相对比较,有效地拉大了故障线路和非故障线路故障判断量的差距,突出了最大故障特征量,极大地提高了保护裕度。ATP和MATLAB仿真验证了该方法的可行性和有效性,能有效地提高选线的准确率。该方法适用于任何一种基于电气量幅值比较原理的选线保护。     

基于电压-时间型馈线自动化的小电流接地故障定位方法

在大力开展配电自动化系统建设的背景下,提出一种基于电压-时间型馈线自动化且适用于小电流接地系统的接地故障定位方法。当接地故障发生时,通过小电流接地选线装置对接地线路做出判断,依据故障发生概率从大至小逐条触发变电站出线断路器跳闸,经过设置时间后重合,线路上的馈线自动化开关逐级得电合闸,当合于接地故障点时,在设定时间内开关自动分闸并闭锁,从而实现接地故障的自动定位与隔离,大幅度减少抢修人员的工作量。所提方法无需依赖配电主站、配电网稳定通信、变电站小电流选线装置选线高准确率,仅依靠现有馈线自动化终端简单的逻辑判断便将故障隔离,并恢复非故障线路的供电,具有更高的可靠性。     

基于零序量采集值的配电网故障定位

中性点不接地系统单相接地故障的定位方法大部分需要安装额外设备,只能实现故障选线,对于故障馈线上的选段技术研究很少。为实现更方便更精确的故障定位,针对故障后配电网零序电路进行分析,得到电气量的故障特征,据此提出基于零序量采集值的故障选相、选线、选段的若干依据,用于故障定位并扩展至含分布式电源的配电网。经过Matlab仿真验证,该方法不仅具有较高的可靠性和定位精度并且节约了设备成本,降低了实施难度,适应于智能配电网的建设。     

信息融合技术在电力系统故障检测中的应用探讨

电力系统故障产生各种故障信息，对故障信息全面分析、综合处理，能提高故障检测的精度和鲁棒性。为实现对各种传感器检测到的多源故障信息进行有机综合处理，需研究信息综合处理技术。信息融合技术是研究多源信息综合处理的新兴边缘学科，已在军事、信息处理等领域中有着成熟的应用。该文把信息融合技术应用于电力系统故障检测，介绍信息融合故障检测的模型与方法；分析信息融合技术在状态监测、继电保护中的应用技术；并以小电流接地系统故障选线为例，提出研究了模糊信息融合故障选线方法技术，提高了故障选线的灵敏度和可靠性。     

A novel controllable crowbar based onfault type protection technique for DFIGwind energy conversion system usingadaptive neuro-fuzzy inference system

This paper proposes a novel controllable crowbar based on fault type (CBFT) protection technique for doubly fed induction generator (DFIG) wind energy conversion system connected to grid. The studied system consists of six DFIG wind turbines with a capacity of 1.5 MW for each of them. The operation mechanism of proposed technique is used to connect a set of crowbar resistors in different connection ways via activation of controllable circuit breakers (CBs) depending on the detected fault type. For each phase of DFIG, a crowbar resistor is connected in parallel with a controllable CB and all of them are connected in series to grid terminals. The adaptive neuro-fuzzy inference system (ANFIS) networks are designed to detect the fault occurrence, classify the fault type, activate the CBs for crowbar resistors associated with faulted phases during fault period, and deactivate them after fault clearance. The effectiveness of proposed CBFT protection technique is investigated for different fault types such as symmetrical and unsymmetrical faults taking into account the single-phase to ground fault is the most frequently fault type that occurs in power systems. Also, a comparison between the behaviours of studied system in cases of using traditional parallel rotor crowbar, classical outer crowbar, and proposed CBFT protection techniques is studied. The fluctuations of DC-link voltage, active power, and reactive power for studied system equipped with different protection techniques are investigated. Moreover, the impacts of different crowbar resistance values on the accuracy of proposed technique are studied. The simulation results show that, the proposed technique enhances the stability of studied wind turbine generators and contributes in protection of their components during faults.     

主动干扰技术在消弧线圈接地系统故障选线中的应用

针对中性点经消弧线圈接地系统提出一种无需额外信号注入装置的故障选线方法:当馈线发生单相接地故障时,通过控制消弧线圈所连接的电力电子开关短时投切阻尼电阻,从而产生频率成分丰富的扰动电流信号,通过在各出线中对扰动电流信号进行检测和分析实现故障选线。所提方法不需要额外的信号发生装置,对于高阻接地故障同样适用。理论分析、仿真分析和模拟实验都验证了该方法的有效性。