Accurate fault locator for EHV transmission lines based on radial basis function neural networks

This paper describes the design and implementation of an artificial neural networks-based fault locator for extra high voltage (EHV) transmission lines. This locator utilizes faulted voltage and current waveforms at one end of the line only. The radial basis function (RBF) networks are trained with data under a variety of fault conditions and used for fault type classification and fault location on the transmission line. The results obtained from testing of RBF networks with simulated fault data and recorded data from a 400 kV system clearly show that this technique is highly robust and very accurate. The technique takes into account all the practical limitations associated with a real system. Thereby making it possible to effectively implement an artificial intelligence (AI) based fault locator on a real system.     

虚拟同步机并网运行下电网谐波抑制和故障穿越策略

针对电网发生对称故障瞬间传统阻抗重塑型谐波电流抑制方法严重加剧虚拟同步发电机(virtual synchronous generator, VSG)故障电流的问题,介绍了传统阻抗重塑型谐波电流抑制方法的原理。基于电网不对称故障下VSG谐波阻抗模型,揭示了传统阻抗重塑型谐波抑制方法加剧VSG故障电流的机理。在此基础上,提出一种VSG谐波电流与故障电流协同抑制方法。通过引入虚拟电感重塑电网故障点至VSG的等效阻抗,实现了VSG并网运行下电网谐波和故障电流的协同抑制,有利于改善电网电能质量并提高VSG的故障穿越能力。最后,通过仿真验证所提控制策略的正确性和有效性。     

Digital fault location for parallel double-circuit multi-terminaltransmission lines

Two new methods are proposed for fault point location in parallel double-circuit multi-terminal transmission lines by using voltages and currents information from CCVTs and CTs at all terminal. These algorithms take advantage of the fact that the sum of currents flowing into a fault section equals the sum of the currents at all terminals. Algorithm 1 employs an impedance calculation and algorithm 2 employs the current diversion ratio method. Computer simulations are carried out and applications of the proposed methods are discussed. Both algorithms can be applied to all types of fault such as phase-to-ground and phase-to-phase faults. As one equation can be used for all types of fault, classification of fault types and selection of faulted phase are not required. Phase components of the line impedance are used directly, so compensation of unbalanced line impedance is not required     

利用暂态行波测距的研究

文章阐述了利用单端量暂态行波实现架空线路故障测距的原理与技术，并在此基础上推出研制的新型故障测距装置。理论分析和装置试验结果表明，在此提出了用于Ａ型行波测距技术是可行和有效的，以行波法测距为主，以阻抗法为辅并廉作启动元件可进一步提高装置的可靠性。     

基于故障分量综合阻抗的输电线路纵联保护

提出了一种基于故障分量综合阻抗的纵联线路保护新原理。利用故障时线路两端故障分量电压相量和与故障分量电流相量和的比值,来判断线路上是否发生了故障。在外部故障时,该比值反映输电线路上的容抗,其模值较大;内部故障时,该比值反映系统电源阻抗和线路阻抗,其模值相对较小,据此可以区分线路上的内部和外部故障。新原理易整定,本身具有选相能力,不受电容电流的影响,可以用于带或不带电抗器补偿的线路,理论上与过渡电阻无关。EMTP仿真和动模数据验证了该原理的有效性。     

一起直流系统接地故障的分析与处理

介绍一起因数字电液调节系统故障导致的直流系统接地故障的处理过程,分析了直流接地处理过程中的风险控制手段,提出了采用便携式直流系统接地故障定位仪进行直流系统接地问题查找的建议。     

现代行波故障测距装置及其运行经验

介绍了XC-11型现代输电线路行波故障测距装置的构成及工作原理，并 总结了该装置自1995年以来在我国电网中的运行经验。该装置直接采集常规电流互感器二次 电流信号，并采用3个独立的单片机系统分别完成高速数据采集与处理、GPS时间同步与 锁定 以及通信和人机对话等功能。装置实现了A，D，E等3种现代行波故障测距原理，其中A型和E 型均为单端原理，而D型为双端原理。运行经验表明，该装置具有较高的可靠性、准确性及 性能价格比，其平均绝对测距误差不超过400 m，最大绝对误差不超过900 m。     

An alternative approach to fault location on power distribution feeders with embedded remote-end power generation using artificial neural networks

In this paper, the design and implementation of a feed-forward artificial neural network (ANN)-based fault locator to classify and locate shunt faults on primary overhead power distribution lines with load taps and embedded remote-end power generation is presented. In the ANN algorithm, the standard back-propagation technique with a sigmoid activation function is used. The fault locator utilizes fault voltage and current samples obtained at a single location of a typical radial distribution system. The ANNs are trained with data under a wide variety of fault conditions and used for the fault type classification and fault location on the distribution line. A 34.5?kV distribution system is simulated using electro-magnetic transients program and their results are used to train and test the ANNs. The ANN-based fault locator gives high accuracy for the vast majority of the practically encountered systems and fault conditions, including the presence of load taps and the remote-end in-feed source.     

基于故障分量正序、负序和零序综合阻抗的线路纵联保护新原理

提出了故障分量正序综合阻抗、负序综合阻抗和零序综合阻抗的概念。发生区外故障时,故障分量正序综合阻抗等于线路正序容抗,负序综合阻抗等于线路负序容抗,零序综合阻抗等于线路零序容抗,数值较大;被保护线路上发生区内故障时,故障分量正序综合阻抗、负序综合阻抗和零序综合阻抗分别反映系统和线路的正序、负序和零序阻抗,数值较小。根据该特征,可以区分线路上是否发生故障,据此提出了基于故障分量正序综合阻抗、负序综合阻抗和零序综合阻抗的纵联线路保护原理,不需对电容电流进行补偿,灵敏度高,不受过渡电阻的影响,整定原则明确,定值裕度大。     

一种耐高阻和抗负荷电流影响线路单相接地距离保护

采用集总参数建模,利用保护安装处测量到的电气量计算保护安装处到接地故障点的电压降,根据线路保护安装处到接地故障点的电压降与故障距离呈线性关系计算接地故障距离和故障线路测量阻抗。该方法原理上消除了过渡电阻和负荷电流对阻抗距离保护动作性能的影响,适用于振荡工况。仿真分析和2套不同电压等级线路的故障录波数据测试表明,所提方法具有很强的耐受过渡电阻和负荷电流影响的能力,具有良好的现场实用价值。     

SSSC对阻抗继电器动作特性的影响分析

将SSSC安装于线路中点,根据SSSC在故障范围之内和之外2种情况,对阻抗继电器的测量阻抗进行了分析,且通过SSSC的不同注入电压和补偿方式,以及过渡电阻的变化,仿真了阻抗继电器的动作特性。结果表明,SSSC在故障范围之内时对阻抗继电器的测量阻抗产生了很大的影响,应该采取措施减小SSSC对阻抗继电器的影响;另外,过渡电阻的影响同样不可忽略。     

零序电流差动保护选相元件

针对零序电流差动保护选相元件受负荷电流影响,在高阻接地故障中灵敏度较低的情况,文中提出了一种基于序分量的零序电流差动保护选相元件。选相元件包括三部分:利用负序与零序差动电流大小相近区分单相接地两相高阻接地故障;利用正序差动电流与负序差动电流的相位关系区分单相接地与两相金属性接地故障;利用低制动系数差动判据防止区外三相短路不平衡零序电流。RTDS仿真结果表明:提出的选相元件不受过负荷影响,无需补偿,可以准确选出单相接地故障相,灵敏度高于零序电流差动保护,保证零序电流差动保护准确分相跳闸。     

变压器保护新原理

变压器通常采用纵差动保护作为主保护,纵差动保护会受到励磁涌流的影响而误动作。目前已有很多识别励磁涌流的方法,但都有其局限性,不能绝对可靠地区分励磁涌流和空投于故障变压器的短路电流。该文提出了一种不受空投时励磁涌流影响的变压器差动保护原理,并用阻抗原理反应空投于内部故障。这种保护配置在内部故障时有很高的灵敏度,在外部故障时又有很强的制动作用,不反映空投时的励磁涌流,却能反映变压器空载合闸时有故障的情况,解决了变压器差动保护的难题。     

基于测量波阻抗的母线保护新方法

为避免电流互感器饱和对母线保护的影响,提出一种基于测量波阻抗的母线保护新方法:对母线区内、外故障的情况进行了理论分析,当发生母线区内故障时,所有线路的测量波阻抗的极性均为负,幅值近似相等;当母线发生区外线路故障时,故障线路的测量波阻抗的极性为正,且其幅值远小于非故障线路的测量波阻抗的幅值;通过对母线上各线路的测量波阻抗的极性和幅值进行比较即能判断母线故障类型。此外,还对该母线保护新方法的实现方案进行了探讨,得到了可行的保护实现方案。理论分析及EMTP仿真表明,基于测量波阻抗的母线保护方法基本不受故障类型、故障过渡电阻、故障距离和故障初始角的影响,且能体现行波的本质,保护方法可靠、有效。     

基于零序差动阻抗的输电线路保护新原理研究

针对现有的输电线路光纤纵联差动保护原理易受分布电容电流影响较大,且要求线路两端信息的严格同步的问题,研究了一种基于双侧信息的零序差动阻抗保护原理。给出了零序差动阻抗的定义为线路两端零序电压与零序电流比值之和。由理论分析可知区内故障时零序差动阻抗为两侧系统零序阻抗和的负值,阻抗位于第三象限,区外故障时零序差动阻抗为线路的阻抗,阻抗位于第一象限。根据零序差动阻抗的阻抗角构成保护判据。在PSCAD中搭建模型进行仿真实验,实验结果表明,零序差动阻抗保护原理不受对地电容电流和过渡电阻的影响,适用于带并联电抗器补偿的线路和弱馈电系统,并不要求两侧信号严格同步。     

A fault location technique for rural distribution feeders

This work presents a digital fault location technique for rural distribution feeders, using the voltage and current data at a single location. Rural distribution feeders include single-phase, two-phase, and three-phase laterals off a main three-phase primary distribution feeder. The fault location scheme presented here attempts to account for the multiphase laterals, the unbalanced conditions, and the unsymmetrical nature of distribution feeders by continually updating voltage and current vectors at set locations within the system. The updated voltage and current vectors are the estimates of the 60-Hz phasor quantities obtained using a recursive optimal estimation algorithm. The distance to the fault is then estimated using a method based on the apparent impedance approach and the updated voltage and current vectors. Another consideration is the ability to determine the fault location on a lateral. A simulation of an actual rural distribution feeder using the Electromagnetic Transients Program (EMTP) is used to test the approach     

GPS travelling wave fault locator systems: investigation into theanomalous measurements related to lightning strikes

A new fault location system based on the travelling wave principle and capable of locating faults on power lines to within ±one tower span (300 m) has been successfully developed and applied to BC Hydro's extensive 500 kV network. Unlike earlier schemes which are based on impedance measurements, its accuracy is not affected by load conditions, high grounding resistance and most notably series capacitor banks. This system measures the time of arrival of a fault-generated travelling wave at the line terminals using the precise timing signals from the Global Positioning System (GPS). Operating experience with the fault locator on lightning related faults indicated highly accurate results were obtained for the majority of the cases. In a few of the lightning-caused disturbances, the system gave anomalous measurements. This paper describes the operation of the system, summarizes the operating experience and explains the observed anomalous measurements     

现代距离保护技术的最新发展——高阻接地故障保护

文章基于负序电流、零序电流和负序零序复合电流,提出了一种适用于单相接地故障的距离继电器故障阻抗测量新原理。新原理基于假设:输电线路故障时,过渡电阻是纯电阻性的,故障点电压和故障分支电流同相位。新算法不受过渡电阻、负荷电流、系统振荡的影响。PSCAD仿真表明本文算法的精确性。     

New smart fault locator in compensated line with UPFC

In this paper, a new smart fault locator in a compensated transmission line with a Unified Power Flow Controller (UPFC) is proposed. Three types of features are extracted from the captured fault signals at one-end of the compensated line by using a time-frequency signal processing tool known as the Hyperbolic S-Transform (HST). The HST, with an asymmetrical window, is an improved version of the S-transform. Then, the regression model of the Support Vector Machines (SVMs) with a non-linear kernel function is applied for the fault location estimation. The proposed smart fault locator gives accurate estimation results by involving hidden statistical features which comprise a new type of time-frequency features. The evaluation of the features and the estimation error obtained under different conditions confirm the efficacy of the proposed smart fault locator.     

A Universal Fault Location Technique for N-Terminal $({N}geqq 3)$ Transmission Lines

This paper presents a universal fault location technique for N-terminal transmission lines based on synchronized phasor measurement units. The development of the technique is based on two-terminal fault location technique. The proposed algorithm is different from traditional multiterminal fault location techniques. We apply two-terminal fault location technique to N-terminal transmission lines and propose a novel fault section selector/fault locator. The proposed method has a very good tolerance. The proposed approach provides an analytical solution and its computational burden is very low since it does not require iterative operations. An extensive series of simulations were conducted to verify the accuracy of the proposed algorithm. The average fault location error under various fault conditions is well below 1%.