A new PMU-based fault detection/location technique for transmission lines with consideration of arcing fault discrimination-part II: performance evaluation

The theory and algorithms of the proposed technique have been presented in Part I of this two-paper set. In Part II of this two-paper set, the proposed technique is evaluated by considerable simulation cases simulated by the Matlab/Power system Blockset simulator. For the proposed fault detector, the trip time achieved can be up to 3.25 ms and the average value of trip times is about 8 ms for both permanent and arcing faults on transmission lines. For the proposed fault locator, the accuracy can be up to 99.99% and the error does not exceed 0.45%. Moreover, the proposed arcing fault discriminator can discriminate between arcing and permanent faults within four cycles after fault inception. It has proven to be an effective tool to block reclosing on the permanent faults in the computer simulations. The simulation results also demonstrate that the presented extended discrete Fourier transform algorithm eliminates effectively the error caused by exponentially decaying dc offset on fundamental and harmonic phasor computations. Finally, a test case using the real-life measured data proves the feasibility of the proposed technique.     

A WAMS/PMU-based fault location technique

A WAMS (wide-area measurement/monitoring system)/PMU (phasor measurement unit)-based fault location technique is proposed in this paper. The technique uses synchronized fault voltages of two nodes of the faulted line and their neighboring nodes for fault location. Based on these fault node voltages measured by PMUs, line currents between these nodes can be calculated. Then, node injection currents at two terminals of the faulted line are formed from the line currents. Based on the calculated fault node injection currents, fault node can be deduced or fault location in transmission lines can be calculated accurately. Fault location formulas are derived in full details. Case studies on IEEE-14-bus system and a testing network with 500 kV transmission lines including ATP/EMTP simulations are given to validate the proposed technique. Various fault types and fault resistances are also considered.     

A new PMU-based fault location algorithm for series compensatedlines

This paper presents a new fault location algorithm based on phasor measurement units (PMUs) for series compensated lines. Traditionally, the voltage drop of a series device is computed by the device model in the fault locator of series compensated lines, but when using this approach errors are induced by the inaccuracy of the series device model or the uncertainty operation mode of the series device. The proposed algorithm does not utilize the series device model and knowledge of the operation mode of the series device to compute the voltage drop during the fault period. Instead, the proposed algorithm uses two-step algorithm, prelocation step and correction step, to calculate the voltage drop and fault location. The proposed technique can be easily applied to any series FACTS compensated line. EMTP generated data using a 30-km 34-kV transmission line has been used to test the accuracy of the proposed algorithm. The tested cases include various fault types, fault locations, fault resistances, fault inception angles, etc. The study also considers the effect of various operation modes of the compensated device during the fault period. Simulation results indicate that the proposed algorithm can achieve up to 99.95% accuracy for most tested cases     

An adaptive PMU based fault detection/location technique fortransmission lines. I. Theory and algorithms

An adaptive fault detection/location technique based on a phasor measurement unit (PMU) for an EHV/UHV transmission line is presented. A fault detection/location index in terms of Clarke components of the synchronized voltage and current phasors is derived. The line parameter estimation algorithm is also developed to solve the uncertainty of parameters caused by aging of transmission lines. This paper also proposes a new discrete Fourier transform (DFT) based algorithm (termed the smart discrete Fourier transform, SDFT) to eliminate system noise and measurement errors such that extremely accurate fundamental frequency components can be extracted for calculation of fault detection/location index. The EMTP was used to simulate a high voltage transmission line with faults at various locations. To simulate errors involved in measurements, Gaussian-type noise has been added to the raw output data generated by EMTP. Results have shown that the new DFT based method can extract exact phasors in the presence of frequency deviation and harmonics. The parameter estimation algorithm can also trace exact parameters very well. The accuracy of both new DFT based method and parameter estimation algorithm can achieve even up to 99.999% and 99.99% respectively, and is presented in Part II. The accuracy of fault location estimation by the proposed technique can achieve even up to 99.9% in the performance evaluation, which is also presented in Part II     

A new fault location technique for two- and three-terminal lines

A method for the computation of fault location in two- and three-terminal high voltage lines is presented. It is based on digital computation of the three-phase current and voltage 60/50 Hz phasors at the line terminals. The method is independent of fault type and insensitive to source impedance variation or fault resistance. Furthermore, it considers the synchronization errors in sampling the current and voltage waveforms at the different line terminals. The method can be used online following the operation of digital relays or offline using data transferred to a central processor from digital transient recording apparatus. The authors start with a two-terminal line to explain the principles and then present the technique for a three-terminal line. The technique was first tested using data obtained from a steady-state fault analysis program to evaluate the convergence, observability, and uniqueness of the solution. The technique was then tested using EMPT-generated transient data. The test results show the high accuracy of the technique     

A new fault location algorithm for radial transmission lines withloads

Conventional fault location schemes do not take loads and their variable impedance behavior into account. This leads to unacceptable errors in the case of radial transmission lines with loads, commonly found at the 120 kV and lower levels. A novel method for such lines is proposed. The fault distance is obtained by solving an implicit equation. Single-phase-to-ground, phase-to-phase, and three-phase-to-ground faults are treated. The effect of the scheme is illustrated by simulated faults     

A novel principle of single-ended fault location technique for EHV transmission lines

A new fault location principle using one terminal voltage and current data for EHV transmission lines is described in this paper, which is based on distributed parameter line model, breaking through the traditional single-ended fault location ideas. The voltage profile along the healthy line could be calculated using single-ended voltage and current data; however, the voltage profile behind the fault point is not true for a faulted line. Even though, notice the fact that the norm value of derivative function of the "fictitious profile" to distance is minimum at fault point, based on which the fault location function is constructed. The numerical algorithm is also described; this principle is proved by EMTP simulations to be immune to fault resistance, fault types, and fault inception angle. Theoretically, the accuracy of the principle is proportional to the sampling rate of the locator.     

A new protection scheme for fault detection, direction discrimination, classification, and location in transmission lines

This paper presents a new adaptive fault protection scheme for transmission lines using synchronized phasor measurements. The work includes fault detection, direction discrimination, classification, and location. Both fault-detection and fault-location indices are derived by using two-terminal synchronized measurements incorporated with distributed line model and modal transformation theory. The fault-detection index is composed of two complex phasors and the angle difference between the two phasors determines whether the fault is internal or external to the protected zone. The fault types can be classified by the modal fault-detection index. The proposed scheme also combines online parameter estimation to ensure protection scheme performance and achieve adaptive protection. Extensive simulation studies show that the proposed scheme provides a fast relay response and high accuracy in fault location under various system and fault conditions. The proposed method responds very well with regards to dependability, security, and sensitivity (high-resistance fault coverage).     

Discussion of "A novel fault detection technique of high impedance arcing faults in transmission lines using the wavelet transform"

The authors comment on the paper by C.-H. Kim et al. (see ibid., vol.17, p.921-9, 2002). They ask the authors to describe the circumstances for 154 kV system arcing faults. They also comment on the fault inception angle, wavelet selection, and the advantages of the wavelet transform in relation to its use.     

高压输电线路单端故障测距新方法

提出了一种新的单端故障测距的方法,根据故障发生后的故障附加网络,利用单端故障电压电流计算沿线故障电压对距离的导数,然后再求其范数在线路上的分布,根据其分布特点确定故障点的位置,实现测距.仿真证明该新方法具有较高的准确度和稳定性.     

基于抗差估计理论的输电线路故障定位新型算法

针对采样中出现的粗差,提出了一种基于抗差估计理论的故障定位算法.通过等价权原理,将抗差估计理论和最小二乘法有机的结合起来,有效地避免了粗差的影响.算法采用微分方程作为数学模型,并利用相模变换解耦;然后,在模域采用输电线路双端信号列写故障点方程;最后,用抗差最小二乘法求解.经过RTDS实验表明,该算法结果稳定,具有很好的准确性和抗干扰能力.     

平行双回线两点故障测距算法的研究

以分布参数作为高压输电线路的模型,对平行双回线一回线上两点异相故障及两回线上两点故障提出了一种新的测距算法.该方法利用线路两端电压、电流的正序和负序分量,不需选代计算,并适用于一点故障情况.其测距精度不受系统阻抗变化、过渡电阻及不同步采样数据的影响.仿真计算表明该方法有效.     

一种无需线路参数的输电线路故障定位算法

提出了一种新的输电线路故障定位算法,该算法利用故障时正、负序网络中各自电压、电流间的关系,导出了故障定位方程.无需线路参数,只需借助GPS实现同步采集线路两端的电压、电流数据,并作相关处理,即可实现故障定位.与传统方法相比,该算法不受线路参数变化、故障发生地点环境以及故障过度电阻等的干扰,实现简单、灵活,实用性更强.同...     

架空输电线路故障测距的方法及应用

当架空输电线路发生故障时．必须对线路进行快速准确的故障测距．目前架空输电线路故障测距所采用的方法有阻抗测距法和行波测距法。通过介绍这两种测距方法的工作原理及其各自在电力系统中的实际应用情况．对它们的优点和存在问题进行了分析比较,并对行波测距法进行了较为详细的分类比较,指出A型行波测距法将会在今后的故障测距领域中逐渐得到推广应用。     

一种反应输电线路故障行波的测距方法

分析了故障暂态电流行波的基本理论,提出了一种故障测距原理,以同母线上任一"有限长"非故障线路作为参考线路,通过比较由故障线路暂态电流行波与该参考线路暂态电流行波形成的反向行波浪涌与其对应的正向行波浪涌的极性,识别来自故障方向的行波浪涌,消除了来自参考线路的暂态行波浪涌的影响。通过以本原理构成的故障测距系统进行实际检验,测距精度明显高于目前故障录波器的测距精度。理论分析和实测波形分析均表明该原理是可行的,并可以同时适用于永久性故障和瞬时性故障,而且不受电压过零故障的影响,在标准模式下还不受线路对端母线反射波的影响。     

A new approach for fault location problem on power lines

In most traditional approaches, fault locations have been detected through the use of lumped models. Since these models do not represent the capacitance of the transmission lines, significant errors are generally encountered in exact location of faults. The authors suggest a novel technique based upon the distributed model of power transmission lines to overcome the problems encountered in traditional approaches. This approach considers the effects of capacitance explicitly and therefore enables the detection of faults in transmission lines more precisely. The proposed method can calculate a fault location even for a zero fault inception angle. It requires a lower rate of sampling frequency. The maximum error of the method is less than Dx/2 where Dx is the distance between two consecutive points along the transmission line at which the values of the new function are calculated     

基于小波变换的超高压输电线路故障选相新原理

介绍了连续小波变换定义、基于多分辨分析的Mallat快速小波分解算法。根据超高压(EHV)输电线路故障暂态电流的特点。提出了基于小波变换能量特征的故障选相新原理和算法。借助MATLAB/SIMULINK仿真分析软件,研究了一实际电网EHV输电线路在区内不同故障条件下选相原理的有效性。结果表明,该方案是可行的。     

A new and accurate fault location algorithm for combined transmission lines using Adaptive Network-Based Fuzzy Inference System

This paper presents a new and accurate algorithm for locating faults in a combined overhead transmission line with underground power cable using Adaptive Network-Based Fuzzy Inference System (ANFIS). The proposed method uses 10 ANFIS networks and consists of 3 stages, including fault type classification, faulty section detection and exact fault location. In the first part, an ANFIS is used to determine the fault type, applying four inputs, i.e., fundamental component of three phase currents and zero sequence current. Another ANFIS network is used to detect the faulty section, whether the fault is on the overhead line or on the underground cable. Other eight ANFIS networks are utilized to pinpoint the faults (two for each fault type). Four inputs, i.e., the dc component of the current, fundamental frequency of the voltage and current and the angle between them, are used to train the neuro-fuzzy inference systems in order to accurately locate the faults on each part of the combined line. The proposed method is evaluated under different fault conditions such as different fault locations, different fault inception angles and different fault resistances. Simulation results confirm that the proposed method can be used as an efficient means for accurate fault location on the combined transmission lines.     

A new non-communication protection technique for transmission lines

This paper proposes a new noncommunication protection technique for transmission line protection. The technique relies on firstly the detection of fault generated high frequency current transient signals. A specially designed multi-channel filter unit is then applied to the captured signals to extract desired bands of high frequency signals. Comparison between the spectral energies of different bands of the filter outputs determines whether a fault is internal or external to the protected zone. In addition to the saving in costs through negating the need for a communication link, the technique also retains many advantages of the `transient based protection' technology, such as insensitivity to fault type, fault position, fault path resistance and fault inception angle. It is also not affected by CT saturation, the power frequency short-circuit level at the terminating busbar or the precise configuration of the source side networks     

A combined impedance and traveling wave based fault location method for multi-terminal transmission lines

A new fault location method suitable for multi-terminal transmission lines that combines the advantages of both impedance and traveling wave based methods has been developed and presented in this paper. The proposed method first determines whether the fault is grounded or ungrounded by comparing the magnitude of the ground mode wavelet coefficients at the measurement end. Next, the impedance based method is used to identify the faulted half of the line in the case of two-terminal line and the faulted line section as well as the faulted half of the line section in the case of multi-terminal lines. Finally the fault location is determined by taking the time difference between the first two consecutive aerial modes of the current traveling waves observed at one end of the multi-terminal line. The proposed method has been tested on four- and five-terminal transmission lines with different types of faults, fault resistances and fault inception angles using ATP simulation.