A transmission line fault‐location system using the wavelet transform

This paper describes the locating system of line‐to‐ground faults on a transmission line by wavelet transform. The possibility of the location with the surge generated by a fault has been theoretically proposed. In order to make the method practicable, we realize very fast processors. We design wavelet transform and location chips, and construct a very fast fault location system by processing the measured data in parallel. This system is realized by a computer with three FPGA processor boards on a PCI bus. The processors are controlled by UNIX and the system has the graphic user interface with X window system. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(4): 27–37, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10040     

大型汽轮发电机定子单相接地故障定位新方法

发电机定子绕组单相接地故障定位能扩展目前定子接地保护的功能,为快速检修故障提供依据。分析了大型汽轮发电机的电动势分布特征,推导了定子绕组电势与故障位置的关系,给出了新的定子绕组电势表达式。分析了定子绕组单相接地故障时零序电压、三相电压的幅值变化特征,推导了三相电压幅值变化与故障位置和接地电阻的关系。在此基础上,提出了一种综合利用零序电压和三相电压幅值特征的定子绕组单相接地故障定位新原理。理论分析和仿真计算表明:应用本方法能可靠识别故障位置,且该方法不受中性点接地方式的影响。该方案仅需要零序电压和机端三相电压,简单易行,不需增加额外设备,适用于高阻接地故障,仿真数据验证了算法的可行性。     

以槽电势为分析单元的大型发电机定子接地故障定位方法

已有的大型发电机定子绕组单相接地故障定位方法一般以线圈匝电势为分析单元,对于短距绕组的机组存在理论误差。为此,提出一种以槽电势为分析单元的大型发电机定子单相接地故障定位方法。首先,基于绕组连接顺序,以槽电势为单元建立定子绕组电势分布的解析表达式。然后,针对发电机是否配备注入式定子接地保护采取不同的故障定位方案。若配备注入式定子接地保护,则基于注入式设备的过渡电阻测量值构造故障评价指标。若未配备注入式定子接地保护,则引入3次谐波测量值构造不含过渡电阻的故障评价指标。最后,在故障相人为设置多个虚拟参考点,结合绕组电势分布计算各虚拟参考点的故障评价指标,将计算值最小的虚拟参考点视为故障位置,进而确定故障所在槽编号。利用在PSCAD中搭建的准分布参数仿真模型验证了所提方法的有效性。     

输电线路行波故障定位技术发展及展望

输电线路是故障率最高的元件,准确的故障定位技术对于电力系统的安全可靠运行具有十分重要的作用。行波原理的故障定位技术的定位精度高,具有不受过渡电阻、线路结构不对称、线路走廊地形变化、电压和电流互感器的变换误差等因素影响的特点,且能够用于直流线路和串补电容线路。近年来行波故障定位技术在新原理的探索、行波信号的提取和分析等方面取得了长足进步,并将高速采样和存储技术应用于行波定位装置的开发。     

基于多回路理论的同步电机定子绕组内部故障仿真的谐波分析

同步电机定子绕组发生内部电气故障时,气隙磁场中存在很强的空间谐波分量。采用多回路理论进行仿真分析,充分考虑了谐波分量的影响。准确的电感参数计算是多回路分析的基础,采用磁路的气隙磁导分析法计算电机故障后各电感参数,分析了谐波的计入次数对电感参数计算的影响,进一步分析了谐波对定子绕阻内部故障仿真结果的影响,并提出了工程中合理的谐波计算次数,既能保证计算精度,又可以减少计算工作量,从而具有较快的计算速度。通过对仿真波形的分析,得出结论:在进行同步电机定子绕组内部故障的仿真计算中,必须充分计及谐波的影响。     

高压线路双端测距新算法

提出了一种新颖的超高压输电线路故障双端测距精确算法。该算法采用相-模变换技术和分布参数线路模型,考虑了双端数据的不同步问题,运用拟牛顿法迭代求解非线性方程组。仿真计算其表明具有很高的精度。     

一种新的输电线路双端测距算法

提出了一种新颖的超高压输电线路故障双端测距精确算法。该算法采用相—模变换技术和分布参数线路模型,考虑了双端数据的不同步问题,运用拟牛顿法迭代求解非线性方程组,仿真计算表明具有很高的精度。     

Accurate one‐terminal fault location algorithm based on the principle of short‐circuit calculation

An alternative method to find the line fault distance in a transmission network employing only one‐terminal measured data is presented. The proposed method applies Z_bus for short‐circuit calculation to find the fault location on a transmission line without the necessity to know the fault type a priori. The well‐known drawback of the standard simple‐reactance one‐terminal algorithm, which neglects the effect of fault impedance, will be minimized by estimating the voltage drop at the fault location by employing the Z_bus technique. Accuracy the proposed method is demonstrated using the short‐circuit simulation of the modified IEEE‐14 bus test system on MATLAB/Simulink and the Simpower Toolbox. Compared to the accuracy obtained from the standard one‐terminal algorithm, test results confirm substantially improved accuracy of the proposed method in all cases of the four types of fault categories: single line‐to‐ground fault; double line‐to‐ground fault; line‐to‐line fault; and balance three‐phase fault. While the accuracy has been significantly improved, especially for the case with a relatively high fault impedance, also the simplicity in the involved computation is well preserved when compared to other iterative‐based techniques. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

一种双端同步采样的时域故障测距算法

输电线路快速准确的故障定位是保证电力系统安全稳定运行的有效途径之一,对电力系统有重要意义。传统的单端故障测距算法易受过渡电阻及对侧助增电流影响,而双端故障测距算法一般基于频域的相量计算。提出一种基于模式理论和双端同步采样的时域故障测距算法。该算法所需传送数据量少,并且不受过渡电阻、运行方式、故障类型等因素的影响,并且可以将其推广到同杆并架双回线。EMTP仿真结果显示该算法有较高精度,测距快速简便。     

一种基于高频量衰减特性的特高压直流输电线路故障测距方法

直流输电线路故障时,高频故障暂态信号将沿线路向两端传播,线路对故障暂态信号高频分量有衰减作用。研究双极特高压直流输电线路频率特性,得到特高压直流输电线路对高频量有衰减作用,线路越长,衰减作用越剧烈的结论。研究基于高频量衰减特性的特高压直流输电线路单端故障测距原理,推导出故障点距测距装置安装点的距离公式,得到基于高频量衰减特性的特高压直流输电线路单端故障测距原理难以准确实现直流输电点线路故障测距的结论。研究基于高频量衰减特性的特高压直流输电线路双端故障测距原理,推导出故障点距测距装置安装点的距离公式,提出频带衰减概念,推导出基于频带衰减的故障距离计算公式。建立云广特高压直流输电系统实际参数仿真模型,对提出的基于高频量衰减特性的特高压直流输电线路双端故障测距原理进行仿真验证,仿真测距结果有较高的准确度。     

High‐impedance fault location using matching technique and wavelet transform for underground cable distribution network

Locating the faulty section of a high‐impedance fault (HIF) is quite challenging for the underground distribution network of a power system. The complexity of the distribution network, such as branches, nonhomogenous lines, and HIF, contributes to the difficulties in locating the faulty section. In this paper, the shortest distance (SD) technique and a database approach have been proposed to determine the faulty section. A multiresolution analysis based on discrete wavelet transforms is chosen to extract the unique features from voltage signals during the HIF event. The output coefficients from the decomposition process is stored in a database and used as the input data for the SD algorithm. The first, second, and third level of detailed coefficients of the post‐disturbance voltage signal were utilized for the identification of the faulty section using the proposed method. A ranking analysis was created to provide a number of possibilities of faulty section. In this paper, a 38‐node underground distribution network system in a national grid in Malaysia was modeled using the PSCAD software. The proposed method was able to successfully determine the faulty section. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A new false‐root identification method based on two‐terminal fault location algorithm for double‐circuit transmission lines

A fault location algorithm without synchronization for double‐circuit transmission lines does not require sampling synchronization, reduces the cost, and has a higher engineering value, but the algorithm still needs to be improved in the false‐root identification. This paper conducts further studies on this issue. First, the false‐root problem of the fault location algorithm without synchronization is analyzed, and then a new false‐root identification method is proposed, which is based on the difference of the existence of the false root in the calculation of the voltage amplitude along the line with different electrical moduli. It can solve the problem of the traditional method, which cannot distinguish between voltage amplitudes when they are close. Second, considering the shortcoming of the existing phase‐mode transformation matrix, a new phase‐mode transformation matrix applied to double‐circuit lines is deduced, which is based on the six‐sequence component method; it can be combined with the new false‐root identification method, thereby realizing false‐root identification under various types of faults. Finally, fault location is realized by using the moduli in the mold domain. The principle does not need to synchronize data in two terminals and is not affected by the fault types, fault resistances, and other factors. As is shown in a large number of Alternative Transients Program version of Electro‐Magnetic Transients Program (ATP‐EMTP) simulation results, the fault location has a higher accuracy © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

利用RTDS测试精确故障定位系统

针对高压输电线路精确故障定位装置的测试问题 ,利用RTDS仿真一个 2 2 0kV的系统 ,在其线路上设置各种特征故障 ,以测试高压输电线路精确故障定位装置的性能 ,并结合高精度测量仪器分析其误差     

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。     

一种采用时间判别法的混合线路故障行波定位方法

为解决三段式混合线路故障测距问题,在分析混合线路行波传播特性的基础上,提出一种采用时间判别法的混合线路故障行波测距方法。首先,假定故障发生路段,利用故障暂态行波到达双端母线测量端的时间差值来推算出故障暂态行波在该路段内传播到线路两侧的时间差值。然后,通过该时间差值与故障发生在该线路首端和末端的时间差值进行比较,选出满足条件的时间差值并结合双端原理给出测距结果。PSCAD仿真结果表明,采用时间判别法的混合线路故障行波测距方法可以准确、可靠地给出测距结果。     

基于基频电气量的输电线路故障测距的滤波探讨

对于采用基频电气量进行输电线故障测距的方法,基频分量提取的精度与故障测距的精度有着直接的关系。本文总结了故障测距过程中遇到的问题及解决方法,通过对不同滤波器的性能的比较,发现故障测距中,滤波的作用非常大。测距结果表明,当电力系统中存在着大量的非周期分量和高次谐波时,只有当滤波的精度满足一定的要求后,故障测距的精度才能完全满足现场要求。     

基于阻抗法和行波法组合的复线牵引网故障测距研究

由于牵引网故障测距常用的两大算法阻抗分析法和行波分析法在不同的情况下各有优缺点,因此很难用一种算法取得理想的测距结果。经过仿真对比阻抗算法和行波算法,发现二者具有优缺点互补的特性。由此提出将两种算法结合应用,取其优点,舍其缺点来提高现有故障测距算法的精确度。分别采用改进的阻抗分析法和行波分析法对30 km长的复线直供带机车牵引网模型进行仿真和误差分析。对仿真结果进行综合分析后提出组合算法,结合阻抗算法和行波算法的优点得出改进精度的仿真数据,误差分析表明结果令人满意。研究提示阻抗法和行波法组合的故障测距算法在牵引网实际应用中可能具有良好的应用前景。     

利用弧光电阻变化提高测距精度

输电线路经高阻短路时助增电流对测距精度的影响不易克服 ,但当弧光电阻阶段性变化时 ,从线路一侧测量到的距离和电阻具有线性变化的关系。通过对测量值的线性拟合 ,能估计出过渡电阻为零时的测量距离。该方法可直接用于微机保护和故障测距装置。     

Estimation of output voltage for high‐speed,surface permanent magnet generator with large air gap length

This paper presents a method to estimate the output voltage of a high‐speed, surface permanent magnet generator with large air gap length at design stage. The output voltage is estimated by the induced electromotive force and the synchronous inductance obtained from the analytical results of the flux linkage using FEM. Also, a method to classify the synchronous inductance per causative factor is proposed. The air gap leakage inductance is not negligible in a large‐air‐gap machine like this generator. The validity of the proposed method has been proved by the measured values of a generator designed by this method, and the measured values also show that the output voltage of the generator is within the permissible range. The method proposed in this paper will be an effective tool to design a high‐speed, surface permanent magnet generator with large air gap length. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(2): 52–60, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20228     

输电线路接地故障行波测距新方法

介绍了一种输电线路接地故障行波测距的新方法 ,该方法可以消除线路参数不同以及雷击时冲击电晕对行波波速的影响 ,通过小波变换得到线模及地模分量到达母线的时间 ,列出三个时间与故障距离的方程 ,最后得到与波速无关的故障测距公式。