Multi-Branch Fault Line Location Method Based on Time Difference Matrix Fitting

The distribution network exhibits complex structural characteristics,which makes fault localization a challenging task.Especially when a branch of the multi-branch distribution network fails,the traditional multi-branch fault location algorithm makes it difficult to meet the demands of high-precision fault localization in the multi-branch distribution network system.In this paper,the multi-branch mainline is decomposed into single branch lines,transforming the complex multi-branch fault location problem into a double-ended fault location problem.Based on the different transmission characteristics of the fault-traveling wave in fault lines and non-fault lines,the endpoint reference time difference matrix S and the fault time difference matrix G were established.The time variation rule of the fault-traveling wave arriving at each endpoint before and after a fault was comprehensively utilized.To realize the fault segment location,the least square method was introduced.It was used to find the first-order fitting relation that satisfies the matching relationship between the corresponding row vector and the first-order function in the two matrices,to realize the fault segment location.Then,the time difference matrix is used to determine the traveling wave velocity,which,combined with the double-ended traveling wave location,enables accurate fault location.

Fault Location Method Based on EEMD and Traveling-Wave Speed Characteristics for HVDC Transmission Lines

This paper presents a method of Traveling Wave Fault location based on the improved Hilbert- Huang Transform. First, Intrinsic Mode Functions (IMF) of traveling waves are extracted by Ensemble Empirical Mode Decomposition (EEMD). Then Hilbert Transform is applied to calculate the corresponding instantaneous frequency of the highest frequency component (IMF1), the instantaneous frequency and corresponding time-frequency graph are obtained. Second, the arrival time and speed can be detected by the first instantaneous frequency’s mutational point. Finally, the improved two-terminal traveling wave fault location principle is used to calculate the fault distance. Relevant simulation results are performed to verify the correctness of the method by EMTDC software.

Fault location method for transmission line based on traveling waves

The single phase grounding fault location is the focus which researchers pay attention to and study in power system. The accurate fault location can lighten the patrolling burden, and enhance the reliability of the power network. It adopts A/D which has high speed, and uses TMS320VC5402 DSP chip as the system core. This paper presented theory of operation based on traveling waves and achieved software and hardware in detail.

Correlation Analysis Algorithm for Transmission Line Fault Location Based on Travelling Wave

This paper introduced correlation method to locate transmission line fault.First it described the principle of transmission line fault location based on traveling waves.The principle of correlation analysis is introduced,then the method using correlation analysis in fault location is given.Transmission line model is established with EMTP-ATP.Basing on the model,some kinds of fault are simulated.The feasibility of this algorithm is proved based on simulation results.By comparing with the classical wavelet analysis,this paper gave the advantages of this algorithm in two cases:noise influence suppression and accuracy of near distance fault location.Experiment is established to simulate transmission line grounding fault.The experiment result showed the correlation algorithm's validity.All the analysis result indicated that the correlation algorithm have a high precision.

Fault location for parallel transmission lines using one-terminal current traveling waves

With proper phase module transformation,parallel lines can be decomposed to the same directional net and the reverse directional net. The propagation characteristics of traveling waves in the reverse directional net were analyzed,and the refraction coefficient at the fault point for a single phase fault was derived. In addition,the module selection was discussed. Simulation results show that satisfying accuracy can be achieved with the proposed method. Moreover,it is immune to fault types,fault resistances,and outside system parameters.

Study on Fault Location in the T-Connection Transmission Lines Based on Wavelet Transform

The results of T-Line Traveling Wave Fault Location is easily influenced by the wave arrival time and traveling wave propagation velocity;it proposes that the traveling wave uses wavelet transform to extract the modulus maxima of breakdown voltage, to confirm the time of the traveling wave reaching the three-terminal line. The speed of the traveling wave reaching three terminals is confirmed by the structural parameters of the transmission line. We apply the arrival time and propagation velocity to the T-type traveling wave fault location algorithm. Different transmission line distance select the corresponding algorithm, excluding the impact of fault branches and in some cases ranging accuracy, the failure dead zone will not appear. After MATLAB simulation analysis, the algorithm analysis is clear;the range accuracy is high, so that it can meet the requirements of fault location.

Research on multi-terminal traveling wave fault location method in complicated networks based on cloud computing platform

Cloud computing technology is used in traveling wave fault location,which establishes a new technology platform for multi-terminal traveling wave fault location in complicated power systems.In this paper,multi-terminal traveling wave fault location network is developed,and massive data storage,management,and algorithm realization are implemented in the cloud computing platform.Based on network topology structure,the section connecting points for any lines and corresponding detection placement in the loop are determined first.The loop is divided into different sections,in which the shortest transmission path for any of the fault points is directly and uniquely obtained.In order to minimize the number of traveling wave acquisition unit(TWU),multi-objective optimal configuration model for TWU is then set up based on network full observability.Finally,according to the TWU distribution,fault section can be located by using temporal correlation,and the final fault location point can be precisely calculated by fusing all the times recorded in TWU.PSCAD/EMTDC simulation results show that the proposed method can quickly,accurately,and reliably locate the fault point under limited TWU with optimal placement.

A novel fault location method for distribution networks with distributed generations based on the time matrix of traveling-waves

To improve location speed,accuracy and reliability,this paper proposes a fault location method for distribution networks based on the time matrix of fault traveling waves.First,an inherent time matrix is established according to the normalized topology of the target distribution network,and a post-fault time matrix is obtained by extracting the head data of initial waves from traveling wave detection devices.A time determination matrix is then obtained using the difference operation between the two matrices.The features of the time determination matrix are used for fault section identification and fault distance calculation,to accurately locate faults.The method is modified by considering economic benefits,through the optimal configuration of detection devices of traveling waves when calculating fault distances.Simulation results show that the proposed method has good adaptation with higher fault location accu-racy than two other typical ones.It can deal with faults on invalid branches,and the error rate is under 0.5%even with connected DGs.

The Comprehensive Evaluation Algorithm with Fault Location in HVDC Transmission Line

China has a vast territory with a great demand for electricity. However, the resources are in reverse distribution in the country. Therefore, high voltage direct current transmission has great practical significance and been widely used. However, traditional fault location methods have a lot of problems in engineering application for the length of transmission line and the complexity of the terrain. This paper proposes a comprehensive evaluation algorithm based on the travelling wave method and time domain method. It also proposes a concept of fault point reliability. This algorithm analyzes the fault point reliability in the whole transmission line to determine the specific location of the fault point. This paper proves that the algorithm has high reliability by PSCAD simulation software.

基于行波模态分解的特高压直流输电线路双端行波测距方法

基于晶闸管换流器的特高压直流输电系统(ultra-high voltage direct current based on line commutated converter,LCC-UHVDC)的故障定位算法对智能电网的安全稳定运行起着重要作用。针对长距离特高压直流输电系统故障测距方法精准度低、快速性差的问题,提出了一种基于变分模态分解法(variational mode decomposition,VMD)和Teager能量算子(Teager energy operator,TEO)的双端行波故障测距方法。首先,研究了LCC-UHVDC线路故障电压行波的传播特性。利用零模电压随线路传播衰减明显的特征,通过VMD算法提取采样点处零模电压行波的时频特性。针对VMD参数选择不当导致的模态混叠问题,利用K-L散度(Kullback-Leibler divergence)对提取的模态指标进行优化。然后采用TEO对分解后信号进行瞬时能量谱提取,精确标定波头到达时间,最后采用双端迭代测距法迭代求解故障距离。在PSCAD/EMTDC搭建±800 kV LCC-UHVDC仿真模型进行验证。结果表明,所提方法在不同故障位置、过渡电阻和故障类型下具有较强的鲁棒性。

基于时域波形特征认知的输电线路近端故障辨识与定位

针对现有单端行波故障测距对近端故障存在测距盲区、双端行波故障测距对近端故障测距误差较大,无法满足工程需要的不足,提出基于波形特征认知的近端故障辨识与定位方法。首先,分析了线路故障行波传播规律,以固定分辨率显示波形。发现线路近端故障时,初始行波及其后续波形在长时窗整体宏观观测下呈堆叠缓变特征,而在短时窗局部放大观测下呈周期性变化特征,且周期与故障距离相关。不同线路的近端故障历史样本能统一作为参照基准为测距提供提示。进而提出基于波形密度和突变分布的近端故障辨识方法。最后,对辨识出的近端故障进行周期估计,利用近端故障与线长的无关性以及历史样本突变周期和故障位置已知性,搜索周期最近邻历史样本,并由已知故障距离插值实现故障位置确定。基于大量实测数据进行仿真测试,结果表明所提方法能够显著提升单端行波测距可靠性和成功率。

基于波形群灵敏角特征的输电线路故障单端行波辨识与测距

针对输电线路单端行波测距难以可靠、有效辨识第二个波头的不足,该文提出基于波形群灵敏角检测的单端行波辨识与测距方法。首先,对线路故障波过程的解析和规律分析,发现波头局部波形呈现灵敏角和非轴对称性的特点。进而提出利用Radon变换变角度投影检测最灵敏角并判别最灵敏角两侧非轴对称特性,实现单端故障初始行波及多次同极性行波群的可靠辨识。最后,基于多次同极性行波到达时差构造多测距算式,输出最合理测距结果。所提方法将时域波头辨识转化为波形图像空间域最灵敏变化方向和几何轴对称性的检测,抗干扰能力强,大幅提升检测可靠性和后续波头的识别能力,提升单端测距算式冗余性。大量实测和仿真数据测试表明,算法有效、可靠、直观,适用范围广,为单端行波分析故障测距及扩展应用提供了新思路。

基于行波全景特征深度挖掘的单端故障定位方法

现有的故障定位方法基于局部波头故障特征,存在微弱故障(过零点附近故障、高阻接地故障)和母线出口处故障定位失败的技术瓶颈。为此,论文提出一种基于行波全景特征深度挖掘的单端故障定位方法。首先,基于时频域行波全景波形,理论和仿真论证了时域各次波头到达时序能反映不同故障区段,各次波头频率分布能反映故障位置,定性分析了行波全景波形与故障位置一一对应的映射机理,论证了行波全景波形唯一性理论;然后,以时频域故障全景波形为输入特征量,利用轻量级LeNet-5模型构建卷积神经网络(convolution neural network,CNN),并采用3×3小尺寸卷积核挖掘全景波形故障特征,建立全景波形特征量与故障距离的映射关系,实现精确故障定位;最后,利用激活热力图可视化技术展现CNN各卷积通道挖掘全景波形故障敏感特征,有力论证了所提方法具有强适应性的内在原因。仿真结果表明该文所提方法具有较高的定位精度,特别是针对微弱故障和母线出口处故障具有较强的算法适应性,故障定位平均绝对误差为99.855 m。

基于双目视觉的应用于行波故障定位的高压输电线长修正方法

输电线路长度受载流量、环境等因素影响发生变化,使用固定线长进行故障定位时误差较大。该文基于双目视觉技术,对输电线路图像信息进行分析处理,提出了一种应用于行波故障定位的高压输电线长修正方法。首先,根据输电线线长计算公式,将决定实际线长的参数定义为应比系数;其次,对采集到的线路图像进行极线矫正和边缘检测,计算全图像素点视差值,根据双目视觉模型恢复输电线的空间立体三维坐标;最后,对特征点坐标进行拟合,更新应比系数后代入悬链线线长计算公式,得到实际环境中输电线线长,再运用于双端行波法中进行精确定位。依据实际工程某500kV输电线路图像展开算例验证,利用PSCAD/EMTDC软件模拟行波故障定位过程,仿真结果表明所提方法能够有效减小故障定位误差,有助于故障的快速排除。

基于时间线性拟合的地缆架空混合线路的行波故障定位

目的研究n段地缆架空混合输电线路中行波故障定位问题,提出一种基于时间线性拟合的行波故障定位方法。方法首先对故障区域进行判断,确定故障所在的区域,其次再将不同波阻抗线路进行归一化处理,减少因波速不同而产生的测距误差,最后使用时间线性拟合的方法对故障进行精确定位。结果解决了初始行波波头识别困难的问题,也减小了行波速度随传输距离变化而变化带来的测距误差问题。结论在MATLAB/Simulink中搭建一个500 kV的地缆架空混合输电线路仿真模型,实验的验证结果表明此故障定位方法能够有效地解决因行波速度不同而导致的双端行波测距方法不适用问题,最终实现对故障点的精确定位。

基于CRS-LMD和SVD的MMC-HVDC线路故障测距方法

直流输电线路故障行波波速不确定、波头提取困难以及噪声干扰等因素制约了直流电网中故障测距技术的应用。为了降低上述因素对定位准确性的影响,提出一种基于局部特征有理样条插值均值分解(LMD based on characteristic rational spline,CRS-LMD)和奇异值分解(singular value decomposition,SVD)的故障测距方法。首先,利用特征尺度选取最优极点系数,结合有理样条插值调节拟合曲线的松紧程度,实现对故障电压行波的局部均值分解。其次,采用奇异值分解对故障行波波头进行准确提取。最后,在PSCAD/EMTDC中搭建了张北±500 kV柔性直流电网的仿真模型,模拟各种故障情况并输出故障数据,利用Matlab对故障数据进行处理并验证定位算法。最后,仿真结果表明,所提故障测距算法在不同故障距离和故障类型下均能实现故障测距,且在叠加噪声和过渡电阻的情况下也能保障较高的精确性。

基于行波的铁路一级负荷(自闭)贯通线路故障定位

一级负荷(自闭)贯通供电系统作为铁路供电系统的重要组成部分,其供电系统的稳定性直接决定了高速(普速)铁路的安全运行程度,因此一级负荷(自闭)贯通线路的运行状态和发生故障时的精确定位显得极为重要。根据行波的特性,通过分析故障状态下行波传输的波过程,实现基于故障状态下行波波形的铁路一级负荷(自闭)贯通线路故障点精确定位,并通过具体案例理解行波定位对运行线路故障排查的重要性。

基于双端行波频率变化特性的中低速磁浮交通供电轨故障定位方法

中低速磁浮供电轨供电过程中容易发生直流接地故障,由于其供电距离较短、接地网结构复杂,发生直流接地故障后不易准确定位故障点。为此针对以上问题,根据列车运行过程中车体与轨道无接触的特点,建立中低速磁浮牵引供电系统,分析双端故障测距与单端故障测距的优缺点,研究供电轨发生接地故障后故障行波时域分布与频域分布的关系;并通过计算式计算分析行波频谱的产生机理,得出故障行波的频率分布不受车站内阻抗、过渡电阻的影响,只与故障点位置和故障行波到达线路两端的时间相关;基于此,提出基于双端频率变化特性的中低速磁浮交通供电轨故障定位方法,根据故障行波频率特性与行波速度计算故障点位置。并且通过仿真验证,该方法不受故障点位置、过渡电阻大小影响,且适用于单处接地故障、多处接地故障类型,故障误差始终保持在1%以内,相比传统的直流牵引供电系统故障定位方法,测量精度更高,适用于中低速磁浮交通供电轨接地故障。

全并联AT牵引供电系统雷击故障测距多路径行波算法研究

针对AT变压器和并联结构导致行波传播路径复杂,行波波头性质难以有效识别和行波色散现象,线路频变参数特性导致波速不稳定的问题,提出一种基于多路径行波测距方法。基于上下行电流行波传播的差异性,利用电流相似度识别故障区段。探讨全并联AT牵引网结构对行波传播特性的影响,并对电流、电压行波传播路径进行标定。基于多路径电流、电压行波极性分析,筛选出用于故障测距的多路径行波,以推导出消去波速的测距方程。仿真表明:所提测距方法可以有效识别波头性质,且计算故障距离基本与波速无关,不受牵引网区段长度、结构影响。

基于稀疏信息差值的集电线路故障精准定位方法

针对集电线路多分支网络结构故障定位过程时精度易受测点数量和行波波速影响的问题,提出一种基于稀疏信息差值的集电线路故障定位方法。按照集电线路划分故障区域。首先,通过变分模态分解从初始行波信号中提取第一本征模函数信号,并通过Stockwell变换将其进一步分解为S矩阵。然后,通过S矩阵计算其模矩阵Q,并计算所有模矩阵之间的能量相似性,建立区域决策矩阵来识别故障区域。最后,在确定的故障区域内设置虚拟故障点,根据故障区域首末端初始行波到达时间,计算测量行波和虚拟故障点之间的信息差异度,采用离散-连续粒子群实时修正故障分支和故障位置。仿真结果表明,该方法无需集电线路所有分支行波信息,大幅降低监测设备数量,消除波速影响,实现多分支集电线路的精准故障定位。