Fault Location Method for STATCOM Connected Transmission Lines Using CCM

Determining the fault location using conventional impedance based distance relay in the presence of FACTS controllers is a challenging task in a transmission line. A new distance protection method is developed to locate the fault in a transmission line compensated with STATCOM with simple calculations. The proposed protection method considers the STATCOM injected/absorbed current to correct the fault loop apparent impedance and accordingly calculates the actual distance to the fault location. The comprehensive equations needed for apparent impedance calculation are also outlined and the performance is evaluated and tested with a typical 400 KV transmission system for different fault types and locations using MATLAB/SIMULINK software. The evaluation results indicate that the new protection method effectively estimates the exact fault location by mitigating the impact of STATCOM on distance relay performance with error less than 0.3%.

Fault Location in Transmission Lines Using BP Neural Network Trained with PSO Algorithm

In modem protection relays, the accurate and fast fault location is an essential task for transmission line protection from the point of service restoration and reliability. The applications of neural networks based fault location techniques to transmission line are available in many papers. However, almost all the studies have so far employed the FNN （feed-forward neural network） trained with back-propagation algorithm （BPNN） which has a better structure and been widely used. But there are still many drawbacks if we simply use feed-forward neural network, such as slow training rate, easy to trap into local minimum point, and bad ability on global search. In this paper, feed-forward neural network trained by PSO （particle swarm optimization） algorithm is proposed for fault location scheme in 500 kV transmission system with distributed parameters presentation, The purpose is to simulate distance protection relay. The algorithm acts as classifier which requires phasor measurements data from one end of the transmission line and DFT （discrete Fourier transform）. Extensive simulation studies carried out using MATLAB show that the proposed scheme has the ability to give a good estimation of fault location under various fault conditions.

Online One-End Fault Location Algorithm for Parallel Transmission Lines

Fault location and distance protection are essential smart grid technologies ensuring reliability of the power system. This paper describes an accurate algorithm for locating faults on double-circuit transmission lines. The proposed approach is capable of identifying the faulted circuit of a parallel transmission line by checking the estimated fault location and fault resistance. Voltage and current measurements from only one of the terminals of the faulty line are used. No pre-fault data are required for the estimation. The lumped parameter line model considering shunt capacitance is utilized for the derivation of the algorithm. It’s assumed that line parameters are known and transmission lines are fully transposed. The method is applicable to all types of faults. It’s evinced by evaluation studies that the proposed algorithm can correctly determine the faulted circuit in most cases. For exceptional cases, the current waveforms during the fault can be used to help identify the faulted circuit. The proposed algorithm generates quite accurate fault location estimates, and may be suitable for distance relaying.

Single Ended Fault Location Estimation for EHV Transmission Systems

A novel numerical algorithm for fault location estimation of single-phase-to-earth fault on EHV transmission lines is presented in this paper. The method is based on one-terminal voltage and current data and is used in a procedure that provides the automatic determination of faulted types and phases, rather than requires engineer to specify them. The loop and nodal equations comparing the faulted phase to non-fauhed phases of multi-parallel lines are introduced in the fauh location estimation models, in which source impedance of remote end is not involved. Precise algorithms of locating fault are derived. The effect of load flow and fauh resistance, on the location accuracy, are effectively eliminated. The algorithms are demonstrated by digital computer simulations.

A fault locating method for multi-branch hybrid transmission lines in wind farm based on redundancy parameter estimation

In order to solve the problem of‘‘abandoned’’wind caused by short circuit faults in a wind farm,a wind farm fault locating method based on redundancy parameter estimation is proposed.Using the characteristics of the traveling wave,transmission equations containing the position of the fault point are constructed.Parameter estimation from statistical theory is used to solve the redundant transmission equations formed by multiple measuring points to locate the faults.In addition,the bad data error detection capability of the parameter estimation is used to determine bad data and remove them.This improves locating accuracy.A length coefficient is introduced to solve the error enlargement problem caused by a transmission line sag.The proposed fault locating method can solve the fault branch misjudgment problem caused by the short-circuit faults near the data measuring nodes of thewind farm based on the proposed fault interval criterion.It also avoids the requirements to the traveling wave speed of traditional methods,thus its fault location is more accurate.Its effectiveness is verified through simulations in PSCAD/EMTDC,and the results show that it can be used in thefault locating of hybrid transmission lines.

基于高频阻抗突变量的双馈风场送出线路保护方法

针对双馈风机的暂态特性呈现多态性且区别于传统同步机,双馈风机的短路电流频率含有比例较大的衰减转速频率分量导致送出线路区内外故障难以区分,传统保护容易出现误动拒动的现象,提出了一种基于高频阻抗突变量的双馈风场送出线路纵联保护方法。首先,结合双馈风电场拓扑结构,考虑集电线上各风机机端电压幅值相角差异,求得双馈风场短路电流,提取高频分量并构造双馈风电场故障高频模型。在此基础上,构建双馈风场送出线路高频突变量网络,并推导送出线路两侧保护所测得的高频阻抗,利用高频突变量网络区内外测得阻抗差异性,构造保护判据。最后,利用RT-LAB平台进行仿真,验证了所提方法可实现区内外故障的准确判别,且无需线路两端信息实时同步。

110 kV及以上输电线路单相接地故障点自动定位方法

为提升单相接地故障定位精度,提出110 kV及以上输电线路单相接地故障点自动定位方法。采集110 kV及以上输电线路故障信号,并使用行波信号对其进行提取分析,基于故障行波信号测量故障距离,定位单相接地故障点。测试结果表明,该方法能够实现高精度的故障定位,应用效果较好。

基于特勒根拟功率定理的直流输电线路故障测距

高压直流输电系统的网络结构和故障特性对线路故障测距方案准确度提出更高要求,对此,该文提出一种基于特勒根拟功率定理的直流输电线路故障测距方案。首先,在分析直流线路贝瑞隆模型的基础上,首次提出特勒根拟功率定理应用于直流线路故障分析的方案,并给出拟功率解析表达式。其次利用贝瑞隆模型构建拟功率基准值,并根据故障点处基准值与计算值相等的原则实现故障测距。最后,通过大量仿真,验证理论推导的正确性以及拟功率能有效反应故障位置,并验证该方案不受过渡电阻及故障类型的影响。该研究实现了低采样频率下高精度测距的目标。

融合故障录波和保护动作的输电线路迁移学习故障分析及定位

针对高比例分布式电源并入导致电网规模增大且结构复杂,使传统输电线路故障分析及定位时依赖人工对录波数据进行分析判别容易造成误判、效率低下等问题,根据迁移学习理论方法,基于输电线路故障录波数据建立输电线路故障类型特征提取模型;利用保护动作信息和故障量判别信息,建立输电线路故障位置范围。将故障录波数据和保护动作信息作为深度学习的输入、故障类型和故障位置作为输出进行训练,将训练模型应用至某实际电网中进行测试,结果表明所提方法能够有效辨识出故障线路类型和位置。

电力工程中输电线路电缆故障定位与检测研究

电力工程中的输电线路和电缆故障定位与检测是保障电网稳定运行和安全供电的重要环节。随着电力系统的发展和电力需求的日益增长,对于故障定位与检测的要求也越来越高。基于此,介绍了电力工程中输电线路电缆故障定位与检测的方法,以期为电缆故障定位与检测提供参考。

基于分布参数的同杆双回线单线故障准确测距原理

针对同杆双回线线间联系紧密,不能忽略线间分布电容对测距结果的影响,该文在同杆双回线分布参数模型下,利用相序变换后双回线反向网络图中不存在系统参数的优势,提出了一种使用单端工频电气量进行故障测距的算法,该算法从原理上解决了系统阻抗及过渡电阻对测距的影响,克服了目前同杆双回线不能精确定位的问题。该算法理论分析简单,迭代求解测距方程不存在伪根问题,ATP仿真结果表明该算法具有很高的测距精度。

基于R-L模型参数辨识的输电线路准确故障测距算法

输电线路的准确故障测距对于保障电力系统安全稳定运行具有重要的意义。该文充分利用了故障分量提供的故障信息,以模量分析与输电线路R-L模型为基础,提出了一种将故障状态网络的微分方程与故障分量网络的微分方程联立求解的单端量时域准确故障测距算法。该算法将故障距离、过渡电阻以及对侧系统的运行参数作为模型的未知参数进行求解辨识,利用数值微分代替测距方程中的一阶与二阶微分,消除了传统单端量故障测距算法中主要由于对侧系统实时运行参数未知而引起的原理性误差。该算法不受故障时系统的运行方式、网络结构以及电网频率波动影响。大量EMTP仿真表明,算法原理正确且具有较高的测距精度,在故障距离20-280km范围内测距的平均误差为0.0796％,最大测距误差小于0.173％,该误差主要来自截断误差,即用差分法计算时域连续信号的微分时所产生的误差。

应用于输电线路单端测距的高阻接地故障电弧模型分析

高压输电线路高阻接地故障大多伴随电弧放电,传统基于实时计算的Cassie、Mayr等电弧微分方程模型,数值求解中每一时刻电弧电压都由上一时刻多参数迭代得到,难以直接应用到继电保护和故障测距中来。现有分析一般将电弧考虑为静态纯阻性元件或稳态电弧电压方波模型,而丧失了最富有价值的动态特性。针对该问题,文中面向输电线路单端高阻接地故障测距需求,基于描述空气放电本质的汤逊原理,利用电子的定向运动来表达电弧电流;利用电弧空间中电场和电子崩运动的耦合关系描述电弧电压与电流的函数关系,建立了输电线路单端测距用的高阻接地故障动态电弧模型。该模型克服了传统电弧微分方程计算复杂、难以直接为保护和测距应用的缺陷,对后续高阻接地故障检测、保护与测距研究奠定了基础。

T型输电线路电弧故障测距时域方法研究

利用单端数据的输电线路故障测距算法 ,较难解决多端系统的故障定位问题 ,实际中一般采用多端数据进行测距。频域法故障测距精度易受时窗位置、直流衰减分量、过渡电阻非线性等因素影响 ,其频域算法的数据多取之于故障后第二周波。随着继电保护技术的发展 ,从故障发生到断路器动作的时间愈来愈短 ,故障后第二周波内断路器可能已动作 ,这将使频域算法失效。本文提出了T型输电线路故障测距时域新方法 ,该方法可采用故障后第二个半周波的数据 ,所有解算均在abc坐标中进行 ,测距无需判断故障类型 ,而且使用了最小二乘技术 ,从理论上保证了该测距算法具有较高的测距精度。

利用双端不同步数据的高压输电线路故障测距实用算法及其实现

利用单侧电压电流工频分量的输电线路故障测距算法,进行双端电源系统的线路故障定位时,远端系统等值阻抗变化对测距精度的影响是无法克服的。文中提出一种双端电源系统的高压输电线路故障定位的实用算法,其特点为:①两端数据不必同步;②用于短、中等长度线路时,不需要迭代求解,即定位方程为一个算式;③不需要区分故障类型;④该方法适用于换位线路。

双端不同步采样的高压输电线路故障测距算法研究

研究双电源的换位、不换位单回以及耦合双回线短路点定位的新方法，其特点为：①两侧之间工频量不必同步。②适于换位和不换位的长线。③线路分布电容、过渡阻抗和系统运行方式等因素对测距精度没有影响。大量的模拟故障测距数字仿真表明，本方法具有较高测距精度。

±800 kV直流线路故障过程中电磁耦合特性与保护研究

为提高直流输电系统运行的可靠性,实现直流线路保护的有效动作,避免误动,必须对直流输电系统的电磁耦合特性进行研究。以云广特高压直流输电工程为研究对象,并参照其线路参数,建立了包含杆塔、输电线路、避雷器、绝缘子串闪络以及换流站内各种设备的仿真模型。采用EMTP,以雷击直流输电线路极导线、一极接地故障后对另一极的影响为具体算例进行仿真计算。对仿真结果进行分析,结果表明在故障情况下,对直流输电线路感应电压影响较明显的是土壤电阻率、极线间距与接地故障位置,而线路运行电压对感应电压的影响不大。比较研究了不同故障过电压仿真结果,对于雷击故障,可以用电压突变量的比值来确定故障极;对于接地故障,用分别对金属性接地和阻抗接地故障波进行小波变换分析的结果作为区分依据。最后,依据故障区分特性,提出了考虑电磁耦合的高压直流输电线路保护判据和保护整定方案,经过验证表明,所提出的保护判据可有效地区分输电线路故障。

特高压输电线路分布式故障诊断系统研制及其关键技术

分布式线路故障诊断系统作为特高压输电线路故障位置定位服务的关键产品,对电力系统的安全、可靠与经济运行具有重要意义。结合实际系统的研制与应用,提出了一种基于分布式安装的线路监测终端、监测运维中心站和移动终端应用服务于一体的新型故障诊断服务系统。阐述了产品与系统的关键实现方案,并提出了基于监测终端的供能及其管理、高速采样及同步、时间同步及坐标定位、行波启动及识别处理技术,基于监测运维中心站的双机冗余和数据安全隔离、测距和故障识别、GIS信息与微气象服务技术以及移动终端App安全服务等自主关键技术。所述系统产品顺利通过国家权威检测机构组织的测试与认证并在西部特高压交流1 000 kV输电线路上挂网运行,取得了稳定可靠运行的实际效果。

基于双端故障信息的高压电缆-架空线混合线路故障测距方法

提出了一种基于双端故障信息的高压混合线路测距算法,利用输电线路首、末端电压、电流工频量分段递推,通过搜索两端线路沿线电压曲线的交点来确定故障点位置,并讨论了伪根的鉴别方法,进而针对双端数据不同步、不同采样频率、不同过渡电阻等各种情况进行了全面的仿真计算。仿真结果表明,该方法测距精度高,且不要求线路两端数据同步,不受线路两端系统阻抗和故障点过渡电阻的影响,具备较高的实用价值。

影响输电线路行波故障测距精度的主要因素分析

行波测距是利用高频故障暂态电流、电压的行波来间接判定故障位置,包括单端行波测距法和双端行波测距法。文章对行波故障测距装置在实际应用过程中可能影响行波法测距精度的一些主要因素进行了讨论,包括雷电波的影响、故障时电压相角的影响、故障类型的影响、故障位置的影响、母线端接线的影响、线路类型的影响等,并提出了相应的解决方案。