架空线路电弧故障的非线性估计单端测距方法

电弧闪络在架空输电线路故障中占很大比例，而大多数故障测距研究没有考虑到电弧的非线性特性。文章提出了一种基于电弧特性的单端故障测距新方法，研究了Mayr模型下线路闪络时交流电弧的频谱特征，依据超高压输电线路首端测量数据构造观测方程，并采用非线性状态估计的方法求解电压特性与故障电弧特性最接近的位置，为电力线路故障测距问题的研究提供了一种新的思路。仿真结果表明，该方法具有较好的稳定性和较高的测量精度。     

Numerical algorithm for medium voltage overhead lines protection and adaptive autoreclosure

In this paper a new numerical algorithm for medium voltage overhead line protection and autoreclosure is presented. It is based on one terminal data processing and it is derived in the time domain. In the algorithm, the fault location and fault nature (arcing or arcless fault) are estimated using the linear least error squares estimation technique. An arc occurring on the fault point during arcing faults on overhead lines is included in the consideration of the problem. Additionally, by introducing the pre-fault load current in the existing model, better algorithm performances are achieved. The algorithm is derived for the case of a three-phase symmetrical fault. The computer simulation results of the algorithm testing are presented and, in particular, the algorithm sensitivity to arc elongation effects and processing of the signals in the presence of harmonics is tested and analysed.     

Numerical algorithm for overhead lines arcing faults detection anddistance and directional protection

In this paper, an overhead lines protection numerical algorithm, based on one terminal data and derived in the time domain, is presented. The fault location, direction and its nature (arcing or arcless fault) are estimated using the least error squares technique. The faulted phase voltage is modeled as a serial connection of fault resistance and arc voltage, offering more sophisticated line protection. The algorithm can be applied for both ordinary and the high impedance faults detection, distance protection, intelligent autoreclosure, as well as for the purpose of directional relaying. The approach presented does not require the line zero sequence resistance as an input datum. The algorithm is derived for the case of the most frequent single-phase to ground unsymmetrical faults. The results of algorithm testing through computer simulation are given. The influence of remote infeed, fault resistance, higher order harmonies, power system frequency, network topology, line parameters and other factors are investigated and systematically presented. Finally, an example of real life data processing is given     

Two-stage numerical algorithm for distance protection, fault location and arcing faults recognition

In this paper, a novel two-stage numerical algorithm devoted to fault distance calculation and arcing faults recognition is presented. The first algorithm stage serves for the fault distance calculation. The fault distance is calculated from the fundamental frequency phase voltages and current phasors, thus utilizing the positive- and the zero-sequence impedances of the line as input parameters. The second algorithm stage serves for the arc voltage amplitude calculation. It utilizes the fault distance calculated in the first algorithm stage as well as the third harmonics of the terminal phase voltage and line current phasors, respectively. From the calculated value of arc voltage amplitude it can be determined whether the fault is transient arcing fault or permanent arcless fault. The phasors needed for algorithm execution are calculated by using the Discrete Fourier Technique. In this paper, the solution for the most frequent phase-to-ground faults is given. The results of algorithm testing through computer simulation and real field data records processing are given.     

谐振接地配电网电弧接地故障暂态分析方法与辨识

谐振接地中压配电网常发生电弧接地故障,传统的故障暂态分析方法多将电弧电阻简化为线性过渡电阻后代入故障暂态等值电路求解,电弧非线性特征难以体现。针对该问题,适当简化电弧黑盒模型,提出一种适用于谐振接地配电网电弧接地故障的暂态分析方法,定量计算不同过渡电阻下电弧接地故障暂态电流的解析表达式,并根据电弧电压的奇频次谐波衰减特性,给出一种综合电弧电流与线路电压信息的稳定电弧接地故障辨识原理。通过仿真计算与现场实验数据验证了所提分析方法的有效性,为后续谐振接地配电网电弧接地故障保护的研究提供了理论依据。     

弧光高阻接地故障建模及数据修正算法

配电网高阻接地故障通常伴随着非线性电弧的产生。传统的固定电阻模型无法模拟电弧的非线性;微分形式的电弧模型依赖于参数的迭代,难以直接应用于相关的故障检测及测距算法中;对数电弧模型较为复杂,按级数展开时易发散。人工模拟此类故障获取实验数据的方法成本高、危险性大且具有一定的局限性。基于汤逊原理,建立了能够表征动态电弧非线性特征的指数电弧模型及其简化模型,并结合PSCAD仿真软件及现场数据验证了模型的有效性。针对该电弧模型无法表征电弧电压、电流间相角差的不足,进一步提出了数据修正算法,为后续弧光高阻接故障的研究提供了更为精确的数据支撑。     

考虑短路及断线故障的有源配电网保护

分布式电源大量接入和极端灾害导致的复杂故障形态,使得有源配电网保护面临新的挑战.基于分析不同故障类型区内外故障时电压故障分量的特征差异,提出一种基于电压故障分量比较的保护新方法.所提方法利用电压故障分量推算公式以及实测的线路一端的电压故障分量、电流故障分量求取线路另一端的电压故障分量,将推算得到的电压故障分量与实测的电压故障分量求比得到电压故障分量比值,再利用电压故障分量比值识别线路内外部故障,从而能够兼顾有源配电网在短路故障、断线故障等不同故障场景下的保护需求,且具有不受不可测分支影响、不受分布式电源渗透率影响、耐受过渡电阻能力强等优点.     

基于多故障特征量提取的配电网单相接地故障类型识别

对配电网发生的故障进行准确的在线识别,有助于快速处理故障。提出一种基于多故障特征量提取的配电网单相接地故障类型识别方法。首先,从故障持续性、过渡电阻大小、故障点燃弧性质3个特征对单相接地故障进行多特征分类。然后,将小波多分辨率分析与数学形态学相结合,提取故障相电压的暂态脉冲信号,并由其识别故障暂态产生次数,判断故障持续性;由故障后的中性点电压偏移量,估算过渡电阻大小;提取故障相电压的总谐波畸变率,判断故障点是否存在燃弧现象。最后,依据以上故障特征量,提出配电网单相接地故障总识别流程,并通过仿真验证了该方法的可靠性。     

输电线路双端故障测距时域算法实用研究

对因山火、树障等引起的输电线路较长过程电弧放电故障,频域故障测距算法的稳定性较差。现有的采用双端不同步数据的时域算法,对这种情况仍存在精度不足的问题。为提高时域算法的实用性,以比较从线路两侧计算的故障点电压波形一致性为基础,提出了时域故障测距方程的数值解法。在分析长过程电弧性故障特征的基础上,给出了算法在实用时的计算过程。基于仿真验证了算法的准确性,并对算法进行了线路参数及测量误差的稳定性验证。利用现场220~1 000 kV不同电压等级的故障数据对算法的实用性进行了分析。     

小电流接地系统单相接地综合电弧模型与选线方法的研究

在小电流接地系统中,发生单相接地故障时,电弧故障会经常产生。现有用于模拟电网的电弧模型大都是通过开关来实现,与实际的电弧接地有一定的差距。将Cassie电弧模型和Mayer电弧模型结合起来,使其更符合实际电弧接地,并运用到10 kV模拟电网中。在EMTP中,对中性点不接地电网、经消弧线圈接地,经高阻接地,电弧发生在不同合闸角,不同馈线时的情况进行了大量仿真。最后在Matlab中,用小波相关分析法进行选线。结果表明,该方法适用于大部分电弧故障,但对于电压过零点附近发生的电弧故障有一定的局限性。     

基于相位差的不对称配电网接地故障选相方法

在配电网中性点不接地及经消弧线圈接地系统中,针对传统接地故障选相方法未考虑泄漏电阻及三相不对称情况导致过渡电阻较高时选相错误的问题,论文提出了基于相位差的不对称配电网接地故障选相方法,考虑线路泄漏电阻及三相不对称参数,分析了故障相电压和故障前后中性点电压变化量的相位差与消弧线圈补偿状态及线路参数的内在联系,得出了接地故障选相判据,最后提出了配电网接地故障选相方法实现方案。在PSCAD/EMTDC仿真环境中搭建配电网接地故障模型,仿真结果表明在不同过渡电阻及消弧线圈不同补偿状态下判据均适用,验证了所提方法的可行性。     

Incipient fault location formulation: A time-domain system model and parameter estimation approach

Power systems faults are unavoidable events which affect distribution networks reliability. The fault process in underground cables is gradual and characterized by a series of sub-cycle incipient faults associated with an arc voltage. These events often are unnoticed and eventually result in permanent faults. This paper presents an incipient fault location formulation for distribution networks with underground cables. Presented formulation is composed by a time-domain system model and parameter estimation strategy. System model derivation considers distribution networks inherent features as unbalanced operation and underground distribution cables capacitive effect. Further, incipient fault characteristics as fault arc voltage are considered. The proposed system model is an overdetermined linear system of equations in which the fault location is estimated through a parameter estimation approach. Parameter estimation is made through a Non-Negative Weighted Least Square Estimator (NNWLSE). Smoothing and curve-fitting procedures are applied to input data aiming to decrease the noise effect. A load current compensation strategy is proposed to reduce its effect in the fault current estimation and a back substitution method is proposed for estimation refinement. Validation is performed using real-life distribution network with underground cable data simulated on ATP/EMTP. Test results are encouraging and demonstrate the method’s potential for real life applications. An average error of 1.95% is obtained when compared with 6.48% derived using the state-of-art.     

Spectral domain arcing fault recognition and fault distance calculation in transmission systems

A new numerical algorithm for recognizing arcing faults for the purpose of automatic reclosing is presented. The fault distance can also be calculated using this algorithm. The solution for both symmetrical and unsymmetrical faults is given. A simple empirical arc voltage model is obtained through a table of numerical values. By means of computer simulation and laboratory testing it is shown that the algorithm can be used as an effective tool in transmission and distribution system protection.     

A new PMU-based fault detection/location technique for transmission lines with consideration of arcing fault discrimination-part I: theory and algorithms

A new fault detection/location technique with consideration of arcing fault discrimination based on phasor measurement units for extremely high voltage/ultra-high voltage transmission lines is presented in this two-paper set. Part I of this two-paper set is mainly aimed at theory and algorithm derivation. The proposed fault detection technique for both arcing and permanent faults is achieved by a combination of a fault detection index |M| and a fault location index |D|, which are obtained by processing synchronized fundamental phasors. One is to detect the occurrence of a fault and the other is to distinguish between in-zone and out-of-zone faults. Furthermore, for discriminating between arcing and permanent faults, the proposed technique estimates the amplitude of arc voltage by least error squares method through the measured synchronized harmonic phasors caused by the nonlinear arc behavior. Then, the discrimination will be achieved by comparing the estimated amplitude of arc voltage to a given threshold value. In addition, in order to eliminate the error caused by exponentially decaying dc offset on the computations of fundamental and harmonic phasors, an extended discrete Fourier transform algorithm is also presented.     

应用于架空线路故障的并行退火单端测距算法

电弧闪络在架空输电线路故障中所占比例很高,而大多数的故障测距研究没有考虑到电弧的非线性特性,故提出一种应用于架空输电线路电弧故障的单端测距的算法。该算法用在工程界广为接受的M ayr模型为电弧建模,以计及故障电弧非线性特性引起的电压畸变,并且使用故障点电压积分值信息判断故障位置;在使用故障点电压特征信息基础上,将单端测距问题转化为优化问题,用并行退火算法快速有效地搜索出架空线路的故障点。仿真研究表明,该算法具有较高的测距精度。     

New Digital Algorithm for Adaptive Reclosing Based on the Calculation of the Faulted Phase Voltage Total Harmonic Distortion Factor

This paper presents a new numerical algorithm suitable for determining adaptive dead time, and blocking automatic reclosing during permanent faults on overhead lines. It is based on terminal voltage input data processing. The decision if it is safe or not to reclose is determined by the voltage signal of faulted and tripped line phase using the total harmonic distortion factor calculated by discrete Fourier transform. The algorithm was successfully tested using signals recorded on the real power system. The tests demonstrate the ability of the presented algorithm to determine the secondary arc extinction time and to block unsuccessful automatic reclosing of high-voltage lines with permanent fault     

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     

基于组合Mayr和Cassie电弧模型的弧光接地故障仿真及分析

弧光接地故障在配电网中发生的概率较大,其动态特性对于检测电弧故障起着十分重要的作用。Mayr、Cassie模型是研究电弧接地故障两种经典模型,适用于描述电弧不同的物理特性。文中以电弧电流为变量建立过渡函数,构造了一种Mayr-Cassie组合模型,该模型综合考虑了电弧对流散热和径向传导散热。在PSCAD/EMTP平台上搭建了单相电弧接地故障模型,分析了电弧电压、电流、电阻的动态特征,并进一步将该模型用于10 kV配电网故障分析中,结果表明该模型可准确反映电弧特性。     

基于MATLAB的电弧建模仿真及故障分析

单相电弧接地故障是中压配电网中的主要故障形式,建立准确的接地电弧模型对于故障分析是十分必要的。文中在MATLAB平台上构建了基于弧隙能量平衡理论的接地电弧模型,通过与实测波形相比较,证明该电弧模型能有效地反映实际接地电弧的特性,并利用小波变换,提取电弧电压、电流的暂态信息,对故障信号的奇异点进行分析,确定故障时刻。     

特高压长线路单相自适应重合闸的新原理

实现自适应重合闸的方法已经很多,但是将输电线贝瑞隆模型应用其中的,国内外还没有见到,因此提出了基于贝瑞隆模型的特高压长线路单相自适应重合闸的新原理。具体方法是在单相重合前,保护使用贝瑞隆模型计算线路故障点两侧的电流,进而求出故障点处的潜供电流,然后根据其有无,来区分线路是永久性故障还是瞬时性故障,从而达到避免重合于永久性故障的目的。通过仿真表明,该原理区分度大,耐受过渡电阻能力强,并且对测距精度不敏感。因为线路越长,电压越高,输电线故障后潜供电流越大,所以该原理在特高压长线路上具有较强的实用价值。