电力系统复杂故障通用算法的研究

我们用补偿法原理开发出电力系统复杂故障的通用计算软件。本文着重讨论其核心部分－故障后补偿导纳矩阵和故障前端口阻抗矩阵的形成，并推导出了有关计算公式。此程序可灵活地修改运行方式，对故障类型、故障特殊相、故障过渡电阻处理简便，易于编程。可满足电力系统继电保护整定计算和事故分析的需要。     

A simple approach to analysis of faulted power systems

In this paper the common approach for analysis of symmetrical faults and the linear circuit theory are used to analyse the unbalanced disturbances in a power network. The positive, negative and zero sequence impedance data of the faulted power system are fed separately to the program developed for analysis of symmetrical (three-phase) faults and the node voltages corresponding to each sequence impedance data are obtained. These sequence node voltages are then corrected to yield the correct sequence node voltages by multiplying them by the actual ‘impedance ratios’ obtained from the orientation of the sequence network for the particular type of fault considered. Numerical examples are presented to support the developed theory.     

A Digital Measurement of Earth Fault Loop-Impedance Using a Parameter Estimation Algorithm

ABSTRACT

In electrical low voltage power system, a neutral earthing is used for protection against electrical shock hazards. Testing of the effectiveness of the earthing system could be achieved by measuring the system fault loop impedance Z. This paper presents a new application of least error squares (LES) parameter estimation algorithm for measurement of earth fault impedance, the proposed method uses the digitized samples of the instantaneous voltage across the fault loop impedance, effects of data window size, sampling rate and the voltage frequency drift on the accuracy of the impedance measurements are studied. Simulated test results are reported in this paper, which from the basis of our conclusion.     

Arc fault location: A nonlinear time varying fault model and frequency domain parameter estimation approach

In this paper a frequency domain formulation for nonlinear arcing fault location is presented. The proposed fault location formulation uses as input data first cycles after the fault inception voltages and currents. The formulation is based on circuit analysis and a parameter estimation method. To consider the main characteristics of nonlinear arcing faults, a time varying resistance embedded in a nonlinear model is proposed and used. The formulation is developed for the case of the most frequent single line-to-ground faults using phase components. The effects of fault inception angle, time-varying series resistance, source impedance, load flow, sampling frequency and others factors are investigated and analyzed. This new approach was successfully tested through computer simulation and real data obtained from a Southern Brazilian Energy Utility. The proposed method was developed as dedicated software and is currently used by CEEE-GT.     

NUMERICAL ALGORITHM FOR ARCING FAULTS DETECTION AND FAULT DISTANCE CALCULATION ON OVERHEAD LINES

ABSTRACT

In this paper a new numerical algorithm for arcing faults detection and fault distance calculation will be presented. It provides the solution for both the symmetrical and the unsymmetrical faults. The algorithm is based on the line terminal voltages and currents processing. A simple square wave are voltage model is assumed to model the long are in free air in computer simulation and algorithm development. The frequency dependence of line parameters is taken into account. A series of computer simulated and laboratory tests have shown that the new algorithm can be utilized in transmission system practice.     

基于相分量法的电力系统复故障计算

为了对电力系统复杂故障直接进行求解,基于相分量法,建立了横向、纵向故障接口电路的通用相分量模型,推导了三相元件与平行线路的相分量阻抗矩阵。相分量算法不要求电力系统元件参数对称或循环对称、不利用多端口网络理论及理想变压器的移相,拓宽了故障计算的适用范围、简化了编程难度,并可推广到处理诸如线路换位不完全的参数不对称等其他电网不对称计算。算例演示了计算过程,与EM TP的仿真结果对比证实了模型与算法的正确性。     

复杂电网多重故障条件下的电压暂降分析

针对复杂电网发生多重故障时的电压暂降问题,提出一种新的分析方法。该方法将所有故障点视为虚拟节点并引入多重故障点位置参数。通过计算虚拟节点与非故障节点、虚拟节点之间的互阻抗和自阻抗,将节点阻抗方程进行扩展。结合各故障点的故障边界条件计算得到各故障电流相量,进而推导出电网中任意节点故障电压相量关于多重故障位置参数的函数,最后结合阀值电压进行电压暂降分析。在标准IEEE 30节点系统中验证所提出的电压暂降分析方法的有效性。     

输电线路单相瞬时性故障的判别研究

对两端均不带并联电抗器的输电线路,当发生瞬时性和永久性这两种不同性质的故障时,断开相端电压的有效值和相角都存在较明显的区别。本文在对故障后电路进行较精确分析计算的基础上,提出了一种基于电压有效值和相角的综合判据。仿真实验验证该判据能可靠区分瞬时性故障和永久性故障,并且有较高的灵敏度。     

Novel transient-energy-based directionalpilot protection method for HVDC line

In long transmission lines, the charging current caused by the shunt capacitance decreases the accuracy in impedance based fault location. To improve the accuracy of fault location, this paper presents a novel scheme, where two Digital Fault Recorders (DFRs) are installed in a line. They can send the transient data of the faults to the both ends of a line. To estimate the distance of a fault, impedance based fault location methods are applied with transient fault data of both ends protection relays and both DFRs installed in a line. To evaluate the proposed scheme, a laboratory setup has been developed. In the lab, several faults have been simulated and associated voltages and currents are injected to a relay IED to compare experimental results.     

Incipient sensor fault estimation and accommodation for inverter devices in electric railway traction systems

This paper proposes an incipient sensor fault estimation and accommodation method for three‐phase PWM inverter devices in electric railway traction systems. First, the dynamics of inverters and incipient voltage sensor faults are modeled. Then, for the augmented system formed by original inverter system and incipient sensor faults, an optimal adaptive unknown input observer is proposed to estimate the inverter voltages, currents and the incipient sensor faults. The designed observer guarantees that the estimation errors converge to the minimal invariant ellipsoid. Moreover, based on the output regulator via internal model principle, the fault accommodation controller is proposed to ensure that the v_od and v_oq voltages track the desired reference voltages with the tracking error converging to the minimal invariant ellipsoid. Finally, simulations based on the traction system in CRH2 (China Railway High‐speed) are presented to verify the effectiveness of the proposed method. Copyright © 2016 John Wiley & Sons, Ltd.     

基于测量阻抗变化的并联电抗器小匝间短路保护

通过分析并联电抗器发生匝间短路后的等效电路,提出了基于测量阻抗变化的电抗器小匝间短路保护方法。此方法根据匝间短路后电抗器测量阻抗降低,辅以电压变化开放判据区分区外故障,能够正确、快速检测正常运行小匝间短路故障以及带匝间故障投入运行的电抗器,并在投入电抗器、区外故障、系统振荡时可靠性高。分析表明,此方法定值整定简单、含义明确,抗电流互感器断线和饱和能力强。动模试验验证了保护方法的正确性与可行性。     

ELECTROMAGNETIC FAULT CURRENT LIMITER (EMFCL)

ABSTRACT

Due to electrical power system expansion, the utility systems are faced with fault currents higher than the momentary and interrupting capabilities of the equipment installed. One method, to convert the problem, is to use a fault current limiter. The limiter must limit the peak current to a level below that of the momentary capabilities of the system components and limit the subsequent current peaks to a level which allows correct relay operation within the interrupting capabilities of the circuit breakers. This paper describe the design and modeling of a new device for limiting the fault currents. Tliis device is an electromagnetic circuit consisting of an iron core and armature with adjustable air gap. With load current, the device has minimum impedance at the supply frequency. During fault conditions, the fault current is used to give the operating force needed to change the device inductance to the maximum impedance. The fault current limiter is successfully modeled using a digital computer and validated in the laboratory.     

带并联电抗器输电线路单相故障性质识别判据

针对带并联电抗器超特高压输电线路,分析了瞬时性故障时低频分量频率基本不受系统阻抗及故障点位置变化的影响,在低频分量频率离线准确计算的前提下,提出采用最小二乘拟合方法快速检测断开相并联电抗器电流低频分量和工频分量幅值实现的单相故障性质识别新判据。瞬时性故障时,低频分量幅值接近或超过工频分量幅值;永久性故障时,低频分量幅值接近0。判别算法仅利用断开相并抗电流,原理简单可靠,且易于实现。大量ATP仿真验证表明,该判据正确有效,能快速实现单相故障性质判别,有望提高单相重合闸动作的成功率。     

基于改进型相关法的单相自适应重合闸新判据

分析了超、特高压输电线路发生单相瞬时性及永久性接地故障时断开相电压的形成机理，指出瞬时性单相接地故障时断开相计算电压与两健全相电压和沿线变化规律的相似程度远大于永久性接地故障时的相似程度，并在此基础上，提出利用改进型相关法的故障性质识别新判据。该判据综合考虑了断开相计算电压与两健全相电压和的幅值与相位的相似性，使瞬时性故障时的相关系数大于永久性故障时的相关系数。该判据实现简单，高阻接地时仍具有较高灵敏度，且受线路长度、负荷电流及故障距离的影响很小，适用 于不带并联电抗器的超、特高压输电线路。大量仿真实验验证了所得结论的正确性。     

High Phase Order Transmission Line Fault Types

Abstract

For high phase order (HPO) transmission systems, a major hurdle to overcome is the fault analysis and protection studies needed to guarantee successful implementation. This paper presents new equations which calculate the number of fault types and significant fault types of n-phase transmission lines. In addition, this paper defines and explains symmetrically significant fault types for HPO transmission systems. Lastly, this paper figuratively shows the significant fault types and symmetrically significant fault types for multiple HPO systems, n?=?3, 4, 5, 6, 9, and 12. The equations and figures presented in this paper will assist in fault analysis and protective relay designs for HPO systems. The equations presented are used to determine the number of fault types a relay will need to account for, and the figurative approach shows the faults to be studied before HPO implementation.     

一种电网调度中心的故障信息识别方法

故障信息的误发，误传及丢失是影响电网调度中心运行人员准确识别故障的重要因素，并可能导致事故的扩大。文中介绍了一种实现故障信息数据滤波的方法，该方法将SCADA系统采集的数据作为数据基，建立动态数据库，以时间为索引，运行方式状态为参照知识库，生成剔除了不良信息的，可用以进行故障识别的动态数据链，文中描述了该方法的理论依据和实现方法。     

Three-phase modeling of unbalanced distribution systems during open conductors and/or shunt fault conditions using the bus impedance matrix

This paper presents a digital simulation technique for unbalanced three-phase distribution systems subjected to a shunt or a series fault. The method is also applicable to multiple faults which involve a shunt fault at one location and blown fuses or open conductors at another. The method utilizes the phase frame representation of network elements. The imbalance conditioned by large single-phase loads, untransposed feeders, conductor bundles, etc., is reflected in the polyphase impedance matrix. Consequently, line removals, additions, impedance changes, conductor and phase openings can be simulated by modifying the base-case impedance matrix. Thus, the proposed method makes it possible to analyze any type of single or multiple fault occurring anywhere in the system.     

基于故障电阻测量的小电流接地系统保护方法

为解决小电流接地系统高阻接地故障检测的难题,分析了单相接地故障前后相电流变化特征:故障线路的故障相与非故障相电流变化量之差等于接地故障电流,非故障线路的故障相与非故障相电流变化量相等;并由故障相电压与故障电流之比计算出接地故障电阻,发明了基于接地故障电阻测量的高阻接地保护方法。EMTP仿真分析和动模实验测试结果表明,该保护方法能够保护各种高阻接地故障,具有较高的保护精度和可靠性,适合在配电自动化终端单元(FTU)上就地实现。     

方向高频保护的动作行为分析：第一部分：复杂系统的复故障计算

方向高频保护高压和超高压输出电线路的主要保护方式,其动作性能对电力系统的安全运行影响甚大。     

H.V. CABLE TRANSMISSION: A STUDY ON TORSIONAL STABILITY

ABSTRACT

The purpose of this paper is to analyze the torsional stability of a turbogenerator, in a case in which, with a.c. 400 kV cable transmission lines, it is necessary to provide shunted compensation.

The problem is brought into focus from the physical point of view by means of a simplified schematic operating presentation. This simplified analysis is then validated by means of a computer program for the dynamic study of the electromechanical system, applied to an example consisting of a turbine shaft, the alternator, the excitation control system, a step-up transformer, and a cable line with shunt compensation and connected to a prevalent power node. Both the methods of analysis show that, unlike the dual case of the series compensation of overhead lines, in this case conditions of torsional instability do not occur.