基于分布参数模型的串联补偿双回线单线故障定位算法

对于装设串联补偿(串补)装置的输电线路,由于与串联电容并联的保护元件金属氧化物可变电阻(MOV)的非线性特征,使得串补线路无法直接使用常规的输电线路故障测距方法。为此,提出了一种基于分布参数模型的串补双回线故障定位算法。按照故障点相对于串补的位置分为两个子算法,利用从本端、对端推算得到的故障点处电压相等的特点,消去串补装置近故障一侧的电压,结合故障点处过渡电阻的纯电阻性和故障序网边界条件,构造故障定位函数。该方法不依赖串补装置模型,不受MOV非线性的影响,无需预知串补装置相对于故障的位置,同时不存在伪根判别问题。EMTDC/PSCAD和MATLAB仿真结果计算验证了该方法的正确性。     

Intelligent relaying scheme for series-compensated double circuit lines using phase angle of differential impedance

The paper presents a comprehensive intelligent relaying scheme using phase angle of differential impedance (PAODI) for series compensated double circuit transmission lines. The differential impedance (DI) is the ratio of differential voltage phasors of any phase across two ends of the transmission line to the differential current phasors of the same phase of the same transmission line. The PAODI of each phase are used as inputs to the data mining model known as decision tree (DT) to generate final relaying decision to identify the faulty phase(s) involved. The proposed scheme is extensively validated for different fault scenarios including inter-circuit and cross-country faults on the series-compensated parallel transmission developed on Real Time Digital Simulator (RTDS) platform. The test results obtained indicate that the proposed PAODI based intelligent relaying scheme is both dependable and secure in protecting series compensated double circuit transmission lines with a response time of less than 1 and 1/2 cycles.     

Adaptive Distance Relaying Scheme for Transmission Network Connecting Wind Farms

This article presents an adaptive distance relay setting for a power transmission network connecting more than one wind farm. The ideal trip characteristics of the distance relay is greatly affected in the presence of complex mutual coupling of transmission lines, as the apparent impedance is significantly affected. Similarly, the reach setting of the relay for the lines connecting wind farms is significantly affected, as the relaying voltage fluctuates continuously. Thus, the proposed study focuses on developing an adaptive relay setting for a transmission network including more than one wind farm and considering variations in operating conditions of wind farms and mutual coupling of transmission lines together. The proposed relay algorithm is extensively tested on two-terminal as well as multi-terminal power networks with wide variations in operating parameters. The performance testing of the proposed adaptive relay characteristics for faults and faults during power swing indicates the potential ability of the approach in handling distance relaying in a transmission system.     

A Fault Location Algorithm for Two-End Series-Compensated Double-Circuit Transmission Lines Using the Distributed Parameter Line Model

A new fault location algorithm for two-end series-compensated double-circuit transmission lines utilizing unsynchronized two-terminal current phasors and local voltage phasors is presented in this paper. The distributed parameter line model is adopted to take into account the shunt capacitance of the lines. The mutual coupling between the parallel lines in the zero-sequence network is also considered. The boundary conditions under different fault types are used to derive the fault location formulation. The developed algorithm directly uses the local voltage phasors on the line side of series compensation (SC) and metal oxide varistor (MOV). However, when potential transformers are not installed on the line side of SC and MOVs for the local terminal, these measurements can be calculated from the local terminal bus voltage and currents by estimating the voltages across the SC and MOVs. MATLAB SimPowerSystems is used to generate cases under diverse fault conditions to evaluating accuracy. The simulation results show that the proposed algorithm is qualified for practical implementation.     

利用单端电流的同杆双回线准确故障定位研究

基于线路分布参数模型,提出了一种利用单端工频电流量的同杆双回线准确测距算法:通过同杆双回线解耦可以得到同向和反向分量,其中反向分量与系统参数无关,并且反向各序电流分布系数是只包含故障距离x的函数。再根据不同故障的反序电流、电压边界条件,可以给出各种双回线接地故障(单线三相故障和同名跨线故障除外)的测距算法。该算法原理上不受过渡电阻、系统阻抗、分布电容的影响。并且由于算法只利用电流量,从而不受电压互感器传变特性的影响。并从理论上证明了测距精度不受电流互感器特性的影响。测距方程求解不存在伪根,具有唯一解。仿真计算结果表明,该算法具有较高的测距精度,最大测距误差仅为0.15%,理论上能够满足高压和超高压输电线路的测距要求。     

An accurate fault location algorithm for parallel transmission lines using one-terminal data

An accurate fault location algorithm for parallel transmission lines, using fundamental frequency components of post-fault voltage and current measured at one terminal, is described in this paper. Parallel transmission lines can be decoupled into the common component net and differential component net. In differential component net, the current distributing coefficient is a function of fault distance, and the differential component current at the fault point can be expressed in terms of the current at the local terminal. Therefore, for asymmetrical faults, the phase fault current can also be expressed as a function of local terminal current and fault distance. With the fault boundary conditions for a given fault type, the fault location equations can then be derived. Based on distributed parameter line model, the proposed algorithm achieves superior locating accuracy, with mutual coupling between circuits, source impedance and fault resistance having very little influence on the locating accuracy. The performance of new algorithm is verified by computer simulation results for transposed and non-transposed lines.     

Unsymmetrical opening of mutually coupled transmission lines

The aim of this paper is to present a systematic approach of solving unsymmetrical faults due to unsymmetrical opening of mutually coupled transmission lines. Opening a transmission line is equivalent to adding, in parallel with it, another transmission line but having the negative impedance of the same line. This is straightforward if the line is not mutually coupled with other lines in the system. Mutual coupling between parallel and adjacent lines exist due to proximity. Such mutual coupling must be taken into consideration when modifying the bus impedance matrix for the purpose of fault studies due to the opening of mutually coupled transmission lines. In this paper, a systematic approach to applying the bus impedance matrix method for faults involving the switching of mutually coupled lines is presented. The approach is applied to several cases of simulation of symmetrical and unsymmetrical switching of mutually coupled transmission lines.     

A new adaptive PMU based protection scheme fortransposed/untransposed parallel transmission lines

This paper proposes a brand-new adaptive phasor measurement unit (PMU) based protection scheme for both transposed and untransposed parallel transmission lines. The development of the scheme is based on the distributed line model and the synchronized phasor measurements at both ends of lines. By means of eigenvalue/eigenvector theory to decouple the mutual coupling effects between parallel lines, the fault detection and location indices are derived. The two proposed indices are used in coordination such that the internal and external fault events can be distinguished completely. By on-line estimation of the line parameters under the actual power system conditions, the proposed scheme will respond more accurately to power system faults. Extensive simulation results using EMTP have verified that the accuracy of the fault location achieved is up to 99.9%. The proposed protection system responds well and fast with regard to dependability and security. All the results show that the performance of the proposed detection/location indices is independent of fault types, locations, resistance, source impedance, fault inception angles, and load flows     

一二次配合的配电线路自适应重合闸

针对配电线路常规重合闸因重合前不能区分永久性和瞬时性故障可能造成多次短路冲击的问题,系统论述了基于一二次配合的配电线路自适应重合闸技术。介绍了基于一二次配合的配电线路自适应重合闸4种实现途径,即：限流试探法、电容放电试探法、脉冲试探法和载波试探法。分别论述了限流试探法串联型和并联型两种结构的工作原理以及技术特点,并给出限流阻抗典型参数。理论分析了电容试探法的回路放电特性及阻容参数的选取原则并给出了典型取值。指出脉冲试探法的关键在于分相快速开关的分闸速度和动作离散度,并建议了脉冲试探法下的阻抗参数识别方法实现原理。给出了载波试探法的信号频率及试探电压的选取原则以及典型值。     

PMU-based Fault Location Technique for Three-terminal Parallel Transmission Lines with Series Compensation

Abstract

This study introduces a fault location technique for three-terminal series-compensated untransposed parallel transmission lines utilizing the three terminals’ synchronized data. The proposed technique is applicable for short or long lines as distributed parameter line model is employed and the potential couplings are considered. The fault location for both uncompensated line sections is obtained adopting previously introduced fault location technique. The faulty phases are required initially to be recognized for series-compensated transmission line. The adopted fault location technique for series-compensated line section is derived based on the resistive nature of the fault impedance. The obtained fault locations for each line section are compared with each other to distinguish the faulty branch and obtain the fault location. DIgSILENT Power Factory and MATLAB programs are utilized for simulation studies and required calculations. The obtained results prove the efficacy of the introduced technique.     

Adaptive distance relay setting for parallel transmission network connecting wind farms and UPFC

The paper presents an adaptive distance relay setting for parallel transmission network connecting wind farms. The ideal trip characteristics of distance relay is greatly affected in presence of mutual coupling of parallel transmission lines as the apparent impedance is significantly affected. Similarly, the reach setting of the relay for the lines connecting wind farms is significantly affected as the relay end voltage fluctuates continuously. Thus, the proposed study focuses on developing adaptive relay setting for parallel transmission network including wide variations in operating conditions of wind farms and effect of mutual coupling, together. Further, the performance of the proposed adaptive relay setting for parallel lines including Unified Power Flow Controller (UPFC) indicates the potential ability of the proposed analytical approach in handling distance relaying in transmission system.     

耦合双回线路电弧故障测距的新相模变换方法

输电线路故障测距一直是经久不衰的研究课题。,根据三相系统和同塔双回线系统的阻抗矩阵关系,从能用单一模量反映所有普通三相系统故障的新相模变换矩阵出发,推导出适用于双回线的相模变换矩阵。提出了一种基于新模量变换的双回线故障定位时域算法,该算法利用某一故障模量电弧电压、电流的转移特性来构造测距算法。它具有如下特点:算法在时域中进行,所需的时间窗短,不需要滤波等环节;用最小二乘法来提高测距精度,且测距的精度不受过渡电阻、故障类型及对端系统阻抗变化的影响。大量的电磁暂态仿真结果表明,该算法具有很高的精度。     

基于双重保护的中压串联补偿装置研究

串联补偿装置在提升配电网线路电能质量方面具有良好的效果,近年来得到了广泛的应用.针对配网线路故障频发的特点,实际运行中应考虑串联补偿装置的自我保护问题,以避免线路发生故障引起电容器过电压而损坏的情况.本文提出了一种基于金属氧化物限压器(metal oxide varistor,MOV)和实时小波变换算法检测故障的双重保...     

High-Resistance Faults on Two Terminal Parallel Transmission Line: Analysis, Simulation Studies, and an Adaptive Distance Relaying Scheme

Performance of conventional nonpilot distance relay is affected by ground fault resistance, prefault system conditions, mutual effects of parallel lines and shunt capacitance influences. The work presented in this paper addresses the problems encountered by conventional non pilot distance relay when protecting two terminal parallel transmission lines. One of the key points of this paper is the detailed analysis of the apparent impedance as seen from the relaying point taking into account the effects of transmission line parameter uncertainties, mutual effects of parallel lines for simple and more complex configuration, shunt capacitance influences and variations in the system external to the protected line. Based on extensive computer simulations of the infeed/outfeed, fault resistance, mutual coupling and shunt capacitance effects on the relay characteristics, an adaptive digital distance relaying scheme is proposed using radial basis function neural network which provides more efficient approach for training, computation, adaptation and tripping than the conventional feed forward network using back propagation algorithm. In addition, the proposed adaptive scheme improves the performance of distance relay for double-circuit lines using modified compensation factor. Moreover, the scheme does not require separate communication channel for data transmission. The results of computer simulation show the improvement of sensitivity and selectivity of the relay     

A performance oriented impedance based fault location algorithm for series compensated transmission lines

This paper proposes a performance oriented fault location algorithm for series compensated transmission lines. The algorithm estimates the fault location based on the calculated fault voltage and current using two end measurements and line parameters. Fault location computations are carried out considering faults existed before or after the compensator location on the line. The calculated MOV impedance is the key factor in determining whether or not the fault is located in front of the compensator. A 380 kV transmission line with a series capacitor and an MOV has been tested for various fault types, fault locations and fault resistances. The results show that the algorithm accurately estimates the fault location for all cases.     

带有串联电容补偿装置的10kV配电网线路短路故障暂态过程研究

配电网是电力系统直接连接用户的关键供电环节。采用串联电容补偿装置来补偿线路电抗的串补技术,在输电线路中可提高交流输电线路输电容量、提高系统的稳定性等优点。串补在配电网中可以改变线路R-L-C参数,有效改善沿线电压质量,但串补的接入会影响配电网的暂态过程,因此需要研究串补的暂态工作特性尤其是发生概率居首位的短路故障下。本文以陕西地区一条典型的10 kV配电线路为例,基于先前的研究成果,在线路串补安装位置及补偿度最优补偿方式下,计算分析了线路不同短路故障下的电磁暂态过程及其影响,获得了串补电容保护装置配置参数对暂态过程的影响规律和保护效果。     

First-zone distance relaying algorithm of parallel transmission lines for single-phase to ground faults

A novel zone-one distance relaying algorithm for single phase to ground faults on parallel lines is proposed. The proposed algorithm only requires sampled current and voltage values at one end of the protected line to calculate the fault impedance. The adjacent circuit zero-sequence current can be calculated from the protected circuit zero-sequence current and without cross-connection. The algorithm can overcome the issues of overreach and under-reach. The study in this paper shows that the new algorithm has higher reliability than that of conventional distance relays with and without cross-connected zero-sequence current compensation. Therefore, the algorithm optimizes the performance of zone-one distance relaying for parallel transmission lines. The results are verified by the simulations using PSCAD software.     

基于串补线性化模型的含串补线路距离保护整定方法

在含串联补偿装置(简称串补)线路的距离保护整定中,往往忽略金属氧化物非线性电阻(MOV)动作时串补对外呈现的非线性阻抗特性,这使得距离保护整定存在不准确、灵敏度低的不足。采用串补线性化模型描述串补MOV的影响,分析了含串补线路距离保护测量阻抗的分布特性,提出了一种基于串补线性化模型的距离保护整定方法,实现了含串补线路距离保护的精细化整定。采用某实际电网算例,验证了所提方法的有效性。仿真结果表明,该方法所得保护定值较传统整定方法具有更高的灵敏性。     

串联电容补偿的平行双回线上方向继电器的性能

研究串联电容补偿地线路保护的影响具有重要意义。文中在导出串联电容补偿的陕行双回线上各保护安装处的等值电源阻抗表达式的基础上,提出了方向继电器应用于串联电容补偿的平行双回线的一个新问题,即在电容器出口一端区内故障时,故障线路对侧方向保护在高阻接地故障时可能判为反向拒动。ＥＭＴＰ仿真试验证实了理论分析结果。     

A novel fast distance relay for series compensated transmission lines

This paper presents a fast distance relay for series compensated transmission lines based on the R–L differential-equation algorithm using the theory of equal transfer process of transmission lines. The measuring distances based on the proposed algorithm can fast approach the actual value of fault distance when a fault occurs in front of the series capacitor. When a fault occurs behind of the series capacitor, the fault loop, including the series capacitor, does not match the R–L transmission line model, so the measuring distances fluctuate severely. Based on this, the relative position of the fault with respect to the series capacitor can be judged effectively according to the fluctuation range of the measuring distances, and the accurate fault location can be obtained fast. A variety of PSCAD/EMTDC simulation tests show that the new relay has fast operating speed and high accuracy when applied to the long series compensated transmission lines.