基于Matlab的计算机距离保护微分方程算法仿真与研究

运用Matlab完成电力系统计算机距离保护的仿真,应用了两种基于线路模型的解微分方程的阻抗算法,分析了其应用于不同参数线路时的适应性,并通过分析在考虑存在干扰和误差时的阻抗计算结果,对两种算法的稳定性进行了研究.还对这两种算法的工程应用提出了有益的建议.     

基于PSCAD/EMTDC的距离保护R-L模型算法研究

应用线路模型算法的特点及适应性分析,可为电力系统距离保护阻抗算法乃至整个保护提供良好的选择性和可靠性保证。针对R-L模型算法,典型设计了在短路时线路分布电容高频分量的情况,运用PSCAD/EMTDC完成电力系统距离保护的仿真,应用基于线路模型的R-L解微分方程的阻抗算法,在双端系统中对算法进行了测试,并对算法的稳定性进行了研究。对电力系统距离保护阻抗R-L模型算法的实际应用提供了理论基础。     

同塔四回线路单相接地故障距离保护

针对同塔四回平行线路零序互感在单相接地故障时对距离保护的影响,提出一种基于单回线路单端信息量的距离保护算法。该算法通过建立四回线路零序阻抗矩阵来分析零序回路特征,综合考虑了系统零序阻抗变化和线路零序阻抗的影响,利用非故障线路与故障线路零序电流比值代替非故障线路零序电流,以此消除线路耦合对整定的影响。仿真结果表明,所提算法在线路发生单相接地故障时,能够保证距离保护正确动作,优于基于单回线路电气量的传统距离保护算法。     

基于Bergeron模型的长线路微分方程算法研究

由于受分布电容作用影响,解微分方程算法应用于长线路阻抗计算时,其计算结果精度降低.针对以上问题,提出一种应用Bergeron模型将长线路进行分段的解决方法.长线路经分段后,利用保护安装处的电流、电压瞬时值应用Bergeron方法计算分段点处的电流、电压瞬时值.利用分段点处电流、电压应用解微分方程算法即可较精确地计算出线路阻抗.新的计算方法对前置低通滤波器滤波特性没有过高要求.仿真计算结果表明,新方法在特高压、长线路情况下仍然可以准确地计算出线路阻抗.     

长距离直流线路谐波阻抗计算方法与直流谐振特性研究

对直流系统低次谐振特性的研究决定了特高压直流工程是否需要装设低频阻波、滤波设备。该文首先从直流线路"极–极"与"两极–地"两种回路结构及单位长度阻抗参数计算原理出发,对计及架空地线影响的双极线路等效参数进行详细推导分析;在此基础上,提出一种卡尔松积分项的优化拟合算法,并结合直流两种回路等效端口波阻抗的计算结论,求解得出直流线路在不同频率下的谐波阻抗;最后,依托灵州—绍兴?800k V特高压直流工程的线路阻抗试验测试数据,结合与原始卡尔松积分法的计算结果进行综合对比,进一步验证线路分布参数推导的正确性以及优化算法的计算精度。     

输电短线路的相间自适应距离保护

针对常规距离保护应用到传统意义的短线路时常常因为末端故障时残压小造成保护超越而退出工作的情况,简要分析了影响距离元件测量误差的因素,并利用仿真数据定量分析了短线路保护范围末端故障时,阻抗测量误差与系统阻抗和线路阻抗比（电源线路阻抗比）的关系。在此基础上提出一种根据系统阻抗和线路阻抗比自适应调整距离保护动作范围的短线路相间距离保护方案。该方案在线路发生故障时,假定故障发生在保护末端,结合实测的电源线路阻抗比按可能出现的最大测量误差调整保护范围,从而消除了短线路末端相间故障时距离保护的超越问题,保证了选择性。EMTP仿真验证,说明该方法可以有效地避免短线路末端故障时距离保护的超越问题,改善了短线路距离保护的性能。     

输电短线路的相间自适应距离保护

针对常规距离保护应用到传统意义的短线路时常常因为末端故障时残压小造成保护超越而退出工作的情况,简要分析了影响距离元件测量误差的因素,并利用仿真数据定量分析了短线路保护范围末端故障时,阻抗测量误差与系统阻抗和线路阻抗比(电源线路阻抗比)的关系.在此基础上提出一种根据系统阻抗和线路阻抗比自适应调整距离保护动作范围的短线路相间距离保护方案.该方案在线路发生故障时,假定故障发生在保护末端,结合实测的电源线路阻抗比按可能出现的最大测量误差调整保护范围,从而消除了短线路末端相间故障时距离保护的超越问题,保证了选择性.EMTP仿真验证,说明该方法可以有效地避免短线路末端故障时距离保护的超越问题,改善了短线路距离保护的性能.     

输电线路故障定位距离修正的等效折算法

针对线路分布电容影响集中参数模型定位精度的问题,提出了一种能有效减小分布电容影响、提高集中参数模型定位精度的修正算法。以集中参数阻抗等效一定长度的线路分布电容,然后依据集中参数线路模型,利用对称双端口网络传输方程进行折算处理,将等效阻抗折算成线路阻抗,得到了分布电容处理的修正计算公式。基于修正计算公式结合集中参数线路模型,形成的修正定位算法,在一定程度上消除线路分布电容带来的定位误差。按此修正算法进行的EMTP仿真分析验证了该算法在改善线路故障定位精度上的有效性。     

一种配电网开路潮流转移危险线路的识别方法

为了避免配电网潮流转移导致输电线路连锁故障跳闸反应,提出了一种基于改进Dijkstra算法的潮流转移情况下对危险线路识别的方法。首先分析了线路发生故障断开后线路潮流转移主要波及的危险线路,然后将电网转化成加权拓扑图。在此过程中,综合考虑潮流转移量和功率传输裕度这两个指标,并引入阻抗修正系数,将综合阻抗作为线路权重。随后采用改进Dijkstra算法搜索最短路径和次短路径,其所包含的有功潮流转移系数较大的线路即为危险线路。该算法通过C++编程实现,无需多次求解,可有效提高运算效率。最后,采用IEEE39节点标准算例开展仿真分析,论证了所述的方法是有效和实用的。     

过渡电阻对距离保护的影响

分析了过渡电阻对单相接地和相间故障时距离保护测量阻抗的影响,提出了通过采集同一时刻故障线路两侧电流、母线电压的补偿算法,消除过渡电阻对测量阻抗的影响。     

Application of Haar functions for transmission line and transformer differential protection

The development of algorithms, based on Haar functions, for extracting the desired frequency components from transient power-system relaying signals is presented. The applications of these algorithms to impedance detection in transmission line protection and to harmonic restraint in transformer differential protection are discussed. For transmission line protection, three modes of application of the Haar algorithms are described: a full-cycle window algorithm, an approximate full-cycle window algorithm, and a half-cycle window algorithm. For power transformer differential protection, the combined second and fifth harmonic magnitude of the differential current is compared with that of fundamental to arrive at a trip decision. The proposed line protection algorithms are evaluated, under different fault conditions, using realistic relaying signals obtained from transient analysis conducted on a model 400 kV, 3-phase system. The transformer differential protection algorithms are also evaluated using a variety of simulated inrush and internal fault signals.     

电力系统故障定位原理综述

在电力系统中,由于输配电网络结构不同,因此适用于各自的故障定位方法各有不同。在现有研究的基础上,介绍了阻抗法和行波法在高压输电线路和中低压配电网线路的故障定位技术中的应用原理,并且对各种原理下的不同算法作出总结。在比较各种算法优缺点的同时,对今后研究趋势作出了展望。     

Fault impedance estimation algorithm for digital distance relaying

Fault impedance is one of the major parameters that must be estimated accurately in digital distance relaying application. In this paper, a new algorithm is proposed based on symmetrical components theory. The proposed algorithm has computational advantage over previously suggested symmetrical components based algorithms. A procedure for applying shunt fault conditions to the sequence equations to estimate fault impedance of the protected transmission line is discussed. The Alternative Transient Program (ATP) that is available on personal computers was used in evaluating the proposed algorithm. ATP models a power system and simulates many fault conditions on a selected transmission line. Fault data obtained were used in calculating fault impedance using the proposed algorithm. Fault impedance estimates were inserted in relay characteristics to determine suitability of the proposed algorithm for first zone distance protection. Sample results of these studies which show stable fault distance estimates are presented and discussed in the paper     

基于自适应阻抗继电器的风电T接线路纵联保护方案

风电的T型接入改变了系统拓扑和故障特性,导致继电保护整定与配合困难,传统距离保护应用于风电T接线路时存在适应问题。基于风电T接线路拓扑,分析了双保护方向对保护范围的影响,推导了测量阻抗表达式并提取了主要影响参数,指出风电的T型接入影响距离保护的动作性能;鉴于此,提出了基于自适应阻抗继电器的风电T接线路纵联保护方案。该方案实现了保护方向的唯一化,且保护动作区域能够根据过渡电阻、三端电源电势幅值比、相位差和风电电源等效序阻抗的变化进行自适应调整,提高了保护的可靠性和灵敏性。同时给出了自适应整定阻抗的具体计算方法,一定程度上降低了保护对通信系统的要求。仿真结果验证了所提保护方案的正确性和有效性。     

Fast and accurate parameter estimation algorithm for digital distance relaying

Response of digital distance relaying depends on the fast and accurate calculation of parameters such as voltage and current phasors and fault impedance. This paper describes a new apparent impedance estimation algorithm that is based on modal components theory. It is shown in the paper that the proposed algorithm has several advantageous features in terms of speed and accuracy over previously suggested symmetrical and modal components based algorithms. The paper discusses a procedure for deriving a fault impedance estimation algorithm that can be used for protecting power transmission lines. The proposed algorithm was evaluated using an alternative transient program (ATP). The program models a power system, simulates many fault conditions on a selected transmission line and generates fault data. The relay software then obtains filtered, scaled and sampled data and calculates fault impedance using the proposed algorithm. The relay characteristic makes trip decisions based on the fault impedance estimates. The paper shows the feasibility of the proposed algorithm for first zone distance protection. Some results of these studies are presented and discussed in the paper.     

Transmission line models for line protection

Methods for the protection of power transmission lines can be based on various line models ranging from a 50 Hz impedance, an L-R series circuit, and a π-equivalent to distributed parameter models. The application of such line models for deriving distance protection schemes is discussed. Fundamental concepts are introduced which allow various protection schemes to be discussed in a unified and novel framework. A large class of algorithms are then examined with regard to their ability to identify the location of a fault on a transmission line in the presence of transient phenomena which distort the sinusoidal voltage and current waveforms shortly after the occurrence of the fault.     

Building algorithms for the formation of the bus hybrid matrix

Two algorithms have been developed in this paper to build the bus hybrid matrix through a step-by-step addition of a transmission line to the power system with consideration of mutual couplings between the lines. Formulas have been derived for the addition of a tree branch and a link, when the buses of the added line are referred to impedance and/or admittance form. The procedure developed eliminates the transformation and the tearing algorithms.     

大串补线路电流差动保护拒动因素及改进保护方法

大串联补偿设备在超高压输电系统中得到越来越广泛的应用,伴随着复杂多系统的互联,含大串联补偿设备的线路(简称串补线路)在特定运行方式下出现线路背侧系统阻抗较小,可能导致线路内部故障时系统电流反向,此时串补线路电流差动保护可能会因灵敏度不足而拒动。基于此,详细分析了串补线路电流反向的原因及其对差动保护的影响。重点对不同串补度、系统功角差和过渡电阻等影响因素下的差动保护的动作特性进行研究。进一步地,为解决差动保护拒动问题,提出一种基于串补线路两侧电流幅相综合制动的电流差动保护改进判据,该判据能够有效解决串补线路内部故障时灵敏度降低的问题。仿真结果显示,相比传统差动保护,改进方案能够明显提高保护灵敏度。     

复用载波机保护命令传输的故障分析与对策

介绍了ABBETL581型电力线载波机在实际运行中的有关规定及电力线载波机的传输原理、基本功能、线路阻抗匹配、传输通道和保护编码传输方式,对故障现象进行了分析并提出了相应的解决办法。