反时限零序电流保护仿真平台的研发

在高压输电网中,应用反时限零序电流保护能够有效改善定时限零序电流保护的选择性问题,大幅降低整定计算工作量,但由于缺乏专门的分析和仿真工具,对其研究还不够透彻和全面,限制了其广泛应用.介绍了研发反时限零序电流保护仿真平台,可以调用整定计算软件中的电网模型与参数,计算出不同故障和参数下全网反时限零序电流保护的零序电流和动作时间,并能动态仿真保护动作过程,实现对反时限零序电流保护特性的深入研究.应用算例表明,通过该仿真平台能够准确计算出研究需要的各种数据,发现以往分析中没有发现的问题.     

Sepam反时限保护深入分析

由于反时限电流保护的特性与负载的故障特性高度契合,因此比定时限保护的性能更为优越,在国外应用极为广泛。但反时限多达十几种的特性曲线,复杂的计算公式,如何选择曲线,整定定值,以及如何与定时限保护配合等问题对用户来说一直是个难题,阻碍了反时限保护在国内的应用。     

定时限过流保护与反时限电流保护的计算与配合

本文介绍了直配电网络中的定时限过电流保护与反时限电流保护的计算与配合方法。     

反时限与定时限过电流保护配合的优化和改进

主要阐述了石油化工企业变电所进线的定时限过电流保护和下级变压器反时限过电流保护之间配合存在的问题,通过对定时限过电流保护整定计算优化后,使反时限与定时限过电流保护做到合理配合。     

基于特性参数自适应修正的花瓣式配电网反时限过电流保护方法

闭环运行的花瓣式配电网具有更为复杂的故障特性,导致传统保护方法难以满足选择性和速动性要求。针对这一难题,分析了花瓣式配电网的短路故障电流特性,揭示了故障点上、下游故障电流随故障位置移动的变化规律,并指出定时限过电流保护与标准反时限过电流保护应用于花瓣式配电网时存在的问题;结合花瓣式配电网的故障电流特性,提出一种基于特性参数自适应修正的反时限过电流保护方法,仅利用本地电流信息对反时限特性参数进行自适应修正,能够在保障保护选择性的同时显著提升保护速动性;基于PSCAD/EMTDC仿真软件搭建10 kV花瓣式配电网模型对所提保护方法进行验证,仿真结果表明该保护方法能在提升保护选择性和速动性的同时,克服传统保护方法应用于花瓣式配电网时的局限性。     

微机式反时限过电流保护整定配合的辅助计算软件

利用微机保护的智能作用,用时间系数ｔｐ整定反时限特性,从而使反时限特性的整定与定时限特性同样简便。编制了反时限过电流保护的整定配合辅助计算软件,极大地减轻了整定计算人员的繁琐劳动。     

新型微机反时限过流保护曲线特性及算法研究

传统反时限过流特性曲线计算微机反时限保护延时时,存在与定时限保护的配合以及计算延时不准等缺陷.该文提出了对反时限特性曲线进行分段计算处理的方法,改进了与定时限的配合,提高了时限的精度.然后针对计算比较困难的一般反时限曲线,介绍了分区查表和泰勒展开法计算时延累加量的算法.     

东北电网500kV线路零序反时限保护应用研究

线路保护中对接地故障的保护为主保护、接地距离保护和零序保护,由于高阻接地故障有时主保护和接地距离保护灵敏度不够,需要靠零序末段切除故障。线路定时限零序电流保护原理和实现很简单,但配合复杂、整定计算工作量大。应用反时限零序电流保护可有效简化零序电流保护整定计算时间,通过理论分析,确定了东北电网500kV线路零序反时限曲线特性,并提出了反时限应用需解决的问题。     

一种微机反时限电流保护设计方法

我国电网的网架结构越来越复杂,运行方式的变化越来越大,采用定时限保护同时保证选择性和灵敏度越来越困难,很多网、省调已开始尝试引入反时限保护作为线路接地故障的后备保护.本文对微机反时限保护的设计进行深入研究,并分析了其动态、静态特性及误差来源,提供了一种反时限保护的设计方案.     

反时限过流保护整定优化研究

反时限过流保护因动作曲线配合困难掩盖了其在原理上紧密反映短路电流变化的固有优势,一定程度限制了其应用。为此,在深入分析保护动作曲线之间严格配合的基础上,从保护选择性角度提出了反时限过流保护之间、反时限保护与定时限保护、定时限保护与反时限保护的整定配合原则;并在保证灵敏性的前提下,采用压缩因子粒子群优化算法(K-PSO)、辅之曲线参数与选择性配合作为约束条件,从快速性角度建立了整定范围内的时间优化目标。整定原则与优化模型可分别用于反时限过流保护整定计算与定值优化,有助于提高国内反时限过流保护的工程实用价值。算例分析验证了该方法的有效性与可行性。     

Gravitational Search Based Algorithm for Optimal Coordination of Directional Overcurrent Relays Using User Defined Characteristic

Due to dependency on Plug Setting (PS), Time Dial Setting (TDS), size of the network, more than one back-up relays for one primary relay and other technical constraints, coordination of Directional Overcurrent Relays (DOCRs) is an extremely constrained and nonlinear optimization problem. In this paper, a new Gravitational Search (GS) based algorithm is presented for achieving optimal coordination of directional overcurrent relays. The proposed algorithm utilizes user defined characteristic for inverse time overcurrent relays than the predefined standard curves. The user defined relay characteristic deals with constants that control the shape of the characteristics as variable adjustable values which are optimally chosen along with TDS and Plug Setting Multiplier (PSM). The performance of the proposed algorithm has been evaluated on 8-bus, 15-bus and IEEE 30-bus distribution network at different fault locations (near-end, far-end and middle point). In addition, the time of operation of some of the primary relays at different fault locations on IEEE 30-bus distribution network is also presented. At the end, comparative evaluation of the proposed algorithm with other optimization algorithms having different relay characteristics presented in the literature clearly indicates its effectiveness and superiority in terms of the sum of total primary relays operating time.     

A new approach for optimal coordination of distance and directional over-current relays using multiple embedded crossover PSO

Proper coordination between distance relays and Directional Over-Current Relays (DOCRs) in power systems is one of the important conditions for the system security. The coordination problem in interconnected systems, because of complexity of the system, is complicated and a powerful optimization program must be used in order to do the best and optimal relay coordination.In this paper at first, a new problem formulation for optimal coordination of distance relays in presence of DOCRs, as the backup relays, is proposed. Then to deal with this complex problem, as another contribution, a new Multiple Embedded Crossover PSO (MECPSO) is proposed. In the presented MECPSO by updating velocity vector, diversity of the swarm is enhanced and exploration and global search capabilities of the PSO is improved as well. In the proposed approach, with considering the effect of in-feed or out-feed currents, the optimal second zone timing of distance relays and optimal settings of DOCRs are computed. The proposed method is tested on two case studies and encouraging optimal results are obtained.     

工频变化量距离继电器的统一表达方式

工频变化量距离继电器具有良好的性能，但是在其应用中也需要注意一些问题。作者在分析已提出的几种工频变化量距离继电器基础上，推导出它们的统一参数表达式，以及参数取值与几种继电器之间的对应关系，并给出了参数的取值范围。在取值范围内，还可以得出一系列相似的继电器。基于统一参数表达式，分析了这一类工频变化量距离继电器的动作特性，以及在灵敏度和抗干能力上的渐近关系。经过分析后指出，在一定的负荷条件下，工频变化量距离继电器有可能出现稳态超越问题。为保证继电器不出现稳态超越，给出了参数取值与系统工况之间的约束关系。在此基础上，提出了一种根据系统运行工况，自动调整参数取值的自适应工频变化量距离继电器方案。     

Implementation of Directional Over-current Relay Coordination Approaches in Electrical Networks

As the smart grid concept is employed in the electric power system, network load flow and topology changes intensively to meet the best generation-demand balancing point. These changes must account for protection devices to enhance their performance. The coordination of directional over-current relays is most commonly studied based on fixed network operation and topology within a mesh power system. But sub-transmission and distribution systems constantly operate differently to satisfy the variety of load demand levels throughout the day and year. Hence, if the setting of directional over-current relays changes according to the different operations of the system, then relay operation time and sensitivity can both be enhanced. This can potentially improve the protection performance in a smart grid system. Therefore, this study is carried out based on the comparison among three coordination approaches: conventional (fixed settings), discrete (groups of settings), and continuous or real time (dynamic settings).     

Computer-aided protective relay setting system for large power networks

This paper introduces a protective relay setting system capable of handling a large network up to 10,000 buses. The remarkable features are such useful functions as network analysis (fault analysis, load flow calculation, zero-sequence current calculation, etc.), relay operation simulation, and automated setting coordination tasks. Fault currents in the maximum and the minimum operation networks are calculated to examine the setting values. The protection zones are searched automatically along the network connection. Protection coordination tasks among the primary and the backup relays composed of different types of relays can be performed by the relay operation simulation. The system is built on an engineering workstation, which works in cooperation with other network operation support systems. Its graphical user interface helps every engineer to examine the relay setting using a variety of databases.     

采用傅里叶算法对部分主设备保护继电器性能的影响分析

在分析傅里叶算法的基础上,指出了基于傅里叶算法的数字式继电器在电力主设备保护中应用的局限性,论证了采用此算法的电流差动、过电压、过负荷、零序过电流等继电器在发电机、串联电抗器、并补电容器、接地变压器等主设备中应用时对保护性能的影响,介绍了该类继电器在实际运行中出现不正确动作行为的事例,提出了改善保护性能的改进算法。     

演化计算在继电保护中的应用

简要介绍了演化计算的一般原理,以及演化计算在实现电流保护、定时限保护时段的整定值最佳配合计算中的应用。最后指出,演化计算可以适用于继电保护装置整定值最优化的问题。     

逆功率继电器特点、原理及调试

根据发电机逆功率运行时的特点,提出了对逆功率继电器的技术要求,分析比较了几种不同的逆功率继电器原理,对逆功率继电器的调试方法也提出了新的要求。     

进口保护应用问题探讨

一批微机型和集成型进口保护因其设计思想源于国外的电力系统，在防止二次保护误动方面考虑不全面，导致实际应用中存在一些问题。通过对TLS1B和LFCB型进口保护装置运行情况的分析。讨了该型号保护在运行中产生的三相不一致保护误动、闭锁重合闸逻辑混乱和允许联跳保护误动等3个主要问题。改进措施有效地提高了进口保护的运行可靠性和系统的稳定性。     

线路保护整定计算中的自动调整问题

对整定计算的自动调整问题进行了研究,提出了基于整定保护灵敏度约束条件、远后备保护灵敏度约束条件和远后备保护灵敏度传递约束条件的线路保护整定计算自动调整算法,由整定计算程序最大限度地代替工作人员自动实现保护定值的调整。算例表明,所提出的自动调整算法可以大大减轻整定计算人员的工作量,具有较好的实用价值。