智能变电站全站快速后备保护系统方案及应用

电力系统继电保护中后备保护按阶梯配合整定,必然使主干电网和发电厂后备保护动作时间太长、影响电网安全的问题。本文提出了一种适用于智能站的全站快速后备保护系统,描述了该快速后备保护系统的原理,建立了动作逻辑方程式。开发了快速后备逻辑单元NSR306装置、各保护装置的快速后备功能模块、所有硬件、软件和系统结构等,对其作仿真验证了其可行性。采用此方法,变电站内所有后备保护动作时间只需整为一个时差0.3s即可,从而缩短整个电网的后备保护动作时间,彻底解决了后备保护延时配合的问题。     

关于500kV变压器低阻抗保护配置的看法

目前,500kV系统联络变压器后备保护的配置,存在着一定的缺陷,整定配合困难,动作时间长,对系统安全运行不利.因此,就此问题,介绍了有关系统联络变压器后备保护的配置设想,可缩短保护动作的时间,增加了保护的动作范围,大大提高了电网安全运行的可靠性.     

应对变电站二次直流失电的超高压输电线路相间保护方案

变电站二次直流失电会导致本站继电保护装置等设备失去供电电源而无法动作,本站出线发生故障时需要依靠上级变电站的远后备保护进行切除。针对变电站二次直流失电情况下超高压输电线路发生相间短路故障时保护远后备灵敏度不足的问题,提出了一种应对变电站二次直流失电的超高压输电线路相间保护方案。首先,根据超高压电网相间故障时负序电流的自然分布特性,探讨了反时限负序过流保护的远后备应用可行性和相间距离保护的补充特性,确定了相间故障远后备保护的构成思路。接着,研究了助增系数和负序电流对反时限负序过流保护整定时间定值的影响,讨论了临界助增系数的确定方法和反时限负序过流保护的时间定值整定方法。然后,提出了反时限负序过流保护为主、相间距离保护为辅的应对变电站二次直流失电的超高压输电线路相间保护方案。最后,以IEEE 39节点系统和某实际500 kV电网作为仿真算例,对所提方案的有效性进行验证。     

基于CORBA的混杂MAS广域后备保护系统设计

为避免系统瓦解,优化后备保护系统的性能,使保护和控制实时沟通,互相配合,提出了后备保护系统,它是将一个地区内不同电压等级,不同变电站的所有后备保护人工智能化,并通过光纤网组合成的一个基于CORBA的大型混杂MAS的分层分布式广域后备保护系统。该系统分为区域级、变电站级后备保护系统中心MAS以及元件Agent三级结构,利用MAS和CORBA技术实现系统的各部分的自治和各部分之间的交互活动。针对断路器失灵、过负荷、重合闸的情况通过调整后备保护系统的动作时间、动作方式以及向稳控装置发控制信号,实现保护与控制的相互配合。动模实验证明该系统及优化策略切实可行、易于实现。     

关于500kV变压器低阻抗保护配置的看法

目前 ,5 0 0kV系统联络变压器后备保护的配置 ,存在着一定的缺陷 ,整定配合困难 ,动作时间长 ,对系统安全运行不利。因此 ,就此问题 ,介绍了有关系统联络变压器后备保护的配置设想 ,可缩短保护动作的时间 ,增加了保护的动作范围 ,大大提高了电网安全运行的可靠性。     

基于多Agent技术的站域保护系统的研究

针对传统变电站基于元件信息的后备保护动作时限和定值配合繁杂的弊端,提出基于本地信息的站域保护。该保护由电流元件和电压元件构成,原理简单可靠,在主保护及断路器拒动时具有后备保护和断路器失灵保护的功能,同时近后备和远后备的动作时限相同,能够快速切除故障。并提出基于多Agent技术的站域保护系统,运行方式改变时该系统能够自适应地调整保护定值,提高了保护灵敏度。     

新设备冲击送电过程中的事故分析及处理

针对青岛电网某35kV变电站二期改造完成后对新设备冲击送电时#1主变高后备保护动作事故,分析保护动作时该站的运行方式、高后备保护的动作原理及其定值情况,进而证明保护动作的正确性,并提出启动送电步骤的改进措施,对以后同类型的工作具有指导意义.     

一次特殊故障的继电保护动作行为分析

详细分析了高频保护区外故障，高频保护及后备保护动作情况，故障电网系统内其他线路保护动作情况，对以后保护实际工作有一定的借鉴意义。     

光纤通道异常时加速线路Ⅱ段后备保护技术

双重化配置的输电线路光纤保护,存在因光纤通道同时异常造成线路区内故障时保护同时拒动的风险。一旦发生,将造成故障切除时间的延迟和相邻线路的无选择性跳闸,带来故障范围的扩大和电网稳定性破坏的严重后果。文中针对这种因光纤通道异常导致的线路光纤纵联保护退出情况,研究了一种自适应缩短线路Ⅱ段后备保护动作时间的技术方案,并进行了试验验证。通过加速线路Ⅱ段后备保护动作时间,达到快速切除故障同时避免相邻线路Ⅱ段后备保护无选择性跳闸的目的,提高了电网运行的稳定性和可靠性。     

基于联锁的110 kV区域电网线路保护原理及其应用

针对110kV电网的特点,分析了阶段式距离保护在多级线路结构的电网中逐级配合困难的问题,提出了基于联锁的区域电网线路保护原理。该保护原理结合了本线路距离保护和线路对侧变电站的母线电流差动保护、线路距离保护的故障判别结果,从而实现全线范围的快速动作后备保护功能。该保护原理集成于区域保护与控制系统中,通过站域保护设备之间的动作信息发布/订阅,实现了基于联锁的区域电网线路保护功能。基于该原理的区域保护与控制系统已通过仿真测试并投入试运行,其原理的正确性得到了验证。     

Applying CTs with digital ground relays

Industrial power distribution system substation transformers and generator step-up transformers in power stations often use resistance-grounded wye secondary windings for medium-voltage power distribution. The purpose of this is to limit damage due to ground-fault currents, while providing sufficient fault current for the operation of ground-fault relaying. The relaying used to protect against ground faults in the system may not provide sufficient protection of the transformer winding against internal faults because the backup ground overcurrent relay in the transformer neutral-to-ground connection must be set to coordinate with downstream relays. In order to protect the winding itself, special relays are utilized. Ground differential protection can be provided by digital overcurrent relays in conjunction with auxiliary ratio matching transformers. Ground differential protection can also be provided in multifunction digital relays. Transformer protection relays may include this feature with one of the schemes used with component relays. If a feeder-protection relay is used on the secondary, in some cases, this may have a ground-directional feature that can be utilized for ground-differential protection     

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.     

Adaptive non-communication protection for power lines BO scheme3-The accelerated operation approach

This paper presents the accelerated operation scheme of the adaptive noncommunication protection technique for power lines with complex configurations, such as multi-end feeders and ring mains. In the scheme, the overcurrent directional relays are arranged in two operating modes, the fixed time operation and accelerated operation. The relays with faster operating time in the conventional time grading coordination remain unchanged. The new technique is employed to enable accelerated operation to be achieved for the relays which are in the positions for which slow operating time is set when using conventional time grading technique. For a fault occurring on the protected system, the relays of fixed time operation mode will operate at the preset time for the fault within its protected direction. The relays which are programmed to use accelerated operation mode will determine whether a fault is on the protected section or not by using the BO technique, that is to detect the circuit breaker operation by determining whether the line section is in a balanced operation condition or not. The relay makes accelerated tripping decisions for a fault on its protected section. Simulation studies of the responses to various system and fault conditions show that the scheme can significantly increase the speed of the relay responses in the protection of power line systems with complex configurations     

A novel neural network and backtracking based protection coordination scheme for distribution system with distributed generation

With the increased installation of renewable energy based distributed generations (DGs) in distribution systems, it brings about a change in the fault current level of the system and causes many problems in the current protection system. Hence, effective protection schemes are required to ensure safe and selective protection relay coordination in the power distribution system with DG units. In this paper, a novel adaptive protection scheme is proposed by integrating fault location with protection relay coordination strategies. An automated fault location method is developed using a two stage radial basis function neural network (RBFNN) in which the first RBFNN determines the fault distance from each source while the second RBFNN identifies the exact faulty line. After identifying the exact faulty line, then protection relay coordination is implemented. A new protection coordination strategy using the backtracking algorithm is proposed in which it considers the main protection algorithm to coordinate the operating states of relays so as to isolate the faulty line. Then a backup protection algorithm is considered to complete the protection coordination scheme for isolating the malfunction relays of the main protection system. Several case studies have been used to validate the accuracy of the proposed adaptive protection schemes. The results illustrate that the adaptive protection scheme is able to accurately identify faulty line and coordinate the relays in a power distribution system with DG units. The developed adaptive protection scheme is useful for assisting power engineers in performing service restoration quickly so as to decrease the total down time during faults.     

Communication-based Adaptive Protection for Distribution Systems Penetrated with Distributed Generators

In this article, a communication-based adaptive over-current protection scheme for distribution systems penetrated with distributed generators is proposed. A communication network between the over-current relays, the distributed generators, and the utility grid is employed to automatically update the settings of the protective relays. Moreover, the communication reliability is increased through the addition of a backup communication system. The proposed scheme has the advantage of operating during grid-connected and islanding modes of operation. The scheme employs two simultaneous algorithms. The first algorithm works when the system configuration is changed due to the connection/disconnection of a distributed generator or the utility grid. The second algorithm efficiently uses the exchanged information between the relays to identify the faulted section and hence speeds up fault clearance. The proposed scheme is tested for difierent fault conditions as well as for different system configurations. The results demonstrated that relay operating times, including the communication delay, are greatly reduced when the faulted section is identified and relay settings are adjusted accordingly. In addition, a negligible time delay was experienced when the backup communication network was put in service.     

Algorithmic-knowledge-based adaptive coordination in transmission protection

Changes in power system operating conditions can affect both the reach point of distance relays and the coordination of distance and overcurrent relays. To improve the performance of the protection system, an adaptive scheme of relay settings is proposed. That is possible since the protection relays became digital . This paper describes a system for online adaptive setting and coordination of protection relays in meshed networks where the backup protection is achieved in remote form. After changes in the state of the network, an expert system (ES) performs the detection and proposes the correction of erroneous settings of protection zones and miscoordinations between relays at different stations; through an algorithm based on a fast determination of a nonminimal set of "break-points" (BPs) relays , new time characteristics for the coordination are found. The results of the application of the developed system to a test network of 34 nodes, 55 branches, and 110 relays are shown.     

京津唐电网继电保护装置异常停运分析

对１９９７年京津唐电网２２０ｋＶ系统继电保护装置异常停运的各种情况进行了统计,分析了造成保护装置故障的各种原因。针对京津唐电网现存问题,提出了缩短故障处理时间的具体措施。     

Time coordination method for power system protection byevolutionary algorithm

A typical industrial power network may consist of hundreds of pieces of equipment and even more protection relays to protect the system are required. Each protection relay in the power network needs to be coordinated with the relays protecting the adjacent equipment. The overall protection coordination is, thus, very complicated. A new concept of protection coordination by time is introduced in this paper to formulate all the system relays and system equipment operation into a set of optimization equations and constraints. Its purpose is to search for an optimal protection setting to minimize the system disturbance time as well as the time of interruption of the power supply. An evolutionary algorithm is applied as a constraint satisfaction optimization tool to search for the optimal relay setting. This method can find the best protection relay coordination, which cannot be achieved by traditional methods. This is the most significant achievement of the paper     

微机变压器的相间后备保护

提出对变压器内部故障应以两套差动保护互为后备,距离继电器主要作为低压母线及馈线故障的后备保护,并建议采用负序距离继电器和椭圆形继电器为宜     

Identifying the Primary Fault Section After Contingencies in Bulk Power Systems

This paper deals with the problem of fault section estimation in electric power systems, undertaken at a control center level and using information about the operation of protection relays and circuit breakers. The developed methodology should be used after the occurrence of contingencies with definitive disconnections, and before beginning the process of network restoration. Due to the absence of an analytic formulation, the problem calls for the use of artificial-intelligence techniques, such as neural networks and expert systems. Neural networks are employed to model the protection systems, dealing with the uncertainties involved with relay and circuit-breaker operation messages. An expert system is used to complement the results provided by the neural networks, considering the network topology. The results show that the developed methodology is applicable to real large-scale power systems. In addition, it is capable of noise suppression in relay and circuit-breaker trip messages, treats multiple faults naturally, and infers a solution even in cases when remote backup protection action occurs.