阶段式保护原理性失效风险的概率评估方法

继电保护对电力系统的安全稳定运行有着重大影响,其可靠性研究一直是电力工作者关注的课题。针对目前继电保护系统可靠性及风险评估方法存在难以反映保护原理特性、动作时序特性等不足,在保护元件原理性失效概率模型的基础上,确定了继电保护系统的风险评估指标,并制定了阶段式保护原理性失效风险评估的详细流程。最后分析了某实际电网中距离保护的原理性失效风险,结果表明该方法有助于寻找保护系统的薄弱环节、发现其他系统难以发现的问题,并能为保护定值校核等系统提供参考冗余信息。     

智能变电站保护用电流互感器配置问题及解决措施

通过一起断路器内部故障相关保护动作行为的分析,指出现有智能变电站保护用电流互感器配置方案存在严重缺陷。当一台保护停运时在断路器内部故障会出现快速保护死区,需要依靠带延时的失灵保护切除故障;而失灵保护会由于感受不到故障电流而拒动,从而威胁电网的安全稳定运行。为此,从工程设计上提出在每台断路器两侧各装设2组TPY绕组和1组5P绕组的保护用电流互感器配置方案,以彻底消除保护死区。同时,还从系统运行及保护配置等方面提出了补救措施,包括停用相关断路器及装设死区保护或改造失灵保护等。上述方法目前已在西北750 kV智能变电站建设和运行中获得应用,提高了保护的可靠性和系统的稳定性。     

Reliability of various industrial substations

Many utility and industrial substation configurations have been designed to interconnect energy sources and individual industrial load points. The design, protection schemes, and operating procedures of a substation configuration directly affect the reliability of the power supply to these load points. When an existing or planned substation configuration is unreliable, the question is: which substation configuration will be more reliable? Another question is: what reliability methodology will account for the protection schemes in place, the operating procedures and the common cause failures of utility supplies? This paper will discuss and present a reliability analysis of eight basic industrial substation configurations that are typically used inside process plants. The zone branch reliability methodology is used to calculate load point reliability indexes of each substation configuration. The reliability analysis includes open and short-circuit failure modes of circuit protective devices, operating practices and common cause failures of utility supplies. The significant impact of common cause utility supply failures on load point reliability levels will be presented and discussed in detail.     

Potential DC system support to enhance AC system performance in theWestern United States

The potentials of utilizing the controllability of DC lines to reduce the complexity of remedial schemes or to increase the stability performance of a system so that the impact of existing and future projects on nonproject systems can be minimized are explored. Less costly and perhaps more environmentally acceptable alternatives of utilizing power transfer overloads of the two existing DC lines of the Western Systems Coordinating Council (WSSC) in the Western US are presented. In addition, a concept to overload one DC line for the outage of the other DC line is investigated. Reducing the complexity of the remedial action scheme would be definite benefit to the WSCC network operating reliability objective     

A study of the application of fast valving and braking resistor for an intelligent SPS

There are some kinds of remedial action schemes that deal with sudden disturbance situations in a transmission network. Generator tripping with an SPS (Special Protection System) is one of the remedial action schemes, and it is a powerful and effective method of solving transient stability problems. When an extra-high-voltage transmission line that is transferring a large amount of power is tripped, generators designated by a SPS are tripped to prevent over-speeding of the generators. However, the tripping of generators can cause difficulties in the power system operation, and if large amounts of power are tripped, load shedding can occur. Therefore, it is desirable that a minimum number of generators is tripped in required stable conditions. For this purpose, an intelligent SPS is currently being developed to reduce the number of generator tripping events. In this paper, an application method involving fast valving and a braking resistor are analyzed as suitable action schemes for a SPS.     

发变组失灵保护的探讨及改进

对于发变组失灵保护,目前还存在模糊认识和错误认识,影响到保护的可靠性。通过对“转子两点接地”等保护量动作结果的分析,说明有些保护量没有能力启动失灵,需借助“程跳逆功率”保护启动失灵,但“程跳逆功率”保护的逻辑回路宜修改;通过对“失磁”等保护量动作结果及其保护目的分析,说明有些保护不需启动失灵。在电流判别方面,从失磁和逆功率2种情况分析,可得出其整定计算原则;在电压判别方面,规程规定的复合电压闭锁会造成失灵拒动,有2种方案可供改进。改进后的失灵保护逻辑加上明确的电流判别整定计算原则,将使发变组失灵保护更加完善可靠。     

Power grid fault traveling wave network protection scheme

Based on study on propagation characteristics of traveling wave in transmission lines, a novel power grid fault traveling wave network protection scheme was proposed in this paper. When a line fault occurs, all traveling wave protection relays (TWPR) record arrival time of initial traveling wave using the precise timing signals from Global Positioning System (GPS). Then the ineffective arrival time of initial traveling wave is eliminated and modified, while the effective arrival time of initial traveling wave is utilized to detect the fault line. Different from the traditional protection schemes, which are only based on fault information of one line, the proposed scheme not only solves the problems of traveling wave protection, which are susceptible to the factors (such as the structure of the lines), but also can make reliable tripping action when one or more TWPRs break down, start-up failure or record wrong arrival time of initial traveling wave. Both theoretical analysis and simulations indicate that the protection method has high reliability, and redounds to further enhancing the practicability of traveling wave protection.     

进线保护、备自投、自复位功能一体化装置

在输配电系统中,为了提高电力系统的供电可靠性,电网供电普遍采用一主一备模式,即:当主工作电源出现故障不能正常供电时,由备自投装置将负荷自动切换到备用电源供电,从而保证不间断对用户供电。对一主一备进线系统的工程典型配置方案、充放电逻辑、动作逻辑进行分析、优化,提出了进线保护、备自投、自复位功能一体化装置的方案,主要针对一主一备进线系统,且需要主进线电源正常既自动投入运行的系统。可以简化系统设计、降低工程造价成本、方便运行值班人员的操作,等等。     

基于VSC的直流配电系统过电流保护研究

针对低压直流配电网,本文利用电压源型换流器的自关断功能来代替直流断路器限流的作用,进行保护方案配置。本文主要聚焦故障中断和隔离,利用继电器检测本保护区域故障信息并把动作信号传输到换流器,换流器动作隔离故障。在PSCAD软件中搭建两端供电的直流配电模型进行仿真,结果表明,在采用继电器的情况下,采用过电流的保护方案可以满足快速响应的要求,为下一步直流配电系统保护方案的研究奠定了良好的基础。     

变电站直流系统用高可靠性充电电源模块

针对某无人值守智能变电站设计了一种高可靠性和高性能的充电电源模块。采用在中小功率得到广泛应用的LLC谐振变换器作为功率拓扑,具有变换效率高和供电质量高的优点。详细地给出了方案的设计过程,并且从蓄电池充电策略和故障保护等方面提出了提高电源可靠性的若干策略。最后完成了样机制作,实验结果验证了设计的可行性和准确性。     

Grounding transformer applications and associated protectionschemes

The use of grounding transformers on three-phase ungrounded governmental, industrial, and commercial distribution systems is addressed. Ground-fault protection schemes that provide selective and reasonably fast tripping are often incorporated with these grounding transformers. The authors first review the state of the art of grounding transformers to assist electric power systems engineers in the proper understanding of the use and applications of these devices and then discuss two governmental system case studies illustrating improperly applied grounding transformers and/or associated ground-fault protection systems. In addition, they describe remedial actions taken to correct these deficiencies. The objective in presenting improper grounding transformer applications is to highlight protection concerns that are often ignored. It is stressed that a single grounding transformer is not adequate for use with a multibus configuration. A unique protection scheme for use on a multibus arrangement is presented     

随机失效指标在继电保护状态评价中的研究与应用

在考虑继电保护随机失效的情况下,提出并分析了继电保护随机失效指标和随机失效率。分析表明,随机失效指标可以通过指数函数描述继电保护的可靠性。在此基础上,根据继电保护系统的实际构成,修正完善了基于随机失效指标的继电保护可靠性模型,并确定了相关随机失效率参数的确定原则。另外,假设随机失效率为常数并与时间无关,构建了实用的继电保护随机失效可靠度函数,以及设备随机失效可靠度计算方法。该方法在重庆电力公司继电保护设备状态评价分析中得到了应用。应用效果表明,该方法能够在一定条件下计算出继电保护设备的随机失效可靠度,反映设备健康状况。     

An improved reliability model for redundant protectivesystems-Markov models

A number of reliability models of power system components including protective-system failures have been proposed. These models have concentrated on modeling a single protective device. When this protections fails, it is usually assumed that backup protection will isolate the faulted component with 100% reliability. In reality, power system components, have redundant protection schemes with two or more protective devices operating in parallel. Existing reliability models have not dealt with redundant protective systems adequately. This paper presents an improved reliability model capable of modeling these systems. The proposed Markov model and the equations for a number of important performance indices are derived and illustrated in this paper using the data for a typical transmission system     

An Investigation on the Nondetection Zones of Synchronous Distributed Generation Anti-Islanding Protection

Anti-islanding protection is an important technical requirement when interconnecting distributed generators. Unfortunately, most anti-islanding protection schemes cannot detect islanding situations under certain system operating conditions - there are nondetection zones within which anti-islanding protection schemes are ineffective. This paper investigates these nondetection zones associated with the common anti-islanding protection schemes of synchronous distributed generators: frequency and voltage-based relays. Moreover, the characteristics of the nondetection zones and the key factors that influence them are analyzed. The results are useful for utility companies and distributed generators owners to design and to evaluate the effectiveness of anti-islanding protection schemes proposed for various distributed generation interconnection projects.     

兼顾经济性和可靠性的不同继电保护配置方案分析

继电保护的目的是保证电网的安全稳定运行,而不同的保护配置方案对电网的影响并不相同。分析了造成保护失效的不同原因,建立了用于评价不同方案的继电保护可靠性的马尔科夫模型,并运用状态空间法对其可靠性进行了分析。在此基础上,进一步分析了成本、故障损失等经济性因素的影响,研究了选择不同配置方案的效果,为实际保护配置方案的分析、评价提供了参考。     

斩波串级调速系统逆变侧电子保护电路的研究与设计

根据常规斩波串级调速系统的拓扑结构,分析了调速设备故障时接触器保护在动作保护过程中主回路的暂态过程。由于接触器动作时间较长,在其动作期间调速设备易受到高电压、大电流的冲击,导致电力电子器件损坏。针对接触器保护的弊端,设计了带电子保护电路的主回路拓扑结构。并分析了高压失电工况下常规的和带电子保护电路的斩波串级调速系统的暂态过程,同时进行详细的理论推导,得出高压失电工况下理论分析的依据。最后在模拟带载试验平台上分别对常规斩波串级调速系统和增加电子保护电路的调速系统在高压失电的工况下进行测试。测试结果表明理论计算与实际测量值基本一致,同时验证了电子保护电路有效解决了有源逆变结构下的高压失电或者逆变颠覆的问题。     

110kV变电站站用电系统隐患分析及解决方案

根据唐山供电公司110 kV变电站的运行方式和站用电系统的现状,分析了当前110 kV变电站站用电系统存在的问题和隐患,提出了改善站用电系统可靠性的建议及失去站用电后的补救措施。     

Adaptive non-communication protection for power lines BO scheme1-The delayed operation approach

This paper proposes a new technique in power line protection, the "adaptive non-communication protection". In this technique, protection relays make operate or restraint decisions, adapting to system and fault conditions, without the need for communication links. Operation without communication links to signal the remote end relay is achieved by the detection and identification of the operation of the circuit breaker at the remote end of the protected line section. An algorithm based on symmetric components is proposed to detect and identify the balance condition of the power system during the fault. The paper is focused on one of the three protection schemes based on the new technique, the delayed operation scheme. Simulation studies carried out for various power systems and fault conditions have demonstrated its feasibility     

基于分布式功能的站域保护

由于保护设备配置以及数据获取的单一化,影响现有智能保护方案在设备故障时的可靠性。为了提高保护方案的可靠性,保证设备故障或者数据丢失情况时保护方案的可靠运行,提出了保护功能分散化、信息获取多元化、数据处理并行化的优化方案。包括以智能保护设备IED为基础构建了基于二次保护信息的RIED;将源数据发送给多个IED/RIED构成数据冗余,提高数据冗余性;通过不同的算法实现相同的功能,并将算法分散到不同的IED,提高算法的冗余性;利用保护算法的中间量信息实现设备可靠性监测。分析表明该优化方案可有效地提高设备故障及数据丢失时的保护性能,增加了保护方案的可靠性。     

Zone-branch reliability methodology for analyzing industrial powersystems

There are many methods available for evaluating the frequency and duration of load point interruptions within a given industrial power system configuration. As systems become larger and more interconnected, these existing methods can become computationally bound and limited in their ability to assess the impact of unreliable protective equipment and unreliable protection-coordination schemes on individual load point reliability indexes within a given plant configuration. These methods also can often not account for complex isolation and restoration procedures within an industrial plant configuration. This paper presents a zone-branch methodology that overcomes many of these limitations and applies the methodology to a large industrial plant power system configuration. The primary advantage of the zone-branch methodology is that it can readily identify faulty protection schemes involving all the components of an industrial power system and evaluate load point reliability indexes