【作者】 王冬青；

【导师】 刘沛；

【作者基本信息】 华中科技大学 ， 电力系统及其自动化， 2006， 博士

【摘要】 继电保护装置以及时可靠的切除被保护对象内部故障为目标。CIGRé的一项研究表明,27%的电力系统的扰动可以归因于保护系统的误动作。其根本原因在于传统的保护所采用的是单元式原理,即根据保护单元的单独决策来隔离故障,保护之间缺乏相应的配合协调,基于本地量的装置难以反映区域电力系统的运行状况,没有从系统的观点出发来做出有利于整个系统的具有系统优化和协调功能的保护动作策略。故障元件被突然切除后,剩余的系统可能会产生连锁的元件运行不正常而被保护跳开,系统的网络拓扑结构和潮流都要发生改变,对电网会产生冲击,这些都可能造成系统故障后失去稳定,或者造成连锁的大面积停电事故,是现有元件保护原理存在的固有缺陷。随着电力通信网架的日趋完善和实时通信技术的发展,电网多个关键节点信息已经有可能做到实时获取并进行快速交互,因此,结合稳定性实时预测理论,采用多Agent的技术,构成网络保护与紧急控制一体化的实时系统,是解决问题的一个新思路。而广域后备保护系统作为其中的一部分,可以首先开展实用化研究。本论文是在河南省电力公司的研究项目“基于数据网的新型自适应保护主动防护系统”这一课题的基础上完成的,其实用化的装置已经试制完成。论文所设计的基于数据网的新型广域后备保护系统,侧重于完成广域的后备保护功能,在一个地区内通过光纤网组成分层分布式的后备保护系统,一方面对传统的后备保护集中化,将一个变电站内的所有后备保护集中到一个智能处理系统;另一方面,将一个区域的后备保护的处理和控制策略的生成部分集中化,站级和区域控制级之间通过光纤数据网联系。这种设计,在传统的后备保护系统中增设了基于整个系统的集中智能控制处理环节,增强了电力系统的安全防御的第一道防线的安全可靠性,能适应大电网的互联,避免可能引发的级联跳闸。论文首先介绍了课题的背景和意义,对目前国内外广域后备保护系统的发展历史和研究现状进行了概述,分析了传统后备保护系统存在的问题,指出了对广域后备保护系统进行实用化研究的可行性。同时分析了广域保护系统的发展趋势,探讨了广域后备保护系统在实际中应用需要解决的问题。在设计系统的过程中,本文就遇到的一些问题作了详细分析。首先,针对广域后备保护所面临的信息处理方面的问题,设计了广域后备保护的信息处理系统,对信息量大,数据不精确、不正确或缺失的问题等等提出了解决方案,同时对信息融合的结构、系统各个部分的信息融合的算法做了阐述,并提出了用于数据层、特征层和决策层的详细的融合方法。并将D-S证据理论引入系统,利用D-S证据理论的可信度和似然度的概念,按照判决规则选择可信度和似然度最大的假设作为融合结果,为广域后备保护系统的信息处理提供了新思路。对广域后备保护系统的故障元件识别,本文提出了一种基于方向元件和网络拓扑分析的故障诊断方法,该方法建立在信息融合的基础上,把来自各子站的方向元件的信息,与所保护系统的网络拓扑结构结合,形成故障元件判别的结果矩阵,根据矩阵来推导出故障元件。仿真的结果表明该方法简单高效,易于实现,可靠性好。为进一步优化系统性能,本文探讨了MAS以及CORBA在电力系统后备保护诊断决策方面的应用,并提出了实际的应用方案,对系统的构造和各部分功能及实现做了分析。鉴于通讯网络对广域后备保护系统的重要性,论文还对广域后备保护通信系统做了进一步分析,设计了广域后备保护系统的通讯系统。对系统的结构,通信系统的介质选择、链路层技术、传输层技术和应用层协议等都做了详细的阐述,并对两种IP QoS(Quality of Service)模型进行了分析和比较,提出了基于MPLS(Multi Protocol Label Switching)网络的广域后备保护通信网络结构。最后利用OPNET(Optimized Network Engineering Tools)网络仿真软件对所设计的通信系统的时延进行了仿真。仿真结果表明所设计的通信系统时延可以满足广域后备保护系统的要求。基于以上研究,在分析传统后备保护所存在的问题的基础上,本文构造了新型的广域后备保护系统,在协调控制策略中考虑了断路器失灵、负荷入侵、高阻接地以及过负荷等异常情况的特殊处理,同时增加了与控制装置协调的环节。系统核心硬件采用486工控机和DSP,在网络连接上应用已经存在于现场的光纤网,把区域控制中心和变电站现场连接起来,组合成基于数据网的新型广域后备保护系统。该系统的方案设计实时可行,而且简单高效,对同步性要求较为宽松,有利于在大系统和大区域的推广应用。系统的样机已经通过了动模实验。最后,对全文进行了总结,并对以后的研究工作做了展望。更多还原

【Abstract】 According to recent studies,the mal-operation or fail-to-trip of protection is determined as one of the origins to raise and propagate major power system disturbances. Backup protections in fault clearance system have the task to operate only when the primary protection fails to operate or when the primary protection is temporarily out of service. The recent complexity and enlargement of power systems makes it difficult to coordinate operation times and reaches among relays especially. In the existed relay protection system,mal-operations of backup protection contribute a lot to system security and stability;furthermore,they are main reasons to system cascade tripping.To solve this problem,an intelligent analyzing and controlling function is added to key process of protection functionality. Therefore,a novel wide-area backup protection system is reported in this paper.First,the background of the paper is described,based on analyzing the disadvantage of traditional backup protection, a novel way to solve the problem is put forward. Then,some key problems in making wide area backup protection are described. To treat with large quantities of information in wide area backup protection,an information fusion system is designed,which has three layers: data layer, character layer, strategy layer,and data flows from data layer to character layer,then to strategy layer.Furthermore,D-S theory is utilized to deal with incorrect,inexact and lost of data. In the proposed backup protection system,the fault unit is selected in virtue of conventional pilot relay protection,and the fault location functions are made up of some kinds of line directional components. Such as negative sequence,zero sequence component direction function and impedance direction function,With the components, the fault unit is deduced. Detail characteristics of the three direction functions are being analyzed,simulation result validates the correctness of the design.Furthermore, a novel decision-making system is put forward for wide-area backup protection system based on CORBA and hybrid MAS system,MAS and CORBA technique is utilized, to realize control and coordinate inside the system on time,moreover,mobile agent is adopted to send or get data from other part of the system. The configuration and function of each agent is described. Service functions in CORBA make each part of the proposed system communicate each other.The communication system for wide area backup protection system is also designed, the system is made up of switching system,router and optic-fiber networks. Measures are taken to make the queue delay of the proposed system as small as possible,and reduce the delay in the network node and prevent data from being abandoned. So TCP and UDP protocol are employed in transport layer. In order to realize perfect QoS,the MPLS/Diffserv network can be utilized in wide area backup protection. Network simulation is made, the delay time of the result can be accepted by wide area protection system.Based on the above researches, the detail structure and function design of the proposed wide area backup protection system is described. The proposed system comprises a master system and several local units. The system is arranged as three layers. The bottom layer consists of PMUs with additional protection functionality. The next layer consists of several Local Backup Protection Centers (LBPCs) , each of which interfaces directly with a number of PMUs. The top layer, System Backup Protection Center (SBPC), acts as the coordinator for the LBPCs. Connected together via fiber-optic communication links, these devices can process intelligent algorithms based on data collected locally. Local part of the proposed wide-area backup system samples vital signals for backup protection system,and then deliver pre-processed results to SBPC via fiber-optic communications between the substation and SBPC. Based on the precise location of the fault,SBPC makes a strategy in several ways to guarantee the global security of the protected region, including coordinate with breaker failure strategy, overload strategy, reclosing strategy and so on. LBPCs perform the correlative operations on the spot, and then fault will be isolated rationally. Based on the dynamic experiment data, the superior performance of the proposed technique is validated in regard of the speed of response, computational burden and reliability.At the end of the thesis,the whole paper is summarized and some future work is discussed.更多还原