【作者】 李振兴；

【导师】 尹项根； 张哲；

【作者基本信息】 华中科技大学 ， 电力系统及其自动化， 2013， 博士

【摘要】 电网是国家关键基础设施，其安全事关国家经济发展和社会安定大局。国内外频繁发生的大停电事故为大电网的安全防御敲响了警钟。继电保护作为保障电网安全的第一道防线，对于快速隔离故障、有效控制事故蔓延至关重要。但在复杂的现代电网中，传统继电保护暴露越来越多的问题，如后备保护整定配合困难，电网结构或运行工况发生非预设性变化，可能发生拒动或误动，在大负荷转移情况下易引发连锁跳闸，造成大面积停电事故等。近年来，随着智能变电站信息共享技术和光纤通信技术的发展，继电保护系统可利用的信息资源发生了显著变化，为从根本上改善传统保护的性能提供了契机。本文在国家自然科学基金面上项目“应对电网灾变的有限广域智能保护的研究”（50877031）资助下，围绕基于信息共享的新型层次化继电保护系统构建模式、协调配合关系、大电网有限广域保护分区和基于多信息的故障元件判别算法等问题开展了系统深入的研究工作。本项研究意在深化热点关注的层次化保护研究内容和技术要求，提高或改善传统保护的性能，对加强电网安全、构建可靠的第一道防线具有重要的理论和现实意义。智能电网下新型变电站具有信息共享和集成的独特优势，对现有继电保护构建模式进行重新审视，以更好适应智能电网的发展需求，成为当前继电保护领域的研究重点之一。本文面向智能电网，基于信息共享技术，提出一种新型层次化继电保护架构体系，由间隔层保护、站域层保护和广域层保护组成。间隔层保护实现常规单个间隔元件的主保护功能和简化的后备保护功能；站域层保护也即站域保护，充分利用站域信息，整合并集成实现变电站继电保护的功能；广域层保护也即广域保护，集中区域电网冗余信息，实现电网的后备保护。进一步基于分层结构，考虑站内测量信息直采/网采模式和站间通信方式，分电压等级提出适应不同模式下的继电保护构建方案，并分析各方案的优缺点。一般来说，各分层继电保护研究都是相互独立的，为更好实现智能电网层次化保护功能，各层保护的保护配置及相互之间的协调配合成为本文的研究重点之一。论文根据层次化继电保护实现的功能，对间隔保护、站域保护和广域保护信息交互过程和跳闸协调配合进行了研究。在分析层次化保护信息流的基础上，研究提出了信息流过程中的信息组织、信息交互及其实现方案中的间隔层距离保护和零序保护整定、广域保护故障区域辨识等关键技术。进一步结合站域保护和广域保护跳闸决策的配合需求，具体研究了广域保护下行决策的辅助判据和复杂决策情况下的跳闸处理等。同时，也为改进间隔层保护性能，针对距离保护在潮流转移时易误动的特点，提出了一种自适应距离保护方案；为防止大范围负荷潮流转移时线路重载运行超出导线运行极限，提出一种基于热稳定约束的过负荷保护方案。现代电网规模庞大、结构复杂，难以对整个大电网实现单一层次化保护，如何将广域大电网划分为若干个合理的保护分区，并按分区域分别实现继电保护功能是层次化保护需解决的关键问题之一。论文在有限广域保护概念的基础上，提出大电网保护分区基本原则，主要包括分电压等级保护分区、中心站的选取、保护范围的划分、分区域边界的重叠交互等。以分区域通信量均衡性和决策中心计算量为指标，以分区数目和区域间的信息交互少、功能配合简单为约束条件，构建了保护分区性能评价体系。进一步，提出一种基于图论技术的保护分区实现方法，该方法基于电网拓扑结构构建邻接矩阵，通过计算得到明确分区范围的可达矩阵，最后，基于可达矩阵的搜索实现多种分区结果，并由分区优化实现大电网的最优分区。继电保护的基本任务是判别故障并快速切除故障，故障元件的判别一直是继电保护研究的重点之一。论文充分利用站域和广域范围内的冗余测量信息，研究融合多点保护动作信息的故障元件综合判据。为解决传统距离保护和零序保护存在的整定配合困难，延时长等问题，提出一种基于多源信息的距离保护和零序保护方案。针对广域信息在测量、判断和传输过程中可能出现信息缺失或信息错误，提出一种基于故障信息测度的信息容错算法，通过计算适应度函数得到广域范围内各元件的故障信息测度，基于故障元件的故障信息测度值最大，实现高可靠、高容错的故障元件判别。目前广域保护的验证一般采用数字仿真，但数字仿真的机电动态特性、测量误差都难以真实反应实际电网物理特性。广域动态模拟实验物理概念清晰，直观，且能真实反映实际系统的特征，是广域保护推向工程应用的重点。本文依托华中科技大学电气学院电力系统动态模拟实验室，搭建3机6节点电网模型，并模拟电网中出现的各种常规故障和复杂故障情况，采集广域范围内的故障信息，对所提出的广域保护故障元件判别算法的性能进行了试验验证。结果表明，算法在各种故障情况下可实现故障元件的准确识别，并具有良好的信息容错性能。论文最后对所取得的主要研究成果进行了总结，并对下一步研究工作重点进行了展望。更多还原

【Abstract】 The power grid is the critical infrastructure whose safe operation is of greatsignificance to the national economic development and social stability. Large scaleblackouts which happen frequently domestic and overseas recently sound the alarm aboutthe security defense of power grid. As the first defense line to ensure the safety of powergrid, relay protection is of great importance for isolating fault element quickly andpreventing the fault development effectively. However, under the background of moderncomplicated power grid, more and more problems of traditional relay protections have beenexposed, such as setting cooperation of back-up protections is very difficult, fail-to-trip ormalopeartion of protections may happen if the structure or operation status of power gridchanges unintentionally, cascading trips and large scale blackout may occur undercondition of heavy load transfer and so on. In recent years, with the development ofinformation sharing technology in smart substation and fiber communication technology,the information resources which can be used by relay protection system have changedsignificantly. Meanwhile, it provides a chance for fundamentally improving theperformance of traditional relay protection. As a part of the project “Limited Wide AreaIntelligent Protection against the Catastrophe of Power Grid”(50877031) which issupported by the Natural Science Foundation of China, this dissertation conducts anin-depth and systematic study on the construction mode and cooperation scheme of novelhierarchical relay protection system based on information sharing, partition of limited widearea protection, fault element identication algorithm based on multi-information and so on.The study can deepen the research contents and technical requirements of hierarchical relayprotection system, improve the performance of traditional relay protection. It is ofimportant therotical and practical significance for the construction of reliable first defenseline and safety of power grid.The novel substation under background of smart grid has the advantages ofinformation sharing and information integration. Based on it, in order to meet therequirements of smart grid, revew the construction mode of traditional relay protection andpropose novel construction mode have been one of the research focuses of relay protection.Based on the information sharing technology, a novel hierarchical relay protection systemwhich consists of bay-level protection, substation-level protection and wide-area-levelprotection is proposed. The bay-level protection realizes the primary protection functionand simplified back up protection function of conventional single bay. The substation-levelprotection which is also called “substation protection” realizes the relay protection functionof the whole substation integratedly by taking full advantages of substation information.The wide-area-level protection which is also called “wide-area protection” realizes the back up protection function of the power grid with redundant information of the regional powergrid. Based on the hierarchical structure, the direct sampling/networked sampling mode ofinformation measurement in the substation and communication mode between substationsare discussed. Meanwhile, according to different sampling modes and communicationmodes, construction modes of relay protection are proposed with respect of differentvoltage levels. The advantages and disadvantages of different construction modes areanalyzed.Generally speaking, the researches of different level protections are independent witheach other. In order to better realize the functions of the hierarchical relay protectionsystem of smart grid, the protection configurations of different level protections and thecoordination principles are studied. According to the functions of different level protections,the information interaction process and tripping coordination among the bay-levelprotection, substation-level protection and wide-area-level protection are studied. Based onthe analysis of information flow of the hierarchical relay protection system, the informationorganization and interaction of the information flow are proposed. Meanwhile, the settingcalculation principles of the bay-level distance protection and zero-sequence overcurrentprotection, as well as the faulted area identification method of the wide-area-levelprotection are proposed. According to the requirements of the cooperation between thesubstation-level protection and wide-area-level protection, the auxiliary criteria for thedownward decisions of the wide-area-level protection and the tripping strategy undercondition of complicated decision-making are studied further. Moreover, specified to thephenomenon that maloperation of distance protection may occur under condition of heavyload transfer, a self-adptive distance protection scheme is proposed to improve theperformance of the bay-level protection. In order to prevent the transimission line operatingbeyond the limit under condition of heavy load transfer, an over-load protection based onthe constraint of thermal stability is proposed.Due to the large and complicated structure of modern power grid, it is difficult toprotect the whole power grid with single hierarchical relay protection system. How todivide the wide-area power grid into several reasonable protection partitions and realize therelay protection functions in accordance with different partitions are the key issues whichneeds to be solved by the hierarchical relay protection. Based on the concept of limitedwide-area protection, the basic principles of protection partition of power grid whichinclude protection partition according to different voltage levels, choice of central station,division of protection scope, the overlap and interaction of different protection partitionsand so on are proposed. The performance evaluation system of protection partition is builtwith the balance index of communication amount between different protection partitionsand calculation amount index of decision-making center. The number of protectionpartitions, the information exchange between different protection partitions and functioncoordination are taken as constraint conditions for the performance evaluation system. Animplementation method of protection partition based on graph theory is put forward. The adjacent matrix is built based on the topological structure of power grid. Then the reachablematrix which can determine the scope of protection partitions can be obtained withcalculation of adjacent matrix. Finally, various partition results can be got based on thesearch of reachable matrix. With the optimization of partitions, the optimal protectionpartition of power grid can be obtained.The basic task of relay protection is identifying and isolating the fault element quickly.Hence, the fault element identification is always the research focus of relay protection. Bytaking full advantages of redundant measurement information within the substation scopeand wide-area scope, the comprehensive criteria of fault element identification with fusionof action information of multi-protection are studied. In order to solve the problem that thesetting cooperations of traditional distance protection and zero-sequenceo over currentprotection are very complicated, novel distance protection scheme and zero-sequenceo overcurrent protection scheme based on multi information sources are proposed. With respect tothe information mistake and information loss which may occur during the measurement,judgement and transfer of wide-area information, an information fault tolerant algorithmbased on the measurement of fault information is proposed. The fault informationmeasurement of different elements within the wide-area scope can be obtained with thecalculation of fitness function. Based on it, the fault element can be identified with highreliability and fault tolerance.Currently, the digital simulation is taken to validate the performance of wide-areaprotection. However, the electromechanical dymanic characteristics and measurement errorof digital simulation can not accurately reflect the physical characteristics of actual powergrid. On the other hand, the physical concepts of dynamic simulation experiment are clearand intuitive. Meanwhile, it can accurately reflect the characteristics of actual power grid.Hence, the wide-area protection dynamic simulation experiment is of great significance forpromoting the wide-area protection into engineering application. Relying on the powersystems dynamic simulation laboratory of CEEE, HUST, a model of the power grid with3-generator and6-node is built. With the dynamic simulation model, the performance of thefault element identification algorithm of the proposed wide-area protection is validated bysimulating various conventional faults and complex faults and collecting the faultinformation within the wide-area scope. The results show that the fault elementidentification algorithm can correctly identify the fault element under various faultconditions and it has high information fault tolerance.In the end, the dissertation gives systematical summary and points out the furtherwork.更多还原