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1、华中科技大学 硕士学位论文 分层式电网区域保护系统的原理和实现 姓名：吴科成 申请学位级别：硕士 专业：电力系统及其自动化 指导教师：林湘宁 20070226 华 中 科 技 大 学 硕 士 学 位 论 文 I 摘 要摘 要 继电保护作为电力系统的第一道防线，是系统安全运行的关键。随着大区电网 互联的规模不断扩大和运行方式日趋复杂，以及电力市场竞争机制的引入，电力系 统经常运行在极限的状况，电力系统的安全威胁问题日益突出，保护问题的内涵也 在不断扩展，保护的协调配合难度越来越大。本文结合河南省电网公司的“分层式 电网区域保护系统的研究”科研项目的工程实际任务，致力于对该领域的相关问题 进行研究
2、。提出和构建了一个使用于保护电力系统关键联络线的分层式电网区域保 护系统，并将其成果应用于具体的工程实践。 首先，在阅读大量文献的基础上，本文介绍了高压线路保护的发展历史以及研 究现状，指出了传统的保护装置所存在的问题，这些问题正是国内外展开讨论建立 广域保护的原因所在。本文随后介绍了广域保护的发展研究现状，并且介绍了国外 的若干广域保护系统的应用实例，指出了现有广域保护系统的不足之处。 继电保护的连锁跳闸是造成大停电直接的原因。因此，本文分析了造成继电保 护连锁跳闸的深层次的原因，包括后备保护的误动作，保护的隐匿故障以及过负荷 引起保护跳闸，并且介绍了国内外关于这些问题的初步的对策。 基于以
3、上分析，本文提出了一种适合于保护能量交汇的关键输电线路的，基于 电网多点信息综合决策的分层式电网区域保护系统，该系统可与传统的主保护和后 备保护协同工作，进一步加强电网的第一道防线。文中详细介绍了区域保护系统的 层次结构以及工作过程，阐述了用于故障定位的零负序方向元件的原理，提出了一 种基于序分量和阻抗的综合选相元件的原理。EMTP 仿真了各种故障，特别是区内 外复杂故障情况下系统的动作行为，结果证明了此系统的正确性。 区域保护系统能够识别出线路的切除带来的潮流转移，而在此暂态过程中常常 会引起系统的振荡，振荡中发生三相故障的破坏性最大，也最难识别。本文通过分 析，提出了基于功率变化率交叉闭锁
4、的振荡中对称故障的快速识别方法。作为一种 积分型判据，其动作稳定性高。仿真结果表明，该方案具有较高的可靠性和速动性。 根据区域保护的原理，采用 APCI5000 系列的工业控制机为开发平台，设计研 制了区域保护系统的样机，本文详细介绍了各层样机的硬件结构，软件设计流程， 最后以河南省洛阳局的三个 220kV 变电站的输电线路搭建了动模模型，并且严格进 华 中 科 技 大 学 硕 士 学 位 论 文 II 行了各种试验，证明此系统具有良好的性能。 在文章的最后，提出了保护与控制一体化的初步方案，在分析了电网的运行状 态后，提出了保护与预防控制的协调以及保护与紧急控制的协调，在具体的协调策 略中，
5、提出了以下几个研究思路：自适应反时限切除故障的方法、基于网络拓扑结 构的过负荷识别，基于网络拓扑结构的控制策略、运用电网运行方式优化保护性能。 文章为进一步展开该方面的研究做了铺垫工作。 关键词：分层式区域保护；综合决策机制；综合选相元件；交叉功率闭锁； 对称故障；动模试验；保护与控制一体化；广域保护。 华 中 科 技 大 学 硕 士 学 位 论 文 III Abstract Relay protection, as the first line of defence of power system, is the key of the safe operation of the system
6、. With the continually enlargement of the scale of local power grid connection and the increasingly complexity of operation mode, as well as the introduction of competition in power market, power systems frequently operate under extreme conditions, leading to serious security problems. On the other
7、hand, the connotation of protection is expanding and the protecting coordination becomes more and more difficult. This thesis aims at studying some practical problems by virtue of the project of the electric power company of Henan province- The research of hierarchical region protective system. It b
8、rings forward a hierarchical region protective system which is used to protect the key tie lines of power systems. The accomplishements of this thesis will be used in the engineering practice. Firstly, on the basis of thorough reading, the developing history and researching actuality of high voltage
9、 transmission line protection are presented in this thesis, showing the questions in traditional protecting device, which cause outgrowth of wide-area protection. After that, the latest survey of research of wide area protection is presented, including some implemented examples of wide-area protecti
10、on. Then some deficiencies of existing wide area protection system are indicated. The cascaded tripping of protections is the immediate cause of blackouts. Therefore, the thesis analyzes the deep reasons of the cascaded tripping of protective relaying system, including the maloperation of backup pro
11、tection, the hidden fault and protection tripping caused by overload. Besides, it also introduces some primary countermeasures presented. Based on this analysis, the thesis presents a hierarchical region protective system which is suitable for protecting the key transmission line of energy convergen
12、ce. This system is implemented by virtue of synthesis decision based on multiple information of power grid. This system can cooperate with traditional main and backup protections, further strengthening the first line of defense of power systems. The hierarchical structure and working process has bee
13、n detailedly introduced. Among them, the theory of zero and negative sequence directional elements used for fault location has also been expatiated, and a theory based on synthesis fault phase selection of sequential components and impedance measurement has been put forward. Various faults are simul
14、ated with EMTP to validate the proposed system, especially the system response under the scenarios of 华 中 科 技 大 学 硕 士 学 位 论 文 IV complex faults within and out of the area, and the results are satisfactory. Region protective system can identify the power transferring caused by removal of faults, and
15、during this transient state process the power swing of the system may be arisen. The damage of three phase fault in the power swing is the most serious, and also the most difficult to recognize. This thesis brings forward a kind of fast-identifying method of symmetrical fault that may occur during p
16、ower swings based on the cross-blocking scheme and power change rate. As an integral-type criterion, the performance of this scheme has high stability. The results of simulation tests show that this method has high reliability and speed. According to the theory of region protection, with the industrial computer of APCI5000 adopted as the platform, the prototype of region protective system has been developed. This thesis detailedly introduced the hard structure and the software design of this pr
