【作者】 汪华；

【导师】 张哲；

【作者基本信息】 华中科技大学 ， 电力系统及其自动化， 2011， 硕士

【摘要】 继电保护是保障电力系统运行安全的重要基础。传统的基于就地电气量构成的后备保护存在整定配合复杂,动作时间长,在大负荷转移情况下可能连锁动作等突出问题,已难以适应复杂大电网的安全运行要求。近年来,随着计算机和网络通信技术的不断进步,特别是广域同步测量和数字化变电站技术的发展与成熟,基于广域测量信息的新型后备保护系统的研究得到了广泛关注。广域测量信息的应用,对广域后备保护的构成模式和实现原理带来了深刻影响,存在许多理论和技术问题有待解决。论文结合国家重点基金项目“集中决策与分布实现相协调的后备保护系统”,重点针对广域后备保护算法、就地变电站的信息组织与后备保护判据、广域后备保护与就地站后备保护的协调配合机制等方面开展研究工作。论文首先对国内外广域继电保护的研究现状及存在的主要问题进行了综述分析,在此基础上,阐述了论文工作的主要内容。在广域后备保护算法研究方面,分析了传统电流差动保护应用于广域后备保护时,线路分布电容电流以及TA测量误差等因素对差动保护性能的影响,并提出了相应的解决方案。针对基于故障方向比较的广域保护算法,提出了利用多点故障方向信息综合比较的改进措施。通过采用正、反负序方向元件,正、反零序方向元件和距离元件结合的判据来提高广域方向保护动作的可靠性,并给出了方向元件之间的配合逻辑。由于广域后备保护影响面广,要求具备高度的可靠性和安全性,采用多种不同原理的广域后备保护算法形成多重化保护配置,有助于进一步提高广域保护的性能。本文提出了一种基于故障电压分布的新型广域后备保护算法。该算法利用线路一侧电压、电流故障分量的测量值估算另一侧电压故障分量,以估算值与测量值的比值构成保护判据。该算法不受过渡电阻的影响;发生过负荷潮流转移时不会误动;且原理简洁,需要信息量少,对数据的同步性没有严格要求,便于实现。仿真算例表明,发生各种类型故障时,该算法均能正确识别故障线路。就地站信息的组织方式以及广域后备保护与传统后备保护之间的协调配合机制是广域保护研究中的重要内容。论文根据不同保护算法对故障信息的需求特点,从提高信息的适应性的角度,对变电站就地信息的组织方式进行了研究,同时,提出了就地站启动判据和就地故障确认判据。基于零序和负序电压以及正序低电压结合的启动判据可以缩小故障范围搜索和减少所需上传信息量,故障确认判据可以进一步加强广域后备保护的动作可靠性。论文根据广域后备保护应用后的新特点,研究提出了就地站后备保护的简化整定原则,以及距离III段的动作判据,在此基础上,给出了广域后备保护以及传统后备保护之间的逻辑配合机制。广域后备保护的应用,可有效解决传统后备保护在大负荷转移下连锁动作的问题,但由此也可能造成输电线路由于严重过负荷而发生故障。为了保证线路的安全运行,论文在对输电线路的承流特性进行研究分析的基础上,提出了一种基于输电线路发热模型的反时限过电流保护方案,文中介绍了保护的基本原理和实现方法。论文最后对课题研究工作进行了总结,并提出了进一步的研究方向。更多还原

【Abstract】 Relay protection is an important foundation to safeguard the power system security. The traditional protection is based on the local information, the setting was complicated, the operation time was long, and it may mal-operate when flow transferring caused by overload happened. The traditional protection cannot adapt the higher requirements of the Complex large grid. Recent years, as the rapid development of computer technology and network communication technology, it aroused wide concern about novel back-up protection system based on wide area measured information. The application of wide area measured information has effect on the structure mode and implementation principle of wide area back-up protection, much theoretical problems and technical issues should be solved. Combined the National Nature and Science Foundation Project“back-up protection system coordinate centralized decision and distributed implementation”, this paper mainly studied wide area protection algorithm, the protection criterion of local substation; solved the setting and coordination problems of the traditional back-up protection, avoided mal-operation when flow transferring caused by overload happened.At first, the current situation of wide area protection and the main problem exited are analyzed in this paper, on the basis represented the primary content of this paper. In the aspect of wide area back-up protection, this paper analyzed the affect of capacitive current of transmission line and TA measurement errors on wide area current differential protection, and proposed the solution. At the basis of wide area protection based on direction elements has been further studied. A new wide area direction protection based on fault direction information from multiple measured points was proposed. Fault recognition algorithm for protected zone within multiple elements has been put forward. And the operation logic of wide area direction protection is presented on the basis of the cooperation relationship among conventional direction component.Considering the wide area back-up protection affected in a big way, it required to be altitudinal reliability and Security. Using wide area back-up protection algorithms based on different principles is helpful to improve the performance of wide area back-up protection. In this paper, a novel wide area back-up protection algorithm was proposed, which based on the distribution of fault voltage. It can help to solve the setting and coordination problems of the traditional back-up protection and the mal-operation when flow transferring caused by overload happened. This algorithm used the value of fault voltage and fault current measured from one side of the line to estimate fault voltage of the other side of line. The ratio of estimated value to measured value makes up the protection criteria. It isn’t affected by transition resistance, and it wouldn’t misoperate when flow transferring caused by overload happened. The principle of this algorithm is simple and it requires little information. It has little request on the synchronization of the information from different sides and is convenient to implement. The simulation proved that the algorithm can successfully distinguish the faulted line under different type of faults.The information organization of local substation and the coordination of wide area back-up protection and convention back-up protection were important content of wide area protection research. According to different algorithms and improve the flexibility of information, this paper analyzed the information organization. Also, the initial criterion and fault recognition criterion were presented at the local substation. Initial criterion was made up of zero and negative sequence voltage, together with positive voltage, which was used for narrowing the fault area down, decreasing the information upload to primary substation. Fault recognition criterion can reinforce the reliability of wide area back-up protection. According to the new features of wide area back-up protection, the simplification of the setting principle of convention back-up protection and the third-zone phase distance protection criterion were proposed. At this foundation the logic of wide area back-up protection and convention back-up protection is analyzed.The application of wide area back-up protection can effectively solve the the mal-operation when flow transferring caused by overload. But it may cause line fault by seriously overload. To ensure the safe operation of transmission line, this paper analyzed the current-carrying characteristic of transmission line, and then proposed an inverse over-current protection scheme based on of transmission line. The primary principle and implementation method was introduced in this paper.At last, this paper summarized the work of research, and the further research directions are given.更多还原