【作者】 汪旸；

【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， 2009， 博士

【摘要】 高压电网继电保护作为电网安全不可缺少的第一道防线,近年来其技术的发展面临电力系统高速发展的挑战,主要来自以下几个方面:基于超、特高压远距离交、直流混合输电技术的超大规模互联电网其运行工况更为复杂和安全稳定问题更为严峻;具有分布式电源、微网接入特征的统一坚强智能电网将呈现更为灵活多样的运行方式;各种形式的自然灾害造成电网结构或运行工况发生非预设性改变甚至系统肢解破坏传统保护的配合模式。学界普遍认为,应对这一系列难题的基本思路之一是突破传统保护仅利用单一被保护元件信息的局限,研究发展基于广域信息的广域继电保护。近年来,各种广域保护原理、模式乃至试验系统的研究受到广泛关注并取得了长足的进步,而当前现代通信技术、智能测控技术和数字化变电站技术的发展为广域保护提供了必需的技术基础,尤其是正在全世界开展的智能电网建设又为广域保护的应用提供了契机。本文在当前研究成果的基础上,围绕广域保护工程化应用中深层次的技术原理与实现方案展开研究和论述:基于电网继电保护功能及配合要求,提出一种利用电网有限范围广域信息并融合智能技术的高压电网有限广域智能保护,并研究解决保护系统结构、保护分区原理、保护跳闸策略以及智能保护算法等多方面的问题。利用广域信息来改善保护对系统变化的适应与配合可归纳为两种方式:一种是通过获取当前电网信息和集中整定计算,然后实时在线整定,其困难表现在大量信息传输与快速整定计算方法上;而另外一种则是利用实时广域信息直接实现保护配合与动作,无需传统意义的整定计算。本文研究的高压电网有限广域智能保护属于后者,其主要特点是基于有限广域信息和智能化方法,即利用保护配合关心的最小范围的广域信息并通过智能技术处理直接进行拓扑识别、故障识别,跳闸判定而实现保护的配合与有选择性动作。为此,本文首先在对比分析多种广域保护构成模式基础上建立了一种分区域集中决策的有限广域保护的系统结构,处理变电站之间的信息互联,保证保护功能故障识别和动作决策性能。论文对充分利用目前主保护纵联通道传输广域保护信息进行了探讨,这对广域保护的工程化应用尤为重要。对于结构复杂的实际大型电网,合理的保护分区是基于分区域集中决策的广域继电保护工程应用中需要重点解决的关键技术之一。论文基于图论技术提出了有限广域智能保护系统的保护分区理论,对保护分区的主要问题:信息域的制定与保护主站的选择进行了研究。提出了根据决策性能、通信能力与保护功能来确定的信息域,以及节点的度的系统主站选取标准,通过实例分析验证了保护分区原则与方法的可行性。论文结合网络结构与变电站主接线方式研究了有限广域智能保护系统的跳闸策略,后备保护进行故障识别、相应主保护失效时,保障在最小范围内切除故障,实现保护的选择性的系统协调配合机制。结合保护关联域讨论故障的关联域模式识别,提出了由保护配合要求界定的配合子站选取思想,保证了子站间清晰的后备保护职责。故障元件识别是有限广域智能保护系统的核心和基础,如何提高故障元件识别的准确性,特别是在由于传感器故障、信息判断错误等原因引起的广域信息部分缺失或出错情况下的正确性,防止保护系统的拒动、误动,是有限广域智能保护工程应用中需要重点解决的关键问题。论文对有限广域智能保护的保护算法进行了深入研究,提出了基于两种不同原理的广域继电保护算法。形成有限广域智能保护原理双重化配置,进一步改善有限广域智能保护系统的整体性能。第一种方法是基于遗传算法的智能保护算法,利用遗传算法构建电网故障识别模型,通过主保护动作、故障方向、测量阻抗判断三组电网信息的期望函数,利用各类电气量间的逻辑关系,实现准确故障识别。多种类电网信息的利用与遗传算法优异的鲁棒性,使算法不仅具备良好的准确性、可靠性,尤其具备优异的信息容错性能,是人工智能技术在广域继电保护原理研究领域的初步探讨。第二种方法是基于信息融合的关联方向比较保护算法。该算法以基于关联方向比较原理的广域继电保护算法为故障识别判据,提出基于进化模型的信息融合技术作为辅助性措施,实时纠正故障方向信息以改善判据应对坏数据能力不足,并为今后故障信息冗余与容错识别技术提供了基础性研究。作为广域智能保护实现技术的重要组成部分,论文对有限广域智能保护的通信系统基本模式进行研究,利用网络通信仿真软件Network Simulator对通信网络性能进行仿真与分析,仿真结果验证了基于SDH广域通信的可行性。最后,论文对所作的工作进行了总结,并对本课题的发展趋势进行了展望。更多还原

【Abstract】 High voltage grid relay protection is indispensable as power grid security and stability first defending line, and the technology has been challenged by development of power system. Operation condition would be more complicated and security and stability problem would be more austere in large-scale interconnected power grid of high and ultra high voltage and transmission system of AC and DC technology. Flexible and multiplex operation mode is need in Smart Grid with character of distributed generation and microgrid. Traditional relay protection coordination would be destroyed in non-presupposed operation mode changed of structure power grid and catastrophe accidents of power grid. Generally, research of wide area protection based on wide area information is an effectual way to deal with the problem of power grid protection.The research of wide area protection principle and experiment system has been concerned widely, and necessary technology is provided with development of communication technology, intelligent measurement and control technology and digital substation, especially, Smart Grid should accelerate the application of wide area protection. Therefore, limited wide area protection system of centralized decision by area division was presented in this paper, combining with current wide area protection development and practical engineering application. And this paper gives a detail discuss on structure, principle and method of protected zone division, tripping strategy and intelligent protection principle.This paper brings forward a limited wide area intelligent protection system based on abundant power network information and intelligent technology by analyzing the practical application of wide area protection and further combining it with the recent development of power network. The system consists of some limited systems by covering with the wide area power grid, and forms the grid protection including integrated backup protection. The selection of protection is realized by exact fault judgment and power network structure, not for traditional multi section delay, so it avoids the accident of load transfer essentially.The principle and method of protected zone division has been researched by using graph theory. It is made up of not only information region, which is decided by wide area communication capability and expectant control range, but also selection of main substation which is decided by the degree of nodes in system. It is a feasible but not optimal way to deal with protected zone division for actual power grid, but it is fit for practical engineering and complicated loop power network.This paper makes some analysis and research on tripping strategy with connection mode in practical engineering, chooses tripping strategy by considering whole power grid not depending on action delay. Protection associated region is made use of identifying associated mode and selection of seed substation, which assures the backup protection duty for substations. At the same time, intelligent failure protection is provided with the function of breaker failure protection, and it is advancement for system intelligence.The basis and kernel of limited wide area intelligent protection system is fault identification, and it is very important to improve the identification veracity for engineering application. This paper gives an intelligent protection principle based on genetic algorithm, and it is a primary research for artificial intelligence application in protection. Conformation for regularization fitness function is good for intelligence principle standardization and expanding. Intelligence protection principle is made up of three expectation functions of main protection action information, fault direction information and impedance information, and the protection principle based on genetic algorithm has good accuracy and robustness, especially, excellent fault-tolerance capability by using logic relation of kinds of power grid information.In order to improve the capability of longitudinal direction comparison principle, this paper brings on a study of information fusion based on evolution model for assistant. This principle should be configured for the second protection principle of limited wide area intelligent protection, and it is useful to improve the capability of protection system, and this chapter also does some research on multiple criterion logic with two different protection principles. A communication system for wide area protection is mentioned in this chapter, and some simulation results for capability of communication system is educed by using Network Simulator. The simulation is about communication in different network environment and repetitious router transmitting, and compares communication delay and packet loss rate. The simulation results provide warrant for the selection of limited wide area radius.Finally the achieved research is concluded and future perspective on development of limited wide area intelligent protection is highlighted.更多还原