【作者】 沈智健；

【导师】 周家启；

【作者基本信息】 重庆大学 ， 电气工程， 2008， 博士

【摘要】 继电保护失效概率模型是输电系统运行可靠性评估研究的重要部分,相关基础理论和应用技术是值得深入研究的前沿性课题。首先,论文分析了微机继电保护系统中软件和硬件的结构及工作原理,阐述了两类失效的机理,其中第二类失效条件概率与继电保护原理和电网实时状态紧密相关,论文重点对其算法进行了系统性的研究。然后计及继电保护的影响,提出了一次设备的实时停运概率算法。用电气连通性分析和最优削负荷方法计算一次设备停运后果,此后计算电网中后备保护动作的概率来评估导致连锁故障的可能性。最后提出了继电保护运行可靠性指标,并研究了输电系统运行可靠性在线监测和评估系统的总体方案。论文的主要内容如下:(1)定义继电保护系统硬件失效为第一类失效,定义由于继电保护配置与电网实时运行方式不配合而产生的失效为第二类失效。区分两类不同的失效机理,提出了等效的多重化配置的继电保护系统可靠性模型。用统计方法计算第一类拒动、误动概率,而根据继电保护构成方案和电网状态计算第二类拒动、误动概率,其中考虑到各种短路故障类型所占百分比的影响,并且以条件概率明确反映继电保护隐蔽性故障所具有的特征。上述研究解决了以往只能够把继电保护系统等效成系统元件,由统计数据估计其失效概率的问题,为进行计及继电保护系统影响的输电系统运行可靠性评估提供了理论依据和算法支持。(2)差动保护、方向比较闭锁保护、距离保护、电流和零序电流保护是输电系统中变压器和输电线路的常用继电保护。根据继电保护的原理和配置方案,研究实时短路故障状态下各种继电保护第二类拒动、误动概率的算法:1.基于阻抗继电器在阻抗复平面上的圆动作特性,推导距离保护不启动概率的分布表达式;2.根据电流和零序电流保护的灵敏系数和保护范围,提出第二类拒动、误动概率分布模型;3.基于变压器差动保护的动作特性曲线和灵敏度要求,推导不启动概率的分布表达式,阐述根据差动量和制动量变化区域计算第二类拒动、误动概率的方法;4.分析闭锁信号启动方式和不灵敏元件的保护范围对方向比较闭锁保护第二类拒动、误动概率的综合影响。(3)考虑天气、潮流、继电保护等因素,建立输电线路、变压器的运行可靠性模型,计算其单独停运和相关停运的实时概率,将所研究的电网模型细化到变电站结构,结合设备状态解析法与输电系统网络拓扑分析,提高了构建实时预想故障集合的效率。就该集合中的事件,用电气连通性分析和最优削负荷方法评估其对电网的影响程度,预测发生连锁故障的可能性,并提出一套新的可靠性指标描述连锁反应的规模。(4)在论文中提出了输电系统运行可靠性在线监测和评估系统的总体方案,分别确定了调度中心继电保护装置信息管理服务器与工作站、一次系统信息管理服务器、运行可靠性分析计算子系统和可视化信息显示子系统的功能,讨论了从变电站综合自动化系统和调度SCADA系统获取所需信息的方式。最后,以6节点的可靠性测试系统IEEE RBTS为评估对象,展示了继电保护失效概率、一次设备实时停运概率和连锁故障条件概率的计算步骤和该实例的部分考虑继电保护影响的运行可靠性数据。更多还原

【Abstract】 Failure probability model of relay protection is an important aspect of the reliability evaluation for power transmission system operation, so correlative basic theories and application technologies are leading topics which is worthy of being deeply studied.Firstly, the framework and principle of software and hardware in microprocessor relay protection system are analyzed, and two types of failure mechanism are expatiated. Considering the close relationship between relay protection principles, real-time condition of power grids and second-type failure conditional probability, the algorithm is systematical researched. Secondly, in view of the impact of relay protection, the algorithm of real-time outage probability of primary components is put forward. Then the effect of outages is estimated based on electric connectivity analysis and optimal load curtailment, after that cascading failure possibility through calculating trip probability of backup protection is evaluated. Finally, a set of operational reliability indices of relay protection are proposed. At the same time, a framework of online reliability supervision and evaluation system of power transmission system is designed.The main contents in detail are included in the following:(1)The so-called first-type failure results from hardware of relay protection system, and that relay protection scheme is not compatible with real-time condition of power grids results in the so-called second-type failure. Based on these definitions, an equivalent reliability model of multiple relay protection system is proposed in view of two different failure mechanisms. The probabilities of first-type failure operation and false operation are gotten through a statistic method. At the same time, the second-type ones is worked out according to relay protection scheme and condition of power grids while the percentage of various short-circuit faults is considered. The characteristic of hidden relay protection failures is definitely showed through these conditional probabilities. So the problem is resolved that in the past relational research relay protection is considered as equivalent component of power system, and its failure probability has to be guesstimated according to the statistic, and power transmission system operational reliability evaluation has got the support of theory and algorithm.(2)Differential protection, direction protection, distance protection, zero-sequence current protection and phase current protection are usually used in power transmission system. Based on the principle and scheme of various relay protection, the probabilities of first-type failure operation and false operation during real-time short circuit in power grids are work out: 1. The formulae of inaction probability distribution are deduced based on the circle performance characters of various impedance relays. 2. According to the real-time sensitivity and coverage of zero-sequence current protection or phase current protection, the models of second-type failure probability distribution are set up. 3. Based on the tripping curve and required minimal sensitivity of transformer differential protection, the formulae of the inaction probability distribution are deduced, the algorithm of the second-type failure probability according to the real-time span of differentia quantity and restraint quantity is expatiated. 4. Both of the block signal startup-mode and coverage of direction protection affect the second-type failure probability.(3)The operational reliability models of transmission line and transformer are put forward considering the impact of weather, power flow and relay protection,and the real-time probability of the single and correlated outage occurrences can be worked out. Thereafter, considering substation structure in power grids model, an efficient method of founding predictive contingency set is studied through combining device state analysis and power transmission system topology. Electrical connectivity analysis and optimal load curtailment algorithm are used to reveal how the occurrences in the set affect power system, and forecast the possibility of cascading failure. In addition a new set of reliability indices are proposed to describe the scale of cascading failure.(4) The main framework of online reliability supervision and evaluation system of power transmission system is designed, which includes protection device message management server and work station in dispatching center, primary system message management server, operational reliability analysis sub-system, visual message displaying sub-system. The functions of these parts and methods of getting messages from integrated autoimmunization system of substation and SCADA systems are discussed. Lastly an application is clarified using IEEE RBTS of six nodes to show the approach of calculating the probability of relay protection failure, primary component outage and cascading failure. As a result, partial data of operational reliability indices considering the effect of relay protection are shown.更多还原