【作者】 莫峻；

【导师】 谭建成；

【作者基本信息】 广西大学 ， 电力系统及其自动化， 2014， 博士

【摘要】 变电站是智能电网的关键节点,承担了电力系统电能传输和转换任务。继电保护是变电站最为重要的功能之一,是电力系统安全稳定运行的重要保障。我国第一代智能变电站通信网络构建以IEC61850标准为基础,采用过程总线通信,引入网络交换机,用简单的过程总线光纤网络取代传统变电站一、二次设备间繁多的电缆联接,并追加合并单元及智能终端对一次设备进行智能化处理,使得数字化保护在物理结构及功能运行方面与传统的继电保护存在一定区别,其可靠性有待进一步研究。另外,过程总线通信网络所固有的缺陷可能会对继电保护可靠性产生一定影响。准确评估过程总线网络性能,对保护系统可靠性分析及其网络方案优化设计具有十分重要意义。为了维持保护系统可靠性,需要对保护系统进行预防性检修。如何利用有限的维修资源使保护系统运行在最佳状态是一个值得研究的课题。本文对上述问题进行了深入研究,主要研究内容及创新成果如下：1)据交换式以太网的工作原理以及IEC61850定义的过程总线发布／订阅机制,提出了通信网络的最小空间模型。利用最小空间模型构建过程总线通信网络的最优交换空间模型。给出了交换空间模型的多播组划分方法,为过程总线网络的优化设计提供了理论依据。2)深入研究了过程总线的两种典型的数据阻塞模型(即,同步信号阻塞和非同步信号阻塞),针对QoS服务特性,推导以优先级为目标的数据传输延时计算公式。根据以太网的固有阻塞特性,提出了一种通过比较订阅端数据到达时间的过程总线网络时延评估算法。其特点是不需要同步时钟源,测量精度高,可作为过程总线网络性能的在线诊断工具。3)开发了过程总线数据流量生成器和接收器,搭建了继电保护数字化仿真平台,实验测试了某一典型变电站的2种过程总线方案的网络性能,验证了所提模型和方法的正确性。4)提出了过程总线通信故障模型,从安全性和信赖性两个方面,分析了通信故障对保护功能的影响。为了评估供电系统可靠性,建立了由通信故障引起的继电保护拒动模型。根据采样值传输特性,提出了过程总线通信故障的检测方法。5)根据国内继电保护设计准则和IEC61850-90-4组网工程设计导则,提出了几种典型过程总线组网方案。针对复杂系统可靠性分析,引入了改进简化割集算法,并对各种过程总线方案进行了可靠性分析。6)提出了分布式保护系统元件可靠性指标分配方法,建立了以系统可靠性和设计费用为目标的最优化分配模型,并采用评价函数法将多目标问题转化为单目标问题求解出系统的Pareto最优解。7)采用状态空间法建立了保护系统的维修模型,提出了保护系统的可维修性指标分配方法。该项研究对数字化保护系统的运行、检修、维护等工作的合理安排具有十分重要的指导意义。更多还原

【Abstract】 Substations are key nodes of smart grid, deliver energy from remote generation to load centers. Protection relays play an important role in substation to ensure safety and stability of the power system. The IEC61850standard is applied in smart substation network communication, and the switched Ethernet based process bus is introduced to replace the miles of copper cables between the primary apparatus in the switchyard and secondary system in the control building. Compared to the traditional relay protection, the first generation of process bus based digital protection system differs in many ways such as the physical layouts and operating mechanism, so its reliability needs further study. Especially the inherent defect of Ethernet network (such as real-time performance and security problem) may decrease the reliability of protection function. Hence, the performance evaluation of process bus has very important significance for the reliability analysis and network optimal design of protection system. To maintain the reliability of protection system, the preventative maintenance is required. How to utilize limited resources to keep the best condition of protection system is a topic which is worth studying.Based on above discussion, this dissertation has made a deeply study of the reliability of process bus based digital protection system. The main works and achievements are as follows:1) According to the working principle of switched Ethernet and the publisher/subscriber mechanism specified in IEC61850, the minimal space model of network is proposed to construct the optimal switch space of process bus. The multicast configuration method with respect to the switch space is presented which provides a theoretical basis of optimal design of process bus network. 2) The block models of two types of process bus data (synchronous and non-synchronous data) are deeply studied. The transmission delay calculation formula for the certain priority message is derived for the QoS based communication. A message capture time based evaluation method of network latency which can work without the help of synchronous clock source and provide very high measurement precision is proposed. It can be used for the real-time monitoring and diagnosis of process bus network performance.3) A process bus simulation system is developed, including network traffic generator and capturer. The network performance of two process bus solutions for a typical substation is tested using the digital protection simulation system, which validates the availability of proposed models and methods.4) The communication failure of process bus is investigated. The influence of communication failure on protection function is analyzed from the aspects of safety and reliance. To assess the power supply reliability, the miss trip model of relay protection caused by communication failure is built. According to the transmission characteristic of sampled value, a method for detecting the fault of process bus is proposed.5) Several typical process bus network solutions are introduced considering the Chinese relay protection design criteria together with the redundancy protocols recommended by IEC61850-90-4Network Engineering Guidelines. For the reliability analysis of complicated network architecture, a reduced cut set method is presented and used to analyze the reliability of proposed process bus solutions.6) An optimal principle based reliability allocation method is presented for distributed protection system. The optimization model of reliability allocation is constructed to pursue two goals:the lowest totalcosts of system design and the highest reliability of protection system. The multi-objective problem is transformed into a single objective problem by means of the evaluation function method to solve Pareto optimal solutions.7) Considering the condition-based and periodic maintenance, the maintenance model of protection system is constructed by means of the state space method. A novel maintainability allocation method of protection system is proposed to plan the operation and maintenance of digital protection system.更多还原