【作者】 戴志辉；

【导师】 王增平；

【作者基本信息】 华北电力大学 ， 电力系统及其自动化， 2012， 博士

【摘要】 继电保护作为电力系统的第一道防线,应具有选择性、快速性、灵敏性和可靠性。其中,保护系统的可靠性是影响电力系统稳定运行的重要因素之一,也是优化保护设计和运行的重要参考依据。论文在分析继电保护可靠性需求的基础上,针对如何建立客观、准确的可靠性模型及符合保护系统工作特点的可靠性与风险评估方法开展研究。首先从继电保护系统可靠性的概念和特点入手,提出了主要针对继电保护硬件系统可靠性分析的“3RF技术”,即继电保护故障模式及影响分析(RFMEA)、保护可靠性故障树分析技术(RFTA)和继电保护故障报告、分析与纠正措施系统(RFRACAS)。研究了3RF技术在保护可靠性分析中的应用,从可靠性预防、分析、处理及数据收集与初步挖掘等方面将其发展成一整套继电保护可靠性程序。其中,RFMEA分析各种失效模式及其影响,主要为RFTA提供定性的建模依据。RFTA方法涵盖了保护系统可靠性模型及其求解方法：动态故障树与马尔可夫(Markov)状态空间相结合的微机保护系统动态可靠性模型能反映实际保护系统的故障与修复过程、拓扑与逻辑关系、备用及闭锁等特性,建模简单,易实现模块化；而基于动态故障树结构函数与蒙特卡罗(Monte Carlo)仿真的模型求解方法在发挥Markov方法与Monte Carlo仿真方法优势的同时,降低了Markov状态划分的难度及系统级故障树模型的求解复杂度,能为寻找系统薄弱环节、提高保护设计可靠性及制定更为合理的检修周期提供参考。RFRACAS是一个信息系统,保证保护的失效信息、缺陷信息能及时准确的收集、分析,为评估和改善保护可靠性提供基础数据支撑。总体上,3RF技术适用于继电保护的设计、研制、应用及维护过程,有助于在相同可靠性要求下缩减研发时间和费用,相同投资情况下提高保护系统的可靠性。其次,提出了继电保护原理性失效的双层概率模型,在真实反映保护原理及时序特性的基础上,根据系统运行情况和保护定值,定量计算保护原理与特定故障或系统运行状态匹配程度的随机性。其第一层是赋时Petri网描述的保护逻辑动态层,用于处理保护逻辑关系和时序关系,反映保护逻辑的动态过程；第二层是模糊信息层,在模糊Petri网中体现各保护逻辑元件及其组合的概率信息。双层模型克服了常规可靠性评估方法只反映某些固定模式下的长期可靠性水平、而忽略实时运行条件及保护时间定值等因素对可靠性影响的不足,旨在为提高保护运行可靠性提供参考。第三,立足新形势下基于通信系统实现的继电保护发展现状,针对至关重要但目前关注有限的该类保护重要支撑技术的可靠性,即保护通信系统的可靠性,以连通可靠性为切入点,以能较全面反映各层次通信系统的区域集中式广域保护的通信系统为载体,进行了分层分析和综合评估。最后,为使保护系统各种失效模式及其对保护系统可靠性的影响可以在一个统一的模型中得以综合反映,从保护失效机理出发提出了基于失效模式竞争的保护可靠性综合分析方法。并在继电保护可靠性分类分析和综合分析的基础上,考虑保护失效发生的可能性及失效后果的严重程度,将脆弱性评估方法与继电保护可靠性分析相结合、将继电保护风险评估与其在电力系统中的动作行为和配合关系相结合进行保护风险的集成评估,评估流程严格模拟相关保护的动作时序特性,旨在提高保护风险评估的准确性。算例表明风险评估可为保护系统运行能力的在线监控与分析、保护定值在线校验等提供可参考的冗余信息,并有助于对保护系统潜在问题的认知和理解。更多还原

【Abstract】 As the first defense line of the power system, protective relays should be selective, speedy, sensitive and reliable. The reliability of protection systems is one of the most important factors that effect the stable operation of power systems, as well as an important reference for protection design and operation. Based on investigation of the reliability requirement of protection systems, this thesis focuses on the research of objective and accurate reliability model and reliability assessment method according with the characteristics of protection systems.Based on the concept and features of protection system reliability,’3RF’technique, i.e. Relay Failure Mode Effect Analysis (RFMEA), Relay Fault Tree Analysis (RFTA), Relay Failure Reporting, Analysis and Corrective Active System (RFRACAS) is firstly proposed mainly for reliability assessment and improvement of protection hardware system. It is a set of cooperative procedures related to failure prevention, failure analysis, failure elimination and basic data collection, which could be used for design, development and maintenance of protection systems. The RFMEA supplies modeling basis for the RFTA by analyzing failure modes and their effect. The RFTA with stronger adaptability includes reliability model of protection system and its analysis methods, the model integrating Markov state space and Dynamic Fault Tree(DFT) takes into account dynamic characteristics of protection system such as fault and repair, topology and logic, spare and block, each part of which has a definite physical signification, so it is easy to implement modular modeling; the indices calculation method based on the structure function of DFT and the sequential Monte Carlo simulation takes advantage of Markov chain and Monte Carlo simulation while reduces the state-division difficulty of Markov method and solution complexity of system-level fault tree model. By quantitative calculation of reliability indices, they could supply reference for weakness identification, design improvement and maintenance cycle establishment. The RFRACAS is an information system which supplies data basis for protection reliability assessment by collecting timely and exact failure information and defect information. As a whole, the3RF technique helps to save time and cost under the same reliability requirement, while to improve protection system reliability under the same investment.Secondly, a two-level calculation model on failure probability of protection principle is built, which is based on Programmable Time Petri Net (PTPN) finishing dynamic simulation of protection logic and sequential characteristics, and Fuzzy Petri Net(FPN) finishing probability calculation of protection elements and their combination. It could be used to simulate protection logic as well as to calculate instantaneous failure probability of protection principle according to system operation mode and protection settings. It supplies reference to research on matching degree between protection characteristics and specific faults or operation modes, and overcomes the shortage of routine method which ignores the effect of real-time operating conditions and protection settings on protection systems reliability.Thirdly, on the basis of recent development on communication-based protection, the reliability assessment of the support technique in this type of protection systems, i.e. the reliability of communication systems is presented. The major focus is put on the hierarchical analysis and synthenic assessment of connection reliability of the communicateon system in limited wide area protection which could comprehensively reflect related communication systems.Finally, a protection system reliability assessment method considering competition of failure modes is presented based on protection failure machanism analysis, which gives full consideration of combined effects of different failure modes on protection reliability in an unified model. A new way of integrated protection risk assessment method is proposed in succession which takes into account the combination of reliability analysis and vulnerability assessment as well as the combination of risk assessment, protection action sequence and protection coordination, it strictly follows the sequential characteristics of associated relay actions and therefore improves the authenticity and accuracy of protection risk assessment. The study cases show that the risk assessment contributes to the online monitoring and analysis of protection reliability level, the protection setting verification and the awareness of potential problems of protection systems and power systems.更多还原