【作者】 王有元；

【导师】 孙才新；

【作者基本信息】 重庆大学 ， 电气工程， 2008， 博士

【摘要】 电力变压器是电网中能量转换、传输的核心,是电网中最重要和最关键的设备之一。长期以来,变压器的健康水平和绝缘运行状况的判断都是通过停电预防性试验和定期维修来实现的,这种不顾变压器的实际运行状态,“到期必修”的维修方式,容易出现“过修”和“欠修”状态。因此,在电力系统高可靠性和经济性的迫切要求下,状态维修取代定期维修已成为电力变压器维修方式的必然发展趋势。本文在对电力变压器进行故障模式和影响分析的基础上,就变压器的可靠性、故障的发生概率、故障的风险以及状态维修决策方法等关键问题进行了深入的研究:①电力变压器的故障模式和影响分析。在对电力变压器的结构和功能进行深入细致分析的基础上,综合采用硬件法和功能法对电力变压器进行组成结构划分,然后对各组成部分所有可能的故障模式及影响进行深入分析,避免了完全按照系统结构进行故障模式和影响分析的复杂性,为变压器可靠性和故障风险评估奠定基础。②基于多特征参量的电力变压器故障发生概率综合评定方法。通过对变压器故障模式及特征参量进行归纳、整理,针对各特征参量的具体特点,提出基于模糊隶属函数和相对劣化度的电力变压器故障发生概率评定方法;针对具有多种特征参量的故障模式,为了充分利用各特征参量的信息,建立了基于改进层次分析法的电力变压器故障发生概率综合评定方法,实现不同评定方法的有机结合,并在一定程度上克服了专家评定方法主观性太强的缺点,使评定结果更符合客观情况。③基于故障树分析的电力变压器可靠性评估方法。目前变压器的可靠性评估主要根据统计数据来实现,评估结果并不能准确反映单台变压器的可靠性。因此,本文在变压器的故障模式和影响分析基础上,利用故障树分析方法构建完整的电力变压器故障树;结合故障模式的重要度,提出基于故障树分析的电力变压器可靠性评估方法;采用模糊层次分析法确定故障模式的重要度,弥补了故障模式重要度确定过程中主观赋权方法主观性太强的不足。④基于模糊多属性决策的电力变压器故障风险评估方法。在深入研究多目标决策理论和方法的基础上,建立电力变压器故障风险评估指标体系,运用三角模糊数对评价指标进行模糊化处理,提出基于模糊多属性决策的电力变压器故障风险评估方法,解决了传统评价方法存在人为因素影响、不区分各指标重要程度以及因风险优先级指数相同而无法评价等问题。⑤基于灰局势决策的状态维修决策和优化方法。在深入研究灰局势决策方法的基础上,结合电力变压器的可靠性和故障风险评估结果,提出基于灰局势决策的变压器状态维修决策方法,克服了仅以变压器运行状态或重要度等单一指标为依据确定维修方案的不足。同时,针对维修方案不能给出最优维修时间的不足,提出了基于蒙特卡罗模拟方法的维修间隔优化方法。更多还原

【Abstract】 As one of the most important and key equipments, a power transformer is the core of energy conversion and transmission in the power grid. For a long time, the judgment of health state and operation condition of power transformer is carried out by preventive test and periodic maintenance. The time-based maintenance mechanism will lead to“over maintenance”or“owing maintenance”for lack of consideration of power transformer’s insulation condition. Therefore, with an urgent request for reliability and economy of the power system, there is an inevitable trend that the condition based maintenance (CBM) will replace the periodic maintenance for the power transformer maintenance. On the basis of the failure mode and effect analysis (FMEA) of power transformer, the key problems, such as the reliability, the failure probability, the failure risk, and the decision making method of CBM, were studied in this thesis.①FMEA of the power transformer. After an in-depth and detailed analysis on structures and functions of the power transformer, the method combining hardware and functions was employed to divide the composition of the power transformer and to analyze all failure modes and effects, which avoided the complexity of FMEA only according to the system structure and laid the foundation for evaluating transformer reliability and failure risk.②Comprehensive evaluation method for the power transformer failure probability based on multi-characteristic parameters. By means of generalizing, systemizing power transformer failure modes and analyzing features of every characteristic parameter, this paper proposed the power transformer failure probability assessment methods based on fuzzy membership function and relative inferiority degree. Besides, in order to take full advantage of characteristic parameters of failure mode which features multi-characteristic parameters, the paper put forward a comprehensive evaluation method for the transformer failure probability based on improved analytic hierarchy process (IAHP). This method realized the organic integration of different assessment methods, and avoided the shortcoming of expert evaluation method to a certain extent, such as subjectivity in order that the assessment results better correspond to reality.③Reliability assessment method of the power transformer based on the fault tree analysis (FTA). To date, to assess the reliability of power transformers primarily depends on statistical data and results of the assessment do not accurately reflect the reliability of a transformer. Therefore, this thesis built a complete power transformer fault tree based on FTA and FMEA tables, and then proposed the reliability assessment method of the power transformer based on FTA method and with the importance degree of failure mode taken into account. The fuzzy analytic hierarchy process (FAHP) reduced the subjectivity in defining importance weight of failure mode.④Risk assessment method of the power transformer based on fuzzy multiple attribute decision making (FMADM). Grounded on an in-depth study of MADM theory and methods, the failure risk assessment index system of the power transformer was established, the triangular fuzzy number was employed to reduce assessment index subjectivity, and the risk assessment method of the power transformer based on FMADM was presented, which overcame the shortcomings of traditional methods, such as the influence exerted by artificial factors, difficulty in distinguishing the importance of the various indexes and no possibility in evaluating the risk grade owing to the same risk priority number (RPN).⑤CBM decision making and optimization method based on the grey situation decision making (GSDM). On the basis of an in-depth study of GSDM method and in combination with results of the reliability and the failure risk assessment of the power transformer, the CBM decision making method of the power transformer was proposed in this thesis, which overcame the defect of maintenance program based on a single index. To bridge the gap that maintenance programs cannot give the optimal maintenance time, a maintenance time optimization method based on Monte Carlo simulation (MCS) was proposed in this dissertation.更多还原