基于可拓理论的变压器在线监测状态综合评估

变压器运行状态的有效评估是指导电力变压器状态检修以及保证电力系统安全可靠运行的重要手段。在变压器智能组件得到的各类在线监测状态信息量的基础上,引入可拓理论,建立了基于在线监测的变压器状态综合评估模型。采用改进层次分析法与灰色关联分析相结合计算得到综合权重,指出该方法克服了单一方法确定指标权重的局限性;基于物元理论和关联函数理论构建变压器状态综合评估模型,实现对变压器状态定性和定量相结合的状态评估,为变压器的状态检修提供了决策依据。实例分析证明了该评估模型的准确性和有效性。     

基于古林法和层次可拓的变压器状态评估

准确评估电力变压器的状态既是合理制定检修策略的基础,同时也对智能电网的发展具有重大意义。针对变压器故障机理复杂,难以客观评估的问题,提出了基于古林法和层次可拓的变压器状态评估方法,将变压器多参数综合评估转化为单目标决策。首先建立层次型指标体系,划分状态等级。利用古林法计算指标权重,通过层次可拓法确定综合评价等级,并与模糊层次分析法(FAHP)计算结果进行对比分析。经实例研究,验证了该方法应用于变压器状态评估的可行性,为变压器绝缘状态检修提供了一种新评估策略。     

基于可拓分析和熵值法的GIS状态评估

GIS运行状态评估是指导GIS状态检修的重要手段。将可拓分析理论引入GIS状态评估中,以SF6气体组分指标为主,并结合SF6气体的纯度、湿度和气体中空气含量指标来构建关联函数。结合关联函数值与规程中规定的注意值和警示值的关系确定GIS状态等级关系及相应的检修策略。运用熵值法理论解决了GIS状态评估中各指标的权重问题。实例分析表明,该评估方法可以准确地评估GIS的各个气室状态,有利于监测预警和制定综合检修策略。     

改进物元模型在继电保护状态评估中的应用

为提高继电保护状态检修机制下状态评估能力,提出一种基于物元模型的继电保护状态可拓评估方法。基于可拓学物元理论,建立了继电保护状态评估的物元模型;综合改进层次分析法和熵权法各自优点,组合赋权确定指标权重值;定义新的可拓学关联函数,定量计算保护状态与各给定状态等级的关联度,按最大关联度值确定待评装置状态等级。算例分析分别从结果客观性、区分精度与模糊综合评价方法等方面进行了比较,验证了所提方法的有效性和合理性。     

基于可拓理论的变压器状态综合评估

笔者基于可拓理论,提出了一种可拓评价法和可拓层次分析法相结合的变压器状态综合评估方法。首先,采用可拓层次分析法(EAHP),将变压器状态信息之间的相对重要度采用一个可拓区间数来表示,构造可拓判断矩阵,准确计算变压器状态信息指标的权重。然后,应用可拓评价法,通过计算物元之间的关联函数同时进行定性和定量分析,实现变压器状态的综合评估。实例分析证明了该方法的正确性和有效性,为变压器的状态维修提供了合理的决策依据。     

多信息量融合的电力变压器状态评估模型

为提高电力变压器状态评估的准确性,促进检修模式向状态检修技术发展,以220kV等级油浸式电力变压器为例,在实际调研的基础上研究了变压器运行状态与评估指标数值之间的隶属关系和指标初始值差异对评估结论的影响,应用未确知数学理论对专家的评估指标权重量化结果进行处理。建立了基于半哥西分布函数的绝缘油试验评估指标状态函数和考虑指标初始值差异的电气试验评估指标状态函数。实例分析表明,所建立的各试验指标的状态函数和基于未确知有理数的指标权重求解方法可以更加便捷地实现变压器的状态评估,为检修决策提供合理建议。     

采用最优云熵改进可拓云理论的变压器本体绝缘状态评估方法

状态评估是电力设备状态检修及健康管理的关键环节。以220 kV油浸式电力变压器为研究对象,构建了一种基于最优云熵改进可拓云理论的变压器本体绝缘状态评估模型。首先,针对绝缘状态等级边界的随机性与模糊性问题,提出使用可拓云理论来构建状态评估的基础理论框架;然后,在充分考虑等级划分分明性与模糊性特点的基础上,提出一种可自适应评估对象的最优云熵计算方法,实现了对传统可拓云理论的改进;最后,针对单一赋权方法存在的不足,构建了一种基于模糊集值统计法与熵权法的主客观组合赋权模型,实现了指标权重基于信息变化程度的动态调整。实例研究表明,相较于传统理论,该文所提方法能够有效处理变压器状态评估中的不确定性因素,其评估结果更接近设备的真实状态,具备较高的应用可行性。     

基于物元理论的变压器绝缘状态分级评估

为提高电网的自愈能力,实现电气主设备的在线监测或预评估,提出了基于物元理论的变压器绝缘状态分级评估模型.通过分析变压器运行过程中影响其绝缘状态的特征参量,构建了层次型状态评估指标体系;各特征参量用物元表征,通过物元差方变换实现了待评价指标的量化处理;在综合多个专家评估意见方面,引入了专家效度物元的概念,使权重处理更为科学客观;应用欧氏贴近度评估函数,实现了变压器绝缘状态的模式识别或分级评估.实例表明,评估结果更客观,对检修工作更具指导意义.     

物元-时域分析法在电力变压器状态评估中的应用

以油浸式电力变压器为研究对象,提出基于物元-时域分析的电力变压器状态评估方法,构造各评估指标的关联函数,函数值在正常运行量值范围内为正,在由量变发展到质变时函数值取负,并且根据评估值在时域上累计描绘出变压器状态评估时域曲线,且可以根据一定要求剔除因监测系统问题出现的离散数据,使得收集的评估数据更准确。     

基于集对分析和综合赋权的电力变压器套管绝缘状态评估

针对当前电力变压器套管绝缘状态评估中各评价参量存在复杂性和不确定性的问题,文中应用集对分析方法对变压器套管进行绝缘状态评估。首先选取用于套管状态评估的指标,对评估结果进行等级划分并制定响应策略,采用层次分析法和熵权法融合的综合赋权法来确定各评估指标的权重,构造联系度数学表达式来描述评估指标与状态等级之间的关联程度,建立起集对分析状态评估模型。实例计算分析表明,基于集对分析方法和综合赋权的状态评估模型能够有效反映变压器套管的绝缘状态,评估结果可为变压器的状态检修提供有效参考。     

基于进化雷达图的油纸绝缘状态进阶评估方法

为提高油浸式变压器运行的可靠性及降低其全寿命周期成本,将状态检修引入大型油浸式电力变压器势在必行。由于油纸绝缘的寿命决定整个变压器的寿命,所以完善的变压器油纸绝缘的状态评估方法的建立是变压器状态检修的实现的前提。文中将进化雷达图引入油纸绝缘的状态评估过程,提出了将单指标初步评价与多指标综合评估相结合的油浸式变压器油纸绝缘状态进阶评估方法,并确立了完整的评估流程,实现了对油纸绝缘状态的定性及定量评估。通过算例分析,证明了该方法具有步骤简洁、快捷有效且易于在线实现的特点,为油浸式变压器油纸绝缘状态评估的实现提供了新的思路。     

变压器信任度与安全指数的对比研究

为准确掌握变压器的真实运行工况,对变压器的状态评估方法进行对比研究,找出不同评估方法的优缺点和共同规律。首先对变压器风险评估和信任度评估的基本原理进行分析,找到各自算法本身的优缺点。在此基础上对云南电网的50台变压器分别进行状态评估,得到其信任度和安全指数。最后进行对比研究,确定了状态检修策略中与评估结果相对应的阀值。该研究为变压器的状态检修提供更全面有效的评估依据,对电网的经济安全运行有着重要的指导意义。     

基于变压器马尔可夫状态评估模型和熵权模糊评价方法的风险评估技术研究

为建立有效的电力变压器设备风险评估方法,针对变压器故障机理的复杂性和不确定性特征,提出了基于状态检修和马尔可夫过程的变压器全态状态评估模型。利用分指标研究变压器缺陷严重度,结合变压器分部位故障频率计算模型,采用熵权模糊计算量化变压器设备风险等级,构建设备风险评估矩阵,给出了一种新的变压器运行风险评估方法。仿真程序实例计算结果表明,所提方法能够准确计算变压器各组成部分的风险值,并获得针对性的维修策略,变压器风险评估结论是准确、有效的。     

Case study: lessons learned from the failure of a new 230-kV transformer-cable termination

Successful power transmission and distribution require a sound and extensive knowledge of condition assessment, testing, and maintenance of HV power transformers. The breakdown of transformer insulation and terminations under various stresses and insulation ageing effects has become a nerve-racking problem for the electricity-supply industry. In critical situations, the failure of a transformer can cause millions of dollars in damage to equipment owned by consumers and/or the utility. It is, therefore, vital to assess the condition of transformers accurately before commissioning and during operation.     

基于集对分析方法的电力变压器绝缘状态评估策略

针对大型电力变压器绝缘状态和故障机理复杂、具有不确定性、难以有效评估的问题,提出了基于集对分析方法的变压器绝缘状态评估策略.建立变压器绝缘状态定量和定性评估指标体系,在状态等级划分和指标参数提取的基础上,构建集对分析算法及实现步骤,用联系度及其数学表达式统一描述系统状态的不确定性问题,结合信度准则实现对变压器绝缘状态的评估.实例研究并与其他状态评估方法的比较表明,该策略可行、有效,为电力变压器绝缘状态评估提供了一种新的思路.     

电压响应方法在电力变压器状态评估中的应用(英文)

Power transformer is one of the most important equipment in the power system.Its operating condition affects the reliability of power supply directly.Therefore,in order to guarantee transformer operation safely and reliably,it is necessary to assess condition of power transformer accurately.Return voltage method based on voltage response measurements is still a new non-intrusive diagnosis method for internal insulation aging of transformer.In this paper the technique and application of return voltage measurement and some results of voltage response measurements of several transformers was introduced.Voltage response measurements were performed on various transformers with different voltage grades,various operating periods,different moisture contents and aging degrees on site.Derived moisture contents from return voltage measurement were compared with the corresponding moisture contents obtained from the analysis of oil samples.Based on on-site experiments and theoretical analysis,the criteria for insulation state of transformer are proposed.Moisture condition of transformer insulation can be determined by using return dominant time constant,and a good correlation between aging degree and the return voltage initial slopes of the aged transformers.Field test performed on several transformers,its interpretation of results are also presented,which proves that return voltage measurements can be used as a reliable tool for evaluating moisture content in transformer insulation.     

变压器油纸绝缘介质响应等值的电路建模研究

回复电压诊断方法是一种无损诊断变压器绝缘状态的方法。目前的研究主要基于试验获得的极化谱分析变压器的绝缘状态,利用等值电路更易于分析其极化机理,但现有的电路模型尚不完善,文中系统地给出了油纸绝缘变压器的基于扩展德拜等值电路建模的详细过程,在此基础上,给出了从等值电路模型求解回复电压特征量的思路,并使用一台变压器油处理前后的数据计算了其回复电压极化谱,计算结果表明基于扩展德拜模型等值电路和回复电压计算方法是可行的,利用计算获得的极化谱可以有效分析变压器的绝缘状态,为准确评估变压器老化提供了新的思路,并为分析相关影响因素奠定了基础。     

Review of condition assessment of power transformers in service

As transformers age, their internal condition degrades, which increases the risk of failure. To prevent these failures and to maintain transformers in good operating condition is a very important issue for utilities. Traditionally, routine preventative maintenance programs combined with regular testing were used. The change to condition-based maintenance has resulted in the reduction, or even elimination, of routine time-based maintenance. Instead of doing maintenance at a regular interval, maintenance is only carried out if the condition of the equipment requires it. Hence, there is an increasing need for better nonintrusive diagnostic and monitoring tools to assess the internal condition of the transformers. If there is a problem, the transformer can then be repaired or replaced before it fails. An extensive review is given of diagnostic and monitoring tests, and equipment available that assess the condition of power transformers and provide an early warning of potential failure.     

变压器状态评估技术现状研究

介绍了变压器状态评估技术的现状和最新进展,列举了目前现有的几种典型变压器状态评估方法,对每种评估方法的评估过程和优缺点进行了分析,指出了目前变压器状态评估技术存在的问题和困难,并提出了变压器状态评估技术的研究方向和发展趋势。分析表明,电力系统要实现状态检修这个长远目标,有效的状态评估手段是其中不可或缺的一部分。     

Risk assessment based on condition and importance criteria for power transformer in Thailand transmission network

This paper proposes an innovative risk‐assessment strategy based on condition and importance criteria for power transformer maintenance in a transmission network. The condition assessment is performed by the analysis of different diagnosis methods such as electrical test, insulating oil test, and visual inspection. The importance assessment is evaluated from various aspects such as load criticality, impact on system stability, possibility of failure, failure consequence, damage to property, as well as social impact and environmental concerns. Weighting and scoring techniques are applied to determine the actual condition and importance of the power transformer with regard to condition and importance aspects. By combining the condition and importance assessment, the overall risk to the power transformer is assessed and differentiated into nine categories in the risk matrix from the lowest to the highest risk. Additionally, by applying distance ‘d’ technique, the risk‐based assessment matrix for the power transformer can be identified into five zones: healthy, good, moderate, bad, and risky. These five zones are also represented by color indicators as green, blue, yellow, orange, and red, which are further interpreted to five steps of maintenance tasks. The transformer with longer distance ‘d’ is subjected to higher risk and should be maintained first. By this method, a total of 19 power transformers were analyzed and are presented as examples for risk‐based maintenance. Then, risks of a total 598 power transformers are shown in the risk matrix. A computerized web application program is developed for practical implementation in a utility in Thailand. Finally, the systematic risk assessment and maintenance task of the power transformer fleet in Thailand are effectively managed. Thereby, the total maintenance cost of power transformer can be reduced. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.