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。     

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。     

基于熵值赋权法的配电变压器状态评估方法研究

当用若干个指标进行综合评估配电系统运行时,合理分配变压器评估过程中各指标的权重值是保证评估结果客观准确的基础,也是保证评估质量的关键。通过对样本数据的分析,运用熵值客观赋权法与改进层次分析主观赋权法相结合的方式得到评估指标的权重值,既避免了主观赋权的相悖性,又考虑了专家经验的重要性。通过对油浸式配电变压器运行实例的分析,验证了所提方法的有效性。     

用于智能GIS设备状态实时评估的状态量综合权重法

在高压设备状态评估中,采用状态量固定的权重进行评判并不能很好地实时反映设备的状态,需要一种既能反映专家意见又能反映设备状态量实时数据的权重的赋值方法。笔者在阐述电网现行GIS设备状态评价导则的原理基础上,分析现行评估方法中存在的不足,提出了基于熵权理论的对固定的主观权重进行修正的方法,得到用于GIS设备状态实时评估的状态量综合权重。通过选择经验因子得到的综合权重既能反映专家经验,又能实时反应设备状态量的实时监测值的变化,用于状态评估时能够更准确地反映高压设备的实时状态。通过算例进一步说明了所提的综合权重的计算和运用。     

电力变压器运行状态可拓层次评估

电力变压器运行状态评估是指导变压器状态检修及提高电力系统运行可靠性的重要手段.由于影响变压器状态信息因素众多,针对多指标评估中易出现指标不相容而导致评估错误的难题,建立了变压器运行状态评估层次指标体系,提出了基于可拓学的变压器运行状态层次评估模型,将影响变压器状态的多指标评估转换为单目标评估,通过定性和定量相结合的分析...     

基于物元可拓理论的高压断路器状态评估方法

高压断路器的运行状态评估是指导高压断路器状态维修、提高其运行可靠性及保证电力系统安全稳定运行的重要手段。文中依据物元可拓理论和证据融合理论建立了一个高压断路器状态评估模型。首先对高压断路器状态评估进行物元分析,通过构造关联函数并计算评估指标的关联函数值,仅凭关联函数值的正负就能初步确定评估指标是否异常;然后依据集对分析理论对评估指标初步所处状态等级的不确定性进行处理,得到评估指标的等级关联度,并将评估指标的等级关联度进行修正作为信任分配函数;最后根据改进证据融合对信任分配函数进行证据融合得到最终的评估结果。实例表明该方法不仅能对断路器整体状态进行有效、准确的评估,而且还能确定各状态量的劣化等级,为高压断路器的状态评估提供了一种新的思路。     

基于可拓分析法的电力变压器本体绝缘状态评估

实现电力变压器状态的准确评估不仅是施行状态检修的核心与基础,同时也是发展智能电网的需要。针对电力变压器故障机理错综复杂和本体绝缘状态具有不确定性,因而难以客观有效评估的问题,以220kV油浸式电力变压器为研究对象,提出了基于物元可拓分析的电力变压器本体绝缘状态评估策略。在对其本体状态评估物元分析的基础上,构造了各评估指标的关联函数,指标关联函数值在正常运行的量变范围内为正,当量变突变到质变时关联函数值取负;通过研究关联函数值与变压器状态的对应关系,探讨了变压器的状态评估策略。实例分析并与其他评估方法比较证明:该方法行之有效,基于物元可拓分析的电力变压器状态评估策略可以为实施状态检修提供参考。     

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。     

A study on condition assessment method of gas‐insulated switchgear. part II. influence of moisture in the SF6, detection of a partial discharge on a spacer,repetition discharge and overheating by incomplete contact

Rationalization of the maintenance of gas‐insulated equipment under operation and lifetime extension based on the results of appropriate diagnosis are necessary to reduce the cost of gas‐insulated equipment. Therefore, condition‐based maintenance (CBM) is required and accurate methods for observing the inside of equipment are important. In this report, we describe a diagnosis method that can be used for actual gas‐insulated equipment, such as to assess the deterioration of the spacers made of epoxy resin and to detect loose connections in the central conductor. The principal results are summarized as follows: (1) The quantity of decomposition gases depends on the moisture and magnitude of the partial discharge. However, decomposition gases were detected even if SF₆ had low moisture content (less than 100 ppm) similar to that used in actual equipment. This means that our method can be applied to actual equipment. (2) It became clear that CF₄ is a typical gas generated by partial discharge on the spacer surface. Therefore, it is possible to diagnose spacer deterioration by monitoring CF₄. (3) Decomposition gases (SF₄, SO₂, SO₄, SO₂F₂) were generated by impulse breakdown, which was assumed to be due to repetition discharge caused by insulation failure and loose connections. (4) SF₆ gas was assumed to be exposed to a loose connection and was heated from room temperature to 800 °C, and the generated decomposition gases were analyzed by FTIR in real time. As a result, the decomposition gases were generated at temperatures above approximately 500 °C in a heating time of 1.5 minutes. Therefore, a loose connection can be detected by analyzing the decomposition gas. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(2): 22–30, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21108     

Study on field demonstration of high‐sensitivity SF6 leakage detection method for gas insulated switchgear

SF6 gas is widely used in power equipment such as gas insulated switchgear or gas circuit breaker. However, its global warming potential is 23,500 times higher than that of CO₂. In consideration of environmental protection, detection of SF6 gas leakage with high sensitivity is necessary. The authors proposed an algorithm to accurately estimate the average gas temperature from the tank surface temperature for establishing a high‐sensitive SF6 slow leak detection technology. Since the gas temperature depends on the temperature of the conductor, the algorithm was characterized by estimating the gas temperature from the tank surface temperature and the load current. The relationship among the tank surface temperature, the gas temperature, and the current was preliminarily investigated by the use of the thermal fluid analysis and stored in the database. By use of this method, the fluctuation of the converted pressure in the basic examination test was suppressed to 20% as compared with that without considering the current. In addition, database was also created from the machine learning of field test result in substitution. In the field test, it was confirmed that the detection time of 0.5%/year slow leak could be detected in about 8 months by considering the load current.     

GIS设备中电能计量装置改造方法的探讨

针对目前GIS内装电能计量装置普遍存在准确度等级过低的问题,探讨出一套效果好、费用低廉的改造方法,该方法对非GIS电能计量装置存在的问题也同样具有改造效果。这些方法在实际使用中证明是切实可行的。     

Breakdown characteristics of gas‐insulated switchgear for nonstandard lightning impulse waveforms under nonuniform electric field

To improve the insulation specification of gas‐insulated switchgear (GIS), it is necessary to recognize the insulation characteristics of SF₆ gas during actual surges (called nonstandard lightning impulse waveforms) occurring at field substations. The authors observed the insulation characteristics of SF₆ gas gap under various types of nonstandard lightning impulse waveforms and compared them quantitatively with those obtained with standard lightning impulse waveforms. The experimental results were used to derive an evaluation method for real surges, which was applied to typical surges for various UHV and 500‐kV systems. In the preceding study, therefore, only the case of a quasi‐uniform electric field (with a typical range of field utilization factors in the bus of a GIS) was investigated. In the present investigation, the insulation characteristics of an SF₆ gas gap for a nonuniform electric field were observed experimentally and an evaluation method for converting nonstandard lightning impulse waveforms equivalently to the standard lightning impulse waveform was investigated. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(1): 11–18, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21144     

气体绝缘管道电缆局部放电的超高频检测技术

该文介绍了用超高频法监测气体绝缘道电缆内部局部放电的基本原理、应用及抗干扰能力。     

全封闭组合电器(GIS)中SF6气体水分控制

结合江门变电站220 kV全封闭组合电器（GIS）中SF6气体水分含量超标的实例,列举GIS设备中SF6气体所含水分的主要来源,并对运行中GIS设备水分含量的测试结果进行分析,提出水分含量超标时现场的处理方法和措施.     

全封闭组合电器(GIS)中SF_6气体水分控制

结合江门变电站220 kV全封闭组合电器(GIS)中SF6气体水分含量超标的实例,列举GIS设备中SF6气体所含水分的主要来源,并对运行中GIS设备水分含量的测试结果进行分析,提出水分含量超标时现场的处理方法和措施。     

基于熵权层次法的油浸式变压器绝缘状态评价

为有效评估油浸式变压器的绝缘状态,文中提出一种综合主观专家经验和指标退化程度的熵权层次法。首先,基于油色谱、环境温度和缺陷信息等指标构建用于绝缘状态评价的层次结构,根据专家经验对各个指标进行主观权重分配;接着,采用组合权重的方法,在指标层权重分配上引入熵权权重,从而在保留专家经验对准则层判断的情况下,对底层权重进行动态调整,体现变压器运行过程中的差异性;然后,将变压器的绝缘状态从常见的4种扩展为5种,实现对绝缘状态更准确的感知;最后,4台500 kV变压器的实例分析表明,相较于仅采用主观权重或客观权重,文中提出的方法可以有效识别运行状态正常的变压器并甄别异常变压器。     

基于灰色关联分析的电站设备状态评价方法

针对发电设备运行状态信息复杂、难以对其进行准确评价的问题,提出基于灰色关联分析的评价方法,建立基于灰色关联的状态评价模型.采用增加权重因子改进邓氏关联度,满足了灰色关联四公理并且在评价的结果中体现各特征参数的重要性程度,构造了度量序列间联系更为准确的量化指标.在状态特征参数权重的确定上,将主观和客观权重相结合,根据需要进行动态调整,提高了权重的准确度和可信度.将该模型用于某厂凝汽器的状态评价,结果表明该模型可为检修决策提供依据.     

基于熵值法和主成分分析法的黑启动模式评估

选取合理的黑启动模式有利于评选最优黑启动方案。分析了黑启动策略、模式和黑启动方案的配合,研究了黑启动模式的约束条件和各种模式的特征。在分析黑启动模式综合评价指标选取原则基础上,提取了黑启动模式的综合评估指标体系并进行层次化处理。对层次化的评估指标体系,指标层利用主成分分析法消除了指标间的关联,准则层利用客观性很强的熵值法给出各模式的最终评价值,最后分析了评估方法的灵敏度。实际算例证明了此方法的有效性和可行性,能够为调度人员选取最优黑启动模式提供参考。