基于部件划分和熵权的变压器绝缘状态评估策略(英文)

Failure mechanisms of power transformers are complex and uncertain; it is difficult to determine index weights of insulation state. Therefore, it is a challenge to acquire an accurate assessment of insulation state of power transformers. In this paper, an assessing strategy for transformer insulation is proposed base on part-division of transformer and a comprehensive weight determination method. An index system of transformer is established on the basis of part-division of transformer. Each index’s weight is consisted of two parts, the constant weight and the variable weight, which are determined by improved analytic hierarchy process (AHP) and entropy method respectively. Af- ter categorizing insulation state into four levels and standardizing assessing indexes, a Cauchy membership function is forged, and a fuzzy algorithm is employed to simulate the uncertainty of the insulation state. Finally, a confidence criterion is employed to perform part-division based condition assessment of transformer. Case studies reveal that the proposed assessing strategy method is effective, convenient, and practical; with the new strategy, potential failures of transformers can be forecasted and insulation state of transformer parts can also be as- sessed. Furthermore, the assessing results can be used to guide condition-based maintenance.     

大型发电机的多特征参量故障发生概率评定方法(英文)

It is conducive to ensure the safety and reliability of the power system by means of timely and accurate evaluation of the reliability of large generators.An evaluation method of fault probability for large generators based on multi-characteristic parameters is proposed in this paper,which can be employed to solve the difficult problem of evaluating the occurrence probability of fault modes of large generators in the process of reliability evaluation.Firstly,the set of fault characteristic parameters for a large generator is established on the basis of a large number of operation experiences and preventive test code for the large generator.Secondly,according to the features of the fault characteristic parameters,two estimation methods of the fault mode occurrence probability are proposed,which are based on the fuzzy membership function and the relative deterioration degree,respectively.Finally,on the basis of the improved analytic hierarchy process(IAHP) method,the composite estimation method of the fault probability for a large generator is presented,which can reasonably and adequately use the information of various characteristic parameters.An assessment case is provided to illustrate the specific process of this evaluation method and verify its effectiveness.     

基于故障树法和层次分析法的电力变压器状态综合评估

变压器状态综合评估为电力变压器检修和维护提供依据。基于故障树法(FTA)分析导致电力变压器故障的因素,并建立评估电力变压器状态的指标体系。应用3标度层次分析法建立了变压器状态的评估模型,进而将变压器状态分为五个等级。等级的划分更有利于运行人员了解变压器的状况,合理安排检修维护计划。经实例分析证明,基于故障树法和层次分析法的电力变压器状态综合评估方法是合理和有效的。     

基于磁压缩系统的纳秒脉冲发生器(英文)

Magnetic pulse compression(MPC)system has been widely-used for over a few decades as a technique for producing short-duration,high-peak-power pulses reliably.A novel MPC system which does not contain external demagnetization circuits,has broadened the application of MPC systems.Improvements for novel MPC systems are presented.To meet the required voltage and compression gain and on considering of the overall system efficiency,two kinds of most popular MPC systems based on the improved MPC topology are designed,which are 2-stage MPC system and 3-stage MPC system,respectively.Based on the improved MPC topology,several kinds of compact pulse generators are built in pulsed power and supply technology laboratory of Institute of Electrical Engineering,Chinese Academy of Sciences.These generators illustrate that the improved MPC topology,together with solid state switches provides an ideal way to generate pulses of around 100 nano-seconds in width,with mid and high voltage of 10 kV to 100 kV,and a high repetition frequency of about 30 kHz.     

面向自愈的智能配电网免疫力评估方法

自愈是智能配电网区别于传统配电网的显著特征,为提高各项自愈技术实用化水平,需要准确掌握智能配电网整体免疫力水平。因此,借鉴人体免疫系统机理,提出了智能配电网免疫系统,包括免疫耐受、免疫自稳、免疫识别、免疫应答和免疫恢复5类功能,在此基础上,提出了基于改进层次分析法与逼近理想解距离法相结合的智能配电网免疫力评估模型构建方法,并构建了智能配电网免疫力评估指标体系以及智能配电网免疫力评估模型。此评估模型能够全面且多层次地考虑影响智能配电网免疫力强弱的各类因素,在实际应用中为智能配电网精细化运维检修和管理提供理论参考。     

基于故障树分析的电力变压器可靠性跟踪方法

电力变压器是电力系统中最重要的输变电设备之一,提高电力变压器的可靠性,对整个电网的安全可靠运行具有重要意义。提出了基于故障树分析的系统不可靠性跟踪和薄弱环节辨识方法。给出了应用故障树评估系统可靠性指标的最小割集法。提出了适用于故障树分析的系统不可靠性指标比例分摊准则和系统不可靠性指标跟踪算法。根据变压器结构、各部件功能和故障模式分析,建立了变压器故障树模型。对变压器进行了可靠性跟踪算例分析,确定了影响变压器可靠性的关键部件,辨识了变压器薄弱环节。     

基于统计分布和相关分析的变压器油中溶解气体注意值计算方法(英文)

Before diagnosed by DGA (dissolved gas analysis) methods, gas caution values, which index the level of gas formation, must be used to evaluate the possibility of incipient faults to reduce the misdiagnosis in the normal state. However, the calculation of these values is now only based on cumulative percentile method without taking into account operating conditions. To overcome this disadvantage, a new approach to calculate the transformer caution values is presented. This approach is based on statistical distribution and correlation analysis, and it takes the individual variation and fluctuation caused by internal and external factors into consideration. Then 6550 transformer DGA data collected from North China Power Grid are analyzed in this paper. The results show that the volume fraction of TH (total hydrocarbon) approximately obeys normal distribution when the 3-sigma rule is used to calculate its caution value. The volume fraction of CO has a strong positive correlation with oil temperature. For H2, the negative correlation with oil temperature is significant when the volume fraction is not very low. The caution value curves for CO and H2 are obtained by regression analyses. Thus, the gas caution values/curves obtained using the new method are not always constant, but vary with oil temperature, which is an advantage of the proposed method compared with cumulative percentile method. The variation of gas caution values/curves also reflects the influence of the external factors, for instance, va- rying with monitoring time ensures that the gas caution values are always consistent with operating status.     

基于自生成FMEA表的配电网可靠性评估方法

应用故障模式影响分析法(failure modeand effect analysis,FMEA),建立预想事故的FMEA表,是配电网可靠性评估中较为普遍的方法.应用配电网络编码技术,提出了一种FMEA表的计算机自生成方法,实现了不同类型复杂配电网FMEA表的自动建立,从而快速计算配电网的可靠性指标.该方法建立了配电网元件编码信息的筛选规则,通过与故障元件编码的对比,自动判断故障后系统内各组成部分的停电情况,进而遍历所有的预想事故生成FMEA表,用于可靠性评估.该方法考虑了孤岛运行方式下分布式电源的容量约束,能够适用于新能源接入配电网后FMEA表的自生成和可靠性评估.通过算例验证了该方法的有效性.     

±1100kV特高压直流输电系统换流变压器设计(英文)

Technical scheme of ±1 100 kV converter transformers is discussed in this paper.Important parameters such as impedance,capacity rating,and insulation level are introduced,and the possible design solution is discussed based on the transportation limitation,which is followed by a structure design and an integrating scheme discussion.The minimum impedance limit and natural impedance are checked considering the voltage fluctuation and the reactive power,and finally the impedance,24% for ±1 100 kV ultra high voltage direct current(UHVDC) projects,is obtained.Lightning impulse withstanding level(LIWL) and switching impulse withstanding level(SIWL) at the valve side of HY transformer is 2 300 kV and 2 100 kV respectively,about 28% and 31% higher than that of ± 800 kV projects.±1 100 kV converter transformers could be designed according to three solutions: conventional design,units in parallel,and components of transformers transported to site and assembled on site.A simple solution to integrate an UHVDC project into UHVAC systems is discussed according to the reduction of transporting transformers by railway.     

基于油气分析的电力变压器状态评估方法*

基于变压器老化机理,引入"基于电网状态评估的风险防范管理体系",讨论了如何采用油气分析数据对变压器的运行工况进行评估,以及能够反映电力变压器运行工况的健康指数、故障发生概率及剩余使用寿命的计算方法。运用该方法对广州供电局的电力变压器进行了状态评价,事实证明变压器实际运行情况与评价结果基本一致。     

基于可靠度的电力变压器寿命分析

为掌握电力变压器全寿命周期的状态变化情况,基于故障树分析法建立了变压器可靠度模型及变压器老化模型,利用最小二乘法拟合变压器运行年限–平均可靠度关系曲线,计算变压器进入各个寿命阶段的年限及平均无故障工作时间,从而为确定最佳维修周期、制定最优维修方案提供科学依据,达到延长变压器有效使用寿命的目的。算例结果验证该方法的有效性。     

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.     

基于故障树法的电力变压器可靠性及失效分析

针对电力变压器运行过程中出现的不同类型的故障事件,确定了变压器可靠性评价的指标以及主要故障模式,运用故障树分析方法及计算机辅助故障树分析系统构建了变压器失效的故障树评估模型,并确定了可靠度、失效率以及重要度参数的计算方法,通过模拟仿真结果对故障树进行可靠性与失效分析。结果表明:通过降低变压器失效概率、提高设备可靠度以及准确掌握变压器可靠性水平为变压器状态检修提供指导,从而提高电力变压器的运行安全性与可靠性,对保障电网安全可靠运行具有重要意义。     

基于物元分析法的电力变压器套管健康状态评估

套管故障率往往高于变压器本体,准确评估套管健康状态对提高变压器整体运行可靠性十分重要。文中基于物元分析理论提出了套管健康状态的评估方法。以试验检测数据为基础,综合考虑巡视检查与维护历史状态参量,构建了套管健康状态评估的层次型指标体系;采用层次分析法(AHP法)确定指标初始权重,并根据指标数据变化量、利用信息熵对试验类指标的初始权重进行修正。基于物元理论构建了套管健康状态的评估物元,考虑到定量指标测量干扰及定性指标主观判断所带来的误差,采用一个数据区间来表征指标状态,在此基础上基于区间可拓理论提出了套管健康状态的评估模型。实例分析表明文中建立的评估模型可以有效评估套管的健康状态,为制定套管后续维护检测策略提供参考。     

基于可靠性需求的电力客户细分和可靠性价值评估方法

从电力用户角度提出可靠性提升的直接经济价值、用户体验价值和社会价值的定义及其计算模型,建立区域供电可靠性需求评估框架,介绍具有较高可靠性价值的7类用户及其特征采集和可靠性价值分类评估算法。针对具有较强主观性的用户体验价值和社会价值的定量评估,提出一种改进层次分析(analytical hierarchy process,AHP)法,并通过区域可靠性需求评价应用实例验证该方法的有效性。该算法既可用于供电企业客观评估不同供电区域的客户供电可靠性需求,也可为实施可靠性电价后的市场需求分析和预测提供技术支撑。     

基于油色谱数据的变压器可靠度评估方法(英文)

变压器是电力系统的枢纽设备,其运行的可靠性直接关系着电力系统的安全运行。为此,提出了一种基于色谱数据统计规律的变压器可靠度评估方法。首先对正常状态以及过热和放电异常状态时变压器的油色谱数据进行分布规律分析,采取曲线拟合的方式求取各状态下气体含量的概率密度函数以及累积分布函数。根据异常状态时数据的分布规律,利用变压器的可靠性与故障的累计概率之间的关系,得出各气体含量达到国标注意值时变压器的可靠度。最后按照国家安全预警体系将变压器异常状态划分为5个严重等级。     

基于改进混合法的电网运行可靠性评估方法研究

针对电网运行可靠性评估中难以计及系统的高阶故障状态影响、使用传统可靠性评估方法已经不能满足运行可靠性指标的计算时间要求等问题,提出一种解析法与蒙特卡洛法相结合的改进混合法,其基本思想是利用解析法处理系统的N-1阶故障,计算初始可靠性指标;对于系统的高阶故障以预想事故链替代,采用蒙特卡洛法抽样出连锁故障的初始环节,再进行...     

基于云理论的电力变压器绝缘状态评估方法

针对电力变压器故障机理复杂,模糊评价隶属函数的确定具有主观性且未考虑随机性,仅凭油中溶解气体单一因素难以有效评估其潜在隐患的问题,提出了一种新的基于模糊云理论的变压器绝缘状态评估方法。建立了绝缘状态评估体系并进行了等级的划分,在用变权动态确定指标权重的基础上,采用隶属云模型描述其模糊性与随机性,并结合红外热像仪与油中溶解气体分析方法对其绝缘状态进行综合评价。通过实例研究,验证该方法有效易行,为变压器状态检修工作提供了一种新方法。     

基于多参量数据回归分析的电力变压器状态监测方法

电力变压器是电网中的核心设备,其运行状态直接关系到系统的供电可靠性和安全。为了充分利用变压器多元状态监测信息,实现对变压器状态的精确感知,对在线监测参量进行了统计分析,确定了监测参数间存在一定相关性。提出基于多状态参量的回归特性进行设备状态分析的PLS-PCA（partial least squares - principal component analysis）方法,即在设备正常运行时,利用偏最小二乘回归（PLS）方法挖掘状态参量之间的关联关系及回归方程,基于回归预测与实际之间的偏差构建了基于主成分分析（PCA）的变压器状态评判方法,通过控制图对比了变压器状态变化检出的能力。通过对变压器正常运行状态和异常运行状态监测数据进行分析,结果表明：多状态参数回归分析可以将变压器的多元监测数据直观地显示出来;该方法利用监测参数间的相关性,通过发现变压器运行过程中状态参数的霍特林统计量,可以提前检测变压器的异常运行状态。