This paper proposed a method for evaluating the oil-paper insulation of transformers based on wavelet analysis and probabilistic neural network (PNN). First, the six-layer decomposition of daubechies 6 (db6) is performed on the depolarization current spectra to obtain the signal components of each frequency band. Then, the signal components of each frequency band are used to generate energy feature vectors; further, the energy feature vectors generated from more than 50 transformers with different insulation states are used to build a training sample set to train a probabilistic neural network and construct a PNN-based evaluation method. Finally, the method is used to evaluate the insulation of the testing sample set. The results show that the proposed method based on wavelet analysis and PNN can quickly and effectively evaluate the aging state of transformer oil-paper insulation, and can provide new ideas to evaluate the insulation of transformers using depolarization current.

针对扩展德拜模型未能有效反映变压器油纸绝缘界面极化反应的不足,为研究油纸绝缘混联等效模型参数与微水量的关联性,以混联等效模型为研究对象:首先,基于该模型推导其频域介电响应函数;然后,基于不同微水量的油浸绝缘纸板的FDS测试结果进行混联等效模型参数求解;最后,基于参数求解结果研究两者的关联性.研究结果表明:当混联等效模型极化支路数为6时,极化支路数分配不同均可较准确地反映油纸绝缘在不同微水量下的介电弛豫过程;混联等效模型参数对油纸绝缘微水量的变化十分敏感,随着微水量增加,绝缘电阻减小,中/小时间常数的极化电容值增加,而几何电容几乎不变.此外,还拟合出绝缘电阻与微水量的函数关系,有助于实现对油纸绝缘微水量的定量评估.

针对目前研究时域特征量评估油纸绝缘老化只对整体状态诊断,并未区分油纸绝缘系统中不同介质的绝缘状态.利用油纸绝缘变压器的回复电压现场测试数据,根据充电时间长短将时域特征量区分处理,形成绝缘油和绝缘纸的标准状态指标;采用标度拓展法与变异系数法确定各指标主客观权重,并根据最小鉴别信息进行最优组合;最后结合一种改进理想解法实现对油纸绝缘不同介质状态的分类分级评估.通过实际油浸式变压器测试数据进行验证,结果表明该方法能实现同一台变压器油和纸绝缘状态的分类评估,通过对比变压器实际状况和绝缘纸聚合度、油中微水量验证了评估结果的准确可靠.

针对时域介电响应法的弛豫响应参数求解的不确定性及特征量提取不够直接、物理意义不易描述等问题,提出基于直接确定性参数辨识与弛豫法谱线特征量的变压器油、纸绝缘老化诊断新方法.首先,采用末端双点解析法确定去极化电流谱线中的弛豫参量;分别绘制表征变压器绝缘油、绝缘纸状态的弛豫最小、最大法谱线,直接提取4个新特征量:弛豫最小法向角θτmin、弛豫最小法线长Pτmin、弛豫最大法向角θτmax、弛豫最大法线长Pτmax;经研究分析证实:绝缘油老化程度越严重,θτmin越小,Pτmin越短;绝缘纸老化程度越严重,θτmax越小,Pτmax越短.多台变压器试验验证:依据新特征量能有效诊断出油、纸绝缘老化状态;弛豫参量辨识新方法和新特征量提取为油纸绝缘老化诊断提供了新思路.

提出一种利用自适应采样间隔Prony算法对去极化电流数据进行拟合,进而辨识出德拜等效电路参数的方法.根据扩展德拜等效模型下去极化电流指数函数叠加的物理性质,对传统单采样间隔Prony算法进行改进:根据不同大小时间常数去极化电流子谱线的衰减特性实现采样间隔的自适应选择,利用自适应采样间隔对去极化电流数据进行多次Prony拟合,得到相应时间常数的子谱线弛豫参数,进而辨识出油纸绝缘的德拜电路参数;搭建扩展德拜模型仿真平台得到PDC仿真数据进行拟合,验证了自适应采样间隔Prony算法对德拜电路参数辨识的准确性,取一台现场实测的油纸绝缘调压器去极化电流数据进行拟合,拟合结果与实测电流吻合,验证了此方法在现场噪声干扰测试条件下的可靠性;对实测数据的拟合结果证实了扩展德拜模型对油纸绝缘介质响应过程描述的准确性,德拜拟合对现场实测的噪声干扰起到了滤波的作用.

针对变压器油纸绝缘评价指标存在的不确定性和评价标准存在的模糊性,提出结合集对分析与模糊集组合方法,将多元模糊联系度模型应用于变压器油纸绝缘老化状态评价中.首先,基于去极化电流谱线解析提取了3个新的绝缘老化特征量,结合变压器的实测数据进行统计分析并建立变压器9项老化评价指标体系,基于模糊C-均值聚类(FCM)算法,确定3等级评价标准;然后,应用同异反分析构建各评价指标与评价等级标准的联系度表达式,引入主客观相结合的组合权重赋权法并对差异度信息进行数据挖掘,确定组合联系度;最后,按最大组合联系度对应的等级作为集对分析结果,实例结果验证了多元模糊联系度模型能有效、准确地评价变压器油纸绝缘老化状态,具有推广应用价值.

Due to the fuzziness and uncertainty of the transformer's insulation state by itself, when using the index to evaluate the insulation of oil paper transformers alone, the insulation state of transformers may appear contradictory and incompatible situations. This paper establishes evaluation models of extension theory to comprehensively evaluate the state of the oil-paper insulation transformers. Firstly, it establishes multilevel framework of the transformer and determines the weight coefficient of each index by means of extensive AHP; Then, this paper establishes the classical domain and joint domain of transformer's four kinds of matter-element models using large amounts of the measured data;Finally, using correlation function to determine the insulation state of transformers to be evaluated, this paper realizes the synthetic evaluation with the qualitative and quantitative combination for the transformer. The validity and feasibility of the method are proved by the example in this paper.

在时域介电响应法变压器油纸绝缘老化诊断的研究中,介电响应谱线的解谱一直存在不确定性,且参数计算过程复杂,间接提取的特征量物理意义较难描述.针对电路模型的确定和特征量的提取问题,提出1种诊断变压器油纸绝缘老化状态的新方法.首先采用去极化电流谱线末端双点解析法确定变压器油纸绝缘等效电路模型,提出新型极化最大直谱线,直接提取3个新特征量:极化小电阻支路数lLow R、极化最大斜率aτmax最大截距bτmax;经研究分析证实:油纸绝缘老化程度越严重,lLow_R越多,aτmax、bτmax越大.多台变压器实验数据分析计算表明:依据新特征量能有效诊断出油纸绝缘老化状态;确定等效电路的新方法和新特征量为诊断油纸绝缘老化提供了新的思路.

基于回复电压测试数据,运用粗糙集理论评估变压器绝缘状态,并建立变压器绝缘状态评估系统。首先选取回复电压法特征量和扩展德拜等效弛豫电路特征量作为评估特征量。其次利用模糊C均值聚类算法对评估特征量进行模糊划分并指标化,生成绝缘状态决策表。接着利用差别矩阵对绝缘状态决策表进行属性约简。最后,利用盲目删除值约简算法对已约简决策表进行属性值约简,得到完全约简的决策表,并在此基础上建立变压器绝缘状态评估的规则表。通过实例分析证明提出的评估方法能够有效地评估变压器内部绝缘状态。

Based on the extended Debye model, the interface polarization branch is introduced to make the oil-paper insulation mixed polarization equivalent model more suitable for the actual polarization process. The mixed polarization equivalent model parameter identification method using frequency domain dielectric spectrum is studied. Firstly, the relationship between the frequency domain spectrum and the circuit parameters is derived based on the mixed polarization equivalent circuit. Secondly, the objective function of the equations for solving the multivariate parameters is established, and the artificial intelligence algorithm is used to solve the parameters. Finally, the method is used to verify the identification of the method. Feasibility and accuracy of mixed polarization equivalent model parameters. The calculation results show that the mixed equivalent model considering interface polarization can more accurately reflect the relaxation process of oil-paper insulation. Compared with the time domain dielectric spectrum parameter identification method, the identification method based on frequency domain dielectric spectrum has the advantages of simple solving process and accurate and reliable parameter calculation results.

变压器绝缘的微水含量是影响其寿命重要因素之一.本文基于去极化电量和介电响应理论,提取去极化电流始端去极化电量Soil和末端去极化电量Spaper来评估变压器油纸绝缘的微水含量.首先,比较绝缘油和绝缘纸在不同水分含量下的去极化电流曲线变化;然后,根据去极化电流曲线的介电响应参数辨识结果提取特征量Soil和Spaper,分析结果表明,Soil与Spaper均随着绝缘油或纸中微水含量的增加呈现指数规律增长.最后,通过实例验证所提特征量能较好地评估变压器油纸绝缘的微水含量.

由于继电保护培训中心多套保护装置仅配备一台断路器,做开关传动试验时需要改接保护装置出口回路.在此背景下,设计一种自动切换出口回路的装置,以防止不同操作电源的互串.首先,切换装置内部的 PIC 单片机判断需投入的操作电源,然后切除已接入的操作电源并投入需要的操作电源,通过闭锁功能保证只有一回操作电源在连接状态.实际应用效果验证了该装置可以快速自动切换出口回路并防止互串.

Previous studies have confirmed that the insulation status of oil-paper transformer can be qualitatively analyzed by its time domain dielectric spectral characteristics. However, it is more important to evaluate the insulation condition of transformers quantitatively in engineering practice. An evaluation system based on characteristics obtained by the return voltage measurements is constructed in this paper for the quantitative evaluation of the insulation state of oil-paper transformers. First, data of characteristics of transformer are normalized and neighborhood radius of each characteristic are calculated. Then, the decision table of oil-paper insulation diagnosis system is generated based on neighborhood rough set theory. Moreover, attribute reduction is carried out to the decision table and the best rules are extracted. Finally, the oil-paper insulation state evaluation system is constructed based on the historical database. Five transformers of known insulation status have verified the accuracy of the evaluation system.

现阶段变压器油纸绝缘等效弛豫机构参数辨识多采用拓扑支路数任意假定、粒子群等智能算法对N组非线性方程组寻优迭代计算.其计算往往具有收敛性差、结果不唯一等问题,且难以从介质响应函数特性分析真实的油纸绝缘弛豫过程,影响后续弛豫参数对老化评估的准确性.基于此,提出一种应用数学解析法的变压器油纸绝缘弛豫机构参数辨识新方法.首先,从介质响应函数特性出发,深入挖掘弛豫项数信息,辨识油纸绝缘等效弛豫机构的拓扑结构;其次,公式推演得到参数辨识的数学计算公式,避免了智能算法对非线性方程组的寻优误差与不唯一性;最后,通过实例验证该方法的有效性与可行性,提出的数学解析法可为变压器油纸绝缘介质内部弛豫响应特性提供可靠的数学分析模型.

变压器油纸绝缘状态的准确诊断对其检修策略制定具有重要指导意义.为实现油纸绝缘状态的客观科学评价,建立基于组合赋权-双基点法的变压器油纸绝缘状态多特征量综合评估模型.首先,针对利用单一特征量评估的不足,基于现有采集的时域介电谱数据分别从回复电压极化谱与扩展德拜等效电路提取多个老化特征量,建立标准评估指标体系;其次,运用计及专家主观经验和数据客观差异的指标组合赋权模型,克服单一赋权法的不足;最后,基于双基点法计算待评估对象与标准状态理想点的贴近度,获取油纸绝缘状态的综合评估结果,并对评估结果数据进行深入分析,进一步了解变压器的油纸绝缘状态.通过实例验证所建评估模型能有效、准确地诊断变压器绝缘状态,可为变压器油纸绝缘状态评估提供一种新方法.

将带有弛豫因子的介质响应函数应用于回复电压时域介电谱的分析,对时域微分介电谱线进行解谱,得到包含不同弛豫信息的子谱线,并确定变压器油纸绝缘拓扑结构和求取弛豫参数值.然后,对30多台不同型号的油纸绝缘变压器的弛豫参数及其绝缘状态进行分析,挖掘弛豫因子与变压器绝缘油劣化、绝缘纸老化等内在关系,提出新的特征量—绝缘油的平均弛豫因子、绝缘纸的平均弛豫因子来评估油纸变压器中绝缘油和绝缘纸的绝缘状态.最后,利用实际变压器测试数据进行分析验证,结果表明2个新特征量可有效地用于评估变压器中绝缘油和绝缘纸的绝缘状态.

微水是变压器的头号敌人,因此准确评估诊断变压器微水含量具有重要意义.针对油纸绝缘变压器,提出一种采用电流极化谱特征量进行微水含量评估的方法.首先,利用去极化电流微分解谱法分析变压器去极化过程,并提取电流极化谱特征量.然后,进一步分析特征量与油纸绝缘微水含量的关系,以此作为油纸绝缘系统微水含量评估判据,并得出结论:去极化电荷量越大,变压器微水含量越高;反之,去极化电荷量越小,变压器微水含量越低.最后,通过变压器实例验证了该判据的准确性和可行性,为变压器微水含量评估提供了一种有效的评估方法.

配电网高阻接地故障时故障电流较小,使得故障定位有了较大的难度.通过提取各检测点纯暂态零序电流以及母线纯暂态零序电压,利用暂态投影法将各检测点的纯暂态零序电流投影到母线纯暂态零序电压后,计算相邻采样点的投影电流动态时间弯曲距离进行区段定位.仿真结果表明,该定位算法在不同情况下具有较高的区段定位准确率.

构建变压器油纸绝缘等效电路模型是研究油纸绝缘老化状态评估的关键,其等效电路参数的唯一辨识是此部分研究的一个难点.针对目前辨识等效电路参数的方法均有非唯一性的不足,结合三次时域微分曲线提出一种对油纸绝缘扩展德拜等效电路参数唯一计算的新方法.首先,利用去极化电流三次时域微分曲线的末端峰值点唯一性,实现对等效电路的极化支路数、时间常数与弛豫系数的唯一辨识;其次,根据等效电路与基本电路理论推导各支路参数与时间常数、弛豫系数的函数关系式,从而计算出各极化等效支路的电阻、电容值;最后,通过实例验证了此方法唯一辨识油纸绝缘等效电路参数的可靠性与准确性.

The improved grey target theory is applied in the research of transformer oil-paper insulation aging state.First the data are measured by recovery voltage method and relative parameters are identified by equivalent circuit of ED,using extracted parameters as the characteristic quantity of assessment of oil-paper insulation aging state.Second,because of the different influence of several characteristic quantities on oil-paper insulation aging state,the improved AHP method and entropy weight method is used in the weight distribution of these characteristic quantities.Last,the data of transformer are collected and grades of oil-paper insulation aging states are calculated.Experimental results show that this method can effectively and reasonably evaluate the transformer oil paper insulation aging status and provide a reference for the transformer condition maintenance.