绝缘电介质薄膜中空间电荷分布测量技术的研究进展

绝缘电介质薄膜广泛用作为高压电气设备中的绝缘材料和传感器件中电介质功能材料,如果用在直流高压应用条件下,空间电荷分布是其重要的特性表征。如果用于功能电介质,空间电荷分布是其功能实现的决定性因素之一。为此总结了厚度为数微米至几十微米的薄膜电介质中空间电荷分布测量方法的研究进展,按照测量的空间分辨率分别介绍了压力波法、热扰动法、电声反射法和基于飞秒脉冲激光器光电测量方法的测量原理。比较了这几种测量方法的特点,讨论了影响测量分辨率的几个关键因素:如对介质的扰动方式、对介质响应信号的探测方式以及对响应信号处理的解卷积方法。压力波法和热扰动法是其中较为成熟有效的测量方法,分辨率介于亚微米及数微米之间,扰动方法及信号监测都相对容易实现,而热扰动法虽然较容易实现亚微米分辨率,但数据处理较为繁琐。目前还处于试探阶段的电声反射法的测量基于网络分析仪,具微米级空间分辨率。基于飞秒脉冲激光器光电测量法是对传统压力波法或电声脉冲法的改进,通过太赫兹窄脉冲扰动,利用光电方式实现极高带宽测量,能够实现数十纳米级空间分辨率。     

共混改善聚乙烯空间电荷分布的研究

在高场强下用电声脉冲法（PEA）测量了低密度聚乙烯和线性低密度聚乙烯共混物中的空间电荷分布,用差示扫描量热法（DSC）研究了共混物的形态。实验结果表明：与纯低密度聚乙烯相比,共混可以降低空间电荷。文章最后分析了共混后对空间电荷影响的机理。     

SF_6／Ar和SF_6／Kr的绝缘特性及分析

本文在Ｅ／Ｐ值为１５．０～９４．０ｋＶ／（ｍｍ·ＭＰａ）范围内，采用稳态汤逊法（ＳＳＴ）测量了ＳＦ６／Ａｒ和ＳＦ６／Ｋｒｊ昆合气体的电子崩电流，用最小二乘法求出了α／Ｐ、／Ｐ、／Ｐ与Ｅ／Ｐ的关系，还求出了各混合比下的ＳＦ６／Ａｆ和ＳＦ６／Ｋｒ的临界耐电强度值（Ｅ／Ｐ）ｌｉｍ，并分析了两种混合气体的绝缘特性。     

玻璃化温度对环氧树脂空间电荷分布的影响

用电声脉冲法(PEA)测量了纯环氧试样在313K(玻璃化温度以下)及343K(玻璃化温度以上)时的空间电荷分布,并测量了两种温度不同电场强度下的空间电荷特性。实验发现两种温度下的空间电荷特性具有明显的差异。并对环氧树脂表面水分对空间电荷特性的影响进行了讨论。     

固体介质中空间电荷分布测量的频域分析电声脉冲法

本文在国内外电声脉冲测量方法发展的基础上，提出了频域分析电声脉冲法测量固体介质中空间电荷分布的思想，报导了测量系统的性能，解决了原电声脉冲法对薄试样计算中的困难，将测量试样厚度范围扩展到０．２～４ｍｍ之间，系统测量灵敏度可达到０．５Ｃ／ｍ３。此系统尤其适合于介质强场下空间电荷分布的动态研究。     

固体介质中空间电荷畸变电场分布的有限元分析

介绍了电声脉冲法测量空间电荷分布的测量原理及装置 ,并以此装置测得试样中空间电荷的分布。用有限元法分析、计算试样中空间电荷引起的电场畸变方便、迅速 ,表现直观。     

GIS 中局部放电产生的超高频电磁波及其测量

分析和测量了ＧＩＳ中ＰＤ信号的传输特性,在超高频（ＵＨＦ）波段,ＰＤ信号的传输不仅以ＴＥＭ波,而且主要是以高次模,即ＴＥ波和ＴＭ波传播。     

适用于PEA空间电荷测量系统的高压脉冲发生器设计

电声脉冲法(PEA)是一种目前较为流行的空间电荷分布测量技术,使用该法的一个前提条件是必须产生一个高压脉冲。阐述了电声脉冲法(PEA)测量电介质中空间电荷的原理,并分析了高压脉冲波形对测量信号的影响。在分析传统高压脉冲发生器的基础上,介绍了一台新型带相位检测的高压脉冲发生器,从而使PEA空间电荷测量系统能够适合交流电压下的电缆绝缘测试,该发生器能够形成50 ns、100 ns和200 ns的5 kV陡脉冲电压信号。     

固体电介质中空间电荷测试系统的设计

介绍了自主制作的用于平板型试品的电声脉冲法（PEA）空间电荷测量原理和测试系统系统。着重介绍了系统的原理和硬件结构以及相应的重要参数。本套测量系统的优点是：结构紧凑，测量精度较高，对于PE类材料中的空间电荷分布可以很好的进行测量。     

基于电声脉冲法的空间电荷测量装置

为了从微观角度分析绝缘材料老化和击穿的原因,研制了一套基于电声脉冲法(PEA)直接测量聚合物中空间电荷分布的试验装置。分析了电声脉冲法测量空间电荷的原理;设计了一种基于测试系传递函数的陡脉冲(幅值600V,脉宽10ns),以消除由系统硬件引起的过冲;讨论了各种干扰对测量结果的影响,设计了前置宽带高频小信号放大电路(增益34dB,带宽340MHz)和压电传感器。试验表明,该测量装置的分辨率可达到30μm,输出波形能直接反映试样中空间电荷分布,避免了复杂的数学处理,并以此装置实测了变频电机绝缘用聚酰亚胺膜中空间电荷的分布。     

Determination of the polarization distribution inelectron-beam-poled PVDF using heat wave and pressure pulse techniques

In the present paper, heat wave (LIMM) and pressure pulse measurements are reported of the polarization and electric field distribution in nonuniformly electron-beam poled PVDF. In order to obtain the spatial distributions from the LIMM spectra, the regularization technique is applied to the deconvolution. In this connection nonlinear grid distributions are discussed. The polarization profiles obtained by the two methods are compared over the whole thickness range, and a satisfactory agreement is found     

Polarization and electric field distribution in thermally poledPVDF and FEP

In the present paper, heat wave (LIMM) and pressure step (PPS) measurements of the spatial polarization and electric field distributions in nonuniformly thermally poled α-PVDF and Teflon FEP films are reported. The spatial distributions obtained by the two methods are compared over the entire thickness range, and a satisfactory agreement is found. For PVDF the results of both methods are in accordance with literature data for similarly poled specimens of similar material, the so-called `thermal profile', a polarization peak near the anode. Furthermore, in the LIMM experiments we found a small peak near the cathode, which can be explained by a positive compensation charge layer extending ≈2 μm in depth. For the first time, LIMM spectra of FEP are published. The space charge distribution in the FEP sample is nearly homogeneous inside the sample. Near the anode side an accumulation of negative charges appear. Near both surfaces a positive compensation charge was found with a thickness of ~1 μm. It is demonstrated that by means of our deconvolution the spatial distribution can be determined simultaneously with two thermal parameters, the diffusivity of the sample material and the heat transfer coefficient between sample and sample holder     

3D High-resolution Mapping of Polarization Profiles in Thin Poly(vinylidenefluoride-trifluoroethylene) (PVDF-TrFE) Films Using Two Thermal Techniques

In this paper, two non-destructive thermal methods are used in order to determine, with a high degree of accuracy, three-dimensional polarization distributions in thin films (12 ?m) of poly(vinylidenefluoride-trifluoroethylene) (PVDF-TrFE). The techniques are the frequency-domain Focused Laser Intensity Modulation Method (FLIMM) and time-domain Thermal-Pulse Tomography (TPT). Samples were first metalized with grid-shaped electrode and poled. 3D polarization mapping yielded profiles which reproduce the electrode-grid shape. The polarization is not uniform across the sample thickness. Significant polarization values are found only at depths beyond 0.5 ?m from the sample surface. Both methods provide similar results, TPT method being faster, whereas the FLIMM technique has a better lateral resolution.     

基于正态模型的电气试验方法优化及参数估计研究

为掌握正态分布电气特性数据的正确试验方法,确定合理的参数估计值,文章基于最小二乘参数估计方法,针对多级法和升降法电气试验数据进行中值及标准偏差统计分析。研究结果表明,多级法与升降法试验数据的中值估计值50%放电电压U50有很好的一致性,仅相差3. 7%;而两种试验方法对应的标准偏差估计值相差较大,达到42. 6%,因此,在实际电气试验工作中,尤其对于获取大尺度绝缘的标偏试验,应优先选择多级法,而获取50%放点电压则两种方法均可以满足要求。     

Electrical and chemical diagnostics of transformers insulation. A.Aged transformer samples

This paper describes the application of two relatively new diagnostic techniques for the determination of insulation condition in aged transformers. The techniques are: (a) measurements of interfacial polarization spectra by a DC method; and (b) measurements of molecular weight and its distribution by gel permeation chromatography. Several other electrical properties of the cellulose polymer were also investigated. Samples were obtained from a retired power transformer and they were analysed by the developed techniques. Six distribution transformers were also tested with the interfacial polarization spectra measurement technique, and the molecular weight of paper/pressboard samples from these transformers were also measured by the gel permeation chromatography. The variation of the results through different locations in a power transformer is discussed in this paper. The possible correlation between different measured properties was investigated and discussed in this paper     

中性点采用两种接地方式的配电网单相接地故障的比较

为了更好地应用小电阻接地方式来提高配电网系统的安全性、可靠性,笔者研究了中性点采用小电阻接地和消弧线圈接地的配电网在发生单相接地故障时的不同特点以及保护方式的差异。首先采用对称分量法对这两种配电网的单相接地故障进行分析,并采用MATLAB进行了仿真。研究结果表明,采用这两种接地方式的配电网在发生单相接地故障时的不同特点导致其继电保护措施也各不相同。因此,随着中性点经小电阻接地的接地方式的推广,其相应的单相接地故障继电保护措施需进一步完善。     

基于样本分位数和log|SαS|的SαS分布参数估计方法

α稳定分布是一类重要的非高斯随机分布,广泛应用于水声、大气和生物医学信号处理等领域。α稳定分布的特征函数由α、β、γ和α等4个参数决定,因此对于参数的估计具有极其重要的作用。由于α稳定分布没有闭合形式的概率密度函数,大多数传统的依赖于显示密度函数的数学统计方法不再适用。本文分别采用基于样本分位数法和log｜SαS｜法对SαS分布的α和γ参数进行估计,克服了传统方法中依赖概率密度函数的缺点,仿真结果显示两种算法均能给出较好的估计结果,并且能够满足后期研究的需要。     

MH-Ni蓄电池正负极阻抗分布的电化学研究

应用电流阶越法、线性电位扫描法及电化学交流阻抗法分析了MH-Ni蓄电池正负极的阻抗分布,考察了电极阻抗在放电过程中的变化,对比了正负极的各个阻抗参数,讨论了上述三种电化学方法在电极体系阻抗分析中的优点及缺陷。测试结果表明,在放电初期,负极的欧姆阻抗和电化学阻抗远大于正极,是电池欧姆阻抗的主要组成部分。随着放电程度的加深,负极的阻抗减小,正极的欧姆阻抗与电化学阻抗不断增大,最终接近或超过负极。正极的浓差极化远大于负极,且随放电深度的增大显著增加,是影响电池性能的主要因素。通过成品电极的阻抗分析为提高电池各项性能提供了有效途径。     

基于支路交换法的配网重构方法分析

根据配电系统特点,建立配网重构数学模型,详细介绍了启发式方法中的支路交换算法,提出对该算法的改进思路,对当前研究较多的解析类、启发式、随机优化及智能优化方法进行分析,就部分算法提出相应改进措施,并提出结合四类方法中的两种或多种方法的思路以求解连续变化的大规模复杂配电网络重构问题。     

A new blind deconvolution algorithm based on the probability distribution method

Blind deconvolution is a method of recovering transmitted signals from only received signals. The probability distribution method is one of the blind deconvolution methods. This method has two problems: it has slower convergence and its reliability is lower. In this paper, we propose a new algorithm for solving these two problems. The proposed algorithm is as follows. (1) It is based on the adaptive processing with each sample. (2) Kurtosis is adaptively estimated by recovered signals with each sample. (3) Cost function is decided by kurtosis. (4) Transmitted signals are recovered by received signals using decided cost function on the sample time. We confirm the validity of the new algorithm by computer simulation. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 56–65, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20317