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。     

塑料绝缘直流高压电缆中空间电荷测量技术的研究

同轴型电缆空间电荷测量系统与片状试样空间电荷测量系统在测试原理上是基本一致的,但是有其特殊性.在分析同轴型直流塑料电缆的衰减和色散特性、脉冲电场耦合方式以及电极系统的基础上,研发出同轴型直流塑料电缆空间电荷测量系统.利用此测量系统测量了某直流塑料电缆在24h冷热循环条件下的空间电荷分布情况.直流塑料电缆空间电荷测量系统...     

氯化聚乙烯共混对聚乙烯的空间电荷效应的影响

在直流电场作用下 ,用电声脉冲法测量了低密度聚乙烯 (LDPE)中空间电荷的分布 ,计算结果表明 ,异极性空间电荷严重畸变试样中的电场的分布。以少量氯化聚乙烯 (CPE)混入低密度聚乙烯中 ,大大降低了试样中的空间电荷 ,电场分布趋向均匀。在正负极性直流预压短路树枝试验中 ,分别提高试样短路树枝起始电压 2 6 8%和 36 3%。通过直流预压和电晕电荷注入后 ,短路过程中空间电荷分布的测量 ,提出氯化聚乙烯的作用机理在于降低了聚乙烯中陷阱的深度和密度。     

压力波法模型电缆空间电荷测试研究

根据压力波法空间电荷测量的基本原理,研制了一套可用于模型电缆试样的压力波(PWP)法空间电荷测试装置。该装置具有高于PEA法的信噪比,原始信号无需处理即可用于空间电荷性能分析。利用此装置分别对交流和直流XLPE电缆进行了空间电荷测试。结果表明:随着外加电场的升高,空间电荷明显增多。另外,直流电缆绝缘中的空间电荷明显小于交流电缆绝缘中的空间电荷。     

基于离子计数法的直流线路空间电荷密度测量

当特高压直流输电线路途经地区的空中悬浮颗粒物较多且空气干燥时,空间电荷分布的变化导致地面合成电场异常增大。为对该问题进行研究,测量空间电荷分布是一种直接且有效的手段。通过分析基于离子计数法的空间电荷密度测量原理和装置电流检测部分的等效电路模型,提出了装置的设计要求,对基于该原理的电荷密度测量装置进行了设计,并采用间接校准方法对装置进行了标定。采用该装置对直流输电试验线段下的空间电荷密度进行了实测,测量结果表明电荷密度的横向分布规律、随导线加压的变化情况与合成电场、离子流密度类似。装置可以实现输电线路周围空间电荷密度的测量。     

基于脉冲电声法的同轴塑料电缆空间电荷测量技术的研究进展

空间电荷现象严重制约着高压直流塑料电缆的发展。目前,脉冲电声法（pulse electric acoustic,PEA）是国际上常用的测量固体电介质中空间电荷分布的非破坏性的方法之一。首先从高压脉冲的注入方式出发,简述了几种基于PEA法的同轴塑料电缆空间电荷测量技术;同时,提出了一种基于高压脉冲从测量电极注入电缆试样的改进测量装置,在该装置中通过蓄电池、环氧底座以及光电转换器等将采集数据的示波器进行对地隔离,从而提高了测量系统测量信号的频带宽度;然后,介绍了同轴塑料电缆空间电荷波形的恢复方法;最后,概述了空间电荷测量技术在评估电力电缆老化程度中的应用和未来在线测量空间电荷的可行性及发展方向。     

以氯化聚乙烯改性交联聚乙烯作为直流电缆绝缘的研究

以少量氯化聚乙烯(CPE)改性交联聚乙烯(XLPE),用电声脉冲法测量了试样中的空间电荷分布,研究了CPE含量与空间电荷的关系,确定了降低空间电荷的最佳含量,研究了CPE对试样直流预压短路树枝起始电压的影响,当CPE含量为1%时,XLPE的50%直流预压短路树枝起始电压决定直流电压的极性,分别可提高42.3%和35.5%。最后作者还测量了试样的其他介电性能,计算了空间电荷畸变的电场强度,分析和讨论了相关的机理。     

高压电力电缆中的空间电荷分布测量

本文介绍了用激光感应的压力波法测量聚乙烯高压电力电缆试样中的空间电荷分布的测量技术，主要讨论了其测量原理以及实际测量中的问题。对于实际样品的测量结果表明，在直流高压下，聚乙烯中的局部场强可能达到外加电场的八至十倍，且极容易引发电树枝。     

EAA改性XLPE中空间电荷和电树、水树的关系

以不同含量的EAA（乙烯－丙烯酸共聚物）改性XLPE（交联聚乙烯）,用电声脉冲法测量了样品中的空间电荷分布。探讨了试样中空间电荷分布与EAA含量的关系,找到了抑制空间电荷的最佳含量。同时测出了在直流预压电压下短路电树枝的起始电压。对交流电压下抑制水树枝的产生和成长了做了研究。试验发现：当试样中含EAA为1．0％wt时,聚乙烯的直流预压短路树枝的起始电压得到提高;交流电压下树枝的出现概率和水树枝长度都减小。     

电缆本体空间电荷电声脉冲法测量装置的研制

聚合物电缆绝缘层中空间电荷的存在和积累对电缆的电导特性、老化、击穿等有强烈的影响。因此,研究聚合物电缆中空间电荷的分布和积累有着重要意义。鉴于此,介绍了电声脉冲（PEA）法测量空间电荷的基本原理,研制了一套新型的可用于电缆试样的PEA空间电荷测量装置。采用平板型电极,此装置可以测量不同绝缘厚度和曲率半径的电缆。利用此装...     

Space charge in XLPE power cable under dc electrical stress andheat treatment

It is well known that the existence and accumulation of space charge in insulation can be harmful to polymer power cable. Although there is much research done on space charge distribution in various samples, there are still some important problems left unsolved, such as the mechanism of formation and elimination of space charge in dielectrics. Because of its superiority, the pulsed electro-acoustic (PEA) measurement method is used widely in the measurement of space charge in various geometries of samples such as the multiple layer plate and cylindrical cables. The space charge in crosslinked polyethylene (XLPE) power cable under dc voltage and heat treatment is investigated by the PEA method in this paper. After heat treatment, the space charge, which previously formed in cable insulation under the applied voltage, disappears. If electrical stress is applied to the insulation again, space charge will appear once more. However, after the cable is heated and degassed in vacuum for a long time, no matter how long the dc voltage is applied to the cable, no more space charge will be formed in the cable. The mechanism of formation and elimination of space charge under the effect of electrical and thermal stress is discussed     

空间电荷在评估绝缘聚合物电老化程度中的应用研究

通过向聚乙烯中添加一种电压稳定剂，能够有效地抑制聚乙烯的电老化。纯聚乙烯和含电压稳定剂的聚乙烯的试样经过不同时间的电老化后，空间电荷测量表明，在电老化过程中，空间电荷的分布发生变化，出现正负电荷峰的分离和叠加。两种性质的试样中的空间电荷总量都近似地随老化时间呈线性增长，并与老化后的残余绝缘强度的变化有对应关系。分析表明，以试样的短路空间电荷总量与老化时间关系，可以评估聚乙烯的电老化程度。     

Some factors for the space charge formation in polyethylene

Information on space-charge behavior in thick insulated samples aids in understanding the dc characteristics of polymer-insulated dc cables. The pulsed electroacoustic method is used to investigate several space charge formation factors in 2 mm-thick polyethylene (PE). The following results were obtained. For measurement factors: (1) A polymeric semiconducting electrode provides a more accurate measurement than does a metal electrode as a result of better matching of acoustic impedance with PE. (2) Within a dc electrical stress range of several tens kV/mm, the space charge distributions under and after dc voltage application are almost the same; this is due to a comparatively long time of space-charge decay. (3) The space-charge distribution of a plate sample agrees with that of a cable sample having the same insulation thickness. For insulating material factors: (1) The amount of space charge in crosslinked polyethylene (XLPE) is much larger than that in low-density PE (base of XLPE). The space charge of XLPE continues to increase even after dc voltage application (24 h); that of LDPE reaches equilibrium with a few hours. (2) The aforementioned space charge difference between XLPE and LDPE is assumed to be caused by ionic impurities in XLPE, not by the additives themselves (acetophenon and cumylalcohol as byproducts of cross linking and antioxidant).     

空间电荷与直流电导联合测试技术用于纳米MgO抑制XLPE中空间电荷的研究

粒径70nm的MgO以不同浓度与交联聚乙烯(XLPE)共混制成聚合物纳米复合介质。采用自主研发的四电极系统同时测量复合介质的高场电导特性和空间电荷分布。通过强场电导实验发现,在室温下,XLPE及纳米MgO/XLPE复合介质的电导机理不是单纯的空间电荷限制电流(SCLC)。此外,添加纳米MgO可以明显地提高空间电荷的注入阈值,并且在低于空间电荷注入阈值的电场下,复合介质的电导电流密度随纳米MgO浓度的增加,先减小后增大。最后从空间电荷的实验数据验证了纳米MgO能有效抑制XLPE中空间电荷,并进一步定性地认为纳米Mgo的添加提高了电子注入的电场强度阈值。     

Space charge measurements in polymeric HV insulation materials

This paper reports on a study using the laser induced pressure propagation (LIPP) method to measure the space charge characteristics in bulk crosslinked polyethylene (XLPE) insulation under dc electric stress. Particular attention has been given to the quantitative appraisal of calibration parameters, and the resultant estimations of space charge and electric stress distributions. A method is described for analyzing the measured raw data from ramp voltage and aging tests to give an estimate of charge and stress without resorting to a complicated mathematical exercise. The consequence of stress enhancement due to the trapped charge on the life of the insulation is estimated using the empirical inverse law. Using analysis of variance and a multivariate analysis technique, the effects of treatment and type of XLPE on the space charge characteristics are also discussed     

DC electrical treeing phenomena and space charge

Influence of space charge on dc tree propagation is studied using many insulating polymer materials under divergent fields. The inception voltage and the propagation of dc treeing are affected strongly by space charge. Space charge formation in polymers was observed directly by using thermally stimulated current (TSC) techniques under divergent field. These results of the space charge effect on dc treeing phenomena are consistent with those obtained by the TSC method. From these results, the origin of space charge in polymers and the suppression techniques for space charge formation were discussed     

Properties of Space Charge Distributions and Conduction Current in XLPE and LDPE under DC High Electric Field

Space charge behavior and conduction current in polyethylene under dc stress were investigated. One of the reasons for the different breakdown property in cross‐linked polyethylene (XLPE) from that in low‐density polyethylene (LDPE) may be based on the existence of cross‐linking by‐products in XLPE. Furthermore, a thermal history in cross‐linking process for XLPE may also cause of the difference. It is generally accepted that the existence of the cross‐linking by‐products increase the conduction current in XLPE under dc stress. It is also said that an anneal treatment in air atmosphere may affect to the electrical properties under dc stress. Therefore, we investigated the effect of the cross‐linking by‐products and the anneal treatment on space charge behavior and conduction current in polyethylene under dc stress. In our research, it is thought that the increasing dissipation power in XLPE is the cause of the breakdown in it under dc stress. Therefore, to calculate the dissipation power in the bulk of test sample, we measured the space charge distribution and the external circuit current simultaneously. Based on the results, we discussed the reason of the difference of the space charge properties in XLPE and LDPE focusing on the cross‐linking by‐products and the oxidation of the test samples.     

伽马射线对低密度聚乙烯的空间电荷陷阱特征影响

为研究伽马射线辐照后的低密度聚乙烯材料在直流电场作用前后的空间电荷形成和衰减的陷阱特征,在60Co伽马射线的辐照源下得到最大辐照剂量为50 kGy的聚乙烯样品,利用电声脉冲法测量其空间电荷分布,进而提出了一种离散陷阱分布模型来解释射线辐照的空间电荷衰减特征。结果表明:在阴极附近出现异号的正电荷积累并随着辐照剂量增加而增加;分析认为射线辐照后样品出现的异号正电荷是由于材料发生了化学变化(氧化)而导致更深能级陷阱的产生;同时,利用所提出的模型计算了陷阱的能级深度和陷阱密度参数,并分析了它们与辐照氧化的微观机制。由陷阱能级和陷阱密度围成的曲线族变化可作为材料辐照老化的特征参量。