交流叠加雷电冲击下SF6中环氧绝缘表面金属颗粒局部放电特性

为掌握交流叠加冲击这种复杂工况下环氧绝缘沿面局部放电激发规律,对交流叠加雷电冲击(lightning Impulse,LI)电压下SF₆中环氧绝缘表面金属颗粒局部放电特性进行了实验研究。在交流电压小于局部放电起始电压(partial discharge inception voltage,PDIV)的情况下,研究了交流叠加雷电冲击电压下的局部放电激发特性;在交流电压大于PDIV的情况下,研究了雷电冲击对交流局部放电的影响。结果表明,PDIV随金属颗粒的长度增加而减小,随金属颗粒的直径减小而减小,随金属颗粒距高压电极的距离增加而减小;交流叠加雷电冲击电压下的局部放电比交流电压单独作用下的放电更剧烈;交流电压低于PDIV时,负极性雷电冲击(negativelightning impulse,NLI)所激发的交流局部放电比正极性雷电冲击(positivelightningimpulse,PLI)所激发的放电剧烈;交流电压高于PDIV时,雷电冲击对交流局部放电无明显影响。     

正负极性雷电冲击作用下棕榈油绝缘油的流注传播和击穿特性试验研究

相比于矿物油,天然酯绝缘油具有生物降解性高、无毒、耐火性强等优点,具有替代电力变压器中矿物绝缘油的潜力。本研究建立了一套包括高速图像采集系统、试验电源以及电信号测量系统的绝缘油雷电冲击放电特性试验系统,针对较为常见的棕榈油绝缘油和电力变压器中常用的矿物油,进行正、负极性雷电冲击放电特性试验研究。对比分析正、负极性雷电冲...     

固体颗粒杂质对变压器油绝缘性能的影响

固体颗粒杂质对变压器油的绝缘性能影响显著,有效控制油中颗粒杂质对变压器的安全运行至关重要。文章介绍了变压器油中颗粒杂质的来源、种类及其危害,并针对变压器制造、检修、运输、安装、运行等各环节提出了控制变压器油中颗粒杂质的措施。     

电压波形对GIS自由金属颗粒放电特性的影响

为了探索较高灵敏度检测GIS设备内部自由金属颗粒的方法,研究了电压波形对自由金属颗粒的影响。在实验室中搭建了自由金属颗粒局部放电试验平台,测量了标准雷电波、标准操作波和工频电压下自由金属颗粒局部放电现象,分析比较了不同电压波形下缺陷的局部放电的特征,获得了冲击电压下不同试验阶段的散点图、柱状图等统计谱图。研究结果表明,在3种电压波形下标准雷电波的局部放电起始电压最低,对自由金属颗粒的检测较灵敏。随着标准雷电电压的升高,在雷电波尾处的放电脉冲个数明显增多,但波头处的脉冲仍仅有一个。随着标准操作电压的升高,在波头和波尾处的放电幅值变大,放电个数增多,且波头处的放电个数增加更明显。不同试验阶段的q-t散点图、q-Δt/Δu散点图及N-Δt/Δu柱状图的形貌特征较有规律,可作为表征GIS自由金属颗粒放电严重程度的特征谱图。     

气泡放电对变压器油流注放电的影响

以流体动力学为基础,建立了脉冲电压作用下含气泡的变压器油流注放电仿真模型。通过改变气泡的位置、大小及数量,研究了含气泡的变压器油的电场强度和空间电荷密度的变化规律。仿真结果表明,当击穿电压达到一定值时,由于气泡内部气体的积聚,气泡内部会形成电场梯度,从而产生内部放电现象。距离高压电极越近的气泡越先被击穿,放电进行的时间也相对更短;气泡的尺寸越大,变压器油流注放电的速度越缓慢;气泡的数量越多,流注放电时的电场越剧烈,放电持续时间越久,对变压器造成的伤害也越大。     

不同电压类型下油流中纤维杂质颗粒运动特性仿真研究

变压器油中纤维杂质颗粒受到油体流动的影响,其运动特性将发生变化,为详细探究其运动规律,采用动力学分析方法构建了单颗粒纤维杂质在流动绝缘油中固-液两相流多物理场模型,对交、直流电场下绝缘油中的不同尺寸纤维杂质颗粒在不同速度油流中的运动特性进行了系统分析。研究结果表明:油流速度对直流和交流电场下的纤维杂质颗粒影响较大,较高流速下纤维杂质颗粒不易发生碰撞,转移电荷机率降低,形成集聚的可能性减小;在直流准均匀电场中,纤维杂质颗粒在油流状态下的最大运动速度以及与电极碰撞次数和颗粒尺寸半径几乎成线性关系,且随着油流速度的增大,线性关系曲线的斜率逐渐减小;与直流电场相比,交流电场下的纤维杂质颗粒在油流作用下更加不易发生碰撞,不易在电极间转移电荷,形成“杂质小桥”的机率进一步降低。     

正极性雷电冲击电压下流注起始时延特性

流注起始时延特性,体现冲击电压作用下流注起始的随机特性,是流注起始特性的重要组成部分.研究流注起始时延特性有助于揭示长空气间隙放电机制.基于实验数据,认为有效自由电子形成的统计时延是流注起始时延的主要部分;从有效自由电子形成过程出发,通过理论推导,引入概率密度函数描述流注起始时延;并用大量实验数据进行统计分析.结果表明流注起始时延服从瑞利分布;瑞利分布的均值即为起始时延的均值,其方差即为起始时延的分散性.瑞利分布的特征参数具有明显的物理含义,可以很好地解释流注起始时延的变化规律.在正极性雷电冲击电压作用下,电压变化率在80～240kV/μs、棒电极半径在0.5～2.5 cm范围内,瑞利分布的特征参数在0.6～2.5之间.     

气压与湿度对绝缘介质表面流注发展特性影响的试验研究

目前,正在建设和规划的特高压线路大多将经过高海拔地区,沿线复杂的气象条件(气压、湿度)将使输电线路及电力设备的绝缘状况面临严峻的考验。因此,有必要重点研究气压、湿度变化对绝缘介质沿面闪络特性的影响,为特高压输电线路的绝缘设计提供理论依据。通过研究流注放电特性,从放电机制上探讨环境因素(气压、湿度)对沿面闪络特性的影响。在"三电极"结构中,利用光电倍增管测量了不同气压、湿度条件下绝缘介质表面流注传播特性。试验结果表明:流注稳定传播场强分别与气压、湿度成正比例关系;在相同的电场强度下,流注平均传播速度、流注头部发光强度都分别与气压、湿度成反比例关系。因此,流注在低气压、低湿度情况下容易发展,流注稳定传播场强较小,相同电场强度下,流注平均传播速度、流注头部发光强度较大。     

TiO2纳米粒子几何形貌对冲击电压下变压器油中流注发展速度的影响

冲击电压下流注的发展速度是衡量纳米改性变压器油绝缘性能的一个重要指标,也是分析纳米变压器油改性机理的关键参数,但是现有研究中大多聚焦于冲击电压下的击穿电压和击穿时间。为此,搭建了基于纹影法的流注高清拍摄平台,拍摄了不同形状、不同尺寸TiO₂纳米粒子改性变压器油在正极性雷电冲击电压下的流注发展过程,分析流注发展速度的变化规律,揭示其与陷阱之间的关系。结果表明,纳米粒子的几何形貌改变可以明显影响纳米变压器油中流注的发展。棒状纳米粒子使得变压器油中流注发展速度更慢,对流注的抑制作用更明显。同时,随着纳米粒子尺寸的减小,纳米变压器油中流注发展速度变慢,从而抑制了流注的发展。分析表明,TiO₂纳米粒子几何形貌对陷阱特性的影响是引起流注发展速度变化的根本原因。     

Motion characteristics of a charged metal particle in insulating oil under flow state

Problems due to discharge by charged metal particles in insulating oil under flow state are examined in this study. The motion characteristics of a charged metal particle in a horizontal transformer oil tract are investigated, and a mechanical model of a charged metal particle under flowing oil and an AC field is proposed. The particle's equations of motion are numerically solved using the fourth‐order Runge–Kutta computational algorithm. The trajectory of a spherical iron particle in typical motion state under flowing oil and AC field is simulated. The influence on the motion characteristics of a charged metal particle in terms of the oil flow rate, electric field strength of the oil tract, particle scale, initial state, and particle rotation is analyzed. Results reveal that when a charged metal particle is moving fast along the direction of oil tract flow, reciprocating oscillation simultaneously occurs in the vertical direction. Its trajectory is significantly affected by the oil flow rate, the electric field strength of the oil tract, particle scale, initial state, and particle rotation. Moreover, the degree of oscillation of the charged metal particle may be the main cause of degradation of the insulating oil under flow state. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

金属钝化剂BTA对变压器硫腐蚀的抑制效果及绝缘油性能的影响研究

油中的腐蚀性硫化物会侵蚀变压器绝缘绕组,导致油纸绝缘性能下降,给变压器的运行带来安全隐患,工程上常通过加入金属钝化剂来抑制腐蚀性硫化物与铜离子的结合,进而延缓硫腐蚀过程的发生。研究了油中常用金属钝化剂苯并三氮唑(BTA)对铜硫化物形成的抑制效果,并研究了钝化剂在长期运行过程中对变压器绝缘油性能的影响。结果表明,在含有腐蚀性硫的绝缘油中加入BTA可以有效缓解变压器硫腐蚀,但高浓度的BTA会促使油中铜离子含量增加,而油中铜离子能通过传递分解过氧化氢产生过氧化自由基,加速油品劣化,导致油纸绝缘老化加速。     

绝缘油的析气性

在6篇文献基础上,综述了绝缘油析气性对充油电气设备绝缘性能的危害 ,比较了国内外部分油品的析气性指标 ,分析了绝缘油的析气机理以及分子结构组成对析气性的影响 ,同时讨论了绝缘油析气性能的改进方法。     

Influence of various compounds on electrostatic charging tendency in insulating oil

The influence of various compounds on the increase of the electrostatic charging tendency (ECT) in insulating oil was investigated. Sulfide compounds, which are contained in new mineral oil, are identified for the first time as the original materials involved in the increase of the ECT. This is verified by heating tests of alkylbenzene with the addition of various compounds. Coexistence with copper and injection of oxygen enhance the increase of the ECT. Some sulfide and sulfoxide compounds increase the ECT markedly. On the other hand, the influence of sulfones, which are oxidation products of sulfoxides, is negligible. Although sulfonic acids, which are oxidation products of sulfones, markedly increase the ECT, the polarity is reverse. Thus, the ECT is influenced by the kinds and the molecular structures of additive sulfur compounds. The influence of nitrogen compounds and that of oxygen compounds are confirmed to be smaller than that of sulfur compounds. Since the amounts of nitrogen compounds and oxygen compounds are much smaller than those of sulfur compounds in mineral insulating oils, the influence of these compounds is considered negligible. Since the ECT of oils with the addition of sulfides or sulfoxides increases after heating, the other compounds should be created from these compounds that increase the ECT directly. Thus, the increase of the ECT is mostly caused by the oxidation of sulfides, which creates sulfoxides. Then certain compounds, which directly increase the ECT, are created from sulfoxides. If sulfones or sulfonic acids are created by the oxidation of sulfoxides, the ECT decreases because of the influence of these compounds on the ECT. It is most likely that some process other than oxidation occurs in the creation of the compounds that increase the ECT directly. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(3): 29–36, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21112     

基于CCD的XLPE电缆料杂质颗粒测量系统的研制

应用电子耦合摄像器件（CCD）一维扫描和试样的行进构成对试样的二维扫描检测方法，研制经XLPE电缆料杂质颗粒测量系统，论文分析了透镜，CCD器件对分辨率的影响，在选定扫描视场下优化了分辨率；测量系统分辨率在20mm视场下达到35um，模板实验测中率为100％，测量每公斤料的颗粒误判率为零，用于110kV交联电缆绝缘料测量，最小颗粒为120um时，测量速度可达2．6kg/h。     

Research on influencing factors of corrosive sulfur attacking copper in insulating oil and prevention

The influencing factors (temperature, electric field, and oxygen) of sulfur attack in transformer oil are studied through comparative tests on new oil, oil in service, and these two oils with the deactivator additive BTA (benzotriazole, C₆H₄N₃H). The influence of these factors on the chemical reaction between copper and corrosive sulfur is analyzed in further. The results show that temperature, electric field, and oxygen can promote the reaction between copper and corrosive sulfur. Moreover, oxygen also accelerates the aging of the insulating oil. On the contrary, recharging nitrogen can remove oxygen and reduce sulfur's corrosive activity. Adding the BTA deactivator can also prevent corrosion, even during the accelerated aging of oil with oxygen. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

关于绝缘油体积电阻率试验和介质损耗因数试验的分析

结合具体实例．分析了在反映绝缘油油质方面．绝缘油的体积电阻率试验和介质损耗因数试验的相同和差异之处,阐述了同时开展体积电阻率试验和介质损耗因数试验的必要性．指出不应简单地以等同的概念去理解和实施这两项试验。     

Corrosion control by antioxidant DBPC in insulating oil

In order to evaluate corrosive sulfur in insulating oil quantitatively, wave length dispersive X-ray (WDX) technique has been reported (1) . Using this technique, antioxidant 2,6-di-tert-butyl-p-cresol (DBPC) was found to be effective to suppress corrosion caused by dibenzyl disulfide (DBDS). The effect of corrosion prevention continues for a long term when a certain amount of DBPC is added to oil. The durability of DBPC was also evaluated by HPLC. It is possible to add relatively a good deal of DBPC to oil because DBPC has higher solubility than passivator and little effect on dielectric strength. Furthermore, DBPC was used with passivator simultaneously, and corrosion control time was far extended by their synergy effect. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

新型全自动绝缘油介质损耗数字测量仪

为解决介质损耗测量仪操作繁琐、测试时间长等问题,研制了一种新型一体化全自动绝缘油介质损耗测量仪,采取相应办法和抗干扰措施提高测量精度,保证测试系统的高精度测量实施,结果证明该仪器测试数据准确稳定,测试时间短,自动化程度高,便于推广使用。