Recurrent plot analysis of leakage current for monitoring outdoor insulator performance

Outdoor insulators are widely accepted in power industry to maintain electrical insulation ranging from distribution to transmission lines. Such increasing development leads to a lack of appropriate diagnostic tools for assessing the performance of insulator in service, particularly in contaminated conditions. In order to monitor operating performance of contaminated outdoor insulators, a recurrent plot technique is proposed to analyze the leakage current passing through the insulator surface. Contamination tests were conducted in a laboratory by employing heavy salt fog with the deposition of non-soluble contamination. The leakage current was decomposed into different frequency components by using a wavelet transform technique. The temporal sequence of the extracted component was extended to mdimensional phase space by using a phase-space reconstructed method. The recurrent plot is obtained to show that the topological structure of the high-frequency components is prominent to identify non-linear properties of discharge activities. Based on the analysis of the high-frequency components, the quantitative indicators of recurrent plot are obtained to reflect the underlying mechanism of flashover process. The results obtained indicate that the recurrent plot technique gives visual recurrent patterns of discharge activities for monitoring outdoor insulator performance. The dynamic behaviors on the insulator surface are graphically illustrated on the rectangular block structures with higher density of points. The structure changes indicate the switches of discharge states during the flashover process.     

典型表面状态下的绝缘子空间电场特性研究

实时监测绝缘子运行状态，可以有效地保证输配电外绝缘的安全稳定运行。目前通常依靠监测绝缘子表面泄漏电流来实现污闪预警，作为一种接触式在线监测手段，其在可靠性、便捷性等方面仍有很大的提升空间。而已有研究指出，不同运行状态下污秽绝缘子其空间电场分布会发生变化，电场作为重要的电气参量之一，可通过非接触的方式有效获取。因此，本文研究典型表面状态下染污绝缘子空间电场分布特性，首先利用有限元仿真软件建立了普通支柱绝缘子的静电场仿真模型，对比分析了干燥、湿润、放电情况下的绝缘子周围空间电场的幅值大小及变化规律；最后利用人工污秽试验，对污闪放电过程中的绝缘子空间电场进行测试，并与仿真结果进行对比分析。研究结果表明，不同表面状态下的绝缘子空间电场所反映的幅值大小差异明显，在表面湿润及有电弧爬电的情况下，空间电场垂直分量分别增长近50%和20%。研究结果可为输配电外绝缘的状态监测提供新思路。     

复合绝缘子界面缺陷对电场分布特性影响的仿真研究

复合绝缘子的芯棒与护套粘接界面常常出现缺陷,畸变周围电场,影响绝缘子的电气和机械性能。为了研究不同缺陷形态下的绝缘子电场特性,文中以110 kV复合绝缘子为考察对象,应用有限元分析软件COMSOL搭建了绝缘子三维模型,对电场分布进行了仿真计算,研究了界面出现气隙、水汽等缺陷对局部电场及绝缘子整体轴向电场分布特性的影响。结果表明:气隙处电场强度相比正常情况下显著增大,场强最大值与气隙跨度、厚度正相关,与气隙长度负相关,并基于气隙等效弧柱体模型给出了理论分析,修正了等效圆柱模型的不足;水分渗入能降低气隙场强,但同时严重畸变绝缘子轴向电场;护套受潮增重会使场强线性增加,超过一定程度会引发电晕放电,导致沿面闪络等事故。     

干燥带对染污支柱绝缘子电场分布的影响

为分析绝缘子污层表面干燥带的产生对其电场分布的影响,在ANSYS中建立了染污110 kV瓷支柱绝缘子的模型,分析了其在干燥带出现前后电场和电位的变化情况,分析了干燥带容易出现的区域以及干燥带位置、宽度、数量、电阻率对沿面场强的影响.结果表明:柱体较之伞裙更易岗发热而出现干燥带;出现干燥带后其附近电位发生突变,干燥带附近...     

三相共箱式GIS中电流互感器部位的三维电场计算及绝缘分析

利用模拟电荷法对三相共箱ＧＩＳ中电流互感器部位的三维电场进行了计算,分析了该结构的绝缘特点,得出了电流互感器一次导体与二次导体之间形成的同轴圆柱体结构为绝缘设计工作中的重点,并对结构中绝缘子部位的电场进行了绝缘校核。     

Analysis of a high voltage active insulator assembly

The concept of an active insulator for high voltage applications is presented. An insulator based on this idea has the potential of performance superior to that of conventional passive insulators. The feasibility of this concept is supported by analytical results obtained using a non-linear mathematical model of an active insulator assembly. The advantages of such a multiple-function dynamic insulator are discussed, as well as technical difficulties which might present practical limitations. The results of the theoretical analysis are promising and indicate that the active insulator concept should be pursued further.     

Boundary element studies on insulator shape and electric fieldaround HV insulators with or without pollution

Capacitive-resistive field computations are carried out around post-type HV insulators of varying shapes. The boundary element method (BEM) has been employed for electric field computations. Different insulator shapes have been obtained by varying several parameters, which define the shape of the HV insulator contour. For each insulator shape, the maximum stress occurring on the insulator surface has been determined with no surface pollution, uniform surface pollution and also partial surface pollution. For partial pollution, several cases have been studied, in which different sections of the insulator surface are polluted. Furthermore, the effect of electrode radius on the maximum stress on insulator surface has been investigated. The results obtained are presented in this paper in detail     

线路绝缘子非均匀染污方法及污闪特性

目前人工污秽试验中绝缘子染污采用均匀涂抹,而自然污秽受风力、雨水、绝缘子形状、污秽粒径等因素影响,在绝缘子表面非均匀累积,非均匀积污对绝缘子U_50%产生影响,通过对多地区、大范围绝缘子自然积污特性研究,获得不同伞形绝缘子上下表面积污特性的差异性规律,提出了基于绝缘子自然积污规律的上下表面非均匀染污方法,开展了交/直流电压下绝缘子非均匀染污人工污秽试验,获得了非均匀染污下污闪特性曲线,采用绝缘子上下表面非均匀染污方法对绝缘子进行染污更接近绝缘子实际运行工况,人工污秽试验结果更准确合理。试验结果表明：上下表面染污非均匀度越大,U_50%值越大;随着染污非均匀度增大,U_50%增大幅度减小,逐渐趋于饱和。主要结论对绝缘子串长优化及选型具有重要参考意义。     

Voltage and temperature distribution along semiconducting glazeinsulator strings

Voltage distribution along a semiconducting glaze insulator string was calculated based on an equivalent circuit. The impedance effect of the insulator unit on voltage and temperature distributions along the insulator string were also examined by calculation. The calculated results agreed well with experimental ones obtained in a laboratory test, showing that the equivalent circuit and the program used are effective for the analysis of electrical/thermal performance of the semiconducting glaze insulator strings     

Y型绝缘子串交流和直流电压分布特性

采用球隙法测量了交、直流500 kV输电线路中Y型串绝缘子的电压分布,采取相应措施减小了环境因素对测量结果的影响,得到了交、直流500 kV电压下Y型串的电压分布曲线。研究结果表明：在交流电压下,Y型绝缘子串的电压分布极不均匀,其电压分布曲线和交流悬垂I串类似;在直流电压下,Y型绝缘子串的电压分布极不均匀,绝缘子串导线侧绝缘子分担电压高于其它绝缘子,总体上呈现导线侧和杆塔侧两端高、中间低的分布趋势。研究结果为Y型串输电系统的外绝缘设计提供了参考依据。     

绝缘材料及其参数对绝缘子表面电场强度和电位分布的影响

为研究材料类型和参数对绝缘子电场强度和电位分布的影响,采用有限元法以支柱绝缘子为对象研究了柱体和伞裙材料分别为电瓷、玻璃、高温硫化(high temperature vulcanization,HTV)硅橡胶时绝缘子及附近场强、电位分布以及沿面和干弧路径上场强和电位,同时研究了材料的电阻率和相对介电常数对绝缘子附近场强...     

Optimization of support insulators used in HV systems using support vector machine

In this paper support vector machine (SVM) has been used for optimization of electric field along the support insulators used in high voltage (HV) systems. To illustrate the effectiveness of SVM in optimizing electric field problems, two axi-symmetric cases have been considered one having an insulator with a contour that is quarter ellipse and the second one having a porcelain core solid insulator. The training and the test data for the SVM have been prepared by electrostatic field computation using indirect boundary element method (BEM). It is observed that once the SVM is trained it is able to give results with mean absolute error of less than 1.5% when compared with the analytically obtained results. The SVM designed for insulator contour optimization is first trained with the results obtained from electric field computation for some predetermined contours of the arrangements under consideration. Then the trained SVM is used to produce an optimized insulator contour in such a way that the desired stress distribution can be obtained on the insulator surface. The results obtained from the present study show that the trained SVM is adequately efficient to optimize insulator contours in order to have the desired stress distribution along the insulator surface     

相对温度分布特征与人工神经网络相结合的零值绝缘子识别方法

提出利用绝缘子串相对温度分布特征和人工神经网络模型相结合的方法识别不同污秽等级、不同湿度条件下的零值绝缘子。试验获取模拟110 kV线路悬式绝缘子的红外运行图像,经图像去噪、分割等预处理后,提取绝缘子串区域相对温度分布特征参数作为识别零值绝缘子的温度信息特征量,并结合环境相对湿度、等值附盐密度作为识别模型的输入向量,将实际测定绝缘子串是否含零值的状态分类信息作为输出向量,通过训练得到优化的识别模型,并用于零值绝缘子识别。试验结果验证该方法准确性高,可为输电线路瓷绝缘设备的故障检修提供参考和方法借鉴。     

Charging characteristics of a solid insulator in vacuum under AC voltage excitation

We have investigated charging and flashover characteristics of a polymeric or glass insulator exposed to AC voltage in vacuum in order to develop compact and reliable high voltage VCBs (vacuum circuit breakers). This paper focuses on charging characteristics of a cylindrical model insulator. The charging of an insulator is investigated using an electrostatic probe that measures the electric field near the triple junction on the grounded electrode. This method allows a time-resolved measurement of the charging process. The insulator was made of borosilicate, fused quartz or polymetyl methacrylate, and was in the shape of a right cylinder with 10 mm in thickness. It has been clarified that the charging is characterized by three sequential states; initiation, quasi-stable and stable states, and that the polarity of the charge is positive for these states irrespective of the voltage phase. The charging characteristics with AC voltage are compared to our previous results with DC voltage excitation. We find that the charge magnitude at the stable state coincides with that obtained by DC. The electric field on the grounded electrode, and therefore the charge magnitude, decreases with the surface roughness, and decreases as the insulation strength is increased. A computer simulation has been conducted to investigate the quasi-stable state, which clarifies that the transition in surface charge distribution being synchronous to the voltage phase is responsible for causing the quasi-stable state.     

500 kV线路绝缘子串分布电压的现场实测与分析

介绍广州地区５００ＫＶ线路绝缘子串分布电压的现场实测,通过分析,得出如下规律;无论单串或双串,中相绝缘子串的电压总比边相串更不均匀;在相同条件下,绝缘子串的元件数越多,电压分布越不均匀;中相Ｖ型串与垂直串的电压分布规律非常接近;酒杯塔与接Ｖ塔的塔型对边相绝缘子串的电压分布规律于明显影响。     

应用新型人工气候室研究长串绝缘子的工频污闪特性

探讨了用绝缘材料简作为简易人工气候室研究长绝缘子串在高海拔条件下工频污闪特性的可行性，理论和试验表明这一工作取得了积极的结果，以很小的投资，实现了模拟高海拔气象条件进行10片及以上串长绝缘子的工频污闪特性研究，对于解决我国西北地区750KV工程中的高海拔问题具有重要价值。     

±800kV特高压直流输电线路极间距优化

目前,我国已(在)建的±800 kV特高压直流输电线路的极间距离均按不小于22 m设计.综合考虑电磁环境、合成绝缘子串长、空气间隙、V型绝缘子串夹角等因素,探讨极间距进一步缩小的可能性,并对其经济效益进行分析,为后续特高压直流输电线路的设计提供参考.     

复合绝缘子直流冰闪试验方法的比较

国内外的运行经验和研究表明,由覆冰引起的输电线路绝缘子串绝缘特性下降是导致电网事故的重要原因之一。绝缘子覆冰试验目前尚无统一的标准,研究绝缘子覆冰试验方法有重要的意义。因此以FXBW-±800/530型短样、FXBW-110/100型两种复合绝缘子为试品,在人工气候室研究了试验方法对覆冰复合绝缘子直流冰闪特性的影响,并比较分析了不同试验方法的差异。结果表明:试验方法对覆冰复合绝缘子的冰闪电压有明显的影响,采用不同的试验方法获得的试验结果有差异。复合绝缘子在相同覆冰水电导率、覆冰程度和覆冰状态以及相同的试验条件下,采用平均闪络法获得的平均闪络电压Uav最高,采用最恒压升降法获得的50%闪络电压U50%其次,采用U型曲线法获得的最低闪络电压Uf,min次之,采用最大耐受法获得的最大耐受电压Uws最低。不同的试验方法获得的试验结果存在内在联系,可以根据试验的具体情况,选择适当的试验方法。     

线路绝缘子直流污闪电压修正研究

为了给出线路绝缘子不同污秽分布条件下直流污闪电压线性海拔修正系数,便于在海拔≤2 km地区直流线路外绝缘的设计,实验研究了在实际海拔1 970 m条件下绝缘子电弧的发展特性。研究表明:绝缘子上下表面污秽分布情况对瓷绝缘子直流电弧发展路径影响较大,造成直流污闪电压随海拔升高下降的程度不同。通过比较不同海拔高度下(0与2 km)210 kN钟罩型绝缘子人工污秽试验结果,提出了绝缘子上下表面污秽分布均匀与不均匀两种条件下直流污闪电压线性海拔修正系数分别为6%和3%,并利用大吨位(300 kN)钟罩型绝缘子试验结果验证了该线性修正系数。结果表明,该修正系数也适用于大吨位绝缘子。     

基于联合分量灰度化算法和深度学习的玻璃绝缘子目标识别算法

针对相近色干扰、不同光照条件下玻璃绝缘子颜色特征不明显而无法准确识别的问题,提出一种基于联合分量灰度化算法和深度学习的玻璃绝缘子目标识别算法.首先,提出一种联合分量灰度化算法,通过补偿玻璃绝缘子目标区域的颜色特征实现目标增强;然后,在均匀分块的基础上,采用动态分块阈值进行玻璃绝缘子图像粗分割,并结合玻璃绝缘子的颜色和空...