局部放电超高频信号时频特性与传播距离的关系

超高频(UHF)检测法具有频带宽、信息量大、抗干扰能力强等一系列优点,近年来在局部放电检测中得到了广泛应用。为此,建立了变压器油纸绝缘局部放电模型,研究了超高频电磁波信号与脉冲电流之间的对应关系,以及超高频电磁波信号与传播距离的关系。实验结果表明:1)随着传播距离的增加,超高频电磁波信号的能量和幅值均呈非线性衰减趋势;2)局部放电超高频电磁波信号幅值与脉冲电流幅值成正比关系,超高频电磁波信号能量与脉冲电流幅值的平方成正比关系,且比例系数随着超高频电磁波信号传播距离增加而减小;3)超高频电磁波信号中高频分量随着传播距离增加而衰减很快。以上结论有助于更加详细地了解局部放电超高频电磁波信号的辐射规律,是超高频检测法用来检测电力设备局部放电的依据。     

用于空间电荷陷阱能量测量的热刺激放电法与光刺激放电法的比较(英文)

The space charge behavior of a dielectric under HVDC is influenced by the charge trap energy distribution in it. Hence, we in- vestigated the charge trap distributions in several kinds of typical polymer materials using thermally stimulated discharge (TSD) and photo-stimulated discharge (PSD) methods, respectively. The experimental results show that,there is a significant difference between the trap energy distributions obtained by the two methods, but the difference decreases with the increase of the melting point of polymers. This is attributed to the change of the trap center environment during TSD caused by the increasing movements of both main chains and branched chains in polymers. PSD method is more accurate for investigating charge trap distribution in dielectrics, especially for polymers with low melting points.     

基于统计分析和模糊推理的运行交联聚乙烯电力电缆绝缘老化诊断(英文)

Cables that have been in service for over 20 years in Shanghai, a city with abundant surface water, failed more frequently and induced different cable accidents. This necessitates researches on the insulation aging state of cables working in special circumstances. We performed multi-parameter tests with samples from about 300 cable lines in Shanghai. The tests included water tree investigation, tensile test, dielectric spectroscopy test, thermogravimetric analysis (TGA), fourier transform infrared spectroscopy (FTIR), and electrical aging test. Then, we carried out regression analysis between every two test parameters. Moreover, through two-sample t-Test and analysis of va- riance (ANOVA) of each test parameter, we analyzed the influences of cable-laying method and sampling section on the degradation of cable insulation respectively. Furthermore, the test parameters which have strong correlation in the regression analysis or significant differ- ences in the t-Test or ANOVA analysis were determined to be the ones identifying the XLPE cable insulation aging state. The thresholds for distinguishing insulation aging states had been also obtained with the aid of statistical analysis and fuzzy clustering. Based on the fuzzy in- ference, we established a cable insulation aging diagnosis model using the intensity transfer method. The results of regression analysis indicate that the degradation of cable insulation accelerates as the degree of in-service aging increases. This validates the rule that the in- crease of microscopic imperfections in solid material enhances the dielectric breakdown strength. The results of the two-sample t-Test and the ANOVA indicate that the direct-buried cables are more sensitive to insulation degradation than duct cables. This confirms that the tensile strength and breakdown strength are reliable functional parameters in cable insulation evaluations. A case study further indicates that the proposed diagnosis model based on the fuzzy inference can reflect the comprehensive aging state of cable insulation well, and that the cable service time has no correlation with the insulation aging state.     

聚合物的击穿(综述摘要)

固体电介质电击穿理论,是以晶体(石英金刚石、硅、锗,特别是碱卤化合物)为中心发展起来的。但是,与晶体相比,聚合物电介质在高压电气绝缘技术中应用日趋广泛,且具有更为复杂的化学组成和结构。因此,研究聚合物的分子链结构、分子聚集态     

无机组分对聚酰亚胺杂化薄膜电性能的影响

初步探讨了聚酰亚胺薄膜在电场作用下的电学行为,采用溶胶-凝胶工艺制备了聚酰亚胺/二氧化硅纳米杂化薄膜,并对薄膜进行浸水24 h处理,利用原子力显微镜对制备的薄膜进行表面形貌表征,讨论了无机组分SiO2和水对薄膜电性能的影响.结果表明:无机组分的引入及两相间的界面形态将对杂化薄膜的电学性能产生重大的影响;偶联剂的引入使得两相间产生紧密的微相结合,并对电性能产生一定的影响.     

聚酯薄膜中的热释光与热激电流

同时测量了聚酯薄膜的热释光与热激电流谱，用作者提出的自动分离法对光强或电流与温度的关系进行了分析。发现低温峰（150－250K）具有复杂的能级分布，其分布宽度近似为0．24－0．46eV，受陷载流子的初始浓度分布函数呈近高斯型。将TSC及TL谱中低温宽峰归结为薄膜中－COO－基团的局部运动导致受陷载流子的热释放。     

量子力学的希尔伯特空间矢量表示法

本文概述了希尔伯特空间矢量的性质,并指出其与函数的相似性,从而介绍了狄喇克左矢及右矢的表达形式,以及这种形式表达出来的若干量子力学基本原理.     

纳米二氧化硅/聚酰亚胺耐电晕薄膜的研究

通过超声机械混合方法制备纳米二氧化硅／聚酰亚胺复合耐电晕薄膜，并对其耐电晕性进行测量。用红外光谱(IR)和原子力显微镜(AFM)观察无机纳米粒子的分散情况及其电晕前后变化。结果表明：纳米二氧化硅／聚酰亚胺复合薄膜耐电晕性比普通的聚酰亚胺薄膜高。     

改性无机填料对低密度聚乙烯电老化性能的影响

本文讨论了不同温度下经表面处理的无机填料对低密度聚乙烯（ＬＤＰＥ）电压寿命的影响，以及该填料对ＬＤＰＥ电击穿性能和电树枝特性的影响。发现含填料低密度聚乙烯（ｆ－ＬＤＰＥ）的电老化性能优于纯ＬＤＰＥ。尤其在７０℃下填料对ＬＤＰＥ电老化性能的改善作用更明显。无机填料的作用机理可能主要有两个方面：一是提供了深电子陷阱，使载流子迁移率和密度降低；二是增加了结晶－非结晶界面，起到散射电子，抑制＂树枝＂生长的作用。ＬＤＰＥ和ｆ－ＬＤＰＥ的电老化实验结果与我们早期完成的击穿强度与温度关系及电树枝长度与时间关系的实验结果有较好的一致性。     

空间电荷对PE薄膜电击穿的影响

本文通过对干、湿两种LDPE薄膜试样在不同模式电压作用下电击穿场强的试验研究,说明了脉冲击穿的预直流效应.脉冲击穿场强为直流击穿场强的88%,助场时击穿场强上升到与直流击穿场强相等,而反场时击穿场强随预应力的增加而线性下降.试样吸潮后其直流击穿场强几乎未发生变化,脉冲击穿场强下降,反场时其空间电荷对电击穿的影响更加显著.干、湿试样的反场击穿时延远大于脉冲和助场对的击穿时延.脉冲发生器输出1/15000μs的准方波且采用记忆示波器观察电压幅值和击穿时延.