2015年特高压规划电网华北和华东地区多馈入直流输电系统的换相失败分析

基于2015年“三华”特高压规划电网的丰大运行方式,采用机电暂态仿真软件PSD-BPA,对华北、华东地区多馈入直流输电系统换相失败问题进行深入研究。研究结果表明,华北、华东地区任一直流发生单/双极闭锁故障时,均不会引起其他直流发生换相失败;华北地区大部分直流逆变站换流母线附近三永故障,不会导致其他直流换相失败;华东地区...     

A comparative study of the oxide breakdown in short-channel nMOSFETs and pMOSFETs stressed in inversion and in accumulation regimes

A comparative study of oxide breakdown in short-channel nMOSFETs and pMOSFETs stressed at high voltages in inversion and in accumulation regimes is reported. We show that in all cases the breakdown location is uniformly distributed along the total channel length, indicating a uniform breakdown process independent of the dopant type in the electrodes. At low stress voltages (i.e., at operating conditions) we expect the breakdown locations to be still uniformly distributed in devices operated in inversion, while occurring preferentially in the source and drain extensions in devices operated in accumulation. Furthermore, we find that the hard oxide breakdown occurs in the case of nMOSFETs stressed in inversion, while in all the other cases almost all the breakdowns are soft.     

普及推广TRIZ理论 助推电力企业创新

介绍了TRIZ理论的由来和该理论在企业创新中的发挥的作用。阐述了TRIZ理论在电力行业的应用效果,尤其表述了TRIZ理论在电力行业中实施进程,以及未来TRIZ理论在电力企业中的应用前景。     

国产大型高参数直接空冷汽轮机组特点与发展

我国大型(300MW、600MW)直接空冷汽轮机是在常规湿冷汽轮机的基础上发展起来的。我国首台300MW亚临界湿冷机组于1987年在山东石横电厂投产;600MW亚临界湿冷机组于1989年在安徽平圩电厂投产。我国自主研发的首台300MW机组于2004年在山西漳山电厂投产;首台600MW机组于2005年在山西大同发电公司投产。     

国内外冷轧电工钢标准中尺寸公差分析

大多数工业化国家的冷轧电工钢都采用IEC标准来制定本国标准,在铁损、磁感相同的情况下,评价标准水平高低和质量优劣的主要指标就是电工钢的尺寸公差。本文对IEC、欧洲、日本、中国、ASTM标准中冷轧电工钢的尺寸公差进行了分析比较,结果表明:取向钢的同板差:IEC、欧洲、日本、中国相同,ASTM标准较严;无取向钢的同板差:ASTM标准最松,中国、日本标准中等,IEC、欧洲标准最严;取向钢的横向厚度差:IEC、欧洲标准严于日本和中国标准0.010 mm,ASTM没有规定;无取向钢横向厚度差:IEC、欧洲标准较严,日本、中国较松,ASTM没有规定;宽度偏差:IEC、欧洲标准最小,ASTM最大,日本、中国标准中等。     

湿热气候变电站防腐工程设计与防腐工程实践

针对中国西南地区典型湿热气候电网设备锈蚀严重的实际情况,以四川某110 kV变电站为例,开展了湿热气候变电站防腐工程设计及防腐工程实践,力求达到"电网设备10年不生锈"的目标要求.该工程设计合理,施工严格,监督到位,质量可靠,效果显著,并成为四川电网在湿热气候环境下变电站防腐施工的标准化流程和典型案例,在四川电网全面推...     

The variation of cage motor losses with skew

A study on the effect of skew on the losses in three different induction motors is presented in this paper. It is shown that skew alters the balance of losses in the motor and that, in larger machines, this can result in an increase in the total losses in the motor.     

2001—2014年阿克苏河流域山区积雪时空变化分析

Mountain snow is one of the main water source for the Aksu River in Xinjiang. A comprehensive analysis of spatio-temporal variations in the mountain snow in the Aksu River basin can provide a basic support for runoff analysis. In this paper, the snow products of Moderate Resolution Imaging Spectroradiometer (MODIS) during the period of 2001-2014 were used to analyze the snow cover area and its spatio-temporal variations in the Aksu River basin. Results show that in this period of 14 years, the snow cover area took a decreasing trend in the annual, seasonal and monthly scales, with particularly significant decreasing in the annual maximum snow cover and the snow cover in summer. The major significant changes of snow cover occurred in Tuoshigan River mountainou area, mountainous border region and the west of Kumalake River mountain area in the winter and summer, and significant reduction in permanent snow area occurred in the east of Kumalake River mountain area. Without considering other meteorological factors, temperature rising could be a major cause for reduction in the snow cover.     

Some considerations on state equations of linear active networks

It is shown that if there equivalently exist the virtual resistive elements in parallel with the inductive elements of the over-normal tree of a given linear active network or in series with the capacitive elements of the corresponding co-tree, an increase in the number of state variables arises. It is also shown that when a virtual resistor equivalently appears in parallel with the distinct resistor in a tree or in series with the distinct resistor in the co-tree, a decrease in the number of state variables may arise. This is, however, a rare case in the usual types of network. Two algebraic methods for obtaining the state equation of linear active networks are presented. One is useful for the networks in which the decrease in the number of state variables does not arise. From the other, the output equation for the required variables is obtained at the same time as the state equation. Further, the initial values are simply determined without iteration in many cases.     

核电机组停运对南方电网运行影响研究

介绍了日本＂3.11＂大地震对东京电力公司供电的影响,分析了若南方电网区域内核电机组停运,南方电网运行的情况将会如何。结果显示：2011年若大亚湾、岭澳核电机组停运,当南方电网以小方式运行时可能造成广东电网低周减载动作;当南方电网以大方式运行时可能引起广西部分地区低压减载装置动作,且事故后深圳地区负荷可能受限。2015年阳江核电、台山核电和防城港核电机组分别停运,不会造成其近区电网供电受限,也不会引起系统低周减载或低压减载动作。2016年若海南昌江核电机组停运,当海南电网与广东电网通过2回或1回500 kV交流联络线保持联网时,海南电网低周减载不会动作。     

500kV变电所保护布置方案研究

以典型 5 0 0kV变电所为例 ,通过对分散布置于保护小间、分散布置于开关场柜、集中布置于主控楼等三个方案进行技术经济比较 ,得出了比较理想的结论 ,即下放布置于配电装置保护小间 ,并提出了二次设备下放布置后的抗电磁骚扰措施     

构皮滩电站水轮机水力设计回顾

尽管构皮滩电站的水头变幅并不大,但最高效率要求较高,而且设计水头附近横向权值大.为了使电站充分发挥经济效益,变流量的工况下保证出力,水轮机必须具有高效宽广的效率圈.本文通过对过流通道及转轮的研究,展示了构皮滩电站水轮机水力开发的全过程,并介绍了实现高效宽广效率圈的指导思想.通过三维粘性流CFD对通流部件进行详细分析和优化,并比较分析了三组不同导叶分布圆对性能的影响.模型试验分别在哈尔滨大电机研究所和瑞士洛桑EPFL-LMH进行.该成果已用于构皮滩电站.     

阻抗匹配平衡变压器的三继电器差动保护接线方式

本文依据电力变压器的继电保护设计技术规程要求，分析了阻抗茶杯平衡变压器高低压侧电流的组合规律，确定了最优化数学模型，在此基础上设计了原理正确，电路新颖，接线简单，功能齐全、工作可靠的三继电器差动保护接线方式，解决了阻抗匹配平衡变压器差动保护的关系，人有推广应用价值。     

多媒体课件中心系统的开发与管理

介绍了多媒体课件中心信息系统的分析、设计、运行等开发与管理的全过程。通过对系统结构、功能和数据流程的分析及对系统总体结构的设计等 ,开发了以SQLServer为后台数据库 ,基于ASP网络编程的web界面的信息系统 ,为课件的保存提供了安全空间 ,为课件的上传提供了安全平台 ,使得现代信息技术在课堂领域广泛应用 ,为传统课堂的教学带来变革     

用于电压稳定分析的配电网动态等值

为了在电压稳定分析中既计入配电网的影响又不增加大量计算 ,提出对配电网进行动态等值处理。针对典型的辐射状配电网 ,提出了两种等值模型 ,即分段等值模型和全段等值模型。分段等值模型只处理了并联有载调压变压器组 ,全段等值模型同时处理了并联和串联有载调压变压器组。提出了配电网等值的方法 ,推导了等值有载调压变压器和等值负荷模型的参数。将等值模型应用于小干扰电压稳定和大干扰电压稳定研究 ,比较了等值模型的精度。     

Inference of sampling on Weibull parameter estimation

The data usable to evaluate the confidence bounds for the Weibull parameter estimates is provided in broad range of values, in the cases of the “mean squares”, “maximum likelihood” and “generalized maximum likelihood” methods. The way to use these results in practice are described in detail. The results are provided in the form of extended Tables for standard use, and in addition in the form of empirical formulae for easy use in computer programs. The extended tabular data also are available on line in the TDEI World wide web pages     

适于可再生能源发电储能系统中的双向直流变换器

研究了一种交错式双向直流变换器,该变换器工作在Boost方向时输入端进行交错并联,减小了输入电流纹波,输出端进行交错串联,提高了升压变比;工作在Buck方向时,输入端进行交错串联,输出端进行交错并联,因此该模式下具有较大的降压变比,同时减小了输出电流纹波。另外,在两种工作模式下,功率器件的电压应力都得到了降低。详细地分析了该变换器在两种模式下的工作原理及稳态特性,最后给出了实验结果以验证理论分析的正确性。     

The Teaching of High Voltage and High Current Engineering in Relation to Practical Engineering and Research

Technological developments in electrical engineering in recent years include substantial progress in the power fields of transmission, distribution, and utilization. Consequently, in common with other disciplines of electrical engineering, these advances make necessary some changes in existing tertiary courses if they are to keep abreast of developing technology. This is the case both in the undergraduate and graduate programs and is generating an increasing need for continuing education courses. This paper describes changes made in the power courses, at all levels, at the University of New South Wales in response to these pressures. Particular emphasis is given to laboratory developments in the high voltage and high current field, as this is seen as one area in particular need of development.     

冰灾期间湖南郴州电网3次黑启动成功的经验与建议

文章介绍了2008年年初湖南郴州电网冰灾期间的3次黑启动情况,分析了3次黑启动的特点,总结了3次黑启动成功的经验,并对灾难天气导致电网大面积停电后黑启动应对措施提出了建议。     

3种地形上高杆塔雷击次数规律的研究

为了更有效地研究电力线路杆塔在不同地形下防雷性能的差异性,笔者针对珠三角地区中的杆塔在3种不同地形下受雷击次数分布差异性问题进行分析。首先建立区域雷击统计模型,研究统计区域雷击次数的方法。然后基于雷电定位系统,对珠三角地区三种地形上10年落雷情况进行统计分析,得出电力杆塔在山区受雷击次数略高于平原建筑区,平原建筑区上的杆塔虽受高层建筑屏蔽保护作用,不易受雷击,但杆塔所处区域受雷击次数高于平原植被区。经过统计得出平原建筑落雷次数增长率明显增大,而山区与平原植被区落雷次数增长率呈下降趋势。最后利用电场仿真软件仿真坐落在3种地形上杆塔周围的电场分布趋势,验证统计出区域雷击次数规律的合理性。