基于双馈机组风电场并入网后的自适应保护

随着风力发电技术的不断发展,风电机组数量及单机容量都在不断增加,这使得风电场对系统提供的容量比重增大;而且风速具有随机性,其控制也难以稳定,导致风场向系统提供的短路电流也在增大。那么随着风场大规模并网,对配电网的保护是不容忽视的。通过分析双馈风机特性及风机数学模型得知传统的继电保护已不能满足要求,为此引入了自适应保护,在剖析其原理的基础上论证了自适应保护可应用于并入风电场后的配电网的继电保护当中。     

大规模风电接入电网及市场消纳问题分析

目前风电外送与接入是电网企业与风电开发企业矛盾比较集中的焦点问题.我国风电场主要分布在距负荷中心较远的地区,电网结构相对薄弱,电网建设对风电开发存在一定的制约.在我国西北、华北以及东北(尤其是内蒙古东部地区)风电基地集中地区,风电发出的电力无法正常并网,已经成为未来风电发展所面临的最大问题.针对这一难题,以电网运行管理者的视角,从风电侧和电网侧两个方面,对风电并网问题进行了深入研究,找出其中的难点,并作进一步分析.在国外相关实际做法的基础上,对发电侧、负荷侧以及并网风电管理等方面,提出了提高发电机组调峰能力、适当建设快速调节机组、实施峰谷电价等旨在促进我国风电健康有序发展的实用化建议.     

县级配电网自动化设计方案分析

结合内蒙古电力公司“十二五”县城电网规划,以内蒙古某县为例,提出一种适用于县级配电自动化的实用建设规划方案:馈线自动化和配电监控管理小系统相结合的模式.该模式通过快速故障定位,自动进行故障隔离和恢复对健全区域的供电以及监测配电网运行状况,实现缩短停电时间,提高供电可靠性的目的,有助于提升电网的运行管理水平,实现县级配电网的科学管理.     

200MW循环流化床机组协调控制策略的研究与应用

针对200 MW循环流化床机组的特点,在机组现有DCS基础上,合理设计、优化了机组的协调控制系统,提出了适合中小容量循环流化床机组的协调控制策略,给出了主蒸汽压力和床温等被控对象特性参数的取值。通过在多台机组上的应用,解决了此类机组协调控制系统中控制对象存在的非线性、大滞后和强耦合等技术难题,取得了良好的调节品质和运行效果。     

The effect of partial crystallization on elevated temperature flow stress and room temperature hardness of a bulk amorphous Mg60Cu30Y10 alloy

Partially crystallized samples of the bulk amorphous alloy Mg₆₀Cu₃₀Y₁₀ were prepared by annealing amorphous samples slightly above T_g. After partial crystallization, the alloy is a nanocomposite consisting of equiaxed Mg₂Cu crystallites with an average diameter of 100 nm homogeneously distributed in an amorphous matrix. The flow stress of the nanocomposites was measured as a function of strain rate above T_g. For fixed strain rate, the flow stress increases monotonically as a function of degree of crystallinity, increasing most rapidly for low degrees of crystallinity. A variety of models describing the rheological properties of composites are compared with the flow stress measurements. In all cases, a significant discrepancy is found between the model predictions and experimental observations. A linear relationship was also found between hardness at room temperature and the degree of crystallinity, consistent with a recently proposed model.     

Eating quality of raw carrots––correlations between flavour compounds,sensory profiling analysis and consumer liking test

Sensory profiling, analysis of aroma, sugar and dry matter, as well as consumer liking test were used to characterise the quality of six carrot cultivars, grown at two locations in Denmark. The carrot samples were examined at harvest, and after three months of cold storage. Carrot cultivar had an effect on most sensory and flavour compound variables, due particularly to the influence of one cultivar; and also location influenced carrot quality. Storage of carrots was characterised by an increase of a range of aroma components, but the changes in flavour compounds were not correspondingly observed by the sensory analysis. By Partial Least Squares Regression (PLSR) two thirds of the flavour compound variables was found to correlate significantly with one or more of the nine sensory attributes; and all of the sensory attributes were significantly correlated with one or more of the consumer liking test variables bitterness, sweetness and liking.     

Modulation instability of dispersion-shifted fiber couplers

The nonlinear coupled-mode equations are rewritten by even and odd modes. We study modulation instability (MI) of dispersion-shifted fiber couplers when either even or odd mode is launched alone by using zero-dispersion waveleng threlatively long (quasi-cw) pulses. The result shows that there are new types of MI in both the normal-dispersion and the anomalous-dispersion regimes. MI is concerned with forth-order dispersion and has no relation with third-order dispersion.Quasi-cw can be changed into pulses array under certain conditions. We can extract super short pulse from this. Furthermore,the bandwidth of gain spectra widens and its strength accretes as the input power increases.     

射频激励金属板条波导CO2激光器的功率输出特性

为了获得较高的激光输出功率,介绍了射频激励扩散冷却全金属板条波导CO2激光器,放电区域由左右两个铝合金壁和上下两个铝合金电极构成,放电区域高2 mm,宽20 mm,长386 mm,工作气体混合比CO2:N2:He:Xe=1:1:3:0.26,该技术代替了过去的金属陶瓷结构,结合纵向电压均匀分布技术和面增比技术,获得了127 W的激光输出功率,光电转换效率高达14%。实验中,照相机放在激光器的纵向轴心上,清楚地记录了CO2激光器的放电现象。实验结果表明,该激光器小信号增益1%/cm,饱和光强1 200 W/cm2,促进了CO2激光器的发展。