光伏电站对送出输电线路选相元件的影响研究

通过某地区电网分析了光伏电站对送出输电线路相电流差突变量选相元件和序分量选相元件的影响。光伏电站的容量相对于系统容量很小,在送出主变中性点接地的系统中,当送出输电线路发生接地故障时,光伏电站侧零序等值阻抗远小于其正、负序等值阻抗,故障电流主要成分为零序电流,因而三相故障电流幅值、相位相近,致使选相元件误选相。以某地区光伏电站并网为例,在PSCAD/EMTDC中分别搭建了基于相电流差突变量和基于序分量的选相元件的仿真模型,并对两种选相元件进行测试。仿真结果表明两种选相元件的动作性能均受到严重影响。     

离子迁移率测量装置研制及其在不同温、湿度下的变化规律

离子迁移率是直流输电线路离子流场计算的关键参数。为研究不同温、湿度条件下离子流场中的离子迁移率变化规律,在分析推导Gerdien离子迁移率测量原理的基础上,提出了一种在常规Gerdien管传感器两端设置屏蔽电极来抑制外部合成电场对测量区电场畸变效应的方法,研制出一套直流输电线路合成电场离子迁移率测量传感器及测控装置。在人工气候室中,搭建了直流输电线路离子流场模拟试验平台,对测量装置的适用性进行了验证。试验表明:常温常湿条件下正、负离子迁移率分别为1.25 cm2/(V·s)和1.59 cm2/(V·s);温度变化范围为10~40℃、湿度变化范围为3~25 g/m3时,正、负离子平均迁移率呈现出随温度增大而减小,随绝对湿度增大而减小并趋于饱和的变化规律,满足指数变化的拟合公式。分析指出:轻、重离子浓度比例变化与离子的水合反应程度为其变化原因。该研究工作可为直流输电线路离子流场的准确预测提供参考。     

六相输电系统的故障暂态分析

六相输电能提高输送功率密度,降低杆塔建设成本,环境指标优于同塔双回线。针对六相输电故障分析主要集中于稳态的研究现状,该文对其故障暂态特性进行了深入分析,利用解耦变换矩阵将故障后的六相系统电压电流转换为六序分量,结合输电线路π型等值电路建立了六序网络的暂态模型。分别推导了频域下考虑线路分布电容、串补电容及并联电抗器的故障暂态电流表达式。与同塔双回线相比,六相系统的故障暂态过程更复杂,谐波频率更高,衰减更迅速。最后利用PSCAD建立六相输电系统模型验证了分析的正确性。     

采用同步变化量的超高压线路保护启动判据研究

超高压线路保护在运行中受负荷波动影响,负荷不对称的线路在正常运行时,都存在较大零序电流,为防止频繁启动不得不提高启动值,从而降低了启动元件的灵敏度,导致现有的零序电流判据对经高阻接地的故障无法灵敏判别,不能满足超高压线路保护对启动元件快速性的要求。提出一种采用线电压、同相间电流同步变化量开放的相间启动判据和零序电流、相电流同步变化量比较方式的零序启动判据。通过PSCAD/EMTDC仿真表明,如果使用同步变化量的启动判据,保护的灵敏度、快速性和可靠性均有一定程度的提高。     

现行输电塔设计规范可靠度水准的评估与分析

为了对输电线路杆塔结构设计规范进行较为系统且准确的可靠水准评估,基于 DL/T 5154—2002《架空送电线路杆塔结构设计技术规定》,对输电塔不同受力构件设计表达式的可靠度展开相关研究,分析了杆塔构件荷载、抗力的统计参数及其影响规律。考虑风速、结构重要性系数及风荷载重现期的影响,对设计表达式的可靠度水平进行了精细化评估,考察了我国杆塔现行规范的可靠度水平。     

基于PCAGSVR的燃煤锅炉N Ox 排放预测

以某超超临界700 MW 机组锅炉为对象,建立了基于主成分分析(PCA)和支持向量回归(SVR)的氮氧化物(NOx )排放预测模型(PCA-SVR 模型)。运用 PCA 方法对包含有2000条锅炉运行记录的数据集进行分析,降低数据集维数,提取有效信息(主成分);以得到的主成分为输入变量,锅炉NOx 排放值为输出变量,利用SVR建立NOx 预测模型。与传统SVR模型相比,PCA-SVR模型的计算时间更短,并且能获得较高的 NOx 排放预测精度,其预测N Ox 排放浓度与实际排放浓度相比平均误差在1％以内。     

Mapping QTLs Controlling Beneficial Fatty Acids Based on the Embryo and Maternal Plant Genomes in Brassica napus L.

This study was mainly carried out to detect the quantitative trait loci (QTLs) located simultaneously in embryo and maternal plant nuclear genomes for beneficial fatty acid contents of rapeseed under different environments by using a mapping model and mapping populations from a cross of ‘Tapidor’ × ‘Ningyou7.’ Eight, three, six, seven and three QTLs respectively for palmitic, oleic, linoleic, linolenic and eicosenoic acid contents were identified and subsequently mapped on chromosomes A1, A3, A4, A6, A8, A9, C1, C3, C5, C7, C8 and C9. Among them, 12 QTLs were major ones that could respectively explain more than 10 % of phenotypic variation. Two specific genomic regions on A8 and C3 were associated with several QTLs relating to multiple fatty acid contents. Some of the markers such as HBr015 and JICB0633 showed tight linkage with the QTLs, which could be used for improving the fatty acid component(s) of rapeseed.     

Triacylglycerol Composition Profiling and Comparison of High‐Oleic and Normal Peanut Oils

Oilseed plants produce huge amounts of fatty acids (FA) stored as triacylglycerols (TAG) in seeds that give a great variation in their composition. The variety and content of TAG directly affect the nutrition and function of lipids. TAG composition of 12 high‐oleic and normal peanut oil samples were profiled by two‐dimensional liquid chromatography (2D LC) coupled with atmospheric pressure chemical ionization mass spectrometry (APCI‐MS). The statistical evaluation of the TAG profiles determined was conducted on the basis of multidimensional data matrix using Principal Component Analysis (PCA). The technique enabled the differentiation of high‐oleic oils from normal peanut oils—as results illustrated TAG of high‐oleic peanut oil were clearly different from those of normal peanut oils. High‐oleic and normal peanut oils had different profiles mainly in the contents of OOO, OPO and POL. This finding provided theoretical foundation for detecting the adulteration of edible oils and analyzing the nutrition and function of high‐oleic peanut oils.     

精磨光学元件面形的干涉检测技术研究

为解决传统接触式检测方法检测精磨光学元件效率低,精度差的问题,提出了一种采用干涉检测技术对精磨光学元件面形进行测量方法,该方法具有非接触,测量效率高,误差小的特点。干涉检测中干涉条纹的对比度与工作波长成正比,与表面粗糙度成反比,干涉条纹对比度直接影响最终的检测结果。因此首先分析干涉条纹对比度与精磨表面粗糙度之间的关系,证明采用可见光干涉仪对精磨粗糙表面进行检测的可行性,并对利用GPI型数字干涉仪检测精磨粗糙表面进行了实验验证,检测面形结果约为PV 1.5μm,并与红外干涉仪以及接触式轮廓仪测量结果进行了对比,验证结果有效性。最后给出了当粗糙度阈值Rq优于150 nm时,可采用该方法进行检测,具有较高的实用价值。