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基于风电接入电网的降损控制方法
Power Grid Control Method of Loss Reduction with Wind Power Integration
 [PDF]

郭红林, 刘文颖, 蔡万通, 刘福潮, 吕思琦, 郑晶晶
Smart Grid (SG) , 2015, DOI: 10.12677/SG.2015.56039
Abstract:
随着风电的大量开发,大规模风电接入电网的网损问题日益凸显出来。首先,本文构建了一个有大规模风电接入的输电系统模型,结合电网实际条件,筛选出风电接入下的网损影响因子;然后,从网损计算公式出发,对电力系统模型及网损表达式进行化简,确定了荷–网–源协调降损的方法;最后,以大规模风电接入的甘肃电网为背景,通过仿真分析,验证了电网降损控制方法的正确性。
With the development of wind power, loss problems of large-scale wind power grid become in-creasingly prominent. First, combined with the actual grid conditions, we establish a model of large-scale wind power transmission system and select the main loss factors of the wind power. Then, starting from the loss formula, we simplify the power system model and loss expression, and fix the load-network-source coordination methods for reducing loss. Finally, we do some simulations to verify the correctness of power control method for reducing loss with the Gansu power grid as the background.
单侧后牙正锁牙合、关节弹响与咀嚼肌肌电的相关性研究
Correlation between Unilateral Posterior Scissors-bite, Joint Clicking Symptoms, and Surface Electromyography of Masticatory Muscle
 [PDF]

贾梦莹, 邵博, 辜文妍, 陈青立, 吕曜光, 龚忠诚
JIA Meng-ying
, SHAO Bo, GU Wen-yan, CHEN Qing-Li, LV Yao-guang, GONG Zhong-cheng

- , 2018, DOI: 10.13701/j.cnki.kqyxyj.2018.03.012
Abstract: 摘要 目的: 探讨单侧后牙正锁牙合、关节弹响与咀嚼肌电活动的相关性。方法: 分别收集新疆医科大学大学生单侧后牙正锁牙合组人数40例,单侧关节弹响组人数40例,无关节弹响的个别正常牙合人数40例,分别记录各组下颌姿势位(mandibular postural position,MPP)及牙尖交错位(intercuspal position,ICP)紧咬时双侧颞肌前束(temporal anterior muscle,TA)及咬肌(masseter muscle,MM)的表面肌电值(surface electromyography,SEMG),并计算出咀嚼肌不对称指数,单侧后牙正锁牙合组、单侧关节弹响组均与无关节弹响的个别正常牙合组比较研究。结果: 单侧后牙正锁牙合组锁牙合侧MMP时TA与MM较正常组均有较弱的肌电活动(P<0.05),非锁牙合侧与正常组差异无统计学意义,锁牙合侧咀嚼肌肌电均较非锁牙合侧高(P<0.05)。单侧后牙正锁牙合组ICP紧咬时锁牙合侧TA及MM肌电活动均较正常组及非锁牙合侧弱。锁牙合组咀嚼肌不对称指数均大于个别正常牙合组。单侧磨牙正锁牙合组较单侧前磨牙正锁牙合组在MMP及ICP咀嚼肌不对称指数高(P<0.05)。单侧关节弹响组在MMP及ICP紧咬时与个别正常牙合组比较咀嚼肌肌电均无统计学差异。结论: 锁牙合与咀嚼肌肌电变化有关,关节弹响与咀嚼肌肌电变化无关
微网继电保护综述
Overview on Micro-Grid Relay Protection
 [PDF]

吴强, 刘红岩, 杨钦臣, 魏承亮, 万信书, 兰穗梅, 施志强
Journal of Electrical Engineering (JEE) , 2016, DOI: 10.12677/JEE.2016.43020
Abstract:
微网技术作为一种普及新能源的新兴方式,具备灵活的运行方式、可靠的供电能力和优质的电能质量,是未来电力工业发展的重要方向,但是传统的继电保护对微网的保护效果并不明显,需要研究新的保护方案。本文在分析微网特性的基础上,提出了微网保护需要考虑的问题;接着比较了微网保护与传统配网保护以及有源配电网保护的异同,在此基础上提出了微网保护配置的特点与难点;然后从含微网的配网保护以及微网系统自身保护研究两个方面对国内外微网保护研究现状和成果进行了总结。最后,就未来微网保护给出了一些建议。
Micro network technology as a new way to popularize new energy, with flexible operation mode, reliable power supply capacity and quality of power quality, is an important direction of the future development of the power industry. But the protective effect of traditional relay protection is not obvious, and the new protection scheme is needed. The paper put forwards the micro grid protection needs to be considered in the analysis based on micro network, and then compared the micro network protection and the protection of traditional distribution network and active distribution network protection of the similarities and differences, based on proposed micro network protection configuration characteristic and the difficulty. And then from containing micro grid distribution network protection and micro grid system, its protection of two aspects of domestic and foreign micro grid protection status and achievements of the research on are summarized. Finally, some suggestions are given for the future micro grid protection.
微波频率和温度对食用植物油介电特性的影  [PDF]
郭文川,吕俊峰,谷洪超
农业机械学报 , 2009,
Abstract: 采用同轴探头技术研究了20~90℃、200~4500MHz内菜籽油、大豆油、花生油、玉米油、调和油的介电特性,分析了介电参数值随频率和温度变化的原因。结果表明:同频率下,菜籽油具有最大的相对介电常数和最小的介质损耗因数,而玉米油则相反。在500~4000MHz间,介电参数与食用油中的饱和与不饱和脂肪酸含量间具有较好的线性相关性。相对介电常数随温度升高线性减小,但介质损耗因数则线性增大。菜籽油的介电参数受温度影响变化最明显,而玉米油最不明显。随着频率或温度的增加,电磁能在食用油中的穿透深度减小。
微网并网转孤网切换的稳定性研究综述
A Survey of the Stability of the Micro-Grid Switched to the Solitary Network
 [PDF]

王建, 边敦新, 单辉, 刘萌
Smart Grid (SG) , 2015, DOI: 10.12677/SG.2015.54022
Abstract:
本文针对微网在并网转孤网的情况下出现的不稳定问题,在切换后采用U/f控制等经典方式的控制策略基础上,切换瞬间加入了储能装置和负荷控制策略相结合的控制方法,借助Matlab/Simulink仿真软件,建立了各种元件的模型,仿真了微电网孤网运行方式,同时通过电源电压跌落工况模拟切换到孤网电压变化。通过对各种微网切换稳定性的控制方法,进行合理的搭配找到最佳方案,对实际系统具有一定的指导意义。
For micro-grid in grid connected turn isolated network, there is unstable problem. After the switch with classical U/f control mode on the basis of the control strategy when switching instantaneously, adding the energy storage device and load control strategy by means of MATLAB/Simulink simula-tion software, setting up the model of various components of the simulation of micro-grid isolated operation mode, also by the dropping of power supply voltage to analog changes of voltage of iso-lated network. Through the control method of the stability of the various micro network switching, we then find the best way by reasonable collocation. The actual system has a certain significance.
ZrO2纳米颗粒对二氧化铅电沉积过程影响的研究  [PDF]
,,赵曼曼,姚颖悟,赵春梅
- , 2013,
Abstract: 采用循环伏安曲线(CV)、电化学阻抗谱(EIS)和阻抗电位曲线(IMPE) 等电化学技术研究了硝酸铅溶液体系中ZrO2纳米颗粒对二氧化铅电沉积过程的影 响.结果表明,加入ZrO2纳米颗粒后二氧化铅电沉积过程的阴阳极峰电位未发生 变化,但峰电流密度有所降低;纳米颗粒作用下电沉积过程的电化学阻抗和沉积 电位也相对较高,说明添加ZrO2纳米颗粒对二氧化铅电沉积起到阻碍作用,有助 于二氧化铅的细化.扫描电镜实验结果显示,添加ZrO2纳米颗粒后二氧化铅电极 的晶粒尺寸明显降低,这与电化学测试结果一致.
基于改进微分进化算法的风电直流微网能量管理  [PDF]
王毅,于明,李永刚
电网技术 , 2015, DOI: 10.13335/j.1000-3673.pst.2015.09.003
Abstract: 针对含蓄电池作为储能元件的风电直流微网系统,提出了能够衡量储能系统老化过程的能量管理模型。该模型通过纳入蓄电池健康状态实现了系统的经济运行,通过功率平衡约束保证系统的稳定性。采用基于群体适应度方差的改进型微分进化算法求解所建模型,并应用Matlab软件在联网工况下对所建模型进行仿真。仿真结果表明所提方法能够有效减少由蓄电池老化引起的系统运行成本,并基于微网预测信息实现了潮流最优管控,满足了风电直流微网系统经济、稳定运行的目标。
基于网压预测的并网换流器前馈控制
Feed-forward control for grid-connected converter based on grid voltage prediction
 [PDF]

杨树德,同向前,陈岁超,黄金亮,尹军
- , 2015, DOI: 10.11860/j.issn.1673-0291.2015.05.14
Abstract: 摘要 在换流器控制中,直接电压前馈被广泛用来抑制电网电压畸变.但系统中的延时环节导致前馈电压和实际电压并不同相,严重影响了电压畸变抑制效果.为了减小延时环节对直接电压前馈性能造成的影响,提高抑制电网电压畸变的能力,提出了基于网压预测的前馈控制方法.利用上一周波的电压采样值来预测PWM装载时刻的实际电压值,保证了前馈电压和实际电网电压较好的同相性.仿真和实验结果表明:采用预测电压进行前馈控制,将3、5、7、11次谐波电压抑制能力由94%、84%、72%、42%提高到99%、97%、94%和85%,提高了电网电压畸变时换流器的输出电流质量.
Abstract: The direct voltage feed-forward control is used in converter control to suppressing the grid voltage distortion. But the delay in the system makes the feed-forward voltage be out of the phase with the actual grid voltage. So the effect of suppressing the voltage distortion is seriously affected. In order to decrease the influence of the delay on the direct voltage feed-forward control, and improve the suppression ability of voltage distortion, the feed-forward control based on grid voltage prediction is proposed aiming at the periodic voltage distortion. The actual grid voltage magnitude at the PWM loading moment is forecasted by using the sampled grid voltage magnitude in previous power frequency periodic, and the better synchronization between the feed-forward voltage and the actual grid voltage is guaranteed. The simulation and experimental results verify that the inhibition rates at frequencies of 3rd,5th,7th,and 11th voltage harmonics are improved from 94%,84%,72%,42% to 99%,97%,94%,85%,by the feed-forward control based on grid voltage prediction, and the output current of the converter can be improved when the grid voltage is distorted.
QGA-SVM在弓网滑动电接触下的最优载荷研究  [PDF]
任志玲, 郭 超, 徐丽霞
高压电器 , 2015,
Abstract: 弓网滑动电接触过程中,电、力、速多个物理域的复杂耦合影响列车的高速、重载、稳定运行。为了提高载荷最优控制,使摩擦副摩擦磨损与受流稳定性达到相对最佳,利用量子遗传算法优化支持向量机的相关参数,建立了受电弓滑板磨损率的预测模型。经过MATLAB仿真结果表明,量子遗传算法比遗传算法有更好的优化性能,建立的模型能够稳定预测滑板磨损率,对选取最优载荷、研究载流摩擦副材料具有重要意义。
风电直流微网的电压分层协调控制  [PDF]
王毅,张丽荣,李和明,刘均鹏
中国电机工程学报 , 2013,
Abstract: 对于以新能源发电为主的微网系统,直流微网以其显著优势成为微网技术新的研究方向。该文以风电直流微网为例,在分析直流微网的构成以及各种运行模式的基础上,提出电压分层协调控制策略。该控制策略通过检测直流电压的变化量来协调各电力电子变流器的工作方式,从而确保在不同工况下都能保持微网内的有功功率平衡。各变流器独立工作,无需相互通信,可简化控制系统结构,并使直流微网具备?即插即用?功能。通过对含永磁风电机组、储能蓄电池的直流微网的仿真分析,验证所提控制策略对直流微网的有效控制。在风速或负荷变化、电网故障、蓄电池达到容量限定值等各种工作状态下,各端变流器都能根据直流电压变化量做出快速响应,从而提高了系统的稳定性和供电质量。
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