基于MMC的虚拟同步发电机技术在船舶与岸电无缝并网中的应用     

解文祥  周昊  郭燚  王超 《上海海事大学学报》2021,42(3):110-118

鉴于船舶与岸电在并网时存在较大冲击电流,以及模块化多电平换流器(modular multilevel converter,MMC)控制的岸电离网运行时对突发状况响应速度较慢的问题,采用改进的虚拟同步发电机(virtual synchronous generator, VSG)技术结合模型预测控制(model predictive control, MPC)算法,对岸电电源输出电流、环流、子模块电容电压进行分层预测控制,实现船舶与岸电的无缝并网。采用MATLAB/Simulink建立MMC VSG并网仿真模型,模拟船舶与岸电并网及突加负载等工况。对所提出的控制策略和算法的有效性进行验证,结果表明,利用所提出的控制策略能实现VSG离网与并网的无缝切换;与经典控制方法相比,所提出的控制策略的动态响应速度提升了5倍。  相似文献   

一种混合模式的CMC分析框架   总被引：1，自引：0，他引：1  

陈向东  张志梅  李洁  夏丽君 《中国远程教育(综合版)》2009,(4)

本文综合多个利用内容分析与社会网络分析等方法进行CMC研究的案例,探讨了两种方法整合的途径,在此基础上提出一个混合模式的CMC的分析框架,从分析内容、使用方法、测量数据、数据来源四个方面介绍如何利用该框架研究CMC,并对该框架进行了初步的应用.  相似文献   

MSI中规模计数器设计课程中的教法探讨     

黄晓明 《培训与研究》2010,(8):126-129

在数字电子技术课程的教学中有一章专门讨论时序逻辑电路的分析与设计,随着MSI中规模芯片的普及,大量的MSI计数器芯片进入了教材。由于课时的限制,教师不可能全面讲授这类芯片的设计方法,从而导致许多同学在考研时或在毕业后的工作中遇到不同的MSI芯片设计时就会出现困难。为此在本文中,我利用多年的教学经验总结归纳了此类问题的相关特征和简便的设计方法,为在校电子专业学习的同学们和从事电子专业教学的教师们提供一个参考。  相似文献   

Effects of online synchronous instruction with an attention monitoring and alarm mechanism on sustained attention and learning performance     

Chih-Ming Chen  Jung-Ying Wang 《Interactive Learning Environments》2018,26(4):427-443

Many studies have shown that learners’ sustained attention strongly affects e-learning performance, particularly during online synchronous instruction. This work thus develops a novel attention monitoring and alarm mechanism (AMAM) based on brainwave signals to improve learning performance via monitoring the attention state of individual learners and helping online instructors or teaching assistants to improve the sustained attention levels of learners with low-attention states as they perform online synchronous instruction activities. Totally, 83 and 65 Grade 7 students were randomly assigned to the experimental and control groups that respectively underwent online synchronous instruction with and without AMAM support. Analytical results reveal that the experimental group of learners exhibited significantly better learning performance and sustained attention than those in the control group, verifying that the AMAM efficiently promotes the learning performance and sustained attention of learners. Moreover, the proposed AMAM was more helpful in improving the learning performance of female learners than those of male learners and improved the sustained attention of both male and female learners. Furthermore, the sustained attention, frequency of attention alarms, and learning performance of the learners in the experimental group were strongly correlated, and the sustained attention and frequency of attention alarms strongly predicted learning performance.  相似文献   

双电机驱动伺服系统的模糊PI控制研究   总被引：1，自引：0，他引：1  

赵海波  周向红 《巢湖学院学报》2009,(3):71-75

在常规PI控制的基础上引入了模糊逻辑的概念,提出了一种模糊PI控制算法,采用模糊推理对PI调节器的控制参数进行在线调整.并用HATLAB中SIHULINK和FUZZY工具箱对三种控制方式进行了仿真.仿真结果表明,所提出的控制策略是有效的,使双电机良好的以一定速度同步运行.  相似文献   

A New Technique: Research and industrial application of a novel compound permanent magnet synchronous machine     

Cheng-zhi FAN  Ming-xing HUANG  Yun-yue YE 《浙江大学学报(A卷英文版)》2009,10(4)

We propose a novel kind of compound permanent magnet synchronous machine (CPMSM), which is applicable in low-speed and high-torque situations. We first explain the structure of the CPMSM. Based on theoretically deducing the calculation formulae of the CPMSM electromagnetic parameters, we analyze the operating characteristics of the CPMSM, and obtain the power-angle curves and working curves. The no-load magnetic field distribution and the cogging torque are analyzed by applying the finite element method of three-dimensional (3D) magnetic fields, to determine the no-load leakage coefficient and the wave0form of the cogging torque. Furthermore, the optimal parameters of the permanent magnet for reducing the cogging torque are determined. An important application target of the CPMSM is in direct-drive pumping units. We have installed and tested a directdrive pumping unit in an existing oil well. Test results show that the power consumption of the direct-drive pumping unit driven by CPMSM is 6 1. 1% of that of the beam-pumping unit, and that the floor space and weight are only 50% of those of a beam-pumping unit. The noise output does not exceed 58 dB in a range of 1 m around the machine when the machine is 1.5 m from the ground.  相似文献   

Gender Scripts and the Internet: The Design and Use of Amsterdam's Digital City,by Els Rommes. Enschede,The Netherlands: Twente University Press, 2002. 304 pp. 24.00. ISBN 9-0365-1774-5     

Danielle Lawson 《The Information Society》2013,29(4):309-310

This article seeks to address how religion fits into the larger domain of Internet studies and why studies of religion within computer-mediated communication (CMC) need to be given more attention. An argument is made for the need to take religion online more seriously, not just because it is an interesting phenomenon or a popular use of the Internet, but also because religion continues to be an important part of contemporary life for many people. A summary of the growth and development of religion online is presented along with an overview of how religion has been approached and studied on the Internet. This review shows what CMC studies of religion might offer in approaching research questions related to authority, identity construction, and community online. It calls for recognition of the contribution, and possibilities that underrepresented areas within interdisciplinary research, like religion, might offer Internet studies as a whole.  相似文献   

光谱法研究芦氟沙星与人血清白蛋白的相互作用     

邵爽 《浙江教育学院学报》2006,(6):47-52

用光谱法研究水溶液中芦氟沙星与人血清白蛋白的结合反应，分别测定了295，310K两个不同温度下二者的结合常数心和结合位点数n，探讨了其荧光猝灭机制；根据热力学参数确定了芦氟沙星与人血清白蛋白之间的作用力类型，以氢键或范德华力为主，并运用Foster偶极-偶极非辐射能量转移原理。测定了其相互结合时授．受体间的距离r；采用同步荧光技术考察确定芦氟沙星对人血清白蛋白构象产生一定的影响．  相似文献   

谈外语知识学习与技能学习的平衡发展     

栾金凤 《辽宁高职学报》2007,9(2):57-59

人类的学习是在社会活动中,以言语为中介,通过积极思维,主动掌握人类社会历史经验和积累个体经验的过程。对于学生来说,学习外语,不仅要掌握外语知识,而且要在掌握必要的语言知识的同时,熟练掌握运用外语进行交际的各种技能。也就是说,我们掌握一门外语,就是要掌握有关的知识和技能,使其平衡发展。  相似文献   

Position Sensorless Control for Permanent Magnet Synchronous Motor Using Sliding Mode Observer     

陈益广  傅涛李响 《天津大学学报(英文版)》2005,11(5):338-342

An approach of position sensorless control for permanent magnet synchronous motor （ PMSM ） is put forward based on a sliding mode observer. The mathematical model of PMSM in a stationary αβ reference frame is adopted, and the system is controlled by the digital signal processor （ DSP; TMS320LF2407 according to the control achieve closed loop operation of the motor, the stator theory of sliding mode observer. In order to magnetic field should be vertical with the rotor magnetic field and be synchronous with rotor rotating, so the position and speed of PMSM is estimated in real time and the estimated position is modified continuously. The simulation results indicate that the proposed observer has high precision is more robust to the parametric variation and load in estimation of PMSM position and speed, and torque disturbance.  相似文献