发电

Especially in direct-driven wind power generation system, it requires the full power converter, so it must pay more attention on multilevel converte.

尤其是对于直接驱动型风力发电系统，需使用全功率变流器，研究多电平变流器有一定的现实意义。

The Direct-Driven variable speed constant frequency wind generation system takes low speed PM generator as the generator,and it has the advantage of no gearbox,low mechanical loss,high efficiency,low maintenance cost.

直驱型变速恒频风力发电系统采用低速永磁同步发电机结构，无需齿轮箱，机械损耗小，运行效率高，维护成本低。

The mathematical model and working modes of a novel three-phase two-arm three-level neutral-point-clamped pulse width modulation rectifier suitable for direct-driving wind power system are analyzed in detail, and the constant frequency control strategies based on space voltage vectors are proposed and applied to the rectification conversion of direct-driven power generation system.

系统分析了新型三相两桥臂三电平中性点箝位脉宽调制(pulse width modulation，PWM)整流器的数学模型和工作模式，提出了基于空间电压矢量的恒频控制策略，并将其应用于直驱风力发电系统整流变换中。

Comparing comprehensive ly the present various current converting circuits, it is proposed an design structure of direct-driven wind power generation current converting systems in megawatt level.

摘 要：在综合比较当前适合直驱型风力发电机组的各种变流电路的基础上[1~ 2]，提出了一种兆瓦级直驱型风力发电变流系统的设计结构，即采用不控整流+升压斩波+SPWM逆变的变流器将电机发出的电能转换为可接入电网的恒频恒压的交流电。

Wind power generation ; permanent-magnet direct-driven ; uncontrollable rectifier ; Boost chopper ; SPWM inverter ; direct-current control

风力发电；永磁直驱；不控整流；升压斩波； SPWM逆变器；直接电流控制

Combined with the nonlinear characteristics of wind turbines and the control strategy of generator-side converter and grid-side converter, used the design method for digital PI regulator, the back-to-back PWM converter on the wind-power system with direct-driven permanent magnet synchronous generator was built in the simulink of the MATLAB.

结合风力机的非线性特性和机侧变换器与网侧变换器的控制策略，应用数字PI调节器参数设计方法，在MATLAB/simulink仿真环境下构建了基于背靠背变换器的永磁直驱风力发电系统，系统包括风力机、永磁同步发电机、变频器、电网及其电气控制部分的数学模型，仿真结果表明风电系统的PI调节器参数设计合理且系统具有良好的运行特性。

Large—size water lead power generation projects need large caliber valve, however, current disk valve production stays at test stage, certain imports are still necessary, which result into delay of project period and high investment cost, some strong enterprises are called to occupied domestic market.

大型引水、发电工程需特大口径蝶阀项目与之相配套，目前特大口径碟阀生产在国内尚处于起步阶段，急待一批生产该类阀门的企业迅速占领国内市场并打入国际市场。

You BE Evolution incompletely of life body, gene mutation of Alien, The senior high school of kindergarten degree living, inborn Mongolia the frog head of disease, The abandoned baby of Mount Everest snow man, the septic tank stop of murderer, The Africa make top black*of descendant, the yin and yang out of tune chimpanzee, The hippo been ran over by the Noah's ark, new volcano eruption, Super big shameless transmit sound to expand a sound trumpet, the humiliation of the Eskimo, With cockroach coexistence live of super individual, the vitality putrefied half plant, Will send out bad smell of**person,"cast off" the source head of word, Everyday deteriorate three time dinosaur, mankind history top most strongly discard a material, God lose the old washer which fall off, ability thinking of have no head living creature, Damage the disaster of compatriot fame in Asia, the ancestry receive for it abashed of descendant, The Fu of deposition thousand years plant quality, the scientist also dare not a research of originality species, The deposition raw material of 1000% petroleum densities, is disfigure of McDonald's uncle, Be like your this kind of damned guy: Only one Tuo muck that can play the inside of the television drama, Canned not compare with a wayside the chewing gum be spread urine by the dog, Connect such as flower all handsome you 1000% above, Seek the girl friend get to even want to leave the Earth to the zoo, Wanting to commit suicide would someone advise you and don't leave corpse in order to prevent a pollution environment, You once touched of keyboard top connect rice the protozoa all live not bottom go to, Jet come of the saliva return than the SARS fatal, Pack the lovely words can the moment solve population inflation of problem, Play cool pack handsome words mankind to have to use asexual reproduction, The idiocy can be you of teacher, mentally retarded can teach you how to say person's words, Want ～only your rise ozone layer meeting hole Wanting to immigrate Mars is in order to leave you, If you of ugly can generate electricity of the nuclear power station of words whole world can be with the lockout, The words bullet missile fight would be unbearable to fly toward you, The hand grenade see you would from explode, Other people would not° until open an airplane to bump a pair of son star line but you as long as bail out and then have same of power, All of the famous spot that you have been to change historic monument, you have been to of the historic monument will become history, 18 generation son all have no stem good matter would understanding you, connect throw into the sun all suspicion not enough environmental protection Anyway horizontal Shu a words:Don't let me see you again, if saw you, I must put out you!

你是 进化不完全的生命体，基因突变的外星人，幼稚园程度的高中生，先天蒙古症的青蛙头，圣母峰雪人的弃婴，化粪池堵塞的凶手，非洲人搞上黑*的后裔，阴阳失调的黑猩猩，被诺亚方舟压过的河马，新火山喷发口，超大无耻传声扩音喇叭，爱斯基摩人的耻辱，和蟑螂共存活的超个体，生命力腐烂的半植物，会发出臭味的**人，&唾弃&名词的源头，每天退化三次的恐龙，人类历史上最强的废材，上帝失手摔下来的旧洗衣机，能思考的无脑袋生物，损毁亚洲同胞名声的祸害，祖先为之蒙羞的子孙，沉积千年的腐植质，科学家也不敢研究的原始物种， 10倍石油浓度的沉积原料，被毁容的麦当劳叔叔，像你这种可恶的家伙：只能演电视剧里的一陀粪，比不上路边被狗洒过尿的口香糖，连如花都帅你10倍以上，找女朋友得去动物园甚至要离开地球，想要自杀只会有人劝你不要留下尸体以免污染环境，你摸过的键盘上连阿米吧原虫都活不下去，喷出来的口水比SARS还致命，装可爱的话可以瞬间解决人口膨胀的问题，耍酷装帅的话人类就只得用无性生殖，白痴可以当你的老师，智障都可以教你说人话，只要你抬头臭氧层就会破洞要移民火星是为了要离开你，如果你的丑陋可以发电的话全世界的核电厂都可以停摆，去打仗的话子弹飞弹会忍不住向你飞，手榴弹看到你会自爆，别人要开飞机去撞双子星才行而你只要跳伞就有同样的威力，你去过的名胜全部变古迹，你去过的古迹会变成历史， 18辈子都没干好事才会认识你，连丢进太阳都嫌不够环保反正横竖一句话：别让我再看见你，要是见着了你，我一定要把你灭了！

This paper describes and compares 4 streamtube models (single-disk single-streamtube, double-disk single-streamtube, single-disk multi-streamtube and double-disk multi-streamtube models) based on the momentum theory for the hydrodynamic performance prediction of the vertical-axis variable-pitch turbine that may be employed to tap tidal stream energy resources, especially for the prediction of the overall turbine power coefficient.

以潮流发电水轮机的设计为研究背景，分析和总结了基于动量定理方法的四种流管模型(单盘面-单流管模型、双盘面-单流管模型、单盘面-多流管模型和双盘面-多流管模型)在竖轴变攻角水轮机的水动力性能计算中的应用，特别是能量利用率预报方面的应用。

Key words :coal mine safety ; vacuum pump ; gas drainage ; generate electricity

主题词：煤矿安全；真空泵；瓦斯抽放；发电

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。