专业英语期末考试 3_专业英语期末考试
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专业外语期末考核
班级：11级电气工程及其自动化2班
姓名：李谦
学号：P11201440Translate the following paragraphs into English.(50 points)
在能源利用方面，大功率并网型风力发电是目前高效利用风能的主要方式。并网型风力发电系统的作用是将不断变化的风能通过风轮机转换成机械能，再通过发电机将机械能转换成电能，最后并入电网。由于带有增速齿轮箱的定速恒频风电机组具有运行效率低、噪声及机械损耗大等缺点，已不能适应时代的需要。因此，能够在额定风速下跟踪风能最大功率点的大功率直驱并网型风电技术已成为目前的研究的热点之一。基于上述原因，本文对直驱式并网变流电路的拓扑结构以及控制方式进行了研究。
本文首先对风力发电的现状以及前景展望作了简要的介绍，并对风力发电并网方式作了详细的分析，总结了直驱式风电系统的优越性。然后，介绍了直驱式各种变流电路及其优缺点，并对永磁同步直驱型风电系统做出了详细的分析。在比较各种变流电路并考虑现有的开关器件的功率水平的基础上，研究了适合直驱并网要求的变流电路的拓扑结构，即采用三相不控整流、三个并联的Boost升压电路以及两个并联的三相SPWM(Sinusoidal Pulse Width Modulation)逆变器的拓扑结构，并描述了永磁直驱式风力发电系统的数学模型。其次，对变流电路的结构进行了说明，并对变流电路的各个部分的工作原理进行了分析。在升压斩波环节中，对采用三个并联的升压斩波器的工作原理以及最优的控制方法进行了研究。在逆变环节中，对采用两个并联的电压源SPWM逆变器的工作原理以及可以使用的直接电流和间接电流两种控制方法进行了详细的分析，针对其优缺点以及对环流和谐波的抑制能力进行了详细的比较，得出适合本文研究的逆变器的控制方法。最后，参考已有的变流器的数学模型和所计算的数据，借助MATLAB7.0/ Simulink环境，对直接电流控制的变流电路进行仿真分析。
论文从系统的安全性、可靠性的角度出发，对并网过程中可能出现的问题进行针对性研究。从仿真结果上可以看出，直接电流控制方法不仅在动态响应、抗干扰能力以及在抑制并联逆变器上所出现的环流和谐波问题上都有明显的优越性。采用直接电流控制方法能够很好的实现文中所提出的变流方案，是最佳的控制方法。并网型风力发电系统中的变流电路以及控制方法具有很好的研究价值，值得继续深入研究与广泛应用。
翻译：
In terms of energy use, high power grid connected wind power is currently the main way of wind energy utilization efficiency.The grid connected wind power generation system is the role of the changing wind energy by wind turbines into mechanical energy, and then convert mechanical energy into electrical energy by a generator, and finally into the grid.Because of constant speed constant frequency
wind turbine with a gearbox has the disadvantages of low efficiency, noise and mechanical lo, has not been able to meet the needs of the times.Therefore, capable of tracking the maximal power point of wind power at rated wind speed direct driven grid connected wind power technology has become one of the hot spots in the present study.Based on the above reasons, this paper studied the topology of converter circuit direct driven grid and control method.Firstly, the status of wind power and prospect are briefly introduced, and the wind power grid connected mode has made the detailed analysis, summarizes the advantages of direct drive wind power system.Then, introduces the converter and the advantages and disadvantages of direct drive type, and the direct driven permanent magnet synchronous wind power system is analyzed in detail.In comparing the various converter circuit and power switching devices based on the existing research, the suitable topology circuit of grid connected direct drive requirements change, namely the three-phase uncontrolled rectifier, Boost boost circuit of three parallel and the two parallel three-phase SPWM(Sinusoidal Pulse Width Modulation)topology inverter, and describes the mathematical model of permanent magnetic direct drive wind power system.Secondly, the structure of variable flow circuit are described, and the working principle of each part of the circuit is analyzed.In the boost chopper in the link, the working principle of boost chopper on the three parallel and optimal control method are studied.In the inverter, the working principle of voltage source SPWM inverter based on two parallel and direct current can be used and the indirect current control method of two were analyzed in detail, and compares their advantages and disadvantages as well as the circulation and harmonic suppreion and compares the inverter, control method for the research the.Finally, reference of the existing converter mathematical model and the calculated data, with the help of MATLAB7.0/ Simulink, direct current control of the converter circuit simulation analysis.From the safety, the reliability of the system point of view, the poible problems in the proce of grid for research.From the simulation results can be seen, the direct current control method is not only the harmony in the circulation dynamic response, anti-interference ability and which appears in the inhibition of parallel inverter on the wave problems have obvious advantages.The direct current control method can realize the variable flow scheme, is the best method of control.The grid connected wind power generation system in the converter circuit and the control method has a good research value, is worthy of further research and application.Writing(50 points)
Directions: For this part, you are asked to write an abstract entitled with Study on Wind Energy.You should write at least 120 words and you should base your abstract on the outline below:
1.The characteristics of wind energy
2.Analyze wind power system.Discuion about wind power generationIn the 21st century, people most pay attention to environmental protection.Because people abuse the earth's resources, caused the natural disasters in the world, so humans began to recycle, to protect the ecological environment.The wind is a kind of new energy with great potential, in the eighteenth century, a strong wind swept through England and France, destroyed many houses and trees.The wind in a few seconds sent a ten million-horsepower power.By some estimates, the earth can be used to power about 10 billion kilowatt wind resources, is now almost 10 times of the world's hydropower generation.The world energy gained by the burning of coal each year, only the wind energy provided by a third in a year.Therefore, paid great attention at home and abroad to use wind to generate electricity, the development of new sources of energy.Wind energy resources are rich, the other is field area need to reach a certain scale, in order to have enough venue layout fan.Wind power, of course, also has many shortcomings.Power generation will produce noise and visual pollution, affect the surrounding residents normal rest;Also take up large areas of land;And is not stable, controllable;Now cost is still high;Finally affect birds flying.As a new energy in the 21st century, has been a large number of development of wind power at home and abroad.Despite the high cost of wind power generation, but people in order to environmental protection, the use of
clean energy.It seems that wind power is how environmental protection!
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