毕业设计(论文).doc

兆瓦级风力发电机控制系统设计液压系统(文献翻译) 3一级标题小二号黑体居中，段前0磅，段后12磅。每一章另起页利用功率电子变频器获取最大的风能策略章节采用三级标题，用阿拉伯数字连续编号，例如1，1.1，1.1.1。二级标题宋体四号，左对齐，段前距12磅，段后距0磅1 绪论地球气候的运作就像一个巨大的加热引擎。世界各地的气候变化都受到了它的影响。但巨大的加热引擎却是充足风能的供应者。按照美国能源部报道：世界上的风能理论上能够满足超过15倍世界当前能源的需求。正文: 中文为小四号宋体，英文为Times New Roman，首行缩进二个字，1.25倍行距。 1.1 变速风力发电机系统的基本组成典型的变速风力发电系统如图1-1-1所示。 图1-1-1 典型变速风力发电机组许多商业用途的 通过对图1-1-1的分析可知，图中虚线方框处为功率电子变换器。在本文中功率电子变换器也被称为逆变器。 1.2风力机性能如一台风力机风轮的摩擦力被忽视的话,那么风力机的动力表达式就为等式(1.2.1)至等式(1.2.4)。在等式（1.2.1）中，是风力机风轮的机械转矩， 公式应另起一行，正文中的公式、算式或方程式等应编排序号，公式按章节顺序编号。公式序号必须连续，不得重复或跳缺。重复引用的公式不得另编新序号。 （1.2.1） 。等式（1.2.4）中的代表的含义是风轮的最大旋转半径。而TSR最确切地含义是风轮桨叶速度与风速的比率。 图1-2-1 垂直轴风力机特征曲线 ;图名位于图的正下方，用宋体小五号加粗;图表按章编号，例如表2-7为第二章第七个表;图3-1为第三章第1个图。1.3风力发电机组及逆变器 三级标题黑体小四号书写左对齐，段前距12磅，段后距0磅1.5研究目的和方法1.5.1目标本文的研究目的是通过对变速风力发电系统的软硬件的调查、策划和实施来获取最大的能源策略。 的建模和仿真结果，且论证了逆变器布局创新的优势。在文中提及了我们研究小组建立的风机仿真系统用于论证最大能量获取算法的方法。32 最大风能获取智能算法2.1看法2.1.1无风速测量的独立算法风力机理论说明当尖速比保持在最佳值时风力机的转换效能才会最大。回顾第一章可知，尖速比控制方式的原理是直接监测和控制尖速比值。然而对于尖速比值的测量难度很大。特别是基于尖速比控制策略的执行相当复杂。而功率信号回馈是一种无须测量尖速比就能获取最大风能的控制方式。这主要是由于功率信号回馈控制方式依赖于风力机的特性。这就意味着在该控制初期和控制计划期间都要实时的获取风力机的特性 图2-1-1 最大功率算法信号流程图 3英文文献格式不限Maximum Wind Energy Extraction Strategies Using Power Electronic ConvertersChapter 1 IntroductionThe atmosphere of the Earth works like a huge heat engine. The air in tropical area arises and the air from the polar area fills its place. This huge heat engine is an abundant wind energy supplier. According to the U.S. Department of Energy, the worlds winds could theoretically supply more than 15 times current world energy demand.Compared to fossil fuel and nuclear electrical power generation, wind energy conversion has several notable advantages, including abundant supplies, renewable sources, environmental friendliness, and economical competitiveness, in addition to its widespread availability and relatively small land usage. As such an attractive means of alternative energy conversion, wind energy generation has a world-wide average growth rate of 31 % in the last 10 years. The cost of electricity from utility-scale wind systems has dropped by more than 80% over the last 20 years. In the early 1980s, wind-generated electricity cost was as much as 30 cents (US) per kilowatt-hour (kWh). Now, large wind power plants are generating electricity at costs as low as 4 cents (US) per kWh. As a result, Wind Power Generation Systems (WPGS) have been developing rapidly in recent years all over the world. Research work on WPGS is also receiving more and more attentions. .1.1 Basic VSWT System ConfigurationFigure1-1-1 shows a typical VSWT energy generation system. Various wind turbines from a hundred watts power level to mega watts power level have been used in WPGSs, such as horizontal axis wind turbines with different numbers of blades, vertical axis wind turbines which are also named as Darrieus Turbines, and other innovative turbines like Savonius wind turbine 1. Horizontal Axis Wind Turbine is the most popular type. Many commercial WPGSs adopt high speed induction or synchronous generators coupled to the wind turbines through gearboxes. In recent years, low speed synchronous generators, which are directly coupled to wind turbines without gear boxes, are gaining popularity. This structure benefits the WPGS in eliminating the gear box maintenance, reducing the noise and lowering the cost. Inside the inverter, the variable-frequency variable-voltage electricity from the generator is first converted from AC to DC through a rectifier. Both controlled or uncontrolled rectifiers may be adopted. An uncontrolled rectifier has the benefit of simplicity, while a controlled rectifier is able to contain the dc-link voltage within the inverters operational voltage range during high wind speed situations. 1.2 Wind Turbine Characteristic If the rotor friction of a wind turbine is ignored, the dynamics of the turbine can be simply expressed using Equations (1.2.1) to (1.2.4)1. In Equation (1.2.1),is the turbine rotors mechanical torque,is the load torque,is the turbine rotors moment of inertia, andis the turbine rotors angular speed. Equation (1.2.2) is derived from Equation (1.2.1) multiplied by, whereand are the turbines mechanical power and the load power respectively. （1.2.1） Chapter 2 Intelligent Maximum Wind Power Extraction Algorithm2.1 Overview2.1.1 An Independent Algorithm without Wind Speed MeasurementsWind turbine theory reveals that a maximum turbine energy conversion efficiency occurs when the Tip-Speed Ratio (TSR) is kept at its optimal value. As reviewed in Chapter 1，the principle of TSR Control method is to directly detect and control the TSR value. However, due to the difficulties of TSR measurement, a control strategy based on the tip-speed ratio is practically difficult to implement. Power Signal Feedback (PSF) control method was then proposed to extract maximum wind power without measuring the TSR. Basically PSF Control method is dependent of the characteristics of a wind turbine, which means the turbine characteristics have to be obtained either before or during the execution of the control scheme. 2.1.2 The Algorithm Existence Analysis