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风电机组状态监测系统的人机界面设计 代前进,风电机组状态监测系统的人机界面设计,代前进,机组,状态,监测,系统,人机,界面设计,前进

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华 北 电 力 大 学 科 技 学 院毕 业 设 计（论 文）附 件外 文 文 献 翻 译学 号： 071901010307 姓 名： 代 前 进 所在系别： 电力工程系 专业班级： 电气07K8 指导教师： 赵 洪 山 原文标题： A Comparative Analysis of Wind Turbine Technologies in Focus on the Grid Integration 2010年 6 月 15 日集中并网的风力发电技术的比较分析摘要 .出处:2010 9th IEEE/IAS International Conference on Industry Applications - INDUSCON 2010 作者：PEREIRA1, Heverton Augusto; LIU2, Silas Yunghwa; RAMOS2, Manoel Candido de Lima; MENDES2, Victor Flores,SILVA2; Selnio Rocha新技术的发展提供了的风力发电机组产业的快速增长。全球各国政府已提出替代能源来源的财政计划。电力系统中的风力发电机增加导致系统操作员制定准则，以规范的风力发电场与电网的整合，确定了支持性的最低条件。本文的目的是探讨在世界上呈现出的不同的风力发电机技术，分析其主要特征。因此，在一个三相电压骤降的一些仿真技术进行了分析。关键词：风力发电机；电网整合；电压骤降。一前言由风力发电机产业实现的技术进步与世界各地的风力发电场数量的增加已经巩固了这种替代为一个安全，可靠和具有成本效益的发电方法。亮点是材料的发展应用于结构，这使得设备更轻，更牢固，在涡轮空气动力学和电力电子技术和自动化集成的进步，每年生产装备更高的功率和尺寸和性能兼容的网络代码的需求日益增加。所有这些进步是可能的，因为可持续发展的理念，适应人类活动的进展情况的便利条件的需要最小化的影响环境1。根据世界风能协会发表的报告书，在2009年年底，全球风力发电总装机容量为159.2万千瓦，预测将在2010年底达到203.5万千瓦2。图1说明了在这个十年装机功率的发展和2010年的预测值，表明即使在2008-2009年全球经济危机，在此期间风电的增长也是惊人的增长。图1全球风电总装机容量变化巴西尚未开发的风力发电的潜力巨大。在该国有约800兆瓦的已安装和正运行的风电，和1900兆瓦以上批准尚未开工建设3。储备能量拍卖2009年是风能的未来在巴西的一个里程碑。国家投资者的参与已经承诺了一个意外的R$ 148.30/MWh平均价格的低能源价格特点，本次拍卖已签约到2012年6月的1800兆瓦的安装，代表列入了71个新的风电场与众多的厂家参与。整合风电场并网发电的，必须符合由全球电力系统营办商制定的电网准则规定的要求。由国家系统操作员制定的巴西电网准则在2009年发布4。这些是连接到电网的基本程序。子模块3,6，题为“连接电网的基本技术最低的要求”，提出了风力发电机必须满足的最低标准。在暂态电压跌落的情况下，图2显示下沉的比例和期限之间的关系，为此风力发电机必须与电网保持连接。这些准则的目的是确保增加了装机容量的风电场的发电，新投资的吸引和政府的计划的激励，加上新的联网的标准，进一步刺激了风与此源纳入更大的前景的能源网络，可能有助于系统承受瞬间电压骤降。力发电机新技术在巴西的到来。在本文中，我们介绍现有的风力发电机技术，其中许多目前没有在巴西，以及当整合到电网和受到短暂的电压变化时对这些技术的性能的比较分析。图2巴西电网规程中风电机组的电压容纳边界二风力发电机技术本节介绍了在国际市场存在的风力发电机的技术和各自的突出特点。目前可用的七种风力发电机技术：一种是固定的速度（SCIG），一种是其速度范围窄（WRIG），另外五种是变速。后者包括在成本和性能（能源使用和鲁棒性干扰），最近在国际市场上推出了两个技术方面最有竞争力的技术：来自福伊特的带液力2变速箱的风力发电机 5和带永久磁铁励磁的双馈异步发电机 6。图3. 鼠笼式感应发电机并网 图4. 绕线转子异步发电机并网 图5 双溃感应发电机并网 图6永磁双溃感应发电机并网图7带励磁转子同步电机并网图8永磁同步发电机并网图9带动态算法齿轮箱的同步发电机并网(一),鼠笼式异步发电机（SCIG）这种风力发电机组的概念，可以从图3看到，它是第一个以商业规模使用，是非常简单，没有任何权力的控制类型。鼠笼式异步发电机工作在固定转速由电网频率决定的，是独立于风速的7。作为发电机工作的机器已经在上面旋转同步，即负滑移速度。由于风力发电机组是直接连接到电网，从风场变化的任何干扰，导致传输电能质量问题直接连接到电网的机器有一个刚性连接特性，即机器上的影响是直接传递到电网，反之亦然8。另一个问题是机械变速箱需要定期维护，但这也是一个更现代的技术问题。由于鼠笼式感应发电机总是从电网吸收无功功率，这个配置使用的电力补偿电容器组。（二），绕线转子感应发电机（WRIG）和转子电阻的动态控制在图4中可以看到，鼠笼异步发电机的进化是绕线转子异步发电机的利用，插入一个可变电阻器在转子和由一个IGBT的开关进行控制。该电阻控制的目的是帮助吸收机械过渡，通过改变电阻值，对滑移和系统的输出功率进行控制，因此，速度控制的范围一般高于同步速0-10。（三），双馈感应发电机(DFIG)在过去的十年中，双馈异步发电机是表现出更多的增长的技术，无论是在安装容量还是在出售的整机数目 9。如图5示，这台机器是一种绕线转子感应发电机，它是由两个电路提供电流。当转子通过使电力具有双向流动的两个静态转换器连接到系统时，定子是由电网直接提供励磁电流。该转换器使用的只有机器额定功率的一部分，通常在25%-30。该技术允许产生的无功功率控制以及速度的变化范围在+ / - 30左右的同步速度。但是这项技术需要的机械变速箱与发电机互连和定子直接连接到电网这使得对电压骤降脆弱。（四），永磁双馈感应发电机（XDFM）与带有反馈异步发电机传统风力涡轮双类比，这种技术使用发电机额定输出功率的25%-30%，和这种技术相比，永磁励磁机输出功率为发电机总功率的16%-18%，正如图六所示。该励磁机允许双馈感应发电机转子连接到无滑环的同步发电机定子，隔离开电网转子回路。带有隔离电网的PWM转换器，正如制造商所倡导的那样，这种技术提供了一个优质能源和支持性。（五）带励磁转子同步发电机（SGER）在实施同步发电机使用的发电企业，在使用变速操作来实现在市场上作为一个有吸引力的选择，消除了机械齿轮箱。如图7示，通过频率转换器连接到电网，由于在发电机有大量磁极，这些机器可以在低转速运行 10。该电网侧变流器，包括IGBTs，控制整个电流注入到电网的直流母线电压，作为逆变器。发电机侧变流器控制使用二极管整流电源和一个升压转换器，将不可调节的直流母线与可调节的输入电网侧转换器的直流母线相连。 该技术主要由德国的Enercon公司拥有优势，可以由六个阶段低速发电机的使用区分，且无变速箱的情况下运作。（六）永磁同步发电机（SGPM）这第二个技术，采用同步发电机已为主要特征的永磁发电机的使用和将PWM整流器作为机器侧的变流器配置，如图8所示。这些设计策略为更好地配合了风力发电机转子，对于一个允许结构尺寸和重量的减少，减少机舱上的涡轮结构的努力。使用的PWM整流器，虽然涉及的成本稍高，使得更好地使用电动机械，改善其变速运行性能。（七） 动态乘法变速箱的同步发电机（SGDG）这项技术介绍由福伊特和合作伙伴DeWind发展的windrive-液力控制变速箱，DeWind已经销售各种类型的风力涡轮机。本装置由风机转子连接到一个固定的比例齿轮箱，从这个变速箱转子，连接到允许以高转速轴运行在一个固定的速度和在一些低转速的速度运行液力变速箱，如图9示。几十年来福伊特销售这项技术将变速泵成功地应用于设计的设备，避免了静态转换器的使用，允许传统的高转速同步发电机的使用。所有这些生产出一系列优点，可总结为如下：利于整合到电网：不产生谐波，常规维护对干扰的易反应和可支持；足够的陆上和海上应用在不同的气候；在与同步发电机相比重量减少；不使用静态转换器的可靠性增加。 这种风电机组不简单的与其他技术相比，因为其特点是接近于传统使用的水电和热电发电机的应用。三.风电机组技术的一些支持性特征为了分析一些风电机组技术的支持性的特点，他们提交到三相电压骤降持续时间为300毫秒到50。通过分析他们的长处和弱点来讨论的技术的主要特点是可能的。图10展示了提交的涡轮机的凹陷。利用Matlab / Simulink的方案进行了所有的仿真且保护性能没有考虑。图10.根据巴西电网程序，电压降低时风电机组必须穿越图11.电压骤降时SCIG的速度图12.电压骤降时SCIG的有功功率图13.电压骤降时SCIG无功功率图14电压骤降时SCIG定子电流图15电压骤降时WRIG有功功率图16.电压骤降时WRIG的无功功率图17.电压骤降时WRIG定子电流（一）鼠笼式感应发电机正如前面提到的，这是第一个进入市场的风力发电机组技术，在1995年占全球安装的发电机70以上。这项技术在2005年在世界各地安装的所有发电机中占20，。这一减少主要由其他更强大的功率和更高的生产技术的发展引起的。使用SCIG的风力发电机组在三相电压下降期间转速增加，如图11示。就功率而论，在骤降时有功功率降低到接近零，无功功率的达到峰值然后减小到零附近，分别如图 12和图13所示。这些减少和剩余电压值是一致的。机械功率和产生的有功功率不平衡转换成转子的加速度。在电压恢复时有功功率返回到额定值伴随一些振荡，由于发电机重磁化无功功率值显示峰值。关于发电机定子电流在他们所研究的电压骤降中增加到大于额定值的三倍，如图14示。而在电压恢复时另一个电流增加。这些电流的变化可以触发过流保护，确定了该技术的脆弱性。（二）绕线转子异步发电机和转子电阻的动态控制对WRIG和转子电阻动态控制的分析，通过图15至图17显示了与鼠笼发电机相比这一技术的发展。如图16示，在电压骤降时和电压恢复后，通过控制转子电阻有可能注意到无功功率在减少。因此发电机定子电流减少情况看图17。（三）双馈感应发电机双馈电机有一些转换控制拓扑。本研究利用速度和无功功率控制，使用dq变换。会议决定，以控制无功功率来维持故障前系统的功率因数为0.93。在三相跌落间，速度也上涨。然而，机器能够维持发电，如图18和图19示。有功功率和无功功率显现摆动，有功功率呈现显著的波动。即使在干扰期间，无功功率控制是能够维持其值的。图18.电压骤降时DFIG有功功率图19.电压骤降时DFIG无功率干扰期间的最大问题之一是代表的转子感应引起的过电压和过电流11-12。由于定子直接连接到电网，电压和电流的峰值由于骤降是显著的。该电流几乎达到额定值的两倍，在图20中可以看到。但更严重的跌落，这个值可以达到三至四个标幺值。图20.电压骤降时DFIG转子电流由于这项技术采用转换器连接到转子，这是极为重要的在电压骤降期间保护变换器并确保发电机的功率。在跌落期间，该系统还遭受高扭矩峰值和crowbar通常是被使用。（四）永磁式双馈感应发电机励磁根据制造商的xDFM技术不要求使用撬杠来限制电压骤降期间的扭矩峰值。因为励磁永磁同步电机和电压被维持，该转换器仍然活跃在整个下降期间。因此，在电压降落期间转换器能够保持转子电流的控制。在与同步发电机相比，xDFM有提供更大的电流的能力，约五倍的额定电流，比全转换技术，大约两倍额定电流容量。（五）转子励磁同步发电机连接转换器的SGER的直流母线，如图23示，制动斩波器是用来驱散多余的能量电容器。每次电容器上的电压超过某一阈值，斩波器被触发，平衡由发电机产生的各种不同功率与电网的潮流限值，如图21和图22所示。斩波器增加了风力发电机组面临骤降的保障性，可作为穿越的重要措施。图21.电压骤降时SGER有功功率图22.电压骤降时SGER无功功率图23.电压骤降时SGER直流母线电压（六），永磁同步发电机 对电压骤降的支持性的观点，SGPM是完全类似于SGER。（七），同步发电机的齿轮箱动态乘法直接连接到电网（无电力电子）的同步发电机的一个主要特征是电压骤降时它的穿越能力与电压骤降期间及之后保持同步的能力相关联。这种特性被称为暂时性的稳定。在骤降期间，同步发电机提供高无功电流，通常远大于使用传统发电机技术所提供的。与其他发电机相比，这给电网的支持更能稳定运行。四.结论对新老风力发电机组技术及其特点进行了调查。电压骤降后，异步发电机直接连接到电网中吸收的重磁化高电流。由于其滑和电源控制，转子电阻感应发电机比SCIG更多穿越能力。DFIG使用的电力电子和控制它的转子，通过两个静态转换器，是可以控制发电机的有功和无功功率。该xDFM使用一种永久磁铁励磁，消除了滑环，从电网孤立转子电路。这两种技术都对电网干扰较敏感性，因为它们直接连接到电网中，这是他们的弱点。SGER和SGPM风力发电机有类似的特征。两者都是通过频率转换器连接到电网，可以最大限度地减少电网干扰，并对机器提供更高的稳定性。而且SGDG产生谐波和消除了电力电子元件的使用。 本文只是提出一个关于每种可用的风力发电机组技术通过三相电压骤降的有限的研究，更多的研究必须作出。随着在世界上风电装机容量的增长，鼓励了更多更可靠的技术支持电网的变化。 12华北电力大学科技学院毕 业 设 计（论 文）开 题 报 告学生姓名： 代前进 班级： 电气07K8 所在系别： 电力工程系 所在专业电气工程及其自动化设计（论文）题目： 风电机组状态监测系统的人机界面设计 指导教师： 赵洪山 2011年 3 月 19日毕 业 设 计（论 文）开 题 报 告一、结合毕业设计（论文）课题情况，根据所查阅的文献资料，每人撰写不低于2000字的文献综述。（另附）二、本课题要研究或解决的问题和拟采用的研究手段（途径）：一、 本课题研究内容：（1） 熟悉风电机组结构和主要元件的作用；（2） 掌握风电机组运行监测状态参数及物理意义；（3） 学习C#程序语言，熟悉可视化界面设计技术和参数曲线显示技术；（4） 利用C#语言编制风电机组状态监测系统用户界面。 二、 拟采用的研究手段（1） 通过查阅国内外相关文献资料书籍；（2） 利用互联网搜索相关资料；（3） 在Visual Studio 2008平台上利用C#语言设计风电机组状态参数可视化曲线和状态监测系统用户界面。三、指导教师意见：1 对“文献综述”的评语： 2对学生前期工作情况的评价（包括确定的研究方法、手段是否合理等方面）：指导教师： 年 月 日 华北电力大学科技学院毕业设计(论文)任务书所在院系 电力工程系 专业班号 电气07K8 学生姓名 代前进 指导教师签名 审批人签字 毕业设计(论文)题目 风电机组状态监测系统的人机界面设计 2011 年 3月 1日一、毕业设计(论文)主要内容1. 熟悉风电机组主要元件组成和运行方式，掌握风电机组运行监测参数及其物理意义；2. 前两周查阅关于风电机组状态监测的文献，总结并分析现有风机监控系统的功能、特点；完成开题报告；3. 熟悉可视化界面的设计技术和相应的编程C#语言； 4. 利用C#设计发电机组主要参数曲线显示技术；5. 利用C#编程实现风电机组状态监测系统用户界面；6. 撰写论文。二、基本要求1在导师的指导下，要独立完成课题的研究工作，培养分析、解决问题的能力；2. 理解掌握风电机组运行方式和状态监测系统主要结构功能； 3. 设计并编程实现风电机组状态监测系统主要用户界面；4. 毕业设计论文要求内容充实、条理清楚、符合规范；5. 对文献综述、开题报告、外文文献翻译、论文撰写的格式与内容要符合华北电力大学本科毕业设计要求；6. 培养认真负责、实事求是的科学态度和刻苦钻研的精神。三、设计(论文)进度序号设计项目名称完成时间备注1熟悉任务书内容与要求，通过调研、查阅文献，撰写文献综述，完成开题报告2011.3.192熟悉风电机组运行方式及状态参数可视化技术2011.3.283利用C#设计主要参数曲线显示程序2011.4.244编程实现风电机组状态监测的主要用户界面2011.6.55总结工作，完成论文撰写2011.06.136设计(论文)预计完成时间： 2011 年 6 月 18 日四、参考资料及文献1. 莫为泽，冯宾春，邓杰. 海上风电机组安装概述J. 水利水电技术，2009，40(9)：5-8.2. 徐甫荣. 大型风电成及风电机组的控制系统J，电气传动自动化，2003，25(6)：5-11.3. Visual C# 编程技巧. A Comparative Analysis of Wind Turbine Technologies in Focus on the Grid Integration PEREIRA1, Heverton Augusto; LIU2, Silas Yunghwa; RAMOS2, Manoel Candido de Lima; MENDES2, Victor Flores, SILVA2; Selnio Rocha 1Universidade Federal de Viosa Electrical Engineering Department 2Universidade Federal de Minas Gerais Electrical Engineering Department E-mail: heverton.pereiraufv.br, silasyl, victor.auto.br, seleniosdee.ufmg.br Abstract-The development of new technologies has provided a fast growth of the wind turbine industry. Worldwide governments have presented financial programs of alternative energy sources. The increase of wind turbines in electrical systems has led the system operators to make codes to regulate the integration of wind farms with the network, setting minimum conditions for supportability. The aim of this paper is to discuss the different technologies of wind turbines present in the world, analyzing their main characteristics. Therefore the simulation of some technologies during a three-phase voltage sag is analyzed. Index Terms Wind turbine, grid integration, voltage sag. I.INTRODUCTIONTechnological advancements achieved by the wind turbine industry and the increase in number of wind farms around the world have consolidated this alternative as a safe, reliable and cost-effective method for electric power generation. Highlights are the evolution of the materials used in construction, which makes the equipment lighter and stronger, advances in the turbine aerodynamics and integration of power electronics and automation, producing each year equipment with higher power and dimensions and performance compatible to the increasing demands of the network codes. All this progress was possible due to the ideals of sustainability, adapting the conveniences of progress of human activities to the needs of minimizing the impacts on the environment 1. In the end of 2009, the world total installed capacity of wind generation was 159.2 GW, with prediction of reaching 203.5 GW by the end of 2010, according to the report released by WWEA, World Wind Energy Association 2. Figure 1 illustrates the evolution of installed power in this decade and the forecast value for 2010, indicating that even with the global economic crisis of 2008-2009, the growth of wind power in this period has grown amazingly. Brazil has yet to develop much of its wind power potential. About 800 MW is installed and in operation in the country and more than 1,900 MW approved that have not yet started construction 3. The Leilo de Energia de Reserva (Reserve Energy Auction) of 2009 was a milestone for the future of wind energy in Brazil. Characterized by the presence of national investors that have committed to an unexpectedly low energy price of R$ 148.30/MWh in average, this auction has contracted the installation of 1,800 MW through June 2012, representing the inclusion of 71 new wind farms with the participation of a large number of manufacturers. To integrate the wind farms to the grid, they must meet the requirements imposed by the network codes that are standards drawn up by operators of electric systems worldwide. YearInstalled Capacity (GW)ActualForecastYearInstalled Capacity (GW)YearInstalled Capacity (GW)ActualForecastFig. 1. Evolution of the world total installed capacity of wind power. Fig. 2. Voltage tolerance boundary for wind turbine generators according tothe Brazilian grid codes 4. 2010 9th IEEE/IAS International Conference on Industry Applications- INDUSCON 2010 -978-1-4244-8010-4/10/$26.00 2010 IEEEIn Brazil the Procedimentos de Rede (Brazilian Grid Codes), standards drawn up by ONS - Operador Nacional do Sistema (National System Operator) 4, was launched in 2009. These are basic procedures for connection to the grid. The sub-module 3,6, entitled “ Requisitos tcnicos mnimos para a conexo rede bsica” (Minimum technical requirements for connection to the basic grid), presents the minimum criteria that the wind generators must meet. In the case of momentary voltage sags, Fig. 2 shows the relationship between the percentage of sinking and duration of absence, for which the wind generator must remain connected to the grid. The aim of these criteria is to ensure that the generation from wind farms, which have increased the installed capacity, with prospects for greater inclusion of this source to the energy network, may contribute to the system to withstand a momentary voltage sag. The attraction of new investments and incentives by government programs, coupled with new standards for network connection, further stimulated the arrival of new technologies of wind turbines in Brazil. In this paper we present the existing technologies of wind turbines, many of them not currently in Brazil, and a comparative analysis of the performance of some of these technologies when integrated to the grid and subjected to voltage variations of short duration. II.WIND TURBINE TECHNOLOGIESThis section presents the technologies of wind turbine that exist in the international market and the outstanding characteristics of each. Seven wind turbine technologies are currently available, one at fixed speed (SCIG), one with a narrow range of speed (WRIG), and five at variable speeds. The latter group includes the most competitive technologies in terms of cost and performance (energy use and robustness to disturbances) and two technologies recently launched in the international market: wind turbine with hydrodynamic gearbox from Voith 5 and doubly fed induction generator with permanent magnet exciter 6. Fig. 3. Squirrel Cage Induction Generator connected to the grid. Fig. 4. Wound Rotor Induction Generator connected to the grid. Fig. 5. Doubly Fed Induction Generator connected to the grid. Fig. 6. Doubly Fed Induction Generator with Permanent Magnet Exciterconnected to the grid. Fig. 7. Synchronous Generator with Excited Rotor connected to the grid. Fig. 8. Synchronous Generator with Permanent Magnet connected to thegrid. Fig. 9. Synchronous Generator with Dynamic Multiplication Gearboxconnected to the grid. A.SQUIRREL CAGE INDUCTION GENERATOR (SCIG)This wind turbine concept, which can be seen in Fig. 3, was the first one used on a commercial scale, being very simple and not having any type of power control. The squirrel cage induction generator operates at fixed speed, determined by the grid frequency and is independent of the wind speed 7. To work as generator the machine has to rotate at a speed above the synchronous, i.e. with negative slip. As the wind turbine is directly connected to the grid, any disturbances from the wind variations are transmitted leading to power quality problems. The machines connected directly to the grid have characteristics of a rigid connection, i.e. the effects on the machines are passed directly to the grid and vice versa 8. Another problem is the need of a mechanical gearbox that needs regular maintenance, but this is a problem of more modern technologies as well. Since the squirrel cage induction generator always absorbs reactive power from the grid, this configuration uses a bank of capacitors for power compensation. B.WOUNDROTOR INDUCTION GENERATOR (WRIG) AND DYNAMIC CONTROL OF ROTOR RESISTANCEAn evolution of the squirrel cage induction generator is the utilization of wound rotor induction generator, with the insertion of a variable resistor in the rotor and controlled by a set of IGBT switches, as can be seen in Fig. 4. The aim of the resistive control is to help the absorption of mechanical transients and therefore by varying the resistance value, the slip and the output power of the system are controlled. The range of the speed control is typically 0-10% above the synchronous speed. C.DOUBLY FED INDUCTION GENERATOR (DFIG)In the last decade the doubly fed induction generator is the technology that showed more growth, both in installed capacity as well as in the number of units sold 9. The machine, as seen in Fig. 5, is a wound rotor induction generator and it is fed by two circuits. The stator is fed directly by the grid while the rotor is connected to the system through two static converters, which enable the bidirectional flow of power. The converters used have only a portion of the rated power of the machine that is usually around 25-30%. This technology allows the control of the reactive power generated as well as the variation in speed in the range of +/- 30% around the synchronous speed. However this technology requires the mechanical gearbox to interconnect the turbine to the generator and the direct connection of the stator to the grid which makes it fragile against voltage sags. D.DOUBLY FED INDUCTION GENERATOR WITH PERMANENT MAGNET EXCITER (XDFM)In analogy with the conventional wind turbine with doubly fed induction generator, this technology uses a power converter with 25-30% of rated output of the generator and, in contrast to that, a permanent magnet exciter with the power of 16-18% of main power generator, as seen in Fig. 6. The inclusion of this exciter allows you to connect the DFIG rotor to the synchronous machine stator without slip rings, isolating the rotor circuit of the power grid. With the PWM converter isolated from the network, this technology offers a superior quality of energy and supportability, as advocated by the manufacturer 6. E.SYNCHRONOUS GENERATOR WITH EXCITED ROTOR (SGER)The use of synchronous generators in the implementation of power plants that operate at variable speed came on the market as an attractive alternative to eliminate the mechanical gearbox. Connected to the grid by means of frequency converters, as seen in Fig. 7, these machines can operate at low rotational speed due to large amount of magnetic poles in the generator 10. The converter of the grid side, consisting of IGBTs, controls the dc bus voltage across the current injection onto the grid, acting as an inverter. The generator side converter controls the power by using a diode rectifier and a boost converter that connects the unregulated dc bus with the regulated dc bus at the input of the converter on the grid side. This technology is dominated by the Germany company Enercon and can be distinguished by the use of a generator of six phases at low speed, and operating without a gearbox. F.SYNCHRONOUS GENERATOR WITH PERMANENT MAGNET (SGPM)This second technology using the synchronous generator has as main features the use of permanent magnet generator and the configuration of the machine side converter as PWM rectifier, as seen in Fig. 8. These design strategies produce a better fit with the rotor of the wind generator that allows for a structure of reduced size and weight, minimizing the nacelle and efforts on the structure of the turbine. The use of PWM rectifier, although involving marginally higher costs, makes better use of the electric machine, improving its operation on variable speed. G.SYNCHRONOUS GENERATOR WITH DYNAMIC MULTIPLICATION GEARBOX (SGDG)This technology was introduced by the development of the windrive gearbox of hydrodynamic control by Voith in partnership with DeWind, who has already marketed various types of wind turbines. This equipment consists of a wind rotor connected to a gearbox of fixed ratio and from this, connects to the hydrodynamic gearbox that allows for the axis of high rotation speed to operate at a fixed speed and allowing the axis of slow speed operating at several speeds, as seen in Fig. 9. This technology marketed by Voith for several decades to variable speed pumps is successfully applied to design an equipment that avoids the use of static converters, allowing the use of conventional synchronous generators of high rotation. All these produce a series of advantages that can be summarized in the following: Good integration to the net: not generating harmonics, conventional maintenance of reactive and supportability to disturbances; Adequate onshore and offshore application in different climates; Weight reduction in comparison with the synchronous generator; Increased reliability for not using static converters. This type of wind turbine cannot be easily compared with other technologies since their characteristics are close to those used in hydroelectric and thermoelectric generators conventionally used. III.SUPPORTABILITY CHARACTERISTICS OF SOME WIND TURBINE TECHNOLOGIESTo analyze the features of supportability of some wind turbine technologies, they were submitted to a three-phase voltage sag to 50% with duration of 300 ms. With this dip it was possible to discuss the main features of the technologies, by analyzing their strengths and weakness. Figure 10 presents the sag to which the turbines were submitted. All the simulations were made using the Matlab/Simulink program and the performance of protections was not considered. A.SQUIRREL CAGE INDUCTION GENERATORAs mentioned earlier this was the first wind turbine technology to spread the market and accounted for 70% of the generators installed in 1995 worldwide. In 2005 this technology accounted for 20% of all generators installed worldwide. This reduction occurred mainly by developments that gave rise to other more robust and higher power producing technologies. During the three-phase voltage sag the turbine with SCIG shows an increase in the velocity as can be seen in Fig. 11. With regards to power, during the dip the active power reduces to around zero and the reactive power has peaks and then reduces to around zero as can be seen in Fig. 12 and 13, respectively. These reductions are consistent with the values of remaining voltage. The unbalance between the mechanical power and the generated active power converts in the acceleration of the rotor. During voltage recovery the active power returns to its rated value despite some oscillations and the reactive power shows a peak due to the generator remagnetization. Regarding the generator stator currents they are increased during the studied sag to greater than three times the rated value, as can be seen in Fig. 14. And during the voltage recovery another current increase occurs. These current variations can trigger the overcurrent protection, defining the fragility of the technology. B.WOUNDROTOR INDUCTION GENERATOR AND DYNAMIC CONTROL OF ROTOR RESISTANCEThe analysis of the WRIG and dynamic control of rotor resistance, made through Fig. 15 to Fig. 17, shows the evolution of this technology compared to the squirrel cage generator. By controlling the rotor resistance it is possible to notice a reduction in reactive power, during the sag as well as after the Fig. 10. Voltage sag that the wind turbine have to ride through according theBrazilian grid procedures. Fig. 11. SCIG speed during the voltage sag. Fig. 12. SCIG active power during the voltage sag. Fig. 13. SCIG reactive power during the voltage sag. Fig. 14. SCIG stator current (RMS) during the voltage sag. recovery of the voltage as seen in Fig. 16. Consequently, a reduction in the generator stator currents occurs as seen in Fig. 17. C.DOUBLY FED INDUCTION GENERATORThe DFIG has several converter control topologies. The study uses the control of velocity and reactive power using the dq transformation. It was decided to control the reactive power to maintain the power factor of 0.93 at the pre-fault system. During the three-phase dip, the speed also rises. However the machine is capable of maintaining the power production, as seen in Fig. 18 and Fig. 19. The active and reactive powers show oscillations and the active power presents significant ripple. The reactive power control is capable of keeping the value even during the disturbance. One of the biggest problems during the disturbance is represented by the overvoltages and overcurrents induced in the rotor 11, 12. Since the stator is directly connected to the grid, the voltage and current peaks due to the sag are significant. The currents reached almost twice the rated value, as can be seen in Fig. 20. However in more severe dips, this value can reach three to four p.u. Since this technology uses a converter connected to the rotor, it is of utmost importance to protect this converter and ensure the generation of power during the sag. The system also suffers high torque peak during the dip and crowbar is usually employed. D.DOUBLY FED INDUCTION GENERATOR WITH PERMANENT MAGNET EXCITERAccording to the manufacturer the xDFM technology does not demand the use of crowbar to limit the torque peak during the voltage sag. The converter remains active during all the dip because the exciter is a permanent magnet synchronous machine and the voltage is kept. Hence the converter is able to keep the control of rotor currents during the sag. In comparison with the synchronous generator, the xDFM has the capacity of providing higher currents, about five times the rated current, than full-converter technologies, about twice the rated current. E.SYNCHRONOUS GENERATOR WITH EXCITED ROTORIn the dc bus of the SGER that connects the converters, as seen in Fig. 23, a brake chopper is used to dissipate the excess energy of the capacitor. The chopper is triggered each time the voltage on the capacitor exceeds a certain threshold, balancing variations in power generated by the machine with the limitations of power flow for the network, as seen in Fig. 21 and Fig. 22. The chopper increases the supportability of the wind turbine facing sags and can be considered as an important measure of ride through 13. Fig. 15. WRIG active power during the voltage sag. Fig. 16. WRIG reactive power during the voltage sag Fig. 17. WRIG stator current (RMS) during the voltage sag. Fig. 18. DFIG active power during the voltage sag. Fig. 19. DFIG reactive power during the voltage sag. Fig. 20. DFIG rotor current during the voltage sag. F.SYNCHRONOUS GENERATOR WITH PERMANENT MAGNETOf the viewpoint of the supportability to voltage sags the SGPM is completely similar to the SGER. G.SYNCHRONOUS GENERATOR WITH DYNAMIC MULTIPLICATION GEARBOXThe main characteristic of a synchronous generator directly connected to the grid (without power electronics) is associated to its ride through capability during voltage sags due to its capacity in remaining synchronized during and after voltage dip. This characteristic is known as transitory stability. During sags, the synchronous generator provides high reactive currents, usually bigger than those provided by the generators using traditional technologies. This support to the grid allows for stable operation compared to other generators. IV.CONCLUSIONSAn investigation of old and new wind turbine technologies and their characteristics were made. The induction generator directly connected to the grid absorbs high currents during the remagnetization, after the voltage sag. The induction generator with resistance in rotor has more ride through capability than the SCIG due to its slip and power control. The DFIG technology uses power electronics and with the rotor control it is possible to control the active and reactive power of the machine, through two static converters. The xDFM uses a permanent magnet exciter that eliminates the slip rings, isolating the rotor circuit from the grid. Both technologies have the susceptibility to grid disturbances, since they are directly connected to the network, as their weakness. The wind turbines with SGER and SGPM have similar characteristics. Both are connected to the grid through frequency