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毕业设计(论文)外文资料翻译学 院： 专 业： 姓 名： 学 号： (用外文写)外文出处： Power System Technology. 2007. 31(20) 附 件： 1.外文资料翻译译文；2.外文原文。 指导教师评语：该生选择的文献与课题研究内容一致，翻译了Influence Research of Wind Power Generation on Power Systems，语句通畅，译文完整准确，论文无语法错误，用词准确，具备了本科生翻译外文资料的能力。 签名： 2012 年 3 月 30 日附件1：外文资料翻译译文风力发电对电力系统的影响简奥斯丁，费力克斯（电力系统及发电设备控制和仿真国家重点实验室，纽约市曼哈顿区）摘要：风力发电依赖于气象条件，并逐渐以大型风电场的形式并入电网，给电网带来各种影响。电网并未专门设计用来接入风电，因此如果要保持现有的电力供应标准，不可避免地需要进行一些相应的调整。讨论了在风电场并网时遇到的各种问题。由于风力发电具有大容量、动态和随机的特性，它给电力系统的有功/无功潮流、电压、系统稳定性、电能质量、短路容量、频率和保护等方面带来影响。针对这些问题提出了相应的解决建议和措施，以及更好利用风力发电。关键词：风力发电；电力系统；影响；风电场0、引言人们普遍接受，可再生能源发电是未来电力的供应。由于电力需求快速增长，对以化石燃料为基础的发电是不可持续的。正相反，风力发电作为一种有前途的可再生能源受到了很多关注。当由于工业的发展和在世界大部分地区的经济增长而发电的消费需求一直稳步增长时，它有减少排放和降低不可替代的燃料储备消耗的潜力。当大型风电场（几百兆瓦）是一个主流时，风力发电越来越更受欢迎。2006年间，世界风能装机容量从2005年的59091兆瓦达到74223兆瓦。在2006年极大的生长表明，决策者开始重视的风能发展能够带来的好处。由于到2020年12%的供电来于1250GW的安装风电装机，将节约累积吨二氧化碳1。大型风电场的电力系统具有很高的容量，动态随机性能，这将会挑战系统的安全性和可靠性。而提供电力系统清洁能源的同时，风农场也会带来一些对电力系统不利的因素。风力发电的扩展和风电在电力系统的比重增加，影响将很可能成为风力集成的技术性壁垒。因此，应该探讨其影响和提出克服这些问题的对策。1、风力发电发展现状从全球风能委员会（GWEC）的报告中，拥有最高装机容量总数的国家是德国（20621兆瓦），西班牙（11615兆瓦），美国（11603兆瓦），印度（6270兆瓦）和丹麦（3136兆瓦）。世界范围内十三个国家现在可以算是达到1000兆瓦的风力发电能力，法国和加拿大在2006达到这一阈值。如图1所示，直到2006年12月世界累计装机容量前10名2。中国开始发展风电很晚。只有在90年代它才走向市场化的发展和规模建设。这些年新增累积装机容量如图2显示。单一机组容量从100千瓦，200千瓦，300千瓦600千瓦，750千瓦，1500千瓦逐步增加。在2006年中国通过安装风能的1347兆瓦，增加了一倍以上的总量容量，比去年的数值增长了70%。这给中国带来多达2604兆瓦的能力，使中国成为世界第六个最大的市场。中国市场在2006年大幅增长，这预计将继续增长并加快增长。根据经批准的和在建设中的项目，在2007年将安装超过1500兆瓦。到2010年底在中国的风电目标为5000兆瓦3。图1 到2006年12月世界累计装机容量图2 在中国累计和新增加安装的风力发电能力2、风力发电项目的特点从风能的角度来看，风能资源的最显特点是其变化性。风电场输出的随机变化主要根源于风速的波动和方向。无论是地理性和时间性，风是很易变的。此外，无论是在空间和时间上，这种变化性持续的范围非常广泛。由于时间和高度的功能，风速不断变化。风变化的时间尺度显示在图3的风力频谱图上4。在一秒到分钟的范围阵风引起动荡的高峰。每日的峰值取决于每天的风速变化和天气高峰取决于天气变化，通常因每天或每周而异，但也包括季节性周期。Fig. 3 Wind spectrum farm Brookhaven based on work by van der Hoven从电力系统的角度来看，湍流高峰可能会影响风力发电的电能质量。然而，昼夜和天气的高峰，可能会影响长期的电力系统的平衡，在这样的系统中风速预测起着显著作用。另一个重要问题是风能资源的长期变化。应知道加速到中心高度的风来计算风电场的输出。大量风速测量表明，风速在一年中大多数是柔和的，介于0和25米/秒的概率是相当大的；年均风速受制于威布尔分布5，如公式（1）。 (1)其中：V是平均风速；k为形状参数；c是尺度参数。风力发电机的输出之间的关系PW和风速集线器V的高度可以近似表示为风力发电机的输出与风速或分段函数的曲线，如公式（2）。 (2)其中：PW是额定功率的风力发电机组的输出；V是风速达枢纽的高度VCI是停机风速；VCO被切出风速；VR被评为风速。3、风力发电对电力系统的影响在电力系统中风力发电面临大型风电场对电网一体化的基本技术限制。风力发电对电力系统的影响包括有效功和无效功流，电压，系统稳定性，电能质量，短路容量和基础设施的特点由于高容量的风力发电的动态和随机性能。在技术上，它通过以下方式影响和必须详细研究：（1）有功和无功流。风力发电是一个间歇性和随机的电源，将功率流复杂化。由于为了捕获更多的风能能源，许多风电场建成远离负荷中心，总有传输风力发电一些的障碍。当引进额外的风力发电时一些传输或配电线路和其他电气设备可能过载。因此，应确保互相连接传输或配电线路不过载。有功和无功要求，都应予以调查。无功功率应不仅在PCC中产生，但也通过整个网络产生，并应本地补偿6。用于常规发电机的分析的方法是确定的，而忽略了不确定性的风速和负荷预测。因此，概率性的方法是比较适合风力发电的。约束以概率形式描述，并且预期参数值，如电压和功率，可以被计算。（2）电压调节一旦风电场已经确定了其地点，连接到电网的点必须确定。小型风力发电场，可以在低电压下连接，从而节省了开关设备、电缆和变压器的成本。如果拟议的发展规模太大导致不可以与当地分布电压的连接，进而不能满足较高的电压传输网络的需要7。在电力系统中随着风力发电安装容量的增加，风力发电的变化引起电压变化，特别是如果并入电网，这可能不是专门设计用于迎合重要和可能快速变化的负载，这是由风力发电变化引起的。因此，需要采取监管措施，使电压保持在指定的范围内。然而，为了控制电压，这可能导致增加对无功功率的辅助服务8。（3）系统的稳定性。在风力发电的电力系统中，电压稳定和频率的稳定性都受到风功率集成影响，这不仅是因为风力发电的加入将改变流量分布，也因为风力发电机与传统的同步机无论是在稳态或瞬态状态时相比表现不同9。对于目前的风力发电场，当发生干扰时，保护操作通常是切断风电场之间的连接电网。因此，在这种时刻的暂态稳定是非常重要的，尤其是当大型风电场的有机结合时最为重要。然而，由于电网结构，风也可能使电源集成系统的瞬态稳定性差。因此，不同的电力系统，暂态稳定性应分别进行分析。固定速度的风力涡轮机输出有功功率时，它吸收无功功率。“风电场无功功率的整体需求是相当大，从而导致减少在PCC附近地区的电压稳定。与此相反，双馈变速风力发电机组对无功功率有一定的控制能力。根据不同的操作和控制计划，这种风力发电机组可以吸收或输出无功功率控制电压，有利于电压稳定。电压稳定也与短路容量相关，传输的PCC行比R / X和在风力发电场使用的无功补偿方法有关。（4）电能质量。风力发电的波动和相关电源（AC或DC）的传输、供电质量有直接的影响。结果，大量的电压波动，可能会导致电压在调控范围外变化，以及违反闪烁和其他电源的质量标准。在连续的运行和开关操作，风力发电机组，引起电压波动和闪烁，这些因素是风力发电影响电网电能质量的主要因素。对于变速风力涡轮机和恒定频率，转换器造成的谐波问题，也应考虑。风力涡轮机对电网干扰有不同的原因，其中大多原因是风力机本体。有关参数列于表110。平均发电量，湍流强度及风切变与气象和地理条件因素相关。所有其他的原因不仅归咎于电器元件的特点，如发电机，变压器等，也是转子和传动系统的空气动力学和机械性能的原因。涡轮形式（即变量与主要固定的速度档位与节距调节）对风力涡轮机和风力发电场的电能质量特性有重要性。表1.风力发电机和风力发电厂对电网造成的影响参数 原因电压升高 电能生产开关操作塔影效应电压波动和闪烁 叶片调节误差偏航误差风切变风速波动谐波 变频器晶闸管控制器电压峰值和谷值 开关操作闪烁是由风力发电机组的有功功率或无功功率的的波动造成的。固定速度的风力发电机闪烁的主要原因是塔的尾流。而变速风力发电机，平滑了快速功率波动，塔的尾流不影响输出功率。因此，变速风力发电机组的闪烁一般比定速闪烁风力发电机低。（5）短路容量。往往是大多数的风力发电场远离负荷中心建造，这意味着他们之间和其他间的电力系统的电气之间的距离，是相当远的。有一常理说，长电距离，使电压变化较大，但短路问题少11。然而，风力发电场将能够给未来的电力系统运行的短路电流计算带来越来越重要的影响。原因是双重的。一个是上述的事实，风力发电网站通常是远离的传统的电力中心。这意味着短路电流的分布可能产生了很大的变化，导致一个完全不同的短路容量地图。其他事实的原因是，今天，越来越多的风力发电，特别是以所谓的大型风力发电场（数百兆瓦）的形式。在风电场大量的个别单位连接在一起，总代能力将大大上升。风电场对相邻节点短路能力有很大影响，然而对远离PCC节点的影响不大9。因此，当具有大容量的风场并入电网时，相邻变压器和交换机的容量可能需要增加。应该进一步研究的是如何判断风力发电对现有网络上的电气设备短路电流额定值的影响12。（6）频率调整。为了在规定的标准范围内控制电力系统频率，要求一些发电厂向电网公司提供频率控制配套服务。然而，风力发电量总额的增加，其变化频率输出是一个很重要的影响8。（7）保护。电流在风电场和电网之间的流动是双向的，这是在保护的设计和配置应予以考虑的。无论风力发电机采用何种发电机，风电场的整合将增加电网故障水平，进而影响原有的电网保护装置继电器的设置。这可能需要增加新的保护装置或修改原有保护设备的继电器的设置。尤其是如果风电场连接到分配网络，断路器可能在风电场装机容量增加时产生超负荷8。4、减轻风力发电的影响的对策无功补偿设备的应用，如静止无功补偿（SVC）和静止同步补偿器（STATCOM）在风力发电中减轻其对电力系统的影响起着重要作用。为了保持电压等级，电网公司可以提供额外的或升级的电压控制设施。无功补偿设备应该安装在风电场升压变电站，这具有快速响应特性，并且可不断调节，如在SVC和STATCOM等。为了减少风力发电造成的电压波动和闪烁，既需要速度控制应加以改善，以便和俯仰角控制最大限度地减少了风力发电机的输出波动，而风力发电机的输出最大化。同时，如在风场安装辅助设备SVC和储能装置也可以减轻电压波动和闪烁。在大多数情况下，快速作用无功补偿设备，包括SVC和STATCOM，应被纳入为提高网络的暂态稳定的设备之中。从风力发电方面，它可以通过不断的功率因数控制或恒压控制提高电力系统的电压稳定增加风力发电的渗透。从电网方面，这对加强和改变目前的网络具有重要意义。电压源换流器系统（VSC）为基础的高压直流输电（VSC-HVDC系统）是一个不需要任何额外赔偿的传输系统，因为这是转换器的控制固有的13。因此，它将是一个很好的工具，它使风力发电成一个网络，即使在一个弱网络中，无需提高点短路比，也能实现。VSC-HVDC的有功功率控制能力，然后是一个完美的处理有源功率/频率控制的工具。它有能力以一个很好的方式处理风电并足以快速反应抵消电压变化，它可以提高系统的稳定性和电能质量。5、结论距今25年，风能已经经过很长的时间，它很可能会在未来20年继续推进。有许多关于整合风力发电系统的运作和发展的问题。虽然风力发电取代了产生相当数量能量的传统植物，关注点都集中在了风力发电和电网之间的相互作用上。本文提供了一个概览风力发电对电力系统的影响和相应的对策建议来处理这些问题，为了适应风在电力系统的发电。参考文献1 EWEAWind force 12EB/OL2 GWECGlobal wind energy markets continue to boom-2006 another record yearEB/OL3 Liu Yan，Wang Wei wind power information Technology，20074 Burton T，Sharpe D，Jenkins N，et alWind energy handbookMChichester：John Wiley & Sons Ltd，20015 Bowden G J，Barker P R，Shestopal V O，et alWeibull distribution functionJWind Engineering，1983，7(2)：85-986 Fan Zhenyu，Enslin J H RChallenges, principles and issues relating to the development of wind power in ChinaCIEEE PES PSCE，2006：748-7547 OGorman R，Redfern M AThe difficulties of connecting renewable generation into utility networksCIEEE Power Engineering Society General Meeting，2003，3：1466-14718 Wang Wei sheng，Chen MoziTowards the integrating wind power into power grid in ChinaJElectricity，2004，(4)：49-539 Chi Yong ning，Liu Yan hua，Wang Wei sheng，et alStudy on impact of wind power integration on power systemJPower System Technology，2007，31(3)：77-8110 Ackermann TWind power in power systemsMChichester：John Wiley & Sons Ltd，200511 Kumano TA short circuit study of a wind farm considering mechanical torque fluctuationCIEEE Power Engineering Society General Meeting，2006：1-612 Strbac G，Shakoor A，Black M，et alImpact of wind generation on the operation and development of the UK electricity systemsJElectric Power Systems Research，2007，77(9)：1214-122713 Eriksson K，Liljegren C，Sobrink KHVDC light experience sapplicable for power transmission from offshore wind power parksEB/OL附件2：外文原文Influence Research of Wind Power Generation on Power SystemsJane Austen，Kurt Felix（State Key Lab of Control and Simulation of Power Systems and Generation Equipments，Manhattan District，New York，United States）Abstract: Wind power generation is always weather dependent and has the trend of being integrated to power systems as the form of large-scale wind farms, which influences on power systems. Since the power network was not designed specifically to accommodate this type of generation, there are inevitably some points at which modifications must be executed if existing standards of electricity supply are to be maintained. This paper discusses in general terms the problems which are encountered by the developers of wind power generation projects and by utility grids when dealing with projects to integrate wind farms to power systems. The influence includes active and reactive power flow, voltage, system stability, power quality, short-circuit capacity, system reserve, frequency and protection due to the characteristics of high-capacity, dynamic and stochastic performance of wind power generation. Corresponding countermeasures to handle these issues are recommended in order to accommodate wind power generation in power systems.Key Words: wind power generation；power system；influence；wind farms0IntroductionThere is widespread acceptance that renewable generation is the future of electricity supply. Generation based on fossil fuels is not sustainable as power electricity is being consumed rapidly. On the contrary, wind power has attracted much attention as a promising renewable energy resource. It has potential benefits in curbing emissions and reducing the consumption of irreplaceable fuel reserves when the demand for power electricity has been steadily growing due to the industrial developments and the growth of the economy in most parts of the world.Wind power generation is becoming more and more popular while the large-scale wind farm(hundreds of megawatts) is the mainstream one. During 2006, the worlds installed wind capacity reached 74 223 MW, up from 59 091 MW in 2005,which include wind energy developments in more than 70 countries around the world. The tremendous growth in 2006 shows that decision makers are starting to take seriously the benefits that wind energy development can bring.There are no technical, economic or resource barriers to supplying 12% of the worlds electricity needs with wind power alone by 2020, and this against the challenging backdrop of a projected two thirds increase of electricity demand by that date. The report is a crucial tool in the race to cut greenhouse gas emissions as 12% electricity from a total of 1 250 GW of wind power installed by 2020 will save a cumulative 10771 million tons of CO21.Large-scale wind farms connected to power systems have characteristics of high capacity, dynamic and stochastic performance, which challenges system security and reliability. While providing the clean power for power systems, wind farms will also bring about some unfavorable influence on power systems. With the expansion of wind power generation and the increase of wind power ratio in a power system, the influence will likely become the technical barriers for wind power integration. Therefore, the influence should be discussed and the countermeasures to overcome these issues should be proposed.According to the issues mentioned above, this paper discusses in general terms the problems which are encountered by the developers of wind power generation projects and by utility grids when dealing with projects to integrate wind farms to power systems. Due to the characteristics of high-capacity, dynamic and stochastic performance of wind power generation, the influence includes active and reactive power flow, voltage, system stability, power quality, short-circuit capacity, system reserve, frequency and protection. After that, corresponding countermeasures to handle these problems are recommended in order to accommodate wind power generation in power systems.1Development situation of wind power generationFrom the report of the Global Wind Energy Council (GWEC), the countries with the highest total installed capacity are Germany (20 621 MW), Spain (11 615MW), the USA (11603MW), India(6270 MW) and Denmark (3 136 MW). Thirteen countries around the world can now be counted among those with over 1000 MW of wind capacity, with France and Canada reaching this threshold in 2006. Fig.1 shows the top 10 cumulative installed capacity of the world until December, 20062.China started to develop wind power very late. It stepped into the stage of commercialized development and scale construction only in 1990s. Accumulated and newly added installed generating capacity over the years is shown in Fig.2.The single-unit capacity increased from 100 kW, 200 kW, and 300 kW to 600 kW, 750 kW, and 1500 kW step by step.Fig. 1 Top 10 cumulative installed capacity of the world until December,2006Fig. 2 Accumulative and newly-added installed capacity of wind power in ChinaChina doubled more than its total installed capacity by installing 1 347 MW of wind energy in 2006, a 70% increase from last years figure. This brings China up to 2 604 MW of capacity, making it the sixth largest market world wide. the Chinese market has grown substantially in 2006, and this growth is expected to continue and speed up. According to the list of approved projects and those under construction, more than 1 500 MW will be installed in 2007. The goal for wind power in China by the end of 2010 is 5000 MW3.2Characteristics of wind power generationFrom the point of view of wind energy, the most striking characteristic of the wind resource is its variability. The stochastic variation of wind farms outputs root mainly in fluctuation of the wind speeds and directions. The wind is highly variable, both geographically and temporally. Furthermore this variability persists over a very wide range of scales, both in space and time.The wind speed varies continuously as a function of time and height. The time scales of wind variations are presented in Fig.3 as a wind frequency spectrum4. The turbulent peak is caused by gusts in the sub second to minute range. The diurnal peak depends on daily wind speed variations and the synoptic peak depends on changing weather patterns, which typically vary daily to weekly but include also seasonal cycles.Fig. 3 Wind spectrum farm Brookhaven based on work by van der HovenFrom a power system perspective, the turbulent peak may affect the power quality of wind power generation. The influence of turbulences on power quality depends very much on the turbine technology applied. Variable-speed wind turbines, for instance, may absorb short-term power variations by the immediate storage of energy in the rotating masses of wind turbine drive trains. That means that the power output is smoother than strongly grid-coupled turbines, fixed-speed wind turbines. Diurnal and synoptic peaks, however, may affect the long-term balancing of power system, in which wind speed forecasts plays a significant role.Another important issue is the long-term variations of the wind resources. The wind speed up to the height of the hub should be known to calculate the wind farm output. A number of measurements of wind speeds show that wind speeds are mostly mild in a year; their probabilities between 0 and 25m/s are considerable; most of the average annual wind speeds subject to the Wei bull distribution5, as in formula(1). (1)where: v is average wind speed; k is shape parameter; c is scale parameter.The relationship between the wind turbine output Pw and the wind speed up to the height of the hub v can be expressed approximately as the curve of wind turbines outputs vs. wind speed or a subsection function, as in formula (2). (2)where: Pw is rated output of the wind turbine; v is wind speed up to the height of the hub; VCI is cut-in wind speed; VCO is cut-out wind speed; VR is rated wind speed.3Influence of wind power generation on power systemsHigh penetration of wind power in the power systems faces fundamental technical limits with regard to the integration of large-scale wind farms to the grid. The influence of wind power generation on power systems includes active and reactive power flow, voltage, system stability, power quality, short-circuit capacity, system reserve and infrastructure due to the characteristics of high-capacity, dynamic and stochastic performance of wind power generation. Technically, it influences the gird in the following ways and has to be studied in detail:（1）Active and Reactive Power Flow.Wind power is a kind of intermittent and stochastic power source, which will complicate the power flow. Because many wind farms are built far away from load centers in order to capture more wind energy, there is always some obstacle of transmitting wind power. Some transmission or distribution lines and other electrical equipments may be over-loaded when the additional wind power generation is introduced. So it should be ensured that the interconnecting transmission or distribution lines will not be over-loaded. Both active and reactive power requirements should be investigated. Reactive power should be generated not only at PCC, but also throughout the network, and should be compensated locally6.The methods utilized for analysis of conventional generators are certain and ignore the uncertainty of wind speed and load forecasts. Therefore, the probabilistic method is more suitable for wind power generation. This model is based on the wind speed distribution, such as formula (1). The constraints are described by probabilistic forms and the expected values of parameters, such as voltages and powers can be computed.（2）Voltage Regulation.Once a wind farm has identified its site, the point at which connection to the grid must be identified. Small wind farm can connect at lower voltage, thereby saving on switchgear, cable and transformer costs. If the size of the proposed development is too large to be connected at the local distribution voltage, access to the transmission network at a higher voltage is required7.After failures, if the transient unstability does not occur in power systems, some wind turbines shut down due to their low voltage protections. Then outputs of wind farms decrease, which means that the power system lose reactive loads. Therefore the voltage levels climb up, even beyond the upper limits of wind farms buses.Capacitors are the common reactive power compensation methods. When voltage levels dropdown, the amount of compensation decreases much. However the reactive power demands increase when the asynchronous machines are utilized in wind farms. So voltage levels drop down more, even beyond the lower limits of wind farms buses.With the increase of wind power installed capacity in power systems, the variability of wind power generation causes variability of voltage level, particularly if integrated into the grid which might not be specifically designed to cater for the significant and possibly rapid load variations (compared with normal customer load variation) caused by highly variable wind power generation. Therefore, the regulatory measures are needed to maintain the voltage level in a specified range. However, the variability of wind power generation is not a low probability; this could result in an increased requirement for reactive power ancillary services to manage voltage control8.（3）System Stability.In the power system with high wind power penetration, the transient stability, voltage stability and frequency stability are all influenced by the wind power integration not only because the injection of wind power will change the power flow distribution, transferred power of each transmission line and total inertia of the whole power system, but also because the wind turbine generators perform differently in either steady-state or transient-state compared with the conventional synchronous machine9.For current operation of wind farms, protections usually cut off the connections between wind farms and the grid when great disturbances occur. This is equivalent to arouse new generators tripping disturbance after the great disturbances. So the transient stability in such moment is very crucial, especially when large-scale wind farms are integrated. Compared the variable-speed wind turbine based on the doubly-fed induction generator (DFIG) with the fixed-speed wind turbine based on the induction motor, the
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