Cluster Analysis of Wind Turbines of Large
Wind Turbine Icing and De- Icing
American Institute of Aeronautics and Astronautics1Wind Turbine Icing and De-IcingG. Fortin * and J. Perron †Anti-icing Materials International Laboratory, Université du Québec à Chicoutimi, Québec, Canada , G7H 2B1This paper presents the wind turbine icing challenge, explains the wind turbine icingprocess and how to address the problem of icing and de/anti-icing wind turbines. Thephysics of ice accretion is explained such as rime and glaze ice accretion as well as howmeteorological parameters such as air speed and temperature, altitude, liquid water contentand water droplet median volumetric diameter, as well as wind turbine rotational speed andblade profile impact on ice accretion. Numerical methods to predict water droplettrajectories, ice accretion and aerodynamic performance degradation are presented. Thesemethods can aid in the positioning of de/anti-icing systems. A recommendation for thepositioning of deicing systems in the profile section and along the blade is provided.NomenclatureA = Area m²Ac = Accumulation parameterc = Chord mC D = Drag coefficientC f = Friction coefficientCp = Specific heat J/(kg K)D = Diameter mD va = Water vapor diffusion coefficient in airm²/s D sh = Safety shedding distance mD WT = Wind turbine diameterm e = Thickness mE = Collection efficiencyE ice = Ice Young modulusPa f = Freezing fractionF = Frequency Hzg = Gravitational acceleration m/s²h = Heat transfer coefficient W/(K m²)h dif = Mass transfer coefficient by diffusion m/sH = Height mH hub = Hub height mk = Thermal conductivity W/(K m²)l = Flat plate length mL = Latent heat J/(kg K)Le = Lewis numberLWC = Liquid water content kg/m³m = Mass rate kg/sMVD = Median volumetric diameter of water droplet mP = Precipitation intensity mm H 2O/hrP v = Water vapor pressure PaP vs = Saturated water vapor pressure PaPr = Prandtl numberQ = Heating Wr = Recovery factor * Associate Professor, Département des sciences Appliquées, 555, bld de l’Université, Chicoutimi, AIAA member. † Professor, Département des sciences Appliquées, 555, bld de l’Université, Chicoutimi.47th AIAA Aerospace Sciences Meeting Including The New Horizons Forum and Aerospace Exposition 5 - 8 January 2009, Orlando, Florida AIAA 2009-274Re = Reynolds numberR v= Water vapor perfect gas constant J/(kg K)s = Curvilinear abscissaS ct= Solar radiation constant W/m²Sk = Stokes numberSt = Stanton numbert = Time sT = Temperature KT0= Initial surface temperature KT rec= Recovery temperature KT s= Surface temperature KT sky= Sky temperature KU = Speed m/sUτ= Friction speed m/sv = Speed m/sv term= Terminal speed of droplet m/sW = Energy Jα = Proportionality constant between thickness and frequency mm/Hzαi= Thermal diffusion coefficient of ice m²/sαw= Absorptivity factor of waterβ = Local collection efficiencyεw= Emissivity factor of waterκ = Roughness height mκs= Equivalent sand grain roughness mΚd= Droplet inertia parameterρ = Density kg/m³ρve= Density of the water vapor at the edge of the boundary layer kg/m³ρvs= Density of the water vapor at the object’s surface kg/m³φ = Relative humidityσSB= Stefan Boltzman constant W/(m² K4)θl= Quantity of movement thickness in a laminar regime mθt= Quantity of movement thickness in a turbulent regime mθz= Azimuth angle °μ = Dynamic viscosity Pa sν = Kinematics viscosity m/sτ = Adhesive shear stressτw= Wall shear stress Paa = Aird = Droplete = Edge of the boundary layeri = Iceimp = Impingementw = Waterws = Wet snowadh = Adiabatic heatingcd = Conductioncv = Convectionevap = Evaporationf = Freezingkin = Kineticrad = Radiationss = Sensiblesub = Sublimation∞= Free Stream2American Institute of Aeronautics and AstronauticsAmerican Institute of Aeronautics and Astronautics3I. IntroductionHIS paper provides an understanding of why and how wind turbines are affected by an icing event and possibilities to de/anti-ice wind turbine blades.Many structures are affected by atmospheric icing such as: airplanes, boats, helicopters, transmission lines and pylons, antenna or communication towers and wind turbines. In many cases, the ice accumulated on the structure can cause breakdowns, but for objects composed of an aerodynamic profile such as airplanes, helicopters and wind turbines, the ice mass accumulated is not as critical as the shape of the ice deposit. The ice shape affects the aerodynamic profile and decreases aerodynamic performance by decreasing lift and increasing drag.Perhaps, wind turbines can produce power with such ice accretion, when the ice is uniformly distributed over the blades; the aerodynamic efficiency and torque are reduced, leading to power losses due to high drag associated with the ice accretion. A light icing event such as frost can produce enough surface roughness to considerably reduce aerodynamic efficiency [1]. However, when the icing event is very severe [2], torque drops to zero, the turbine stops, and a complete loss of production ensues. Also, wind turbines can stop rotating due to heavy vibrations under uneven ice cover [3]. These vibrations can cause chunks of ice to detach and, during the accretion-expulsion process vibration intensity can increase, leading to the collapse of the wind turbine if it is not stopped. In some cases, when large chunks of ice are ejected, the wind turbine must be shut down to protect other turbines in a wind farm, as well as nearby residents [4].The increased commercial use of wind turbines in a wide range of weather conditions, for example, in cold regions of North America, Northern and Central Europe and Asia, off-shore or in mountains, means that there is growing interest acquiring wind turbines adequately equipped to face the associated extreme working conditions [5] and at least some form of icing clearance. As an example, wind turbines operating in cold climates are equipped with heated nacelles because mechanical and hydraulic components of the turbine cannot properly operate at very low temperatures and for offshore wind turbines operating in cold regions, high water vapor content can cause frost and sea spray ice growth. Ice accretion, frequent in these regions, generates an overload for the whole wind turbine and mechanical wear can be significantly accelerated. The aerodynamic performance of the blades is significantly affected by accreted ice and, therefore, it is important to consider de-icing systems. Unfortunately, these systems are rarely used, mostly for economical reasons and technical drawbacks. Installing de/anti-icing systems on wind turbines is more difficult than on aircraft. Much of aircraft de/anti-icing technology is inadequate for the wind turbine industry due to system power requirements as well as the blade rotation speeds. Wind turbines have limited available power; manufacturers prefer to use the power to produce electricity, rather than for powering ice-protection systems. Moreover, ice protection systems reduce the wind turbine capacity due to the de/anti-icing systems power consumption as well as the blade rotation involves adding a slip ring to transfer the power generator energy to the de/anti-icing systems. A slip ring decreases considerably the ice protection systems’ reliability and increases the maintenance costs. Currently, deicing systems are used for safety reasons as public protection or to allow for non-stop use. Different technologies have been considered to deice wind turbine blades such as microwave hot airflow or electro-thermal systems as well as pneumatic deicers and ice phobic coatings. However, hot airflow and electro-thermal systems are mostly used because they involve fewer modifications to the wind turbine blades. Electro-thermal systems are used in some sites such as Yukon (Canada) and Pori and Olostrunturi (Finland) [2]. In Pori, the system was used for public safety reasons and its power consumption was 1% of the wind turbine’s annual production (average between 1999 and 2001) with a maximum of 6% of the nominal power. In Olostrunturi (Finland), the de-icing system consumed 3.6% of the annual wind turbine production during 2000. Since icing, even light, can cause 30% loss in the instantaneous power production [1] or stopping of the wind turbine during icing events, can lead to a loss of up to 10% of the annual production, the percentage is linked to the number and the severity of icing vent. II. Icing Event FormationIcing occurs in presence of precipitation such as freezing drizzle or rain, wet snow or hydrometeors such as icing fog or cloud or frost and at temperatures below freezing.In the atmosphere, cloud formation results from the cooling of an air volume until the condensation of a part of its water vapor. Generally, a cloud is composed of water vapor, small water droplets below 70 µm, and ice crystals in suspension in the atmosphere. Fog is caused by the same phenomenon occurring at ground level. Fog often occurs near seacoasts or along large lakes. Onshore breezes bring moist maritime air over a cold land surface and the water vapor condenses in small water droplets to form fog. Water droplets only freeze spontaneously below -40ºC; for temperatures between 0 and -40ºC, the water droplets are in a meta-stable state called supercooling and will freeze only after a long time period. This phenomenon prevails at temperatures between 0 and -20ºC. A cloud or fog, at orTAmerican Institute of Aeronautics and Astronautics4below freezing is composed of supercooled water droplets; when the droplets touch an object, they freeze on contact. This type of cloud or fog is referred to as a freezing cloud or fog.Dew moisture content in the air condenses when the air is in direct contact with a cooler surface. The surface is cool below the ambient temperature by radiation to a clear night sky. When this phenomenon occurs at or below freezing, moisture sublimates to deposit with crystalline appearance. The thin skin of ice deposited over a surface is called frost. Generally, frost occurs on cold clear night and it is more present near a large water body or river. A hydrometeor is characterized by its median volumetric diameter of water droplets and by its liquid water content which is a measure of the water density of the hydrometeor formed by droplets. It is the total mass of water contained in all the liquid cloud per unit volume of cloud and does not include water in vapor form and it is expressed in grams of water per cubic meter of air. The liquid water content varies from cloud to cloud; convective clouds have higher liquid water contents than stratiform clouds. Fog or clouds at low altitude have liquid water contents generally below, or equal to, 0.3 g/m³. The median volumetric diameter of the water droplet is a single representative value of the cloud droplets which split the droplet distribution into two equal parts. Typical values for the median volumetric diameter are between 10 and 50 µm for stratiform clouds and for cumuliform clouds, composed of larger droplets; it is usually between 20 to 50 µm and for fog is 15 and 50 µm. A typical medianvolumetric diameter in conventional icing event due to hydrometeor is 25 µm. Due to the presence of a warm air mass (T > 0ºC) inaltitude, the ice crystals in clouds melt and the water dropletsgrow in size by condensation (Figure 1). The turbulence inclouds contributes to the droplet growth processes. When thedroplets are heavy enough, they fall out of the cloud as rain ordrizzle. During the fall, the temperature can descend, reachingthe freezing point, or below, due to the presence of a cold front(T < 0ºC) near the ground. When the supercooled water dropletsimpact the ground, or other objects, they freeze on contact; thisprecipitation is called freezing rain or drizzle. Rain is composedof water droplets greater than 0.5 mm in diameter. Themaximum water droplet diameter is about 5 to 6 mm, above thissize, the droplets break to form smaller droplets during fall.Rain falling from a convective cloud is composed of largedroplets changing rapidly in intensity as compared to rainfalling from stratiform clouds. Drizzle consists of small anduniformly dispersed droplets that appear to float whilefollowing air currents, but droplet diameter is too large toremain suspended in clouds unless they fail with a substantial updraft speed. Drizzle is composed of droplet sizes less than 0.5 mm called super large droplet. A typical median volumetric diameter in a conventional freezing drizzle is 250 µm. Drizzle usually falls from low status clouds and is frequently accompanied by fog and reduced visibility.Precipitation intensity, which is the rate at which rain or drizzle falls, is express in mm of H 2O per hour. For a light shower, the precipitation intensity is about 1 mm H 2O per hour, for a normal shower, the intensity is about6.5 mm H 2O per hour and for a heavy rainfall, the intensity can be greater than 25 mm H 2O per hour. The precipitation intensity can be translated in liquid water content byterm w v PLWC 51036×=ρ (1)where the precipitation intensity is in mm of H 2O per hour. For a light shower, the liquid water content is about 0.05 g/m³, for a normal shower about 0.3 g/m³ and for strong rainfall it is greater than 1 g/m³.Snow occurs in meteorological conditions similar to those in which rain occurs, except that with snow the initial temperatures must be at or below freezing. Generally, snow consists of combinations of individual ice crystals and has a diameter between 1 and 20 mm. During a snow fall, the temperature can rise, above freezing but below 5ºC due to the presence of a warm front near the ground. The snow flakes melt partially and become wet. This condition is referred to as wet snow. The wet snow particles have a diameter between 0.5 to 5 mm. When the wet snow touches an object the snow flakes adhere due to the water surface tension.Figure 1. Freezing precipitation formation.American Institute of Aeronautics and Astronautics5III. Water Collection Supercooled water droplets in suspension inair (clouds or fog) or falling on the ground willimpact an object moving through the air. Todetermine the quantity of liquid water collectedby an object, the traditional approach is todetermine where and at what rate the cloud waterdroplets impact. This requires a droplet trajectoryanalysis (Figure 2) which provides the proportionof the liquid water impacting on an object and theimpingement surface. A. Water Droplet Trajectory CalculationsThere are two main types of trajectory calculations; the most used method is the Lagrangian formulation in which individual water droplets are tracked from a specified starting point upstream of the body. The second method is the Eulerian, in which the volume fraction is calculated at the same point at which the aerodynamic parameters are known. For both methods, a flow solution is needed. A simple panel method or a full Navier-Stokes solver is used to find a flow solution. The trajectory equations are based on the following assumptions: the droplets are spherical and not deformable, there is no collision or coalescence between droplets, the water droplet concentration is small enough so that droplets have no effect on the flow analysis, the turbulence effects are negligible and the only forces acting on the droplet are aerodynamic drag, gravity and buoyancy. In the Lagrangian formulation, the trajectory is determined by solving the motion equation()g v v K C dt v d w a d a d d D d r r r r ⎟⎟⎠⎞⎜⎜⎝⎛−+−=ρρ1124Re (2) Where the droplet Reynolds number is given byd a d aa d v v D r r −=μρRe (3) And the inertia parameter is given by 2181d aw d D K μρ= (4) The droplet drag coefficient is assumed to equal to the drag coefficient of a sphere. Many empirical relations were developed over the last 75 years to approximate the drag coefficient of a sphere. Clift and Gauvin in 1970 [6] developed a simple relation valid for droplet Reynolds numbers below 300 000.()16.1687.0Re 42500142.0Re 15.01Re 24−+++=d d d D C (5) For a droplet falling at constant acceleration, the left part of equation 2 is equal to zero and the droplet terminal velocity isd a w D term D C g v ⎟⎟⎠⎞⎜⎜⎝⎛−=134ρρ (6) Figure 2. Water Droplet Trajectories.American Institute of Aeronautics and Astronautics6B. Collection EfficiencyThe water droplets following streamlines tend to deviate from curved streamline due to their mass inertia; water density being 850 times greater than air. Near the leading edge of an aerodynamic profile, streamlines are curved, small droplets follow the streamlines and the other droplets are deviated and impinge on the profile. The liquid water mass rate collected is the impingement of supercooled water droplets present in the air. It is related to local collection efficiency, liquid water content, free stream velocity and the deposit surface corresponding to the impingement surface.imp a imp A U LWC mβ=& (7) The collection efficiency is the fraction of the freestream water concentrationwhich impacts at a givensurface location of the object(Figure 3). It is defined as theratio of the liquid water masscollected by the objectbetween the lower and upper limits of droplets impact andthe liquid water mass collected if the droplets follow rectilinear trajectories.The local collection efficiency is determined by calculating the water droplets deflection in the air flow. Under the differential form, the local collection efficiency isdsdy =β(8) The total collection efficiency is a measure of the total water collected by the object and is∫=supinf 1s s ds H E β (9)NACA0012 airfoil with an air speed of 67 m/s, a dropletdiameter of 20 µm and an angle of attack of 4º. Generally,the collection efficiency distribution has a peak near the stagnation point and decrease to zero at the lower andupper surfaces of the object.The collection efficiency and the impingement surface increase when the droplet size increases (Figure 5). Themass inertia of the droplet increases with the dropletperturbed, the streamlines are only slightly curved and theacceleration is insufficient to deflect the droplets. For the same reason, the collection efficiency and the impingement surface decrease when the object’s thickness increases(Figure 6) or the air speed decreases (Figure 7). The flow around a thick object is accelerated due to the greater perturbation and the streamlines are highly curved, a greater droplet mass inertia is needed to not be deflected.The collection efficiency is about the same when the angle of attack changes and the impingement surface increases when the angle of attack increases (Figure 8). The lower impingement limit increases more than the upper limit. The stagnation point moves in the upper wing section when the angle of attack increases. In the same way, when the angle of attack decreases (negative value), the stagnation point moves in the lower direction.Figure 3. Collection Efficiency Definition.American Institute of Aeronautics and Astronautics7IV. Ice AccretionC. Thermodynamics of Ice AccretionThe supercooled droplets, when they are disturbed such as been impacting on a surface, tend to freeze instantly to form an ice accretion on the surface. The freezing can be complete or partial depending on how rapidly the latent heat of fusion can be released into the ambient air.Under a dry regime all the water collected in theimpingement area freezes on impact to form rimeice, and, for a wet regime, only a fraction of thecollected water freezes in the impingement area toform glaze ice and the remaining water runs backand can freeze outside the impingement area(Figure 9). Usually rime ice is associated withcolder temperatures, below -10°C, lower liquid water contents and smaller median volumetricdiameters. Often, rime ice quite closely takes on the original contour of the aircraft components due to the impinging water droplets which freeze on impact and the performance penalties are not as serious as that of glaze ice. Often, the impingement limit is small and close to the leading edge. This makes the prediction of rime ice relatively easy. Rime ice usually has a milky appearance because of imprisoned air within the ice structure (Figure 10).Glaze ice glaze is transparent (Figure 10) and associated with warmer temperatures, above -10°C, higher liquid water contents and greater median volumetric diameters. The actual physics of glaze ice accretion is not well understood. Glaze is the most dangerous type of ice, because of its wet nature, and the resulting shapes tend to substantially deform the accreting surface component with the formation of horns and feathers. The horn andFigure 9. Ice types.American Institute of Aeronautics and Astronautics8feathers have complex shapes, rugged structures which growforwards into the airflow. Glaze ice formation severelydecreases the airfoilaerodynamic performance bycausing dramatic increases indrag and decreases in lift. Thelarge increase in drag is due principally to local air flow separation which occurs beyondthe horn and feathers. Glaze ice also substantially decreases the stall angles of attack.Generally, during an icing event, the ice accreted on theobject is heterogeneous, i.e. composed of rime and glaze ice.Often rime ice is formed at the beginning of the accretion. Allthe latent heat release in the impingement zone is absorbed inthe ambient milieu and the surface temperature is belowfreezing. During accretion, the surface temperature increases,due to the liberation of latent heat during ice solidification, ifthe accretion conditions are favorable, the surfacetemperature will reach the freezing point and glaze ice isformed. Only a fraction of the latent heat released in theimpingement zone is absorbed in the ambient milieu. Othersituations of mixed accretion, due to the speed distributionaround the object, near the stagnation point, the speed is low and the ambient milieu can not absorb all the released latentheat, glaze ice is formed with a water film. The water runsback over the surface, freezes partially inside or outside ofthe impingement zone to form horns and at a critical point(Figure 11), the runback water will freeze totally, theaccretion regime changes to dry, and rime ice forms. Thecritical point position depends on the energy balance.Sometimes, the runback water does not freeze totally andruns over the entire surface.The usual way to determine the ice accretion over anobject is the Messinger approach. Considering a steadystate, energy conservation is applied on a control volumeas shown in Figure 12. The heat balance on each panel isthe sum of the following energies: latent heat ofsolidification, evaporation and sublimation, sensible,convection, conduction and radiation heats, as well asadiabatic and kinetic heating. The steady state assumption requires that the rate at which the energy is added to each control volume is equal to the rate at which it is removed:rad cv cd evap sub ss kin adh f Q Q Q Q Q Q Q Q &&&&&&&&++++=++/ (10) Heat is added to the impingement surface mainly from the latent heat of fusion released during freezing, from adiabatic heating induced by the aerodynamic heating, and to an even smaller extent from the kinetic energy of the droplets impacting the surface. The adiabatic heating is not significant for Mach numbers below 0.3 as compared to the latent heat of fusion and can be very significant for Mach numbers above 0.7. Heat is removed from the surface principally by convection and evaporation when the surface is wet, and by convection and sublimation when the surface is dry, and, to a lesser degree, by conduction in the ice and by radiation to the atmosphere. A fraction of the heat is used to bring the liquid water from the initial to the final temperature. Convective and evaporative or sublimation heat transfers are crucial to determine the ice accretion regime because they control the magnitude ofFigure 11.Glaze Ice Accretion. Figure 12. Control volume energy balance for ice accretion. Figure 10.Rime and glaze ice.American Institute of Aeronautics and Astronautics9the heat that can be absorbed in the ambient milieu. In the following sections, the heat rates are calculated for a control volume delimited by the impingement surface.D. Solidification HeatWhen water freezes, the water phase changes from liquid to solid gives off energy in the control volume, known as the latent heat of solidification. The solidification heat is the product of the collected water mass, the freezing fraction, which is the part of the liquid water that freezes on the surface, and the latent heat of solidification: f imp fL f m Q &&= (11) E. Adiabatic HeatThe heat introduced by air friction on the object is from a viscous adiabatic heat which occurs inside the boundary layer. It is defined as the convective heat of the flow whose temperature goes from the free stream temperature to an average temperature known as the recovery temperature, and it is expressed as:()imprec cv adh A T T h Q ∞−=& (12) The recovery temperature defined by Schlichting [7], consists of the average temperature at the edge of the boundary layer corrected as a function of the boundary layer air pressure for a non-conducting plate: ae rec Cp U r T T 22+=∞ (13) The recovery factor, r, is a function of the Prandtl number and depends on the flow regime:For laminar flow Pr =r and for turbulent flow 3Pr =r (14) with Prandtl number defined as a aa k Cp μ=Pr (15)F. Sensible HeatSensible heat is provided by the temperature change of water and ice respectively. First it is calculated for the water that goes from its initial temperature to its solidification temperature. Then, it considers the enthalpy variation of frozen and liquid water from the solidification temperature to the surface temperature. The temperature of the liquid water mass is that of the droplet at the edge of the boundary layer. The total sensible heat is given by: ()()()()s f w imp s f i imp f d imp imp ssT T Cp f m T T Cp f m T T Cp m Q −−+−+−=1 &&&& (16) G. Convective HeatConvection heat transfer is produced by the airflow over the wing’s surface and is given by Newton’s cooling law. The convective heat is expressed in terms of the convective heat transfer coefficient and the difference between the undisturbed flow temperature and the surface temperature:()imps cv cv A T T h Q −=∞& (17)American Institute of Aeronautics and Astronautics10The calculation of the convective heat transfer coefficient is based on a modified Nusselt number. The former is expressed as a function of the Stanton number, the speed at the edge of the boundary layer, the air density, and its specific heat.St U h e cv a a Cp ρ= (18) The Stanton number is defined using the Chilton-Colburn [8] analogy in laminar regime, and by the Spalding [9] analogy in turbulent regime, which takes into consideration the surface roughness.The Chilton-Colburn analogy defines the Stanton in a laminar regime [8] as a function of the friction coefficient and the Prandtl number: 3/2f 21Pr C −=St (19) The friction coefficient for a flat plate can be expressed in a laminar regime as a function of the kinematic viscosity, the speed at the edge of the boundary layer and the momentum thickness: e l af U C θν225.021= (20)Spalding’s analogy [9] defines the Stanton number for a rough flat plate in a turbulent regime as a function of the friction coefficient, the turbulent Prandtl number, and the rough Stanton number: κSt C C St f f21219.0+= (21)The rough Stanton number is defined as a function of the Prandtl and Reynolds numbers:8.045.0PrRe 92.1−−−=κτκSt (22) Here, the Reynolds number is based on the roughness height, the friction speed and the kinematic viscosity of air: a Re νκτκτsU =− (23)The friction speed is proportional to the speed at the boundary layer limit and the friction coefficient in the turbulent regime. f e C U U 21=τ (24) The local friction coefficient [10] in the turbulent regime is a function of the momentum thickness and the roughness height: 221568.2864ln 1681.0⎥⎦⎤⎢⎣⎡⎟⎟⎠⎞⎜⎜⎝⎛+=s t f C κθ (25)。
英语 风力机 英文简介
3.Show the horizontal axis wind turbine
The first successful application of horizontal axis wind turbine——holland pinwheel
Thank you for your attention!
electric gene rator
electric generator
Fan is controlled by many computers
Every change of fan are monitoring by control controller
electric generator
anemograph(风速仪)
Yaw motor（偏航电机）
Let the wind turbines absorb wind energy to the greatest extent
Let the wind turbines absorb wind energy to the greatest extent
3.Show pictures of wind machine
Used to measure wind speed
Used to measure wind speed
wind indicator（风向标）
Used to measure the direction of the wind
Used to measure the direction of the wind
The internal gear box
Gear box outside
High-speed shaft
Generator connected to the gear box with high-speed shaft
风力发电常用名词解释
风力发电常用名词解释/wind energy resources 大气沿地球表面流动而产生的动能资源。
空气的标准状态/standard atmospheric state 空气的标准状态是指空气压力为101 325Pa，温度为15℃（或绝对288.15K），空气密度1.225kg/m 3 时的空气状态。
风速/wind speed 空间特定点的风速为该点空气在单位时间内所流过的距离。
平均风速/average wind speed 给定时间内瞬时风速的平均值。
年平均风速/annual average wind speed 时间间隔为一整年的瞬时风速的平均值。
最大风速/maximum wind speed 10分钟平均风速的最大值。
极大风速/extreme wind speed 瞬时风速的最大值。
阵风/gust 超过平均风速的突然和短暂的风速变化。
年际变化/inter-annual variation 以30年为基数发生的变化。
风速年际变化是从第1年到第30年的年平均风速变化。
[风速或风功率密度]年变化/annual variation 以年为基数发生的变化。
风速（或风功率变化）年变化是从1月到12月的月平均风速（或风功率密度）变化。
[风速或风功率密度]日变化nal variation 以日为基数发生的变化。
月或年的风速（或风功率密度）日变化是求出一个月或一年内，每日同一钟点风速（或风功率密度）的月平均值或年平均值，得到0点到23点的风速（或风功率密度）变化。
风切变/wind shear 风速在垂直于风向平面内的变化。
风切变指数/wind shear exponent 用于描述风速剖面线形状的幂定律指数。
风速廓线/wind speed profile, wind shear law 又称“风切变律”，风速随离地面高度变化的数学表达式。
<i>常用解释</i>湍流强度/turbulence intensity 标准风速偏差与平均风速的比率。
新型海上风机浮式平台运动的频域分析_唐友刚
第46卷 第10期 2013年10月天津大学学报(自然科学与工程技术版)Journal of Tianjin University (Science and Technology )V ol.46 No.10Oct. 2013收稿日期：2012-05-09；修回日期：2012-11-08.基金项目：天津市应用基础及前沿技术研究计划资助项目(11JCYBJC07300)；教育部高等学校博士点基金资助项目(20110032110041)；国家自然科学基金创新研究群体科学基金资助项目(51021004). 作者简介：唐友刚（1952—），男，博士教授． 通讯作者：唐友刚，tangyougang_td@.DOI 10.11784/tdxb20131005新型海上风机浮式平台运动的频域分析唐友刚1, 2，李嘉文1, 2，曹 菡1, 2，陶海成1, 2，李溢涵1, 2(1. 天津大学水利工程仿真与安全国家重点实验室，天津 300072；2. 天津大学建筑工程学院，天津 300072) 摘 要：以5MW 风机为模型，概念性地设计了一种新型海上风机浮式平台．基于三维势流理论和Morison 经验公式，利用HydroD 软件计算了浮式平台的水动力系数；根据悬链线理论，编程计算了系泊系统提供的回复刚度；考虑风机与平台、系泊系统与平台之间的耦合以及黏性阻尼的影响，在频域范围内编程计算了风机系统的运动响应，得到新型浮式平台的幅频响应曲线，并在此基础上研究了波浪入射角、水深等因素对浮式平台运动的影响．结果显示，在波浪角为0° 时运动响应最大，且浮式平台更适用于较大水深． 关键词：海上风机；浮式平台；耦合作用；频域分析中图分类号：O353 文献标志码：A 文章编号：0493-2137(2013)10-0879-06Frequency Domain Analysis of Motion of FloatingPlatform for Offshore Wind TurbineTang Y ougang 1, 2，Li Jiawen 1, 2，Cao Han 1, 2，Tao Haicheng 1, 2，Li Yihan 1, 2(1. State Key Laboratory of Hydraulic Engineering Simulation and Safety ，Tianjin University ，Tianjin 300072，China ；2. School of Civil Engineering ，Tianjin University ，Tianjin 300072，China ) Abstract ：Taking a 5MW wind turbine as an example ，a new type of floating platform for offshore wind turbine wasdesigned conceptu ally. Based on potential theory and Morison equ ation ，the hydrodynamic coefficients were com-puted using HydroD software. The restoring stiffness provided by mooring system was calculated by program using catenary method. By considering the coupling effects of wind turbine ，mooring system and platform ，as well as the effect of viscous damping ，the dynamic responses in frequency domain were computed by program ，and then the amplitude-frequency response curves were obtained. Furthermore ，the effects of incidence angle of wave and water depth on the responses of the platform were studied. The result showed that response of move of wave reached max-ium at the angle of zero deyree, and the floating platform was suitable for profoundal zone ．Keywords ：offshore wind turbine ；floating platform ；coupling effect ；frequency domain analysis风能作为一种可再生的清洁能源，在国家能源战略中占有重要地位，而海上风能由于其资源丰富、风速大、切变小等特点，受到沿海国家越来越多的关注．由于风机高耸的特点，在海上风能开发中，风机支撑平台的选择非常重要．在水深小于30m 的近海区域，多采用单桩或重力式平台；在水深30m 到60m 的过渡区域，多采用多桩或导管架平台；在水深大于60m 的深水区域，固定式平台由于经济成本急剧上升而竞争力下降，因此多采用浮式平台[1]．目前已经研究的浮式平台有驳船式、半潜式、Spar 式、TLP 式和Hybrid 混合式等，相比于固定式平台，浮式平台需要考虑系泊缆与平台、平台与风机系统的耦合作用，动力响应更加复杂．Wayman 等[2]以驳船和TLP 作为风机的浮式平台，在150m 水深条件下，考虑风机和平台之间的耦合作用，在频域范围内计算了不规则波作用下水深和风速对浮式平台运动响应的影响，但是忽略了气动弹性载荷以及系泊与平台之间的耦合作用．Chujo 等[3]以小比例的Spar 模型平台在有水池的风洞中，试验了系泊点位置对模型运动响应的影响，以大比例模型·880· 天津大学学报(自然科学与工程技术版) 第46卷 第10期试验了纵摇控制器对控制模型纵摇响应、系泊线对首摇运动的影响．Ormberg 等[4]以NREL 的5MW 风机为模型，基于叶素-动量理论计算叶轮的气动载荷，计算了浮式风机系统的载荷，利用SIMO 来计算水动力，利用Reflex 来进行求解非线性时域内的运动响应，分别对固定式塔柱和漂浮式塔柱、全耦合柔性模型和简化的刚性模型的运动响应结果进行了对比. Roddier 等[5]以NREL 的5MW 风机为模型概念设计了WindFloat 的浮式平台，详细描述了其尺寸、质量、系泊系统，分别使用频域、时域理论对平台纵荡、横荡和垂荡自由度的运动进行了预报，并和试验结果进行了对比．笔者综合驳船与Spar 平台的优缺点，概念性地设计了一种新型的海上风机浮式平台，在频域范围内计算并分析了风机系统的运动响应．1 平台结构新型浮式平台由浮箱、垂荡板、立柱、压载舱4部分组成，如图1所示．浮箱为圆柱式，垂荡板为两层，最底部为压载舱，各部分由立柱连接．浮箱为整个浮式风机系统提供浮力和回复力，垂荡板增加浮式平台的阻尼，抑制平台的垂荡运动，压载舱中填充压载物，不仅降低系统的重心，而且在平台的运动过程中有减缓摇摆运动和加速回复运动的作用．平台结构的参数如表1所示．图1 浮式平台的结构模型Fig.1 Floating platform model针对本文中设计的浮式平台结构，以美国再生能源研究所(NREL )公布的5MW 风机模型为例进行运动分析[6-7]，进行建模和计算分析．风机的主要参数如表2所示．系泊系统采用4组共8根系泊缆对称布置，锚链的参数选取参照文献[8]，参数如表3所示，系泊系统布置如图2所示．表1 浮式平台结构参数Tab.1 Parameters of floating platform浮箱高度/m浮箱直径/m垂荡板边长/m立柱高度/m立柱直径/m压载舱高度/m压载舱直径/m9 36 24 2133 24 板厚/m 系统重心/m 系统浮心/m 压载物质量/kg平台质量/kg总吃水/m0.01(0，0，－5.73)(0，0，－9.27)2134.4(浮箱)，3391.2(压载舱)6,102.286 28.5表2 风力发电机参数Tab.2 Parameters of wind turbine叶片直径/ m 轮毂直径/ m 轮毂中心与海 平面距离/m 塔柱质 量/kg 叶片质量/kg 机舱质量/kg 126390347460 110000240000表3 锚链参数Tab.3 Parameters of mooring lines链径/m 单位长度质量/(kg ·m -1) 轴向刚度/(108 N ) 锚链长度/m 0.0809130.45.89430图2 系泊系统的布置Fig.2 Arrangement of mooring system2 计算理论2.1 系泊系统的回复力海上浮式结构物的定位主要依靠锚链的约束. 结构物在环境载荷作用下偏离中性平衡位置以后，系泊系统提供一定的回复力使浮体回到中性平衡位置．系泊系统的回复力主要通过两种效应提供：①悬链线效应，即通过系泊系统的重力提供回复力；②弹性效应，即通过系泊系统自身的弹性拉伸变形提供回复力[9]．以悬链线效应为主的系泊方式称为悬链线系泊，即采用自重较大的锚链系泊．悬链线通过几何形状的改变和轴向弹性力共同作用，保证结构物在环境载荷作用下的运动是顺应性的．锚泊系统一般由多根锚链组成，作用在锚链上的力有水动力、重力和张力等，具有明显的非线性特征，由于锚链是由钢质材料制成，可视重力为主要外力，忽略水动力的作用，此时可用悬链线法计算锚链力．2013年10月 唐友刚等：新型海上风机浮式平台运动的频域分析 ·881·根据悬链线理论推导得出的导缆孔处锚链提供的水平分力和竖直分力[10]分别为 0V Sw V =+ (1)1100()(sinh sinh )()V H V V H VX w H H w EA −−−=−+ (2)2202()V V HZ ww EA −=+(3)202V V H L EA ωω−=+110sinh V V H H −−⎤⎥⎥⎦(4)式中：X 和Z 分别为锚链悬垂部分在x 和z 方向的投影长度，0X x x =−，0Z z z =−；V 和H 分别为张力T 的水平和竖直分量；A 为锚链横截面积；E 为弹性模量；S 为锚链悬垂部分的未拉伸长度，T 0S S S =−，T S 为未拉伸锚链的总长度；L 为锚链悬垂部分拉伸后的长度．根据悬链线理论计算得到锚链随浮体水平运动提供的水平分力和竖直分力如图3所示，可以看出锚链提供的回复力大小与平台水平位移近似呈线性关系，根据曲线斜率可以得到系泊系统提供的回复刚度.（a ）水平分力 （b ）竖直分力图3 锚链回复力与水平位移的关系Fig.3 Relationship between mooring restoring force andhorizontal displacement2.2 垂荡板黏性阻尼利用势流理论计算平台的水动力系数时，无法计算垂荡板和水泥压载舱的黏性阻尼．文献[11]表明，垂荡板的辐射阻尼在总阻尼中所占比例较小，基本可以忽略，而黏性阻尼成为垂荡板总阻尼的主要部分．垂荡和纵荡自由度的阻尼系数为 d2b C DL ρ=(5)纵摇自由度的阻尼系数为221123ddd 26d d d d b C D z z C DL ρρ==∫ (6)式中：D 为构件的基准长度；L 为结构的总长度；1d 、2d 分别为结构上下边缘的吃水深度．2.3 海上风机浮式平台运动方程海上风机浮式平台水下舱室为大尺度构件，采用势流理论计算波浪力，桁架式结构属于小尺度构件，采用Morison 公式计算波浪力． 考虑阻尼、波浪力激励力、静水回复力、系泊力回复力等，得到线性规则波浪作用下的海上风机浮式平台频域运动方程为()a12()(())ωξωξ++++M M C C (1)wave moor ()ω+=+K ξF F(7)式中：M 、a ()ωM 分别为6×6质量矩阵、附加质量矩阵；1()ωC 、2C 分别为6×6波浪辐射阻尼矩阵和黏滞阻尼矩阵；K 为6×6静水力回复矩阵；(1)wave ()ωF 、moor F 分别为一阶波浪激励力和系泊回复力．式(7)为频域运动控制方程，且只含有一个非线性项，即系泊系统回复力．非线性的系泊系统回复刚度在很多情况下可以采用浮式结构物平均漂移位置处的等效回复刚度来表征[12]．因此，经过线性化的系泊系统回复力与平台响应成正比，式(7)可改写为()a 12()(())ωξωξ++++M M C C (1)moor wave ()()ξω+=K K F (8)式中moor K 为系泊系统线性回复刚度矩阵．直接求解线性方程式(8)，可以得到平台在一阶波浪力作用下的频域响应，即(1)(1)wave ()()()H ωωω=X F(9)式中：(1)()ωX 为一阶频域响应；()H ω为响应传递函数，()H ω=()2a 12moor 1(())i (())ωωωω⎡⎤−+−+++⎣⎦M M C C K K (10)得到传递函数后，可以定义浮式平台的响应幅值算子(response amplitude operator ，RAO )，即 RAO ()()()R H L ωωω=(11)式中：()L ω为波浪力的线性传递函数．RAO R 反映了在单位波幅的规则波作用下，浮式基础随频率变化的一阶响应幅值．利用HydroD 软件计算了新型浮式平台的水动力系数，通过迭代方法求解系泊系统的回复刚度，采用四阶龙格库塔法编程求解式(8)，对不同频率波浪作用下的运动幅值进行求解，得到新型浮式平台在频域范围内的运动响应．·882· 天津大学学报(自然科学与工程技术版) 第46卷 第10期3 计算结果3.1 计算模型针对本文中设计的浮式平台结构，考虑5MW 风电机，建立计算模型，进行计算分析．选取的坐标系原点位于海平面处、浮箱的正中心，z 轴竖直向上，且与塔柱的中心轴重合．在该坐标系中建立的海上5MW 风机整体模型如图4所示．图4 5MW 海上风机整体模型及坐标系Fig.4 Global model and coordinative system of 5MWoffshore wind turbine3.2 自振周期考虑黏性阻尼系数，建立简化的单自由度运动的 控制方程()()()a12()()cos w w t ξξξωθ++++=+M M C C K F(12)式中：θ表示波浪激励力对应的初始相位角． 使用数值计算的方法获得浮式平台的无阻尼自由衰减运动曲线．令式(12)的右端为零，并分别给浮式平台垂荡、纵摇和纵荡自由度分别施加一个初始的小位移，根据龙格库塔法可以求得静水中的衰减运动曲线，由衰减运动曲线可以得到浮式平台在3个自由度上运动的固有周期，如图5所示．由图5可知，垂荡的固有周期在9.8s 左右，纵摇的固有周期在20.5s 左右，在计算纵荡的衰减运动时考虑锚链的回复力作用，纵荡的固有周期在58s 左右． 3.3 频域计算结果 在初始设计阶段，频域范围内的运动响应预报对新型海上浮式风机有重要的意义．频域分析的工作水深为150m ，波浪周期范围为2～60s ，间隔为2s ，（a ）垂荡 （b ）纵摇 （c ）纵荡图5 垂荡、纵摇、纵荡自由衰减曲线Fig.5 Free decays in heave ，pitch and surge 考虑系泊系统提供的非线性回复刚度、垂荡自由度的运动响应对纵摇自由度运动响应的影响，得到新型浮式平台的响应幅值算子R RAO ，如图6所示．风机正常工作时，由于在纵荡方向受到风力作用，海上浮式风机系统会到达新的平衡位置，所以纵荡的R RAO 反映的是平台在新的平衡位置的运动响应幅值．（a ）垂荡 （b ）纵摇 （c ）纵荡图6 垂荡、纵摇、纵荡的R RAOFig .6 R RAO of heave ，pitch and surge 由图6可以看出，在垂荡自由度上，平台在10s时运动幅度达到最大，共振周期与第3.2节求得的固有周期接近，平台在短周期波浪(高频)区域运动幅值较小，在波浪的长周期波浪(低频)区域幅值随波浪周2013年10月唐友刚等：新型海上风机浮式平台运动的频域分析 ·883·期的增大变化不明显；在纵摇自由度上，平台在20s 附近运动幅值最大，与第3.2节得出的固有周期接近，平台在波浪低频区域幅值较小，几乎为零，在高频区域运动响应增大；在纵荡自由度上，平台运动幅度随波浪周期的增大而增大．3.4 波浪入射角对运动的影响在线性势流理论的前提下，附加质量和辐射阻尼与频率相关，与水深和角度等关系不大，所以不同入射角和水深影响的是波浪激励力，进而影响平台的运动响应．改变波浪入射角计算得到的R RAO如图7所示．由于平台的对称性设计，在垂荡自由度上各个角度的波浪激励力基本相同，运动响应也基本一致；而纵摇和纵荡自由度上的波浪力随着波浪入射角度而改变，运动响应也随波浪入射角度的增大而减小．（a）垂荡（b）纵摇（c）纵荡图7不同波浪入射角下的R RAOFig.7R RAO for different incident angles of wave 3.5 水深对运动的影响由于平台吃水为28.5m，该平台可以应用于不同水深的海域，所以计算不同水深下平台的运动响应，对研究风机系统的运动性能有重要意义．选择水深为60m、90m、120m和150m，垂荡、纵摇和纵荡3个自由度的运动响应随水深的减小有不同程度的增大，如图8所示，其中垂荡的响应增加不明显，纵摇和纵荡增加得比较明显．该新型浮式平台在较大水深时适应性更好．（a）垂荡（b）纵摇（c）纵荡图8不同水深下的R RAOFig.8 R RAO for different water depths4 结 论(1) 根据悬链线理论编程计算得到了回复刚度，系泊系统提供的回复力与位移近似呈线性关系．该新型浮式平台的系泊系统采用对称布置，在纵荡自由·884·天津大学学报(自然科学与工程技术版)第46卷 第10期度提供了良好的回复力．(2) 根据运动控制方程，编程得到平台在垂荡、纵摇和纵荡自由度上的自由衰减时间历程曲线，并得到其运动的固有周期，其中垂荡自由度的固有周期与自然波浪的周期较为接近，需要增大平台的阻尼，抑制垂荡共振的发生．(3) 根据频域运动方程，计算了不同波浪周期作用下的平台的运动幅值响应．此外研究了波浪入射角和水深对平台运动造成的影响．通过R RAO曲线可知，在波浪入射角为0°时，运动响应最大，且该浮式平台更适用于较大水深．参考文献：［1］黄维平，刘建军，赵战华. 海上风电基础结构研究现状及发展趋势[J]. 海洋工程，2009，27(2)：130-134.Huang Weiping，Liu Jianjun，Zhao Zhanhua. Devel-opment trendy and study situation of offshore windpower foundation structure[J]. Ocean Engineering，2009，27(2)：130-134(in Chinese).［2］Wayman E N，S clavounos P D，Butterfield S，et al.Coupled dynamic modeling of floating wind turbine sys-tems[C]//2006 Offshore Technology Conference. Hous-ton，USA，2006：1-4.［3］Chujo Toshiki，Ishida S higesuke，Minami Yoshimasa，et al. Model experiments on the motion of a spar typefloating wind turbine in wind and waves[C]// Proceed-ings of the ASME 2011 30th International Conference onOcean，Offshore and Arctic Engineering. Rotterdam，Holand，2011：2011-49793.［4］Ormberg Harald，Passano Elizabeth，Luxcey Neil.Global analysis of a floating wind turbine using an aero-hydro-elastic model(Part 1)：Code development andcase study [C]//Proceedings of the ASME 201130th In-ternational Conference on Ocean，Offshore and ArcticEngineering. Rotterdam，Holand，2011：2011-50088. ［5］Roddier Dominique，Peiffer Antoine，Aubault Alexia，et al. A generic 5MW wind float for numerical tool vali-dation and comparison against a generic spar[C]// Pro-ceedings of the ASME 2011 30th International Confer-ence on Ocean，Offshore and Arctic Engineering. Rot-terdam，Holand，2011：2011-50278. ［6］Jonkman J，Butterfield S，Musial W，et al. Definition of a 5MW Reference Wind Turbine for Offshore SystemDevelopment[R]. Oak Ridge，USA：US Department ofEnergy Office of Scientific and Technical Information，2009.［7］Jonkman J M，Jr Buhl M L . Loads analysis of a floating offshore wind turbine using fully coupled simula-tion[C]//Wind Power 2007 Conference and Ex hibition.Los Angeles，California，USA，2007：3-6.［8］Jonkman J M，Jr Buhl M L. Development and verifica-tion of a fully coupled simulator for offshore wind tur-bines[C]//The 45th AIAA Aerospace Sciences Meetingand Ex hibit，Wind Energy Symposium. Reno，USA，2007：8-11.［9］阮胜福. 海上风电浮式基础动力响应研究[D]. 天津：天津大学建筑工程学院，2010.Ruan S hengfu. S tudy on the Dynamic Response forFloating Foundation of Offshore Wind Turbine [D].Tianjin：S chool of Civil Engineering，Tianjin Univer-sity，2010(in Chinese).［10］耿宝磊. 波浪对深海海洋平台作用的时域模拟[D]. 大连：大连理工大学建设工程学部，2010.Geng Baolei. Time S imulation of Waves on Deep-S eaOffshore Platform[D]. Dalian：Faculty of InfrastructureEngineering，Dalian University of Technology，2010(in Chinese).［11］滕 斌，郑苗子，姜胜超，等. S par平台垂荡板水动力系数计算与分析[J]. 海洋工程，2010，28(3)：1-8.Teng Bin，Zheng Miaozi，Jiang Shengchao，et al. Thecalculations and analysis of hydrodynamics coefficient ofspar platform heave plate[J]. Ocean Engineering，2010，28(3)：1-8(in Chinese).［12］李彬彬. 新型深吃水多立柱平台的水动力与运动响应研究[D]. 哈尔滨：哈尔滨工业大学市政环境工程学院，2011.Li Binbin. Investigation on Hydrodynamics and MotionPerformance of an Innovative Deep Draft Multi-S parPlatform[D]. Harbin：S chool of Municipal and Envi-ronmental Engineering，Harbin Institute of Techno-logy，2011(in Chinese).。
建环专业英语翻译
Southwest university of science and technology 专业英语翻译学院名称：西南科技大学专业名称：建筑环境与能源应用工程学生姓名：学号：指导教师：2015年 12 月论文要求：The final assignment:To translate part of Introduction of an English academic article related to our mayor(refrigeration，heat and mass transfer, fluid dynamic, ventilation, new energy, etc.).Requirements：1.The translation partshould be No less than 300 English words.2. The article should be published in the journals of the periodicals databases of ScienceDirect.(/science/journals).3. The publish year of the article should be no earlier than 2010.4. The article of each student should be different.5. The final assignment includes: the cover page, the first page ofsource article, the translation part and its corresponding Chinese version.打分标准：理解准确,30%语句通顺,30%用词规范专业，40%。
Simulation of electricity generation by marine current turbines at Istanbul Bosphorus Strait∙Hasan Yazicioglu a,∙K.M. Murat Tunc b,∙Muammer Ozbek b, , ,∙Tolga Kara b∙a Technical University of Denmark, Department of Wind Energy, Denmark ∙b Istanbul Bilgi University, Faculty of Engineering and Natural Sciences, TurkeyReceived 9 July 2015, Revised 29 October 2015, Accepted 17 November2015, Available online 24 December 2015doi:10.1016/j.energy.2015.11.038Highlights•Simulations are performed for a 10MW marine turbine cluster located in Bosphorus.•360 different simulations are performed for 15 different virtual sea states.•8 different configurations are analyzed to find the optimum spacing between turbines.•Annual energy yield and cluster efficiency are calculated for each simulation.AbstractIn this work, several simulations and analyses are carried out to investigate the feasibility of generating electricity from underwater sea currents at Istanbul Bosphorus Strait. Bosphorus is a natural canal which forms a border between Europe and Asia by connecting Black Sea and Marmara Sea. The differences in elevation and salinity ratios between these two seas cause strong marine currents. Depending on the morphology of the canal the speed of the flow varies and at some specific locations the energy intensity reaches to sufficient levels where electricity generation by marine current turbines becomes economically feasible.In this study, several simulations are performed for a 10 MW marine turbine farm/cluster whose location is selected by taking into account several factors such as the canal morphology, current speed and passage of vessels. 360 different simulations are performed for 15 different virtual sea states. Similarly, 8 different configurations are analyzed in order to find the optimum spacing between the turbines. Considering the spatial variations in the current speed within the selected region, the analyses are performed for three different flow speeds corresponding to ±10% change in the average value. Foreach simulation the annual energy yield and cluster efficiency are calculated.Keywords∙Renewable energy;∙Marine current turbine;∙Energy yield simulations;∙Cluster/farm optimization;∙Offshore engineering;∙Dynamic interactions1. IntroductionThe growing world population and rapid industrialization seen in developing countries cause a continuous increase in the global energy demand. Today the major source of energy comes from fossil fuels such as oil, coal and natural gas. However, considering the rate of increase in the consumption, it can easily be realized that these limited sources cannot be a long term solution to satisfy the global energy demand and are definitely bound to run out. Besides, using fossil fuels asprimary source of energy has irreversible negative impacts on the environment which force many countries to seek for alternative environmental friendly renewable energy sources.Turkey, as a rapidly growing economy with very limited national hydrocarbon resources, is also heavily dependent on fossil fuels (e.g. natural gas) imported for electricity production[1]. However, some recent political instabilities in the supplier countries, the heavy economic burden of importing these resources and the most importantly, the increasing awareness of environmental issues have been encouraging policy makers to increase the use of renewable energy sources. Indeed, very detailed investigations and analyses were performed to determine the wind, solar and geothermal energy capacity of the country [1]. However, the potential of harnessing some other renewable sources, particularly sea current energy has not been fully realized yet.Compared to the other types of renewable energy such as wind and solar, current energy can still be considered in development phase and is not commercially available in large scales. Existing marine turbine systems are mostly in prototype testing stage. Although initial results are quitepromising [2], [3], [4], [5], [6], [7], [8]and [9]some further verification for long term performance and durability under severe environmental conditions is still required.The average current speed needed for most commercial turbines is approximately 4–5 knots (2–2.5 m/s). Areas that typically experience high marine current flows are in narrow straits, between islands and around headlands. Entrances to lochs, bays and large harbors often also have high marine current flows. Generally the resource is largest where the water depth is relatively shallow and a good tidal range exists [10].The flow in Bosphorus does not originate from tidal currents but the differences in elevation and salinity ratios between two seas and wind and pressure variations [11]. The unique characteristics of the strait enable very high energy intensities to be reached at some locations and sections.This paper aims at investigating the feasibility of generating electricity from the streams at Bosphorus by using marine current turbines. Extensive simulations and analyses are performed for a 10 MW marine turbine farm (10 – SeaGen 1 MW) where several important design parameters such as the size, orientation, depth and spacing of the turbines areoptimized according to the specific morphology and flow patterns seen at Bosphorus.翻译1.引言发展中国家快速增长的人口和工业化进程造成了全球能源需求的持续增长。
风应力输入到海洋中的能量的气候变率特征
大尧科擘学拍■http ://2019年第42卷第2期：184!96风应力输入到海洋中的能量的气候变率特征谢泽林！，王召民，武扬南京信息工程大学极地气候系统与全球变化实验室，江苏南京210044 !联系人,E-mail:zelin_xie@ 2017-05-20 收稿，2017-06-26 接受 国家自然科学基金项目（41276200)摘要利用麻省理工学院海洋环流模式研究了风应力输入到海洋中的能量的气候变率 特征。
结果表明：风应力输入到海洋中的能量对气候变化有显著的响应。
在北大西洋 涛动％ North Atlantic Oscillation ,N A O )正位相的年份，风应力输入到海洋中的能量的大 值区北移且加强，主要由于暴风路径的北移和天气尺度大气扰动的加强导致；同样，在 南半球环状模％ Southern Annular Mode , SA M )正位相年份输入到南大洋的能量大值区 南移并加强，且输入到南极大陆沿岸流中的能量也有显著增加。
经验正交函数分解分 析结果表明：N A O 主导了风应力输入到北大西洋区域的能量变化。
S A M 解释了南大 洋区域风应力输入能量的第一模态，第二、三模态解释了受EN SO (El Nifio-SouthernOscillation )影响的情况。
最近几十年，在南大洋区域，风应力及其输入能量的年代际变化都有所增强，而在北半球的中高纬度区域有所下降。
关键词风应力；能量输入;大气扰动； 气候变率海洋环流是风应力、潮汐和浮力通量（热通量、淡水通量）等共同驱动的结果（Huang ，2004; Ferrariand W u n sh ，2010)，外部因素输人到海洋中的能量用来抵消因摩擦和耗散而损失的能量从而维持海洋 环流的运动。
在上述驱动因素中，风应力是海洋环 流的主要驱动因素（Wunsch and Ferrari ，2004 )，其 次是潮汐和浮力通量的作用。
风力发电涡轮机中英对照
风力涡轮机也可以为机械提供电力使其做特殊的工作，例如研磨谷粒或抽水。在加拿大大草原上，举个例子，就有几千个抽水的风力涡轮机。
风力涡轮机的基本组成部分
电力生产的风力涡轮机有4个基本组成部分：
·旋转轮是由附属于旋翼叶毂的两片或三片叶片组成。
·发电机产生的是交流电的形式。
·优化控制和保护系统，确保在安全限度之内进行作业。
· a tower that raises the rotor off the ground.
Modern wind turbines make use of very few but very large blades (ranging between 40 to 80 metres in diameter) to capture wind energy, extracting energy from the largest possible volume of air. The blades are set at different angles to cope with varying wind speeds, and the generator and the blades can be turned to face the changing direction of the wind. The turbines are mounted on towers 40 to 80 metres tall, so as to capture stronger wind flows.
Wind turbines can also be used to generate mechanical power for specific tasks such as grinding grain or pumping water. On the Canadian Prairies, for example, there are several thousand wind turbines that pump water.
考虑风电与负荷时序性的分布式风电源选址定容
考虑风电与负荷时序性的分布式风电源选址定容初壮;乔福泉【摘要】In this paper,the timing characteristics of wind turbine output and node loads are considered during the lo?cating and sizing of distributed wind generation(DWG)in distribution network. The hourly wind speeds in one year are sampled using Monte Carlo simulation(MCS),and the corresponding wind turbine output is obtained. Then,hourly sce?narios are constructed considering both the hourly output efficiency of the wind turbine and the corresponding hourly loading rate at nodes,and an improved K-means clustering algorithm is used to perform scenario clustering. According to the clustering results,which include the average of wind turbine output efficiencies,the average of loading rates,as well as the probability of the corresponding scenario,an improved genetic algorithm is employed to locate and size the DWG with the minimum annual cost of a distribution company as an objective function. The simulation results of a 33-node distribution network show that the timing characteristics of wind turbine output and node loads have a significant impact on the locating and sizing of DWG. Meanwhile,the effectiveness of the proposed model and method is verified.%配电网中分布式风电源选址定容时,计及风电机组出力和节点负荷的时序性特征.利用蒙特卡洛模拟MCS(Monte Carlo simulation)对一年内每小时风速进行抽样,并求出对应的风机出力.综合考虑每小时风机出力效率以及对应的节点小时负荷负载率,构建小时场景,利用改进K-means聚类法进行场景聚类.根据聚类后每个场景的风机出力效率均值、负荷负载率均值以及对应场景的概率,以配电公司最小年费用成本为目标函数,利用改进遗传算法对分布式风电源进行选址定容.对33节点算例的仿真分析结果表明,风机出力与节点负荷的时序特性对分布式风电源的选址定容有重大影响,同时也验证了所提模型及方法的有效性.【期刊名称】《电力系统及其自动化学报》【年(卷),期】2017(029)010【总页数】6页(P85-90)【关键词】分布式风电源;时序性;场景;改进K-means聚类法【作者】初壮;乔福泉【作者单位】东北电力大学电气工程学院,吉林 132012;东北电力大学电气工程学院,吉林 132012【正文语种】中文【中图分类】TM715随着能源危机、环境危机逐渐加剧，分布式电源，尤其是以风电为代表的可再生能源类型的分布式电源越来越受到重视。
涡流发生器布置位置对小型垂直轴风力机气动性能的影响
第51卷第9期2020年9月中南大学学报(自然科学版)Journal of Central South University(Science and Technology)V ol.51No.9Sep.2020涡流发生器布置位置对小型垂直轴风力机气动性能的影响张立军，朱怀宝，胡阔亮，顾嘉伟，缪俊杰，江奕佳，李想，于洪栋，刘静(中国石油大学（华东）机电工程学院，山东青岛，266580)摘要：为提高垂直轴风力机的气动性能，针对小型双叶片H型垂直轴风力机，提出3种涡流发生器在叶片表面安装位置方案。
建立风力机整机仿真模型并进行了网格独立性验证。
利用ANYSY FLUENT软件对垂直轴风力机进行三维流体力学仿真研究。
研究结果表明：在上风区叶片内表面和下风区叶片外表面加装涡流发生器均可提高叶片的转矩系数，但分析流场显示下风区流场紊乱，下风区叶片外表面加装涡流发生器提升效果变差。
3种方案中，叶片内外表面加装涡流发生器时垂直轴风力机风能利用率CP提升效果最好，与原型风力机相比CP提升6.4%。
关键词：垂直轴风力机(V AWT)；涡流发生器(VG)；布置位置；气动性能；FLUENT软件中图分类号：TK83文献标志码：A文章编号：1672-7207（2020）09-2634-09Effect of arrangement position of vortex generator on aerodynamic performance of small vertical axis wind turbineZHANG Lijun,ZHU Huaibao,HU Kuoliang,GU Jiawei,MIAO Junjie,JIANG Yijia,LI Xiang,YU Hongdong,LIU Jing(College of Mechanical and Electronic Engineering,China University of Petroleum,Qingdao266580,China) Abstract:In order to improve the aerodynamic performance of V AWT,for a small double-blade H-type vertical axis wind turbine,three kinds of arrangement position schemes of vortex generator on the blade surface were proposed.The simulation model was established for the wind turbine,and the grid independence was verified.By using ANYSY FLUENT software,three-dimensional hydrodynamic simulations of conventional airfoils were performed.The results show that the blade torque coefficient can be improved by adding vortex generators on the inner surface of the upwind zone and the outer surface of the downwind zone,but the analysis of the flow field shows that the flow field in the downwind zone is disordered,and the lifting effect of vortex generator installed on the outer surface of the blade in the downwind area becomes worse.Among the three schemes,when the vortexgenerator is installed on the inner and outer surface of the blade,the wind energy utilization ratio CPof the verticalaxis wind turbine is the best,and the wind energy utilization ratio is increased by6.4%compared with CPof the original wind turbines.DOI:10.11817/j.issn.1672-7207.2020.09.029收稿日期：2019−09−12；修回日期：2020−05−01基金项目(Foundation item)：国家自然科学基金资助项目(51707204）；中央高校基本科研业务专项资助项目(17CX05021) (Project(51707204)supported by the National Natural Science Foundation of China;Project(17CX05021)supported by the Fundamental Research Funds for the Central Universities)通信作者：张立军，博士，教授，硕士生导师，从事可再生能源技术和绿色装备制造研究；E-mail：*************第9期张立军，等：涡流发生器布置位置对小型垂直轴风力机气动性能的影响Key words:vertical axis wind turbine(V AWT);vortex generator(VG);arrangement position;aerodynamic performance;FLUENT software根据风轮旋转轴与地面的几何拓扑关系来划分，风力发电机分为水平轴风力机(HAWT)与垂直轴风力机(V AWT)。
高等学校英语拓展系列教程-科技英语阅读课文翻译
Text AUnit2 The Future of Alternative Energy替代能源的前景Residential energy use in the United States will increase 25 percent by the year 2025, according to U.S. Department of Energy (DOE) forecasts. A small but increasing share of that extra power will trickle in from renewable sources like wind, sunlight, water and heat in the ground.美国能源部(DOE)预测，美国居民所使用的能源将在2025 年前增加25%。
增加的电能中将有一小部分来源于再生能源(如风、阳光、水、地热)，而且这部分还会不断增大。
Last year alternative e nergy sources provided 6 percent of the nation’s energy supply, according to the DOE.美国能源部称，去年全国能源供应总量中有6%来自于替代能源。
“The future belongs to renewable energy,” said Brad Collins, the executive director of the American Solar Energy Society, a Boulder, Colorado-based nonprofit organization. “Scientist and industry experts may disagree over how long the world’s supply of oil and natural gas will last, but it will end,” Collin said.“未来属于再生能源，”美国太阳能协会执行主席布拉德·柯林斯说。
IEC61400-1-2005风电机组设计要求标准英汉对照
需要什么文档直接在我的文档里搜索比直接在网站大海捞针要容易的多也准确省时的多
INTERNATIONAL STANrbines – Part 1:
Design requirements
Publication numbering As from 1 January 1997 all IEC publications are issued with a designation in the 60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.
Further information on IEC publications The technical content of IEC publications is kept under constant review by the IEC, thus ensuring that the content reflects current technology. Information relating to this publication, including its validity, is available in the IEC Catalogue of publications (see below) in addition to new editions, amendments and corrigenda. Information on the subjects under consideration and work in progress undertaken by the technical committee which has prepared this publication, as well as the list of publications issued,is also available from the following: IEC Web Site (www.iec.ch) Catalogue of IEC publications The on-line catalogue on the IEC web site (www.iec.ch/searchpub) enables you to search by a variety of criteria including text searches,technical committees and date of publication. Online information is also available on recently issued publications, withdrawn and replaced publications, as well as corrigenda. IEC Just Published This summary of recently issued publications (www.iec.ch/online_news/justpub) is also available by email. Please contact the Customer Service Centre (see below) for further information. Customer Service Centre If you have any questions regarding this publication or need further assistance, please contact the Customer Service Centre: Email: custserv@iec.ch Tel: +41 22 919 02 11 Fax: +41 22 919 03 00 .
超高钢混风电塔筒自提升液压技术
超高钢混风电塔筒自提升液压技术陈建平1 米智楠1 陈 杰2 李鲜明2 张伦伟31同济大学机械与能源工程学院 上海 200092 2上海同力建设机器人有限公司 上海 2004363同济大学航空航天与力学学院 上海 200092摘 要：目前陆上风电高风速资源日趋稀缺，在低风速区域大幅提高风电机组的塔筒高度能够充分利用高空风能资源，大幅提高平均发电量，对我国中、东部低风速区域发展风电清洁能源有着积极意义。
而传统大吨位起重机安装作业方式不利于超高风电塔筒的安装。
针对这一难题，文中研制了超高钢混风电塔筒自提升液压系统，将液压提升器集群作为起重机械，以钢绞线作为索具，通过传感检测和智能控制算法，确保同步提升高差小于5 mm，依次将混凝土内塔筒和中塔筒提升到位，高质量地实现了某170 m高的风电钢混塔筒的安装。
液压自提升技术作为一种新颖的超高钢混风电塔筒的安装技术，其高度、质量不受限止，自动化控制程度高，技术可行、安全可靠。
关键词：自提升液压技术；超高；钢混风电塔筒；提升策略；安装中图分类号：TH211 文献标识码：A 文章编号：1001-0785（2023）17-0031-05Abstract: Currently, the high wind speed resources of wind power on land are increasingly scarce. Increasing the tower height of wind turbines in low wind speed areas can make full use of high-altitude wind energy resources and greatly improve the average power generation, which is of positive significance to the development of clean energy such as wind power in low wind speed areas in central and eastern China. However, the installation and operation mode of traditional large-tonnage crane is not conducive to the installation of ultra-high wind tower. Considering this difficulty, a design of self-lifting hydraulic system for ultra-high steel-concrete wind tower is proposed in this paper. In this design, the hydraulic lifter cluster is used as lifting machinery, and the steel strand is used as rigging. Through sensing detection and intelligent control algorithm, the synchronous lifting height difference is ensured to be less than 5 mm, and the concrete inner tower and the middle tower are lifted in place in turn, so as to realize the accurate installation of a 170 m high steel-concrete wind tower. Hydraulic self-lifting technology is a novel installation technology of ultra-high steel-concrete wind tower, which is not limited by height and quality, has high degree of automatic control, and is feasible, safe and reliable.Keywords:self-lifting hydraulic technology; ultra-high; steel-concrete wind tower; optimization strategy; installation0 引言某风电场170 m钢混塔筒风电机组应用自提升液压技术安装，其叶轮直径为155 m，轮毂高度为170 m，总高度为247.5 m，是当前国内最高的陆上风力发电机组。
Aerodynamics of Wind Turbines风力涡轮机的空气动力学
Appendix A: Basic Equations in Fluid Mechanics Appendix B: Symbols Index
List of Figures and Tables
Figures
1.1 1.2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 4.1 4.2 4.3 Horizontal-axis wind turbine (HAWT) Machine layout Schematic view of streamlines past an airfoil Definition of lift and drag Explanation of the generation of lift Polar for the FX67-K-170 airfoil Different stall behaviour Computed streamlines for angles of attack of 5° and 15° Viscous boundary layer at the wall of an airfoil Schematic view of the shape of the boundary layer for a favourable and an adverse pressure gradient Schematic view of the transitional process Streamlines flowing over and under a wing Velocity vectors seen from behind a wing A simplified model of the vortex system on a wing More realistic vortex system on a wing Induced velocity from a vortex line of strength Γ The effective angle of attack for a section in a wing and the resulting force R, lift L and induced drag Di Computed limiting streamlines on a stall regulated wind turbine blade at a moderately high wind speed Rotor of a three-bladed wind turbine with rotor radius R Radial cut in a wind turbine rotor showing airfoils at r/R Schematic drawing of the vortex system behind a wind turbine Illustration of the streamlines past the rotor and the axial velocity and pressure up- and downstream of the rotor Circular control volume around a wind turbine Alternative control volume around a wind turbine 4 6 7 8 9 11 12 12 14 14 15 18 19 20 20 21 22 23 24 24 25 28 29 30
风电场站单机聚合模型倍乘元件阻抗参数设计
第51卷第21期电力系统保护与控制Vol.51 No.21 2023年11月1日Power System Protection and Control Nov. 1, 2023 DOI: 10.19783/ki.pspc.230553风电场站单机聚合模型倍乘元件阻抗参数设计王晗玥，许建中(新能源电力系统全国重点实验室(华北电力大学)，北京 102206)摘要：现有较大规模风电场站等值模型中常采用倍乘方式实现机组聚合，以节省建模与仿真计算等资源。
针对风电场站单机聚合模型倍乘元件在风电场建模中应用广泛、参数设置缺少规律性的现状，对倍乘元件阻抗参数在风电场等值建模中的影响展开研究。
首先，以PSCAD软件官网的经典倍乘元件入手，分析各个自定义阻抗参数间的关系与重要程度。
其次，搭建风电场基准测试模型并展开等值聚合，通过参数遍历测试，研究倍乘元件阻抗参数对等值误差的影响机理，依据稳态运行点等值误差、仿真步长两个方面的限制，提出倍乘元件阻抗参数选择方法。
最后，选取稳态运行点、三相电压跌落、宽频振荡3个工况，对影响机理与推荐参数展开验证。
从等值误差的角度，对大型风电场建模仿真中倍乘元件阻抗的参数设计提供了参考建议。
关键词：风电场；单机聚合模型；倍乘元件；阻抗参数；等值误差Design of impedance parameters of a multiplier element in an aggregation model ofa single wind turbine of a wind farmWANG Hanyue, XU Jianzhong(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University), Beijing 102206, China)Abstract: In existing equivalent models of large-scale wind farms, multi-wind turbines are often aggregated using a multiplier element to save modeling and simulation computing resources. The multiplier element of a single-wind turbine aggregation model of wind farm is widely used in wind farm modeling, but the parameter setting lacks regularity. Thus this paper studies the influence of multiplier element impedance parameters on wind farm equivalent modeling. First, it starts with a multiplier element on the official website of PSCAD to analyze the relationship and importance of each self-defined impedance parameter. Second, a reference test model of a wind farm is built and equivalent aggregation is carried out. Through a parameter traversal test, the influence mechanism of impedance parameters of multiplier elements on equivalent error is studied. From the limitations of steady-state operating point equivalent error and simulation time step, the method of impedance parameter selection of the multiplier element is proposed. Finally, three operating conditions of steady-state operating point, three-phase voltage dip and broadband oscillation are selected to verify the influence mechanism and recommended parameters. Some suggestions are provided for the parameter setting of the impedance of the multiplier element in modeling and simulation of large wind farms in terms of equivalent error.This work is supported by the National Natural Science Foundation of China (No. 52277094).Key words: wind farm; aggregation model of a single wind turbine; multiplier element; impedance parameters;equivalent error0 引言近年来我国风电、光伏等可再生能源快速增基金项目：国家自然科学基金项目资助(52277094) 长，电力系统作为能源枢纽，正在向以新能源为主体的新型电力系统快速转变[1-4]。
Control of Wind Turbines
CONTROL OF WIND TURBINES© M. Ragheb1/6/2008INTRODUCTIONWind turbines are optimized to produce maximum power output at the most probable wind speeds around 15 m/s, 33 mph, or 33 knots. It would be uneconomical to design them for operation at the improbable higher wind speeds.It is necessary to limit the power output in high wind conditions on all wind turbines; otherwise a runaway turbine will be overloading its rotors, mechanical power train, as well as its electrical generator leading to catastrophic failure.It is unavoidable in order to protect the structural integrity of the wind turbine to ignore the energy production potential of these improbable wind gusts and to provide power controls in modern wind turbines to stop the turbine when these occur.Fig. 1: Electronic orientation yaw drive and pitch control mechanism in the direct drive Enercon E66 1.5MW wind turbine. Notice the absence of a gear box in thisdesign.Wind turbines have to also be oriented perpendicular to the wind stream using wind orientation mechanism or yaw control. In addition their brakes must be applied under unfavorable high wind conditions. Some of these controls are performedmechanically in older wind machines, but in newer machines they are performed hydraulically, and in the most recent designs they are done using stepped up motors. This is similar to the evolution in aircraft from manual controls to hydraulic controls to fly by wire controls.Fig. 2: Mechanical orientation drive, brake and pitch control mechanism in anearlier design wind turbine.MECHANICAL PITCH CONTROLIngenious methods were developed to control the pitch or the angle of attack that a rotor airfoil presents to the wind stream. In a spring operated mechanism, the higher rotational speed of the rotor generates a centrifugal force on a regulating balancing weight which compresses a spring. The force of the weight rotates the blade about a pivot decreasing the angle of attack of the airfoil to the wind stream and reducing its rotational speed. The compressed spring tends to restore the airfoil to its original angle of attack once the wind speed decreases.Fig. 3: Mechanical spring loaded pitch control of rotor blades.In modern wind generators the mechanical spring loaded pitch control was replaced by power operated controls.PITCH POWER CONTROLIn pitch power controlled wind turbines an electronic controller senses the power output of the turbine several times per second. If the power level exceeds a prescribed safe level, an electronic signal is generated which turns or pitches the blades out of the wind. When the power level is lower, they are pitched back to catch the wind at the optimal angle of attack of the blade’s airfoil.In pitch control the rotor blades are rotated around their longitudinal axis a fraction of a degree at a time while the rotor continues its normal rotation.Clever design is needed to pitch the rotor blades the optimal amount so as to maximize the power output at all wind speeds.The pitch control mechanisms are hydraulically controlled, even though electrical controls using stepped electrical motors are replacing them much the same as fly by wire is replacing the hydraulics in airplane controls.About one third of the installed wind machines use pitch control mechanismsFig. 3: Passive and active stall regulation and pitch power control.PASSIVE STALL POWER CONTROLPassive stall power controlled wind turbines use a simpler form of blades that are attached to the hub at a fixed angle. The rotor airfoil profile is aerodynamically designed such as when the wind speed exceeds a safe limit, the angle of attack of the airfoil to the wind stream is increased, and laminar flow stops and is replaced by turbulence on the top side of the airfoil. The lift force on the blade stops acting stalling its rotation.In stall controlled wind turbines the blade is slightly twisted along its longitudinal axis. This ensures that the blade stalls gradually rather than abruptly as the wind speed reaches its critical stall value.The advantage of stall control in wind turbines is that it avoids the introduction of moving parts into the rotor. This advantage is obtained as interplay between the aerodynamic design and the structural dynamic design of the rotor airfoil so as to avoid stall induced vibrations. Two third of the installed wind turbines are stall controlled.ACTIVE STALL POWER CONTROLLarger wind turbines with larger than 1 MW rated capacity are equipped with active stall power control mechanisms. In this case they use pitchable blades resembling the pitch controlled machines.To get a large torque or turning force at low wind speeds, the control system pitches the blades in steps like the pitched control machines at low wind speeds.The situation is different when the turbine reaches its design rated power level, at that point the stall controlled machines operate differently than pitch controlled machines. If the electrical generator is going to be overloaded, the control system pitches the blades in the opposite direction of what a pitch controlled machine would do. In this case itincreases the angle of attack of the airfoil leading to a stall condition, rather than decreasing the angle of attack to reduce the lift and the rotational speed of the blades.An advantage of active stall control is that the power output can be controlled so as to avoid overshooting the generator’s rated power at the start of wind gusts. A second advantage is that the machine would deliver its rated power at high wind speeds, in contrast to a passive stall controlled machine which will normally experience a drop in its electrical power output level at high wind speeds since its rotor blades experience a deeper stall.COMBINATION PITCH AND STALL CONTROLCONSTANT SPEED TURBINES: STALL-PITCH REGULATIONCombined stall-pitch regulation was used on constant-speed turbines such as the Siemens SWT-1.3-62 and SWT-2.3-82 turbines. At low and medium wind speeds, the blade pitch setting is slowly adjusted to provide maximum power output at any given wind speed. When the rated wind speed is reached, the blades are adjusted to a more negative pitch setting, tripping aerodynamic stall and thereby spilling the excess power. At higher wind speeds, the pitch angle is adjusted continuously to maintain the maximum power specified.The advantage of such regulation is that it is very simple and efficient, working well with constant speed operation. The disadvantages are that the noise level and blade deflection in high wind are somewhat higher than with pitch-stall regulation. These disadvantages are of minor importance for smaller turbines, but for very large turbines they tend to outweigh the benefits of the robust constant speed operation.VARIABLE SPEED TURBINES: PITCH-STALL REGULATIONCombined pitch-stall regulation was used on variable speed turbines such as the Siemens SWT-2.3-82 VS, SWT-2.3-93 and SWT-3.6-107 turbines. At low and medium wind speeds the blade pitch setting is slowly adjusted to provide maximum power output at any given wind speed. When the rated wind speed is reached, the blades are adjusted to a more positive pitch setting, thereby reducing the aerodynamic forces and maintaining the power level programmed into the turbine controller. At higher wind speeds, the pitch angle is adjusted continuously to maintain the maximum power specified.The advantage of pitch-stall regulation is that it provides low aerodynamic noise and moderate blade deflections. Lower noise can be obtained by special operation. The disadvantage is that variable speed operation is required to provide the necessary flexibility in regulation. This disadvantage is of minor importance for large turbines, where the benefits of pitch-stall regulation outweigh the added complexity of variable speed operation.FLAP POWER CONTROLSome wind machines have their rotors equipped with ailerons or flaps like aircraft. In this case the geometry of the wing airfoil is altered to provide increased or decreased air lift.YAW POWER CONTROLIt is possible to yaw or rotate the whole rotor mechanism out of the wind to decrease its rotational speed and power output. This technique is used for small wind turbines of 1 kW rated power or less. It would subject large wind turbines to cyclic stresses that could lead to the fatigue failure of the entire structure.ORIENTATION YAW CONTROLThe yaw position control mechanism is used to orient the wind turbine rotor in such a way that it perpendicularly faces the wind stream.The wind turbine undergoes a yaw error, if the rotor is not perpendicular to the wind. The existence of a yaw error suggests that a lower fraction of the energy in the wind will be flowing through the rotor area and available for extraction. The lost power fraction is proportional to the cosine of the yaw error angle:cos(P )αε∆l (1)where: ε is the yaw error angle,∆P is the power loss caused by the yaw error.If the yaw error would only lead to a decrease in the power output, it would be an acceptable method of power control. However this is not the case since a side effect occurs.The part of the rotor that is closer to the wind becomes subject to a larger bending torque than the rest of the rotor. This means that the rotor has a propensity to automatically yaw against the wind and this applies to either upwind or downwind machine designs. The rotor blades under a yaw error would be bending back and forth in a flap-wise fashion for each turn of the rotor. Running a wind turbine with a yaw error subjects it to a large fatigue load that could lead to its eventual fatigue failure. It becomes necessary to equip wind machines with yaw mechanism placing them in a direction that is perpendicular to the wind direction.Forced yawing is used in most horizontal axis wind turbines. The mechanism uses electric motors and gear boxes to keep the turbine yawed perpendicularly to the wind stream.Fig. 4: Wind generator yaw mechanism.The yaw mechanism under the nacelle of a 750 kW machine looking from the bottom is shown in Fig. 4. The yaw bearing is situated around its outer edge, and the gears of the yaw motors and the yaw brakes are placed on the inside. Manufacturers of upwind machines include provisions for braking the yaw mechanism whenever it is not used. The yaw mechanism is activated by the electronic controller which interrogates the position of the wind vane on the turbine, several times per second.SAFETY FEATURE: CABLE TWIST COUNTERA wind turbine accident situation is that it could continue yawing continuously in the same direction direction. Electrical cables carry the current from the wind turbine generator down through the structural tower. These cables could become twisted if the turbine accidentally keeps yawing in the same direction more than one rotation.Wind turbines are equipped with an engineered safety feature consisting of a cable twist counter which informs the controller when it becomes necessary to untwist the power cables. It is connected to a circuit breaker which is activated if the cables become too twisted and brakes the yaw rotation mechanism. No more than five full twist rotations are allowed.。
雷诺数和侧风对S型垂直轴风力机气动特性的影响
Chinese Journal of Turbomachinery Vol.66，2024,No.1Effects of Reynolds Number and Crosswind on AerodynamicCharacteristics of S-type Vertical Axis Wind Turbine *Yang Zhu 1Hang Zuo 1Jian-yong Zhu 1，*Xiu-yong Zhao 2(1.College of Aero-engine,Shenyang Aerospace University；2.China Energy Science and Technology Research Institute Co.,Ltd.)Abstract：Compared with the large wind turbine working in wild wind field,the small wind turbine is easily affected by low wind speed,high turbulence and time-varying wind speed and direction in urban wind environment.The effects of Reynolds number and inflow angle on the aerodynamic performance of small S-type vertical axis wind turbine are numerically studied.The results show that the aerodynamic performance of S-type wind turbine is not sensitive to Reynolds number,the power coefficient of which almost does not change with Reynolds number.The crosswind leads to the deterioration of the aerodynamic performance,mainly reflected in the decrease of the static torque coefficient and the power coefficient,and the higher the crosswind inflow angle is,the worse aerodynamic performance is.The flow mechanism of crosswind on the aerodynamic performance is revealed mainly in two aspects.On the one hand,the inflow angle obviously decreases the horizontal velocity component of the incoming flow.On the other hand,the vertical velocity component decreases the pressure difference of the advancing blades,while increases the pressure difference of the returning blades,thereby further decreasing the aerodynamic performance.Keywords：Wind Energy;S-type Vertical Axis Wind Turbine;Reynolds Number;Inflow Angle;Numerical Simulation摘要：相较于工作在郊外良好风场的大型风力机，小型风力机易受城市风环境如低风速、高湍流度以及时变风速风向的影响。
how does wind turbine works
How Wind Turbines WorkWind is a form of solar energy. Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth's surface, and rotation of the earth. Wind flow patterns are modified by the earth's terrain, bodies of water, and vegetation. Humans use this wind flow, or motion energy, for many purposes: sailing, flying a kite, and even generating electricity.The terms wind energy or wind power describe the process by which the wind is used to generate mechanical power or electricity. Wind turbines convert the kinetic energy in the wind into mechanical power. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity.So how do wind turbines make electricity? Simply stated, a wind turbine works the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity. Take a look inside a wind turbine to see the various parts. View the wind turbine animation to see how a wind turbine works.This aerial view of a wind power plant shows how a group of wind turbines can make electricity for the utility grid. The electricity is sent through transmission and distribution lines to homes, businesses, schools, and so on.Learn more about wind energy technology:∙Types of Wind Turbines∙Sizes of Wind Turbines∙Energy 101: Wind Turbines Video∙Inside the Wind TurbineMany wind farms have sprung up in the Midwest in recent years, generating power for utilities. Farmers benefit by receiving land lease payments from wind energy project developers.GE Wind Energy's 3.6 megawatt wind turbine is one of the largest prototypes ever erected. Larger wind turbines are more efficient and cost effective.Types of Wind TurbinesModern wind turbines fall into two basic groups: the horizontal-axis variety, as shown in the photo, and the vertical-axis design, like the eggbeater-style Darrieus model, named after its French inventor.Horizontal-axis wind turbines typically either have two or three blades. These three-bladed wind turbines are operated "upwind," with the blades facing into the wind.Sizes of Wind TurbinesUtility-scale turbines range in size from 100 kilowatts to as large as several megawatts. Larger turbines are grouped together into wind farms, which provide bulk power to the electrical grid.Single small turbines, below 100 kilowatts, are used for homes, telecommunications dishes, or water pumping. Small turbines are sometimes used in connection with diesel generators, batteries, and photovoltaic systems. These systems are called hybrid wind systems and are typically used in remote, off-grid locations, where a connection to the utility grid is not available.Energy 101: Wind Turbines VideoThis video explains the basics of how wind turbines operate to produce clean power from an abundant, renewable resource—the wind.Inside the Wind TurbineAnemometer:Measures the wind speed and transmits wind speed data to the controller.Blades:Most turbines have either two or three blades. Wind blowing over the blades causes theblades to "lift" and rotate.Brake:A disc brake, which can be applied mechanically, electrically, or hydraulically to stop therotor in emergencies.Controller:The controller starts up the machine at wind speeds of about 8 to 16 miles per hour (mph) and shuts off the machine at about 55 mph. Turbines do not operate at wind speeds above about 55 mph because they might be damaged by the high winds.Gear box:Gears connect the low-speed shaft to the high-speed shaft and increase the rotational speeds from about 30 to 60 rotations per minute (rpm) to about 1000 to 1800 rpm, the rotational speed required by most generators to produce electricity. The gear box is a costly (and heavy) part of the wind turbine and engineers are exploring "direct-drive" generators that operate at lower rotational speeds and don't need gear boxes.Generator:Usually an off-the-shelf induction generator that produces 60-cycle AC electricity.High-speed shaft:Drives the generator.Low-speed shaft:The rotor turns the low-speed shaft at about 30 to 60 rotations per minute.Nacelle:The nacelle sits atop the tower and contains the gear box, low- and high-speed shafts, generator, controller, and brake. Some nacelles are large enough for a helicopter to land on.Pitch:Blades are turned, or pitched, out of the wind to control the rotor speed and keep the rotor from turning in winds that are too high or too low to produce electricity.Rotor:The blades and the hub together are called the rotor.Tower:Towers are made from tubular steel (shown here), concrete, or steel lattice. Because wind speed increases with height, taller towers enable turbines to capture more energy and generate more electricity.Wind direction:This is an "upwind" turbine, so-called because it operates facing into the wind. Other turbines are designed to run "downwind," facing away from the wind.Wind vane:Measures wind direction and communicates with the yaw drive to orient the turbine properly with respect to the wind.Yaw drive: Upwind turbines face into the wind; the yaw drive is used to keep the rotor facing into the wind as the wind direction changes. Downwind turbines don't require a yaw drive, the wind blows the rotor downwind.Yaw motor: Powers the yaw drive.。
基于扩散映射理论的谱聚类算法的风电场机群划分
基于扩散映射理论的谱聚类算法的风电场机群划分林俐;陈迎【摘要】针对地形复杂或布局不规则的风电场,将谱聚类方法应用于风电场机群划分,提出了一种风电场的机群分类方法.该方法以风电机组具有相同或相近运行点为机组分群原则,应用基于扩散映射理论的谱聚类算法对风电场各机组的实测运行数据进行聚类分析,找到风电机组之间动态运行过程的相似性,从而实现对风电场内所有风电机组的聚类划分.通过算例仿真验证了所提出的机群划分方法的有效性.%For the wind farms with complex terrain or irregular layout,a wind turbine aggregation method based on the spectral clustering technique is proposed,which groups the wind turbines with same or similar operating point together.The spectral clustering algorithm based on the diffusion mapping theory is employed,which clusters the measured operating data of all wind turbines in a wind farm,captures the similarity among them in the dynamic operating process,and divides them into differentgroups.Simulative verification demonstrates the effectiveness of the proposed grouping method.【期刊名称】《电力自动化设备》【年(卷),期】2013(033)006【总页数】6页(P113-118)【关键词】风电场;动态等值;机群划分;谱聚类;聚类算法【作者】林俐;陈迎【作者单位】华北电力大学新能源电力系统国家重点实验室,北京102206;华北电力大学新能源电力系统国家重点实验室,北京102206;安徽省电力公司检修公司,安徽合肥230000【正文语种】中文【中图分类】TM862;TM6140 引言风力发电在我国迅速发展。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
variability of the power output of a wind farm could pose a substantial negative impact on the power system reliability, especially for a power system with high penetration of wind generation [2]-[4]. In order to address this issue, accurate forecast and control models of the power output of wind farm have to be developed. Dimensionality challenges the modeling of the total power output of all turbines of a large wind farm. In the previous research, a number of wind turbine level models have been developed for controlling voltages, seeking maximum utilization of wind power based on single wind turbine model or model of a small number of turbines. For example, [5] presented some concepts of evaluation of the system’s reliability based on a simplified wind power generation model; [6] as well as many others presented controller design for single wind turbine. However, the control of the total output of all turbines of a wind farm hasn’t been explored. A modern wind farm usually consists of hundreds of wind turbines and each wind turbine is a nonlinear dynamic system. The behavior of the total power output of all wind turbines of entire wind farm is not a simple aggregation of behaviors of individual turbines. The modeling is a real challenge because of dimension. For instance, it is almost impossible to control the output of wind farm by sending control signals to each turbine for the desired aggregate output of wind farm. One possible solution to this dimensionality issue is model reduction. Model reduction seeks to replace a large-scale system by one or several lower order systems that maintain the dominating characteristics of the input-out behavior of the overall system response [7]-[9]. Various model reduction methods have been developed and applied to complex engineering systems which exhibit complex behavior. For example, [10] used Krylov subspace methods to simplify the model of a power system; [11] represented the complicated thermodynamic behavior of heat pumps with a reduced model of two steady operation states. In bimolecular dynamics, clustering of different conformations has been suggested to be an effective method to shed light on the nature of bimolecular dynamic behavior and their influence in biochemical reactions [12]. It is very interesting to see if cluster analysis can be used to reduce the dimension of dynamic wind farm model. If the turbines can be clustered, then the entire wind farm can be represented by several representative turbine models, which significantly reduces the dimension of the system.
1
Cluster Analysis of Wind Turbines of Large Wind Farm
Yong Ma, Student Member, John N. Jiang, Senior Member, Thordur Runolfsson, Senior Member, IEEE
Abstract— Understanding the dynamics of the power output of a wind farm is important to the integration of large scale wind energy into the power system. In a large complex dynamic engineering system, such as a wind farm, clustering is an effective way to reduce the model complexity and improve the understanding of its local dynamics. The paper proposes a novel methodology to cluster wind turbines of a wind farm into different groups based on a particular distance measure. We first build a weighted graph to represent the complex relationships between power output of wind turbines. The graph is used to construct a Markov Chain and estimate the likelihood of any two wind turbines belong to the same cluster. We analyze the spectral properties of the Markov chain to identify the number of clusters. With the proposed method, the elements of each cluster can be identified in the feature space. Theoretical study showed that the proposed methodology simplifies the model of the dynamics of power output of wind farm without compromising the overall dynamic characteristics of the original system asymptotically. This paper also presents the results of clustering of 25 wind turbines located in three distinct locations of a wind farm with the proposed methodology based on the real power outputs for illustration and verification purpose. Then the results of a comprehensive study of all turbines of the wind farm are also included. We show that the method effectively cluster the wind turbines into three groups. The methodology is very useful for simplification of controller design, operation and forecast of wind generation. Index Terms--Clustering Analysis, Markov chain, Diffusion Distance, Wind Turbine, Wind Farm Power Output.