118 research outputs found
Effect of wind speed gradients on AEP in a wind farm cluster
No full textThe engineering flow models used to estimate annual energy production (AEP) in offshore wind farm layout optimization typically assume inflow homogeneity over the model domain. This assumption lies in contrast with observations of horizontal wind speed gradients in coastal regions where many offshore wind farms are being constructed. Accounting for wind speed gradients in wind farm models may lead to reduced uncertainty in AEP estimates and reduced bias inoptimized wind farm layouts. This thesis examines whether accounting for horizontal wind speed gradients with WRF simulated wind resource inputs to engineering wake models impacts AEP prediction for a wind farm cluster in the Irish Sea by comparing results with calculation methods which assume homogeneous inflow. Analysis of a wake free two turbine case under a gradient shows that the assumption of homogeneity leads to errors with the true power which a gradient based method is able to predict. Despite this, results suggest that the overall impact of modelling wind speed gradients on AEP predictions in the Irish Sea cluster is small. Homogeneous and gradient methods using the same wind resource data predicted differences in AEP of between 0.1% and 0.75%, with most cases below 0.75%. Filtering by wind direction reveals AEP differences larger than the assumed wake model uncertainty for two sectors with inflow from land. The AEP contribution from sectors with mean wind speed gradients is limited by low frequencies and mean wind speeds. Additionally, positive and negative power differences predicted by homogeneous and gradient methods were found to balance over the year.Rotor Design TrackEuropean Wind Energy Masters (EWEM
Metode latihadan pembelajaran bola voli untuk umum
No full textAktivitas olahraga telah bergerak dari pelatihan tradisional menuju pelatihan yang progesifvi,218 hlm.; 24 cm
DEVELOPMENT OF UNDERARM PASSING IN VOLLEYBALL THROUGH TRADITIONAL GAME APPROACH
No full textThis research is aimed to develop a model of underarm passing involleyball through traditional game’s basic movement approach. The methodused for this learning method development is Research and Development (R &D) Development Method. By choosing SMPN III Parongpong in West BandungRegency as the location of this study, this study is done through 8 stages: first,determining idea to develop; second, producing a design; third, evaluating,improving and completing the text; forth, revising a product by the expert; fifth, aprototype product done by taking product picture; sixth, prototype test, the testof subject field both in stage I and stage II test; seventh, revising a secondproduct of which revision was done by an expert; eighth, producting a completeto be the final product. From those stages, the result of the study is gained byfirst stage evaluation analysis of ten products. The total respondent score isresulted with data number = 123. Therefore, effectiveness of new teachingmethod in total = 123 : 144= 0,85 or 85% from the expected criteria and basedon stage II evaluation analysis by using numbered final product, the totalrespondent score is resulted with data number = 246. Therefore, the totaleffectiveness of teaching method = 246 : 288 = 0,85 or 85% from the expectedcriteria to fulfill valid criteria. Based on the result of the study, it can beconcluded that: (1) Underarm passing learning model in volleyball through gatriktraditional game approach in SMPN 3 Parongpong is needed by PhysicalEducation teachers and improving the learning process of underarm passingeffectively and efficiently. (2) Application of the developed learning model willmake students more motivated in joining learning process.
Key Words: Model development, underarm passing, traditional gameapproac
Perkembangan Motorik : Pengantar Teori dan Implikasinya dalam Belajar
No full textxii, 168 hlm.; ilus.: 24 c
Improving Annual Energy Production of Doubly-Fed Induction Generators
No full textDoubly fed induction generator (DFIG) based wind turbines are most employed for onshore applications because of their cost-effectiveness. The drivetrain improvement is barely studied due to the maturity of the DFIG based systems. This paper investigates two methods for improving the annual energy production (AEP) of the DFIG based wind turbines. They are referred to as short-circuited and -Y-connected DFIGs. The origins of the AEP improvement are elaborated from the drivetrain perspective. The improvement is quantified by the aerodynamic model of the turbine and the steady-state model of the DFIG. The two methods are then compared when applied to six regions with different wind speed distributions. The AEP improvements at six regions are evaluated and compared to derive the feasibility of the methods for different locations.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-car Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport Engineering and Logistic
Clustering Wind Profile Shapes to Estimate Airborne Wind Energy Production
No full textAirborne Wind Energy (AWE) systems use tethered flying devices to access higher altitudes, typically up to 500 meter, where wind is generally stronger and more persistent. To estimate the Annual Energy Production (AEP) of AWE systems, the wind speed statistics close to the ground are typically extrapolated to higher altitudes, introducing substantial uncertainties. A methodology is developed for characterising a site’s wind resource using a set of wind profile shapes. It is demonstrated how this wind resource representation is used together with a performance model to do fast AEP calculations for flexible-kite pumping AWE systems.greenWind Energ
A frequency-time domain method for annual energy production estimation in floating wind turbines
No full textA new method is proposed to estimate a floating wind turbine's annual energy production (AEP) using frequency and time-domain design techniques. The approach demonstrated herein estimates the AEP by performing a convolution between the floating platform response and the response power operators (RPOs) that map the average power produced by the turbine as a function of the amplitude and frequency of the platform motions. One advantage of this approach is that it can be performed early in the conceptual design phase to help discover design space trade-offs between the platform and rotor design. The methodology is applied to the IEA Wind 15 MW WindCrete spar-buoy model using OpenFAST. The RPOs are obtained by prescribing single-DOF platform motions to the turbine with a given amplitude and frequency. This methodology is then validated by comparing the AEP estimation from the RPOs with the AEP estimation from fully-coupled simulations. The results indicate that the method is able to estimate the value of AEP for a realistic sea-state and regular waves. However, further validation is needed as, in the first case, the turbine is moving too little and, in the second case, the contribution of the controller may be dominant. Wind Energ
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