WorldWideScience

Sample records for wind load reduction

  1. Wind load reduction for light-weight heliostats

    OpenAIRE

    Pfahl, Andreas; Brucks, Antje; Holze, Carsten

    2014-01-01

    At SolarPACES 2012 conference a new heliostat concept was presented. It is equipped with wireless communication, sandwich facets, wind protection devices for wind load reduction, rim drives with winch wheels and ground anchor foundation. Crucial for the development of the light-weight structures is the precise determination of the maximum loads. By full scale wind load measurements the duration of the peak loads could be determined. They are caused by gusts with such short duration that their...

  2. Mean and peak wind load reduction on heliostats

    Energy Technology Data Exchange (ETDEWEB)

    Peterka, J.A.; Tan, L.; Bienkiewcz, B.; Cermak, J.E.

    1987-09-01

    This report presents the results of wind-tunnel tests supported through the Solar Energy Research Institute (SERI) by the Office of Solar Thermal Technology of the US Department of Energy as part of the SERI research effort on innovative concentrators. As gravity loads on drive mechanisms are reduced through stretched-membrane technology, the wind-load contribution of the required drive capacity increases in percentage. Reduction of wind loads can provide economy in support structure and heliostat drive. Wind-tunnel tests have been directed at finding methods to reduce wind loads on heliostats. The tests investigated both mean and peak forces, and moments. A significant increase in ability to predict heliostat wind loads and their reduction within a heliostat field was achieved. In addition, a preliminary review of wind loads on parabolic dish collectors was conducted, resulting in a recommended research program for these type collectors. 42 refs., 38 figs., 1 tab.

  3. Load Reduction of Wind Turbines Using Receding Horizon Control

    DEFF Research Database (Denmark)

    Soltani, Mohsen; Wisniewski, Rafal; Brath, Per

    2011-01-01

    Large scale wind turbines are lightly damped mechanical structures driven by wind that is constantly fluctuating. In this paper, we address the design of a model-based receding horizon control scheme to reduce the structural loads in the transmission system and the tower, as well as provide...... constant (or at least smooth) power generation. Our controller incorporates two optimization problems: one to predict or estimate mean wind speed, given LIDAR data, and the other to carry out receding horizon control to choose the control inputs. The method is verified against an existing wind turbine...... control system, and shows reductions in both extreme loads and power fluctuations by 80% and 90% respectively when compared to a conventional controller....

  4. Blade-Pitch Control for Wind Turbine Load Reductions

    DEFF Research Database (Denmark)

    Lio, Alan Wai Hou

    Large wind turbines are subjected to the harmful loads that arise from the spatially uneven and temporally unsteady oncoming wind. Such loads are the known sources of fatigue damage that reduce the turbine operational lifetime, ultimately increasing the cost of wind energy to the end-users. In re...

  5. Preview-based Asymmetric Load Reduction of Wind Turbines

    DEFF Research Database (Denmark)

    Madsen, Mathias; Filsø, Jakob; Soltani, Mohsen

    2012-01-01

    Fatigue loads on wind turbines caused by an asymmetric wind field become an increasing concern when the scale of wind turbines increases. This paper presents a model based predictive approach to reduce asymmetric loads by using Light Detection And Ranging (LIDAR) measurements. The Model Predictive...... Controller (MPC) developed is based on a model with individual blade pitching to utilize the LIDAR measurements. The MPC must also maintain a given power reference while satisfying a set of actuator constraints. The designed controller was tested on a 5 MW wind turbine in the FAST simulator and compared...

  6. Wake-Effect Minimising Optimal Control of Wind Farms, with Load Reduction

    DEFF Research Database (Denmark)

    Borchersen, Anders Bech; Larsen, Jesper Abildgaard; Sivabalan, Senthuran

    2014-01-01

    A power generating wind turbine causes a speed reduction and an added turbulence to the wind. Wind turbines in wind farms are often caught in these wakes and are found to have a higher structural load than non affected wind turbines. This article investigates the possibility of designing a contro...

  7. Model Based Open-Loop Wind Farm Control Using Active Power for Power Increase and Load Reduction

    OpenAIRE

    Hyungyu Kim; Kwansu Kim; Insu Paek

    2017-01-01

    A new wind farm control algorithm that adjusts the power output of the most upstream wind turbine in a wind farm for power increase and load reduction was developed in this study. The algorithm finds power commands to individual wind turbines to maximize the total power output from the wind farm when the power command from the transmission system operator is larger than the total available power from the wind farm. To validate this wind farm control algorithm, a relatively high fidelity wind ...

  8. Performance enhancement and load reduction on wind turbines using inflow measurements

    Energy Technology Data Exchange (ETDEWEB)

    Abildgaard Kragh, K.

    2013-06-15

    by applying inflow measurement based control are assessed. The potential for increasing the power output through improved yaw alignment is studied by analyzing operational data from different turbines, and through experiments with a modified yaw controller. The results demonstrate that there is no significant potential for increased power output through improved yaw alignment for well calibrated turbines. The potential for increasing the power output through pitch control is studied through optimization of collective and individual pitch actuation. The results show that there is a potential for increasing the power output through individual pitch control. However, the increased power output is penalized by increased load variations. The load variations on a wind turbine can be alleviated using either yaw or pitch actuation. A method is presented for alleviating load variations using yaw control, and it is shown how the method can be efficiently applied for decreasing the load variations that are caused by a vertical wind shear. The potential of reducing the load variations using both inflow measurement based collective and individual pitch control is studied through simulations. The results demonstrate that tower and blade load variations can be efficiently alleviated in situations with large scale inflow variations using collective pitch control. For individual pitch control, it is demonstrated that control based on upstream inflow measurements can lead to great load reductions in certain situations. However, it is also shown that the potential load variation reductions are sensitive to uncertainties relating to the estimated inflow. This thesis is comprised of a collection of scientific papers that covers the various results presented in this summary. (Author)

  9. A Wind Farm Active Power Dispatch Strategy for Fatigue Load Reduction

    DEFF Research Database (Denmark)

    Zhang, Baohua; N. Soltani, Mohsen; Hu, Weihao

    2016-01-01

    One of the biggest challenges in wind farm management is to cope with requirements from the grid companies and to optimize efficiency and minimize wear on wind turbines. This paper addresses an optimized active power dispatch strategy of a wind farm to reduce the fatigue load of wind turbines, wh...

  10. Wind Loads on Structures

    DEFF Research Database (Denmark)

    Dyrbye, Claes; Hansen, Svend Ole

    Wind loads have to be taken into account when designing civil engineering structures. The wind load on structures can be systematised by means of the wind load chain: wind climate (global), terrain (wind at low height), aerodynamic response (wind load to pressure), mechanical response (wind...... pressure to structural response) and design criteria. Starting with an introduction of the wind load chain, the book moves on to meteorological considerations, atmospheric boundary layer, static wind load, dynamic wind load and scaling laws used in wind-tunnel tests. The dynamic wind load covers vibrations...... induced by wind turbulence, vortex shedding, flutter and galloping. The book gives a comprehensive treatment of wind effects on structures and it will be useful for consulting engineers designing wind-sensitive structures. It will also be valuable for students of civil engineering as textbook...

  11. Wind Structure and Wind Loading

    DEFF Research Database (Denmark)

    Brorsen, Michael

    The purpose of this note is to provide a short description of wind, i.e. of the flow in the atmosphere of the Earth and the loading caused by wind on structures. The description comprises: causes to the generation of windhe interaction between wind and the surface of the Earthhe stochastic nature...... of windhe interaction between wind and structures, where it is shown that wind loading depends strongly on this interaction...

  12. Methods and apparatus for reduction of asymmetric rotor loads in wind turbines

    Science.gov (United States)

    Moroz, Emilian Mieczyslaw; Pierce, Kirk Gee

    2006-10-10

    A method for reducing load and providing yaw alignment in a wind turbine includes measuring displacements or moments resulting from asymmetric loads on the wind turbine. These measured displacements or moments are used to determine a pitch for each rotor blade to reduce or counter asymmetric rotor loading and a favorable yaw orientation to reduce pitch activity. Yaw alignment of the wind turbine is adjusted in accordance with the favorable yaw orientation and the pitch of each rotor blade is adjusted in accordance with the determined pitch to reduce or counter asymmetric rotor loading.

  13. Influence of wind loading

    OpenAIRE

    MAVLONOV RAVSHANBEK ABDUJABBOROVICH; VAKKASOV KHAYRULLO SAYFULLAHANOVICH

    2015-01-01

    Each wind load is determined by a probabilistic-statistical method based on the concept of “equivalent static wind load”, on the assumption that structural frames and components/cladding behave elastically in strong wind.

  14. Performance Enhancement and Load Reduction on Wind Turbines Using Inflow Measurements

    DEFF Research Database (Denmark)

    Kragh, Knud Abildgaard

    excessively. The operation of a wind turbine is governed by a number of controllers that are based on a series of sensors and actuators. Classical wind turbine control utilizes sensors for measuring turbine parameters such as rotor speed, power and shaft torque, as well as actuators for applying generator...... “Light Detection and Ranging”. In this thesis, the potentials for improving the power production and decreasing the load variations of horizontal axis upwind turbines by applying inflow measurement based control are assessed. The potential for increasing the power output through improved yaw alignment...... is studied by analyzing operational data from different turbines, and through experiments with a modified yaw controller. The results demonstrate that there is no significant potential for increased power output through improved yaw alignment for well calibrated turbines. The potential for increasing...

  15. Reduction of aerodynamic load fluctuation on wind turbine blades through active flow control

    Science.gov (United States)

    Velarde, John-Michael; Coleman, Thomas; Magstadt, Andrew; Aggarwal, Somil; Glauser, Mark

    2015-11-01

    The current set of experiments deals with implementing active flow control on a Bergey Excel 1, 1kW turbine. The previous work in our group demonstrated successfully that implementation of a simple closed-loop controller could reduce unsteady aerodynamic load fluctuation by 18% on a vertically mounted wing. Here we describe a similar flow control method adapted to work in the rotating frame of a 2.5m diameter wind turbine. Strain gages at the base of each blade measure the unsteady fluctuation in the blades and pressure taps distributed along the span of the blades feed information to the closed-loop control scheme. A realistic, unsteady flow field has been generated by placing a cylinder upstream of the turbine to induce shedding vortices at frequencies in the bandwidth of the first structural bending mode of the turbine blades. The goal of these experiments is to demonstrate closed-loop flow control as a means to reduce the unsteady fluctuation in the blades and increase the overall lifespan of the wind turbine.

  16. Study of wind change for the development of loads reduction techniques for the space shuttle

    Science.gov (United States)

    Adelfang, S. I.

    1987-01-01

    Wind change statistics are analyzed for Vandenberg AFB, California (VAFB) and Kennedy Space Center, Florida (KSC). Means and standard deviations of wind component change and vector wind change modulus within 3-9 and 9-16 km altitude bands are tabulated. The contribution to 3.5 hr wind component change by wind perturbations in various wavelength bands is evaluated. Probability distributions of maximum 3.5 hr wind change in an altitude band are presented and a model for wind change at a specified altitude is tested with data derived from six data bases from VAFB and Santa Monica, California.

  17. Reduction of fatigue loads on jacket substructure through blade design optimization for multimegawatt wind turbines at 50 m water depths

    DEFF Research Database (Denmark)

    NJOMO WANDJI, Wilfried; Pavese, Christian; Natarajan, Anand

    2016-01-01

    This paper addresses the reduction of the fore-aft damage equivalent moment at the tower base for multi-megawatt offshore wind turbines mounted on jacket type substructures at 50 m water depths. The study investigates blade design optimization of a reference 10 MW wind turbine under standard wind...... on the efficient design of other components such as the constituents of the nacelle....

  18. Reduction mechanism of dynamic loads on down wind rotor; Furyoku hatsuden system down wind rotor no doteki kaju no keigen kiko ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Seki, K.; Shimizu, Y.; Yasui, T. [Tokai University, Tokyo (Japan)

    1997-11-25

    Dynamic force on blades in a large wind mill changes with rotational speed for various reasons, such as wind shear that causes vertical distribution of wind velocity or titling angle. Therefore, a 2-blade system on a teetered hub is a practical selection for the coned, down-wind type. Use of teetered axis greatly reduces bending moment in the flap direction and that at the axis of rotation. An attempt was made to understand dynamic loads by inertial force resulting from oscillation of the blade rotating on the teetered axis, and thereby to avoid them. The in-plane load can be diminished to zero when the teetered axis is coincided with the center of gravity, but generally cannot be avoided when the blade is strained significantly, except it is operated at the rated condition. The in-plane load and bending moment can be avoided, when rotational freedom is given around the y axis. Dynamic load on a down-wind rotor can be avoided by use of universal joint. 3 refs., 6 figs.

  19. Load alleviation on wind turbine blades using variable geometry

    DEFF Research Database (Denmark)

    Basualdo, Santiago

    2005-01-01

    ) wind turbines, which mainly operate under this flow condition. The results show evident reductions in the airfoil displacements by using simple control strategies having the airfoil position and its first and second derivatives as input, especially at the system's eigenfrequency. The use of variable...... in loads in real wind turbines. Keywords: Variable Geometry, Wind Turbine, Load Alleviation, Fatigue Load, Trailing Edge Flap....

  20. Ultimate loading of wind turbines

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Ronold, K.; Ejsing Jørgensen, Hans

    1999-01-01

    An extreme loading study has been conducted comprising a general wind climate analysis as well as a wind turbine reliability study. In the wind climate analysis, the distribution of the (horizontal) turbulence standard deviation, conditioned on the meanwind speed, has been approximated by fitting......, a design turbulence intensity for off-shore application is proposed which, in the IEC code framework, is applicable for extreme as well as for fatigue loaddetermination. In order to establish a rational method to analyse wind turbine components with respect to failure in ultimate loading, and in addition...... to the event of failure in ultimate loading in flapwise bending in the normal operating condition of a site-specific turbine....

  1. Load alleviation of wind turbines by yaw misalignment

    DEFF Research Database (Denmark)

    Kragh, Knud Abildgaard; Hansen, Morten Hartvig

    2014-01-01

    Vertical wind shear is one of the dominating causes of load variations on the blades of a horizontal axis wind turbine. To alleviate the varying loads, wind turbine control systems have been augmented with sensors and actuators for individual pitch control. However, the loads caused by a vertical...... wind shear can also be affected through yaw misalignment. Recent studies of yaw control have been focused on improving the yaw alignment to increase the power capture at below rated wind speeds. In this study, the potential of alleviating blade load variations induced by the wind shear through yaw...... be applied without power loss for wind speeds above rated wind speed. In deterministic inflow, it is shown that the range of the steady-state blade load variations can be reduced by up to 70%. For turbulent inflows, it is shown that the potential blade fatigue load reductions depend on the turbulence level...

  2. Full-scale test of trailing edge flaps on a Vestas V27 wind turbine: active load reduction and system identification

    DEFF Research Database (Denmark)

    Castaignet, Damien; Barlas, Thanasis K.; Buhl, Thomas

    2014-01-01

    model, from trailing edge flap angle to flapwise blade root moment, was derived and compared with the linear analytical model used in the model predictive control design model. Flex5 simulations run with the same model predictive control showed a good correlation between the simulations......A full-scale test was performed on a Vestas V27 wind turbine equipped with one active 70 cm long trailing edge flap on one of its 13 m long blades. Active load reduction could be observed in spite of the limited spanwise coverage of the single active trailing edge flap. A frequency-weighted model...

  3. Wind and load variability in the Nordic countries

    DEFF Research Database (Denmark)

    Holttinen, Hannele; Rissanen, Simo; Larsén, Xiaoli Guo

    This publication analysed the variability of wind production and load in Denmark, Finland, Sweden, and the Nordic region as a whole, based on real data measured from large-scale wind power during 2009–2011. The Nordic-wide wind power time series was scaled up such that Sweden had same amount...... the three years analysed in this publication there were few storm incidents and they did not produce dramatic wind power ramps in the Nordic region. Wind and load variations are not correlated between the countries, which is beneficial from the viewpoint of wind integration. The smoothing effect is shown...... as reduction of variability from a single country to Nordic-wide wind power. The impact of wind power on the variability that the system experiences is evaluated by analysing the variability of net load with different wind power penetration levels. The Nordic-wide wind power production increases the highest...

  4. Hydraulic Soft Yaw System Load Reduction and Prototype Results

    DEFF Research Database (Denmark)

    Stubkier, Søren; Pedersen, Henrik C.; Markussen, Kristian

    2013-01-01

    operates. Further it is analyzed how the soft yaw system influence the power production of the turbine. It is shown that the influence is minimal, but at larger yaw errors the effect is possitive. Due to the implemeted functions in the hydraulic soft yaw system such as even load distribution on the pinions......Introducing a hydraulic soft yaw concept for wind turbines leads to significant load reductions in the wind turbine structure. The soft yaw system operates as a shock absorption system on a car, hence absorbing the loading from turbulent wind conditions instead of leading them into the stiff wind...... turbine structure. Results presented shows fatigue reductions of up to 40% and ultimate load reduction of up to 19%. The ultimate load reduction increases even more when the over load protection system in the hydraulic soft yaw system is introduced and results show how the exact extreme load cut off...

  5. Aeroelastic modelling and comparison of advanced active flap control concepts for load reduction on the Upwind 5MW wind turbine

    NARCIS (Netherlands)

    Barlas, A.; van Kuik, G.A.M.

    2009-01-01

    A newly developed comprehensive aeroelastic model is used to investigate active flap concepts on the Upwind 5MW reference wind turbine. The model is specially designed to facilitate distributed control concepts and advanced controller design. Different concepts of centralized and distributed control

  6. Aeroelastic Modelling and Comparison of Advanced Active Flap Control Concepts for Load Reduction on the Upwind 5MW Wind Turbine

    NARCIS (Netherlands)

    Barlas, A.; Van Kuik, G.A.M.

    2009-01-01

    A newly developed comprehensive aeroelastic model is used to investigate active flap concepts on the Upwind 5MW reference wind turbine. The model is specially designed to facilitate distributed control concepts and advanced controller design. Different concepts of centralized and distributed control

  7. Reliability analysis of wind turbines exposed to dynamic loads

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2014-01-01

    Wind turbines are exposed to highly dynamic loads that cause fatigue and extreme load effects which are subject to significant uncertainties. Further, reduction of cost of energy for wind turbines are very important in order to make wind energy competitive compared to other energy sources......, substructure and foundation considering especially fatigue loads. The function of a wind turbine is highly dependent on many electrical and mechanical components as well as a control system also reliability aspects of these components are discussed and it is described how there reliability influences...

  8. Load Extrapolation During Operation for Wind Turbines

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    2008-01-01

    In the recent years load extrapolation for wind turbines has been widely considered in the wind turbine industry. Loads on wind turbines during operations are normally dependent on the mean wind speed, the turbulence intensity and the type and settings of the control system. All these parameters...... must be taken into account when characteristic load effects during operation are determined. In the wind turbine standard IEC 61400-1 a method for load extrapolation using the peak over threshold method is recommended. In this paper this method is considered and some of the assumptions are examined...

  9. Wind Climate Parameters for Wind Turbine Fatigue Load Assessment

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Svenningsen, Lasse; Moser, Wolfgang

    2016-01-01

    established from the on-site distribution functions of the horizontal mean wind speeds, the 90% quantile of turbulence along with average values of vertical wind shear and air density and the maximum flow inclination. This paper investigates the accuracy of fatigue loads estimated using this equivalent wind...... climate required by the current design standard by comparing damage equivalent fatigue loads estimated based on wind climate parameters for each 10 min time-series with fatigue loads estimated based on the equivalent wind climate parameters. Wind measurements from Boulder, CO, in the United States...... and Høvsøre in Denmark have been used to estimate the natural variation in the wind conditions between 10 min time periods. The structural wind turbine loads have been simulated using the aero-elastic model FAST. The results show that using a 90% quantile for the turbulence leads to an accurate assessment...

  10. Characterising Turbulence Intensity for Fatigue Load Analysis of Wind Turbines

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose; Larsen, Gunner Chr.

    2005-01-01

    Turbulence in wind velocity presents a major factor for modern wind turbine design as cost reduction as are sort for the dynamic structures. Therefore this paper contains a parametrisation of the turbulence intensity at given sites, relevant for the calculation of fatigue loading of wind turbines....... The parameterisation is based on wind speed measurements extracted from the “Database on Wind Characteristics” (www.winddata.com). The parameterisation is based on the LogNormal distribution, which has proven to be suitable distribution to describe the turbulence intensity distribution....

  11. Design Load Basis for Offshore Wind turbines

    DEFF Research Database (Denmark)

    Natarajan, Anand; Hansen, Morten Hartvig; Wang, Shaofeng

    2016-01-01

    DTU Wind Energy is not designing and manufacturing wind turbines and does therefore not need a Design Load Basis (DLB) that is accepted by a certification body. However, to assess the load consequences of innovative features and devices added to existing offshore turbine concepts or new offshore...... turbine concept developed in our research, it is useful to have a full DLB that follows the current design standard and is representative of a general DLB used by the industry. It will set a standard for the offshore wind turbine design load evaluations performed at DTU Wind Energy, which is aligned...

  12. Reducing Turbine Mechanical Loads Using Flow Model-Based Wind Farm Controller

    DEFF Research Database (Denmark)

    Kazda, Jonas; Cutululis, Nicolaos Antonio

    WindFarm [2]. SimWindFarm allows for the simultaneous simulation of the turbulent hub height flow field in the wind farm, the turbine dynamics and the wind farm control. The tests show a reduction of loads when compared to other optimal wind farm control approaches. Future work shall enhance the controller......Cumulated O&M costs of offshore wind farms are comparable with wind turbine CAPEX of such wind farm. In wind farms, wake effects can result in up to 80% higher fatigue loads at downstream wind turbines [1] and consequently larger O&M costs. The present work therefore investigates to reduce...... these loads during the provision of grid balancing services using optimal model-based wind farm control. Wind farm controllers coordinate the operating point of wind turbines in a wind farm in order to achieve a given objective. The investigated objective of the control in this work is to follow a total wind...

  13. Wind loads on flat plate photovoltaic array fields (nonsteady winds)

    Science.gov (United States)

    Miller, R. D.; Zimmerman, D. K.

    1981-01-01

    Techniques to predict the dynamic response and the structural dynamic loads of flat plate photovoltaic arrays due to wind turbulence were analyzed. Guidelines for use in predicting the turbulent portion of the wind loading on future similar arrays are presented. The dynamic response and the loads dynamic magnification factor of the two array configurations are similar. The magnification factors at a mid chord and outer chord location on the array illustrated and at four points on the chord are shown. The wind tunnel test experimental rms pressure coefficient on which magnification factors are based is shown. It is found that the largest response and dynamic magnification factor occur at a mid chord location on an array and near the trailing edge. A technique employing these magnification factors and the wind tunnel test rms fluctuating pressure coefficients to calculate design pressure loads due to wind turbulence is presented.

  14. Assessment of wind turbine load measurement instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Morfiadakis, E.; Papadopoulos, K. [CRES (Greece); Borg, N. van der [ECN, Petten (Netherlands); Petersen, S.M. [Risoe, Roskilde (Denmark); Seifert, H. [DEWI, Wilhelmshaven (Germany)

    1999-03-01

    In the framework of Sub-Task3 `Wind turbine load measurement instrumentation` of EU-project `European Wind Turbine Testing Procedure Development`, the load measurement techniques have been assessed by laboratory, full scale and numerical tests. The existing methods have been reviewed with emphasis on the strain gage application techniques on composite materials and recommendations are provided for the optimisation of load measurement techniques. (au) EU. 14 refs.

  15. The Potential of Combined Heat and Power Generation, Wind Power Generation and Load Management Techniques for Cost Reduction in Small Electricity Supply Systems.

    Science.gov (United States)

    Bass, Jeremy Hugh

    Available from UMI in association with The British Library. Requires signed TDF. An evaluation is made of the potential fuel and financial savings possible when a small, autonomous diesel system sized to meet the demands of an individual, domestic consumer is adapted to include: (1) combined heat and power (CHP) generation, (2) wind turbine generation, (3) direct load control. The potential of these three areas is investigated by means of time-step simulation modelling on a microcomputer. Models are used to evaluate performance and a Net Present Value analysis used to assess costs. A cost/benefit analysis then enables those areas, or combination of areas, that facilitate and greatest savings to be identified. The modelling work is supported by experience gained from the following: (1) field study of the Lundy Island wind/diesel system, (2) laboratory testing of a small diesel generator set, (3) study of a diesel based CHP unit, (4) study of a diesel based direct load control system, (5) statistical analysis of data obtained from the long-term monitoring of a large number of individual household's electricity consumption. Rather than consider the consumer's electrical demand in isolation, a more flexible approach is adopted, with consumer demand being regarded as the sum of primarily two components: a small, electricity demand for essential services and a large, reschedulable demand for heating/cooling. The results of the study indicate that: (1) operating a diesel set in a CHP mode is the best strategy for both financial and fuel savings. A simple retrofit enables overall conversion efficiencies to be increased from 25% to 60%, or greater, at little cost. (2) wind turbine generation in association with direct load control is a most effective combination. (3) a combination of both the above areas enables greatest overall financial savings, in favourable winds resulting in unit energy costs around 20% of those of diesel only operation.

  16. Load prediction of stall regulated wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Bjoerck, A.; Dahlberg, J.Aa. [Aeronautical Research Inst. of Sweden, Bromma (Sweden); Carlen, I. [Chalmers Univ. of Technology, Goeteborg (Sweden). Div. of Marine Structural Engineering; Ganander, H. [Teknikgruppen AB, Sollentua (Sweden)

    1996-12-01

    Measurements of blade loads on a turbine situated in a small wind farm shows that the highest blade loads occur during operation close to the peak power i.e. when the turbine operates in the stall region. In this study the extensive experimental data base has been utilised to compare loads in selected campaigns with corresponding load predictions. The predictions are based on time domain simulations of the wind turbine structure, performed by the aeroelastic code VIDYN. In the calculations a model were adopted in order to include the effects of dynamic stall. This paper describes the work carried out so far within the project and key results. 5 refs, 10 figs

  17. Wind loads on solar energy roofs

    NARCIS (Netherlands)

    Geurts, C.P.W.; Bentum, C.A. van

    2007-01-01

    This paper presents an overview of the wind loads on roofs, equipped with solar energy products, so called Active Roofs. Values given in this paper have been based on wind tunnel and full scale measurements, carried out at TNO, and on an interpretation of existing rules and guidelines. The results

  18. Damping Wind and Wave Loads on a Floating Wind Turbine

    DEFF Research Database (Denmark)

    Christiansen, Søren; Bak, Thomas; Knudsen, Torben

    2013-01-01

    Offshore wind energy capitalizes on the higher and less turbulent wind speeds at sea. To enable deployment of wind turbines in deep-water locations, structures are being explored, where wind turbines are placed on a floating platform. This combined structure presents a new control problem, due...... to the partly unconstrained movement of the platform and ocean wave excitation. If this additional complexity is not dealt with properly, this may lead to a significant increase in the structural loads and, potentially, instability of the controlled system. In this paper, the wave excitation is investigated......, and we show the influence that both wind speed, wave frequencies and misalignment between wind and waves have on the system dynamics. A new control model is derived that extends standard turbine models to include the hydrodynamics, additional platform degrees of freedom, the platform mooring system...

  19. Variability and smoothing effect of wind power production compared to load variability in the Nordic countries

    DEFF Research Database (Denmark)

    Holttinen, Hannele; Rissanen, Simo; Giebel, Gregor

    2012-01-01

    the viewpoint of wind integration. The smoothing effect is shown as reduction of variability from a single country to Nordic wide wind power. The impact of wind power on the variability that the system sees is depicted by analysing the variability of net load with different wind power penetration levels...

  20. Load attenuating passively adaptive wind turbine blade

    Science.gov (United States)

    Veers, Paul S.; Lobitz, Donald W.

    2003-01-07

    A method and apparatus for improving wind turbine performance by alleviating loads and controlling the rotor. The invention employs the use of a passively adaptive blade that senses the wind velocity or rotational speed, and accordingly modifies its aerodynamic configuration. The invention exploits the load mitigation prospects of a blade that twists toward feather as it bends. The invention includes passively adaptive wind turbine rotors or blades with currently preferred power control features. The apparatus is a composite fiber horizontal axis wind-turbine blade, in which a substantial majority of fibers in the blade skin are inclined at angles of between 15 and 30 degrees to the axis of the blade, to produces passive adaptive aeroelastic tailoring (bend-twist coupling) to alleviate loading without unduly jeopardizing performance.

  1. Database on wind characteristics - Analyses of wind turbine design loads

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, G.C.; Hansen, K.S.

    2004-06-01

    The main objective of IEA R and D Wind Annex XVII - Database on Wind Characteristics - has been to provide wind energy planners, designers and researchers, as well as the international wind engineering community in general, with a source of actual wind field data (time series and resource data) observed in a wide range of different wind climates and terrain types. Connected to an extension of the initial Annex period, the scope for the continuation was widened to include also support to the international wind turbine standardisation efforts.. The project partners are Sweden, Norway, U.S.A., The Netherlands and Denmark, with Denmark as the Operating Agent. The reporting of the continuation of Annex XVII falls in two separate parts. Part one accounts in details for the available data in the established database bank, and part two describes various data analyses performed with the overall purpose of improving the design load cases with relevance for to wind turbine structures. The present report constitutes the second part of the Annex XVII reporting. Both fatigue and extreme load aspects are dealt with, however, with the main emphasis on the latter. The work has been supported by The Ministry of Environment and Energy, Danish Energy Agency, The Netherlands Agency for Energy and the Environment (NOVEM), The Norwegian Water Resources and Energy Administration (NVE), The Swedish National Energy Administration (STEM) and The Government of the United States of America. (au)

  2. H∞ Based Control for Load Mitigation in Wind Turbines

    Directory of Open Access Journals (Sweden)

    Aron Pujana-Arrese

    2012-04-01

    Full Text Available This article demonstrates a strategy to design multivariable and multi-objective controllers based on the H∞ norm reduction applied to a wind turbine. The wind turbine model has been developed in the GH Bladed software and it is based on a 5 MW wind turbine defined in the Upwind European project. The designed control strategy works in the above rated power production zone and performs generator speed control and load reduction on the drive train and tower. In order to do this, two robust H∞ MISO (Multi-Input Single-Output controllers have been developed. These controllers generate collective pitch angle and generator torque set-point values to achieve the imposed control objectives. Linear models obtained in GH Bladed 4.0 are used, but the control design methodology can be used with linear models obtained from any other modelling package. Controllers are designed by setting out a mixed sensitivity problem, where some notch filters are also included in the controller dynamics. The obtained H∞ controllers have been validated in GH Bladed and an exhaustive analysis has been carried out to calculate fatigue load reduction on wind turbine components, as well as to analyze load mitigation in some extreme cases. The analysis compares the proposed control strategy based on H∞ controllers to a baseline control strategy designed using the classical control methods implemented on the present wind turbines.

  3. Variability of load and net load in case of large scale distributed wind power

    OpenAIRE

    Holttinen, Hannele; Kiviluoma, J.; Estanqueiro, Ana; Gómez-Lázaro, E.; Raw, Barry; Dobschinski, Jan; Meibon, Peter; Lannoye, Eamonn; Aigner, Tobias; Wan, Yih H.; Milligan, Michael

    2011-01-01

    Large scale wind power production and its variability is one of the major inputs to wind integration studies. This paper analyses measured data from large scale wind power production. Comparisons of variability are made across several variables: time scale (10-60 minute ramp rates),number of wind farms, and simulated vs. modeled data. Ramp rates for Wind power production, Load (total system load) and Net load (load minus wind power production) demonstrate how wind power increases the...

  4. Variability of load and net load in case of large scale distributed wind power

    OpenAIRE

    Holttinen, Hannele; Kiviluoma, Juha; Estanqueiro, Ana; Aigner, Tobias; Wan, Yih-Huei; Milligan, Michael R.

    2010-01-01

    Large scale wind power production and its variability is one of the major inputs to wind integration studies. This paper analyses measured data from large scale wind power production. Comparisons of variability are made across several variables: time scale (10-60 minute ramp rates), number of wind farms, and simulated vs. modeled data. Ramp rates for Wind power production, Load (total system load) and Net load (load minus wind power production) demonstrate how wind power increases the net loa...

  5. Active load control techniques for wind turbines.

    Energy Technology Data Exchange (ETDEWEB)

    van Dam, C.P. (University of California, Davis, CA); Berg, Dale E.; Johnson, Scott J. (University of California, Davis, CA)

    2008-07-01

    This report provides an overview on the current state of wind turbine control and introduces a number of active techniques that could be potentially used for control of wind turbine blades. The focus is on research regarding active flow control (AFC) as it applies to wind turbine performance and loads. The techniques and concepts described here are often described as 'smart structures' or 'smart rotor control'. This field is rapidly growing and there are numerous concepts currently being investigated around the world; some concepts already are focused on the wind energy industry and others are intended for use in other fields, but have the potential for wind turbine control. An AFC system can be broken into three categories: controls and sensors, actuators and devices, and the flow phenomena. This report focuses on the research involved with the actuators and devices and the generated flow phenomena caused by each device.

  6. Behaviour of glass plates under wind loads

    Science.gov (United States)

    Gavanski, Eri

    Glazing damage during strong windstorms has been considered to result mainly from windborne debris. However, recent windstorm damage reports have revealed the necessity of studying fluctuating wind loads, which appear to be another factor contributing to this damage. From an experimental point of view, studies on this topic have been limited to the application of rather simple loading patterns. Moreover, there is an uncertainty surrounding both load resistance and design load used in the current North American window glass design codes. It is of concern that these regulations may not offer sufficient accuracy on account of the limited understanding of time-dependent glass strength derived from the technology available at the time of codification. Unprecedented full-scale glass breakage tests under realistic wind pressure loading were conducted to investigate these issues. The obtained results revealed significant new information about the behavior of glass plates under fluctuating loads. Along with these tests, a numerical simulation using the Monte-Carlo technique was also performed with a subtle modification of the initial glass strength. This adjustment resulted in better correspondence with test results. Using the test and numerical simulation results, the current window glass design method was examined. The calculation methods of LR, and the reference time conversion used in the codes, were found to require further investigation. By creating a particular wind pressure time history, the practice of using peak pressures from ASCE7-05 as the design load was investigated. The results showed that there are cases when the current practice may underestimate the design load because of the duration of windstorms. KEYWORDS: Glass, Fluctuating load, Full-scale test, Load resistance, Design load, Static fatigue, Numerical simulation, Monte-Carlo technique, Brown's integral.

  7. Atmospheric stability and its influence on wind turbine loads

    DEFF Research Database (Denmark)

    Sathe, Ameya; Mann, Jakob; Barlas, Thanasis K.

    2012-01-01

    Simulations of wind turbine loads for the NREL 5 MW reference wind turbine under diabatic wind conditions are performed for mean wind speeds between 3 { 16 m/s at the turbine hub height. The loads are quantified as the cumulative sum of the damage equivalent load for different wind speeds...... that are weighted according to the wind speed and stability distribution. It is observed that atmospheric stability influences the tower and rotor loads. The difference in the calculated tower loads using diabatic wind conditions and those obtained assuming neutral conditions only is approximately 16%, whereas...... the difference for the rotor loads is up to 11%. The blade loads are hardly influenced by atmospheric stability, where the difference between the calculated loads using diabatic and neutral input wind conditions is less than 1%. The wind profiles and turbulence under diabatic conditions have contrasting...

  8. Wind turbine blade testing under combined loading

    DEFF Research Database (Denmark)

    Roczek-Sieradzan, Agnieszka; Nielsen, Magda; Branner, Kim

    2011-01-01

    The paper presents full-scale blade tests under a combined flap- and edgewise loading. The main aim of this paper is to present the results from testing a wind turbine blade under such conditions and to study the structural behavior of the blade subjected to combined loading. A loading method using...... anchor plates was applied, allowing transverse shear distortion. The global and local deformation of the blade as well as the reproducibility of the test was studied and the results from the investigations are presented....

  9. The nature of wind turbine fatigue loads in wind farms

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Larsen, Torben J.; Aagaard Madsen, Helge

    2013-01-01

    agreements were found between the extend of wake affected direction regimes. As for the magnitude of the (mean) wake loading, the tower top moments were under-estimated with of the order 15%, whereas the tower bottom moments were found to agree well with the measured results.......The aim of the present paper is to further validate the predictive capability of the DWM/HAWC2 package for simulation of structural loadings in wind farms. The validation in particular focus on tower fatigue loading characteristics (i.e. equivalent moments) as function of turbine relative position...... tower top and bottom bending moments as well as tower the top torsion moment. The numerical predictions are based on a simulation package, where the Dynamic Wake Meandering model is interfaced with the in-house aeroelastic code HAWC2. Comparing simulated and measured tower fatigue loading, good...

  10. Convergence of Extreme Loads for Offshore Wind Turbine Support Structures

    OpenAIRE

    Stewart, Gordon; Lackner, Matthew; Arwade, Sanjay R.; Myers, Andrew T.; Hallowell, Spencer

    2015-01-01

    Extreme loads of wind turbines are historically difficult to predict through simulation due to uncertainty in input conditions as well as in the simulation models. In addition, many long time series must be simulated for the statistics of the peak loads to become stationary. Offshore wind turbines require even more simulation due to the addition of stochastic wave loading. Floating offshore wind turbines, the subject of this paper, experience free-body motion as a result of wind and wave load...

  11. Influence of atmospheric stability on wind turbine loads

    DEFF Research Database (Denmark)

    Sathe, Ameya; Mann, Jakob; Barlas, Thanasis K.

    2013-01-01

    at the turbine hub height. The loads are quantified as the cumulative sum of the damage equivalent load for different wind speeds that are weighted according to the wind speed and stability distribution. Four sites with a different wind speed and stability distribution are used for comparison. The turbulence...... turbulent energy. The tower base loads are mainly influenced by diabatic turbulence, whereas the rotor loads are influenced by diabatic wind profiles. The blade loads are influenced by both, diabatic wind profile and turbulence, that leads to nullifying the contrasting influences on the loads...

  12. Wind loads for bar-truss structures

    Science.gov (United States)

    Katow, M. S.

    1981-01-01

    An analysis method developed to calculate the wind loads on the nodes or joints of the truss type support structure of the 64 meter antenna is described. The method uses the CBAR element and GRID coordinate cards of the NASTRAN or IDEAS structural analysis programs as inputs to the computer model of the structure. Cross flow principles and vector analysis are also used in the analysis. The algorithms used are described and probable accuracy of the solution is discussed.

  13. Field Testing of LIDAR-Assisted Feedforward Control Algorithms for Improved Speed Control and Fatigue Load Reduction on a 600-kW Wind Turbine: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Avishek A.; Bossanyi, Ervin A.; Scholbrock, Andrew K.; Fleming, Paul; Boquet, Mathieu; Krishnamurthy, Raghu

    2015-12-14

    A severe challenge in controlling wind turbines is ensuring controller performance in the presence of a stochastic and unknown wind field, relying on the response of the turbine to generate control actions. Recent technologies such as LIDAR, allow sensing of the wind field before it reaches the rotor. In this work a field-testing campaign to test LIDAR Assisted Control (LAC) has been undertaken on a 600-kW turbine using a fixed, five-beam LIDAR system. The campaign compared the performance of a baseline controller to four LACs with progressively lower levels of feedback using 35 hours of collected data.

  14. Influence of wind conditions on wind turbine loads and measurement of turbulence using lidars

    NARCIS (Netherlands)

    Sathe, A.R.

    2012-01-01

    Variations in wind conditions influence the loads on wind turbines significantly. In order to determine these loads it is important that the external conditions are well understood. Wind lidars are well developed nowadays to measure wind profiles upwards from the surface. But how turbulence can be

  15. Model of wind shear conditional on turbulence and its impact on wind turbine loads

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov; Natarajan, Anand; Kelly, Mark C.

    2015-01-01

    fatigue load is achieved. The proposed wind shear model based on the wind measurements is thereby probabilistic in definition, with shear jointly distributed with wind turbulence. A simplified model for the wind shear exponent is further derived from the full stochastic model. The fatigue loads over......We analyse high-frequency wind velocity measurements from two test stations over a period of several years and at heights ranging from 60 to 200 m, with the objective to validate wind shear predictions as used in load simulations for wind turbine design. A validated wind shear model is thereby...... different turbine components are evaluated under the full wind measurements, using the developed wind shear model and with standard wind conditions prescribed in the IEC 61400-1 ed. 3. The results display the effect of the Wöhler exponent and reveal that under moderate turbulence, the effect of wind shear...

  16. Assessment of Wind Parameter Sensitivity on Ultimate and Fatigue Wind Turbine Loads: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Amy N [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sethuraman, Latha [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jonkman, Jason [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Quick, Julian [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-02-13

    Wind turbines are designed using a set of simulations to ascertain the structural loads that the turbine could encounter. While mean hub-height wind speed is considered to vary, other wind parameters such as turbulence spectra, sheer, veer, spatial coherence, and component correlation are fixed or conditional values that, in reality, could have different characteristics at different sites and have a significant effect on the resulting loads. This paper therefore seeks to assess the sensitivity of different wind parameters on the resulting ultimate and fatigue loads on the turbine during normal operational conditions. Eighteen different wind parameters are screened using an Elementary Effects approach with radial points. As expected, the results show a high sensitivity of the loads to the turbulence standard deviation in the primary wind direction, but the sensitivity to wind shear is often much greater. To a lesser extent, other wind parameters that drive loads include the coherence in the primary wind direction and veer.

  17. Assessment of Wind Parameter Sensitivity on Extreme and Fatigue Wind Turbine Loads

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Amy N [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sethuraman, Latha [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jonkman, Jason [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Quick, Julian [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-01-12

    Wind turbines are designed using a set of simulations to ascertain the structural loads that the turbine could encounter. While mean hub-height wind speed is considered to vary, other wind parameters such as turbulence spectra, sheer, veer, spatial coherence, and component correlation are fixed or conditional values that, in reality, could have different characteristics at different sites and have a significant effect on the resulting loads. This paper therefore seeks to assess the sensitivity of different wind parameters on the resulting ultimate and fatigue loads on the turbine during normal operational conditions. Eighteen different wind parameters are screened using an Elementary Effects approach with radial points. As expected, the results show a high sensitivity of the loads to the turbulence standard deviation in the primary wind direction, but the sensitivity to wind shear is often much greater. To a lesser extent, other wind parameters that drive loads include the coherence in the primary wind direction and veer.

  18. Evaluating the risk-reduction benefits of wind energy

    Energy Technology Data Exchange (ETDEWEB)

    Brower, M.C. [Brower & Company, Andover, MA (United States); Bell, K. [Convergence Research, Seattle, WA (United States); Bernow, S.; Duckworth, M. [Tellus Inst., Boston, MA (United States); Spinney P. [Charles River Associates, Boston, MA (United States)

    1996-12-31

    This paper presents preliminary results of a study to evaluate the risk-reduction benefits of wind power for a case study utility system using decision analysis techniques. The costs and risks of two alternative decisions-whether to build a 400 MW gas-fired combined cycle plant or a 1600 MW wind plant in 2003-were compared through computer simulations as fuel prices, environmental regulatory costs, wind and conventional power plant availability, and load growth were allowed to vary. Three different market scenarios were examined: traditional regulation, a short-term power pool, and fixed-price contracts of varying duration. The study concludes that, from the perspective of ratepayers, wind energy provides a net levelized risk-reduction benefit of $3.4 to $7.8/MWh under traditional regulation, and less in the other scenarios. From the perspective of the utility plant owners, wind provides a significant risk benefit in the unregulated market scenarios but none in a regulated market. The methodology and findings should help inform utility resource planning and industry restructuring efforts. 2 figs., 3 tabs.

  19. Wind models for the NSTS ascent trajectory biasing for wind load alleviation

    Science.gov (United States)

    Smith, O. E.; Adelfang, S. I.; Batts, G. W.

    1990-01-01

    New concepts are presented for aerospace vehicle ascent wind profile biasing. The purpose for wind biasing the ascent trajectory is to provide ascent wind loads relief and thus decrease the probability for launch delays due to wind loads exceeding critical limits. Wind biasing trajectories to the the profile of monthly mean winds have been widely used for this purpose. The wind profile models presented give additional alternatives for wind biased trajectories. They are derived from the properties of the bivariate normal probability function using the available wind statistical parameters for the launch site. The analytical expressions are presented to permit generalizations. Specific examples are given to illustrate the procedures. The wind profile models can be used to establish the ascent trajectory steering commands to guide the vehicle through the first stage. For the National Space Transportation System (NSTS) program these steering commands are called I-loads.

  20. Dynamic Response of Offshore Wind Turbines subjected to Joint Wave and Wind Loads

    DEFF Research Database (Denmark)

    Liu, Weiliang; Chen, Jianbing; Liu, Wenfeng

    2013-01-01

    into consideration. Wind and wave loads are generated by the physical random models. The aerodynamic loads on blades are calculated by the Blade Element Momentum (BEM) theory, and the wave loads are calculated by the linear theory of wave. The dynamic response of the NREL-5MW wind turbine system is carried out...

  1. Validation of wind loading codes by experiments

    NARCIS (Netherlands)

    Geurts, C.P.W.

    1998-01-01

    Between 1994 and 1997, full scale measurements of the wind and wind induced pressures were carried out on the main building of Eindhoven University of Technology. Simultaneously, a comparative wind tunnel experiment was performed in an atmospheric boundary layer wind tunnel. In this paper, the

  2. Numerical prediction of wind loads on low buildings | Ahmad ...

    African Journals Online (AJOL)

    In the present study, 2-D numerical simulation of wind loads on low-rise buildings has been carried out. The simulation was carried out under FLUENT package environment in which full-scale Reynolds number, boundary layer and turbulence properties have been simulated. Wind loading effect numerically obtained on flat ...

  3. Methods and apparatus for rotor load control in wind turbines

    Science.gov (United States)

    Moroz, Emilian Mieczyslaw

    2006-08-22

    A wind turbine having a rotor, at least one rotor blade, and a plurality of generators, of which a first generator is configured to provide power to an electric grid and a second generator is configured to provide power to the wind turbine during times of grid loss. The wind turbine is configured to utilize power provided by the second generator to reduce loads on the wind turbine during times of grid loss.

  4. An Optimal Control Scheme to Minimize Loads in Wind Farms

    DEFF Research Database (Denmark)

    Soleimanzadeh, Maryam; Wisniewski, Rafal

    2012-01-01

    This work presents a control algorithm for wind farms that optimizes the power production of the farm and helps to increase the lifetime of wind turbines components. The control algorithm is a centralized approach, and it determines the power reference signals for individual wind turbines...... such that the structural loads of the wind turbines in low frequencies are reduced. The controller is relatively easy to implement on a wind farm, and in here the results of simulating the controller on a small wind farm is presented....

  5. Morphological Response of Eight Quercus Species to Simulated Wind Load.

    Science.gov (United States)

    Wu, Tonggui; Zhang, Peng; Zhang, Lei; Wang, Geoff G; Yu, Mukui

    Leaf shape, including leaf size, leaf dissection index (LDI), and venation distribution, strongly impacts leaf physiology and the forces of momentum exerted on leaves or the canopy under windy conditions. Yet, little has been known about how leaf shape affects the morphological response of trees to wind load. We studied eight Quercus species, with different leaf shapes, to determine the morphological response to simulated wind load. Quercus trees with long elliptical leaves, were significantly affected by wind load (Pwind load, such as bigger leaf thickness, larger stem diameter, allocation to root biomass, and smaller stem height (Pwind can reduce drag and increase the mechanical strength of the tree. Leaf dissection index (LDI), an important index of leaf shape, was correlated with morphological response to wind load (Pwind load.

  6. Wind loads on flat plate photovoltaic array fields

    Science.gov (United States)

    Miller, R. D.; Zimmerman, D. K.

    1981-01-01

    The results of an experimental analysis (boundary layer wind tunnel test) of the aerodynamic forces resulting from winds acting on flat plate photovoltaic arrays are presented. Local pressure coefficient distributions and normal force coefficients on the arrays are shown and compared to theoretical results. Parameters that were varied when determining the aerodynamic forces included tilt angle, array separation, ground clearance, protective wind barriers, and the effect of the wind velocity profile. Recommended design wind forces and pressures are presented, which envelop the test results for winds perpendicular to the array's longitudinal axis. This wind direction produces the maximum wind loads on the arrays except at the array edge where oblique winds produce larger edge pressure loads. The arrays located at the outer boundary of an array field have a protective influence on the interior arrays of the field. A significant decrease of the array wind loads were recorded in the wind tunnel test on array panels located behind a fence and/or interior to the array field compared to the arrays on the boundary and unprotected from the wind. The magnitude of this decrease was the same whether caused by a fence or upwind arrays.

  7. Wind/Wave Misalignment in the Loads Analysis of a Floating Offshore Wind Turbine: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Barj, L.; Stewart, S.; Stewart, G.; Lackner, M.; Jonkman, J.; Robertson, A.

    2014-02-01

    Wind resources far from the shore and in deeper seas have encouraged the offshore wind industry to look into floating platforms. The International Electrotechnical Commission (IEC) is developing a new technical specification for the design of floating offshore wind turbines that extends existing design standards for land-based and fixed-bottom offshore wind turbines. The work summarized in this paper supports the development of best practices and simulation requirements in the loads analysis of floating offshore wind turbines by examining the impact of wind/wave misalignment on the system loads under normal operation. Simulations of the OC3-Hywind floating offshore wind turbine system under a wide range of wind speeds, significant wave heights, peak-spectral periods and wind/wave misalignments have been carried out with the aero-servo-hydro-elastic tool FAST [4]. The extreme and fatigue loads have been calculated for all the simulations. The extreme and fatigue loading as a function of wind/wave misalignment have been represented as load roses and a directional binning sensitivity study has been carried out. This study focused on identifying the number and type of wind/wave misalignment simulations needed to accurately capture the extreme and fatigue loads of the system in all possible metocean conditions considered, and for a down-selected set identified as the generic US East Coast site. For this axisymmetric platform, perpendicular wind and waves play an important role in the support structure and including these cases in the design loads analysis can improve the estimation of extreme and fatigue loads. However, most structural locations see their highest extreme and fatigue loads with aligned wind and waves. These results are specific to the spar type platform, but it is expected that the results presented here will be similar to other floating platforms.

  8. Load flow analysis for variable speed offshore wind farms

    DEFF Research Database (Denmark)

    Chen, Zhe; Zhao, Menghua; Blaabjerg, Frede

    2009-01-01

    A serial AC-DC integrated load flow algorithm for variable speed offshore wind farms is proposed. It divides the electrical system of a wind farm into several local networks, and different load flow methods are used for these local networks sequentially. This method is fast, more accurate, and many...... factors such as the different wind farm configurations, the control of wind turbines and the power losses of pulse width modulation converters are considered. The DC/DC converter model is proposed and integrated into load flow algorithm by modifying the Jacobian matrix. Two iterative methods are proposed...... and integrated into the load flow algorithm: one takes into account the control strategy of converters and the other considers the power losses of converters. In addition, different types of variable speed wind turbine systems with different control methods are investigated. Finally, the method is demonstrated...

  9. Database on wind characteristics - Analyses of wind turbine design loads

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Hansen, K.S.

    2004-01-01

    The main objective of IEA R&D Wind Annex XVII - Database on Wind Characteristics - has been to provide wind energy planners, designers and researchers, as well as the international wind engineering community in general, with a source of actual wind fielddata (time series and resource data) observed...... in a wide range of different wind climates and terrain types. Connected to an extension of the initial Annex period, the scope for the continuation was widened to include also support to the international windturbine standardisation efforts.. The project partners are Sweden, Norway, U.S.A., The Netherlands...... and Denmark, with Denmark as the Operating Agent. The reporting of the continuation of Annex XVII falls in two separate parts. Part one accounts in detailsfor the available data in the established database bank, and part two describes various data analyses performed with the overall purpose of improving...

  10. Wind shear estimation and wake detection by rotor loads — First wind tunnel verification

    Science.gov (United States)

    Schreiber, J.; Cacciola, S.; Campagnolo, F.; Petrović, V.; Mourembles, D.; Bottasso, C. L.

    2016-09-01

    The paper describes a simple method for detecting presence and location of a wake affecting a downstream wind turbine operating in a wind power plant. First, the local wind speed and shear experienced by the wind turbine are estimated by the use of rotor loads and other standard wind turbine response data. Then, a simple wake deficit model is used to determine the lateral position of the wake with respect to the affected rotor. The method is verified in a boundary layer wind tunnel using two instrumented scaled wind turbine models, demonstrating its effectiveness.

  11. Optimized Control Strategy For Over Loaded Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Knudsen, Torben; Wisniewski, Rafal

    2015-01-01

    Abstract Optimized control strategy for overloaded offshore wind turbines Introduction Operation and maintenance cost are an important part of cost of energy especially for offshore wind farms. Typically unplanned service is called for due to detection off excessive loads on components, e.......g., the tower. In the process of decreasing the cost of energy of wind turbines it is relevant to continue some level of production while awaiting service and repair of the offshore wind turbine. This is typically done operating the wind turbine in a power de-rated operation mode, assuming that lower power...... generation results in lower loads on the wind turbine, which enables continued production until next service. Approach Recent results in Model Predictive Control (MPC) applied to wind turbines show a potential for presenting possible controller tunings which weighs multiple conflicting objectives...

  12. Impact of Higher Fidelity Models on Simulation of Active Aerodynamic Load Control For Fatigue Damage Reduction

    NARCIS (Netherlands)

    Resor, B.; Wilson, D.; Berg, D.; Berg, J.; Barlas, T.; Van Wingerden, J.W.; Van Kuik, G.A.M.

    2010-01-01

    Active aerodynamic load control of wind turbine blades is being investigated by the wind energy research community and shows great promise, especially for reduction of turbine fatigue damage in blades and nearby components. For much of this work, full system aeroelastic codes have been used to

  13. Aeroelastic Ground Wind Loads Analysis Tool for Launch Vehicles

    Science.gov (United States)

    Ivanco, Thomas G.

    2016-01-01

    Launch vehicles are exposed to ground winds during rollout and on the launch pad that can induce static and dynamic loads. Of particular concern are the dynamic loads caused by vortex shedding from nearly-cylindrical structures. When the frequency of vortex shedding nears that of a lowly-damped structural mode, the dynamic loads can be more than an order of magnitude greater than mean drag loads. Accurately predicting vehicle response to vortex shedding during the design and analysis cycles is difficult and typically exceeds the practical capabilities of modern computational fluid dynamics codes. Therefore, mitigating the ground wind loads risk typically requires wind-tunnel tests of dynamically-scaled models that are time consuming and expensive to conduct. In recent years, NASA has developed a ground wind loads analysis tool for launch vehicles to fill this analytical capability gap in order to provide predictions for prelaunch static and dynamic loads. This paper includes a background of the ground wind loads problem and the current state-of-the-art. It then discusses the history and significance of the analysis tool and the methodology used to develop it. Finally, results of the analysis tool are compared to wind-tunnel and full-scale data of various geometries and Reynolds numbers.

  14. Extreme load predictions for floating offshore wind turbines

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher

    2009-01-01

    An effective stochastic procedure for extreme value predictions related to wave and wind induced stochastic loads is applied to a tension-leg concept for floating offshore wind turbines. The method is based on the First Order Reliability Method (FORM) and as the procedure makes use of only short...... time-domain simulations all kinds of non-linearities can be included. The procedure has been used previously for wave induced loads and is in this note extended to combined wave and wind loads....

  15. Effects of Icing on Wind Turbine Fatigue Loads

    International Nuclear Information System (INIS)

    Frohboese, Peter; Anders, Andreas

    2007-01-01

    The external conditions occurring at cold climate sites will affect wind turbines in different ways. The effects of ice accretion on wind turbines and the influence on the turbine fatigue loads are examined. The amount of icing prior to turbine installation needs to be estimated by using standard measurement data and considering the geometry of the proposed turbine. A procedure to calculate the expected ice accretion on wind turbines out of standard measurement data is explained and the results are discussed. Different parameters to describe the accreted ice on the turbine are examined separately in a fatigue load calculation. The results of the fatigue load calculation are discussed and selected cases are presented

  16. Modelling of a chaotic load of wind turbines drivetrain

    Science.gov (United States)

    Bielecki, Andrzej; Barszcz, Tomasz; Wójcik, Mateusz

    2015-03-01

    The purpose of this paper is to present a model of the load of the wind turbine gears for simulation of real, varying operational conditions for modelling of wind turbine vibration. The characteristics of the wind, which generates chaotically varying loads on the drivetrain components generating load in teeth and bearings of gears during torque transfer, are discussed. A generator of variable load of wind turbines drivetrain is proposed. Firstly, the module for generation of wind speed is designed. It is based on the approach in which the wind speed was considered as a time series approximated by the Weierstrass function. Secondly, the rotational speed of the main shaft is proposed as a function of the wind speed value. The function depends on a few parameters that are fitted by using a genetic algorithm. Finally, the model of torque of the main shaft is introduced. This model has been created by using a multi-layer artificial neural network. The results show that the proposed approach yields a very good fit for the experimental data. The fit brings about the proper reproducing of all the aspects of the load that are crucial for causing fatigue and, as a consequence, damaging of gears of the wind turbines.

  17. Thermal loading of wind power converter considering dynamics of wind speed

    DEFF Research Database (Denmark)

    Baygildina, Elvira; Peltoniemi, Pasi; Pyrhönen, Olli

    2013-01-01

    ), and the thermal stress of power devices is investigated from the frequency spectrum point of view of wind speed. It is concluded that because of the strong inertia effects by the aerodynamic behavior of wind turbines, thermal stress of the semiconductors is relatively more stable and only influenced by the low......The thermal loading of power semiconductors is a crucial performance related to the reliability and cost of the wind power converter. However, the thermal loading impacts by the variation of wind speeds have not yet been clarified, especially when considering the aerodynamic behavior of the wind...

  18. Grid faults' impact on wind turbine structural loads

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Cutululis, Nicolaos Antonio; Iov, F.

    2007-01-01

    The objective of this work is to illustrate the impact of the grid faults on the wind turbine structural loads. Grid faults are typically simulated in detailed power system simulation tools, which by applying simplified mechanical models, are not able to provide a throughout insight...... on the structural loads caused by sudden disturbances on the grid. On the other hand, structural loads of the wind turbine are typically assessed in advanced aerolastic computer codes, which by applying simplified electrical models do not provide detailed electrical insight. This paper presents a simulation...... of the wind turbine during grid faults. The effect of a grid fault on the wind turbine flexible structure is assessed for a typical fixed speed wind turbine, equipped with an induction generator....

  19. Turbulence and turbulence-generated structural loading in wind turbine clusters

    Energy Technology Data Exchange (ETDEWEB)

    Frandsen, Sten

    2007-01-15

    Turbulence, in terms of standard deviation of wind speed fluctuations, and other flow characteristics are different in the interior of wind farms relative to the free flow and action must be taken to ensure sufficient structural sustainability of the wind turbines exposed to 'wind farm flow'. The standard deviation of wind speed fluctuations is a known key parameter for both extreme- and fatigue loading, and it is argued and found to be justified that a model for change in turbulence intensity alone may account for increased fatigue loading in wind farms. Changes in scale of turbulence and horizontal flow-shear also influence the dynamic response and thus fatigue loading. However, these parameters are typically negatively or positively correlated with the standard deviation of wind speed fluctuations, which therefore can, if need be, represent these other variables. Thus, models for spatially averaged turbulence intensity inside the wind farm and direct-wake turbulence intensity are being devised and a method to combine the different load situations is proposed. The combination of the load cases implies a weighting method involving the slope of the considered material's Woehler curve. In the context, this is novel and necessary to avoid excessive safety for fatigue estimation of the structure's steel components, and non-conservatism for fibreglass components. The proposed model offers significant reductions in computational efforts in the design process. The status for the implementation of the model is that it became part of the Danish standard for wind turbine design DS 472 (2001) in August 2001 and it is part of the corresponding international standard, IEC61400-1 (2005). Also, extreme loading under normal operation for wake conditions and the efficiency of very large wind farms are discussed. (au)

  20. Optimized Control Strategy For Over Loaded Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Knudsen, Torben; Wisniewski, Rafal

    2015-01-01

    .g., the tower. In the process of decreasing the cost of energy of wind turbines it is relevant to continue some level of production while awaiting service and repair of the offshore wind turbine. This is typically done operating the wind turbine in a power de-rated operation mode, assuming that lower power...... controller tuning for a given wind turbine. It also enables a very safe and robust comparison between a new control strategy and the present one. Main body of abstract Is it true that power de-rating indeed the best way to reduce loads? The power de-rating approach has the drawback of only indirectly...... and service at offshore location, where accessibility can be problematic. The controller objectives are focused directly on the actual objective like lowering of fore aft fatigue loads, instead of using an indirect objective of de-rating the power production of the wind turbine. This means what the wind...

  1. Adaptive pitch control for load mitigation of wind turbines

    Science.gov (United States)

    Yuan, Yuan; Tang, J.

    2015-04-01

    In this research, model reference adaptive control is examined for the pitch control of wind turbines that may suffer from reduced life owing to extreme loads and fatigue when operated under a high wind speed. Specifically, we aim at making a trade-off between the maximum energy captured and the load induced. The adaptive controller is designed to track the optimal generator speed and at the same time to mitigate component loads under turbulent wind field and other uncertainties. The proposed algorithm is tested on the NREL offshore 5-MW baseline wind turbine, and its performance is compared with that those of the gain scheduled proportional integral (GSPI) control and the disturbance accommodating control (DAC). The results show that the blade root flapwise load can be reduced at a slight expense of optimal power output. The generator speed regulation under adaptive controller is better than DAC.

  2. A model of rotationally-sampled wind turbulence for predicting fatigue loads in wind turbines

    Science.gov (United States)

    Spera, David A.

    1995-01-01

    Empirical equations are presented with which to model rotationally-sampled (R-S) turbulence for input to structural-dynamic computer codes and the calculation of wind turbine fatigue loads. These equations are derived from R-S turbulence data which were measured at the vertical-plane array in Clayton, New Mexico. For validation, the equations are applied to the calculation of cyclic flapwise blade loads for the NASA/DOE Mod-2 2.5-MW experimental HAWT's (horizontal-axis wind turbines), and the results compared to measured cyclic loads. Good correlation is achieved, indicating that the R-S turbulence model developed in this study contains the characteristics of the wind which produce many of the fatigue loads sustained by wind turbines. Empirical factors are included which permit the prediction of load levels at specified percentiles of occurrence, which is required for the generation of fatigue load spectra and the prediction of the fatigue lifetime of structures.

  3. Loads on Wind Turbines Access Platforms with Gratings

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Frigaard, Peter; Rasmussen, Michael R.

    2011-01-01

    The present paper deals with loads on wind turbine access platforms. The many planned new wind turbine parks together with the observed damages on platforms in several existing parks make the topic very important. The paper gives an overview of recently developed design formulae for different types...

  4. Load calculation methods for offshore wind turbine foundations

    DEFF Research Database (Denmark)

    Passon, Patrik; Branner, Kim

    2014-01-01

    Calculation of design loads for offshore wind turbine (OWT) foundations is typically performed in a joint effort between wind turbine manufactures and foundation designers (FDs). Ideally, both parties would apply the same fully integrated design tool and model for that purpose. However, such solu...

  5. Operation and Equivalent Loads of Wind Turbines in Large Wind Farms

    Science.gov (United States)

    Andersen, Soren Juhl; Sorensen, Jens Norkaer; Mikkelsen, Robert Flemming

    2017-11-01

    Wind farms continue to grow in size and as the technology matures, the design of wind farms move towards including dynamic effects besides merely annual power production estimates. The unsteady operation of wind turbines in large wind farms has been modelled with EllipSys3D(Michelsen, 1992, and Sørensen, 1995) for a number of different scenarios using a fully coupled large eddy simulations(LES) and aero-elastic framework. The turbines are represented in the flow fields using the actuator line method(Sørensen and Shen, 2002), where the aerodynamic forces and deflections are derived from an aero-elastic code, Flex5(Øye, 1996). The simulations constitute a database of full turbine operation in terms of both production and loads for various wind speeds, turbulence intensities, and turbine spacings. The operating conditions are examined in terms of averaged power production and thrust force, as well as 10min equivalent flapwise bending, yaw, and tilt moment loads. The analyses focus on how the performance and loads change throughout a given farm as well as comparing how various input parameters affect the operation and loads of the wind turbines during different scenarios. COMWIND(Grant 2104-09- 067216/DSF), Nordic Consortium on Optimization and Control of Wind Farms, Eurotech Greentech Wind project, Winds2Loads, and CCA LES. Ressources Granted on SNIC and JESS. The Vestas NM80 turbine has been used.

  6. Simulation of probabilistic wind loads and building analysis

    Science.gov (United States)

    Shah, Ashwin R.; Chamis, Christos C.

    1991-01-01

    Probabilistic wind loads likely to occur on a structure during its design life are predicted. Described here is a suitable multifactor interactive equation (MFIE) model and its use in the Composite Load Spectra (CLS) computer program to simulate the wind pressure cumulative distribution functions on four sides of a building. The simulated probabilistic wind pressure load was applied to a building frame, and cumulative distribution functions of sway displacements and reliability against overturning were obtained using NESSUS (Numerical Evaluation of Stochastic Structure Under Stress), a stochastic finite element computer code. The geometry of the building and the properties of building members were also considered as random in the NESSUS analysis. The uncertainties of wind pressure, building geometry, and member section property were qualified in terms of their respective sensitivities on the structural response.

  7. Wind Loads on Ships and Offshore Structures Estimated by CFD

    DEFF Research Database (Denmark)

    Aage, Christian; Hvid, S.L.; Hughes, P.H.

    1997-01-01

    Wind loads on ships and offshore structures could until recently be determined only by model tests, or by statistical methods based on model tests. By the development of Computational Fluid Dynamics or CFD there is now a realistic computational alternative available. In this paper, wind loads...... on a seagoing ferry and on a semisubmersible offshore platform have been estimated by CFD. The results have been compared with wind tunnel model tests and, for the ferry, a few full-scale measurements, and good agreement is obtained. The CFD method offers the possibility of a computational estimate of scale...... effects related to wind tunnel model testing. An example of such an estimate on the ferry is discussed. Due to the time involved in generating the computational mesh and in computing the solution, the CFD method is not at the moment economically competitive to routine wind tunnel model testing....

  8. Distributed Wind Cost Reduction: Learning from Solar

    Energy Technology Data Exchange (ETDEWEB)

    Tegen, Suzanne

    2016-02-23

    The distributed wind energy industry can learn several lessons from the solar industry regarding reducing soft costs. Suzanne Tegen presented this overview at the 2016 Distributed Wind Energy Association Business Conference in Washington, D.C., on February 23, 2016.

  9. Influence of Nonlinear Irregular Waves on the Fatigue Loads of an Offshore Wind Turbine

    NARCIS (Netherlands)

    Van der Meulen, M.B.; Ashuri, T.; Van Bussel, G.J.W.; Molenaar, D.P.

    2012-01-01

    In order to make offshore wind power a cost effective solution that can compete with the traditional fossil energy sources, cost reductions on the expensive offshore support structures are required. One way to achieve this, is to reduce the uncertainty in wave load calculations by using a more

  10. On the relationship between wind profiles and the STS ascent structural loads

    Science.gov (United States)

    Smith, Orvel E.; Adelfang, Stanley I.; Whitehead, Douglas S.

    1989-01-01

    The response of STS ascent structural load indicators to the wind profile is analyzed. The load indicator values versus Mach numbers are calculated with algorithms using trajectory information. The ascent load minimum margin concept is used to show that the detailed wind profile structure measured by the Jimsphere wind system is not needed to assess the STS rigid body structural wind loads.

  11. A review of the wind loading zones for flat roofs in code provisions

    NARCIS (Netherlands)

    Geurts, C.P.W.; Kopp, G.A.; Morrison, M.J.

    2013-01-01

    The provisions for wind loads on flat roofs differ considerably between current wind loading standards in different jurisdictions. For a number of major wind loading codes, both the definition of roof zones, and the values applied to determine the wind loads are discussed. This paper concentrates on

  12. Design of a new urban wind turbine airfoil using a pressure-load inverse method

    Energy Technology Data Exchange (ETDEWEB)

    Henriques, J.C.C.; Gato, L.M.C. [IDMEC, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Marques da Silva, F. [LNEC - Laboratorio Nacional de Engenharia Civil, Av. Brasil, 101, 1700-066 Lisboa (Portugal); Estanqueiro, A.I. [INETI - Instituto Nacional de Engenharia, Tecnologia e Inovacao Estrada do Paco do Lumiar, 1649-038 Lisboa (Portugal)

    2009-12-15

    This paper presents the design methodology of a new wind turbine airfoil that achieves high performance in urban environment by increasing the maximum lift. For this purpose, an inverse method was applied to obtain a new wind turbine blade section with constant pressure-load along the chord, at the design inlet angle. In comparison with conventional blade section designs, the new airfoil has increased maximum lift, reduced leading edge suction peak and controlled soft-stall behaviour, due to a reduction of the adverse pressure gradient on the suction side. Wind tunnel experimental results confirmed the computational results. (author)

  13. Telescope loading: A problem reduction approach

    Science.gov (United States)

    Bresina, John L.

    1994-01-01

    This paper presents a problem reduction approach to telescope loading. To study time-varying celestial behavior, astronomers submit periodic observation campaigns which involve a sequence of observations at a given sampling frequency over months or years. The loader's task is to generate an assignment of observation tasks to each night in the time window such that resource demand does not exceed resource capacity and such that the observations usefully contribute to the campaigns' scientific purposes, in a manner that is fair to all participating astronomers.

  14. Wind Turbine Controller to Mitigate Structural Loads on a Floating Wind Turbine Platform

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, Paul A.; Peiffer, Antoine; Schlipf, David

    2016-06-24

    This paper summarizes the control design work that was performed to optimize the controller of a wind turbine on the WindFloat structure. The WindFloat is a semi-submersible floating platform designed to be a support structure for a multi-megawatt power-generating wind turbine. A controller developed for a bottom-fixed wind turbine configuration was modified for use when the turbine is mounted on the WindFloat platform. This results in an efficient platform heel resonance mitigation scheme. In addition several control modules, designed with a coupled linear model, were added to the fixed-bottom baseline controller. The approach was tested in a fully coupled nonlinear aero-hydroelastic simulation tool in which wind and wave disturbances were modeled. This testing yielded significant improvements in platform global performance and tower-base-bending loading.

  15. Wind loads on post-panamax container ship

    DEFF Research Database (Denmark)

    Andersen, Ingrid Marie Vincent

    2013-01-01

    An investigation of the influence of the container configuration on the deck of a 9000+ TEU container ship on wind forces has been carried out through a series of wind tunnel tests with a 1:450 scale model. An analysis of earlier studies was used to select a series of appropriate loading conditions...... are presented as two different types of non-dimensional coefficients. It was apparent, as expected, that the measured forces and moment depend on the container configuration on deck. The test results may provide a general idea of how the magnitude of the wind forces is affected by a given container...

  16. Multivariate Modelling of Extreme Load Combinations for Wind Turbines

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov

    2015-01-01

    We demonstrate a model for estimating the joint probability distribution of two load components acting on a wind turbine blade cross section. The model addresses the problem of modelling the probability distribution of load time histories with large periodic components by dividing the signal...... into a periodic part and a perturbation term, where each part has a known probability distribution. The proposed model shows good agreement with simulated data under stationary conditions, and a design load envelope based on this model is comparable to the load envelope estimated using the standard procedure...... for determining contemporaneous loads. By defining a joint probability distribution and full return-period contours for multiple load components, the suggested procedure gives the possibility for determining the most critical loading direction in a blade cross section, or for carrying out reliability analysis...

  17. Small-Signal Stability of Wind Power System With Full-Load Converter Interfaced Wind Turbines

    DEFF Research Database (Denmark)

    Knüppel, Thyge; Nielsen, Jørgen Nygaard; Jensen, Kim Høj

    2012-01-01

    Small-signal stability analysis of power system oscillations is a well established field within power system analysis, but not much attention has yet been paid to systems with a high penetration of wind turbines and with large wind power plants (WPP). In this paper a comprehensive analysis...... is presented which assesses the impact of full-load converter interfaced wind turbines on power system small-signal stability. The study is based on a 7 generator network with lightly damped inter-area modes. A detailed wind turbine (WT) model with all grid relevant control functions is used in the study...

  18. Wind profiles for Space Shuttle loads analysis

    Science.gov (United States)

    Adelfang, S. I.

    1978-01-01

    The small scale wind velocity perturbations in vertical wind profiles at Cape Kennedy, Florida were analyzed in order to derive information for simulations of space shuttle ascent through the perturbed atmosphere. The available statistical data does not permit specification of various aspects of idealized singularities and wavelike perturbations with a reasonable degree of confidence. The information developed as a result of the analysis described in Section 3 of this report is suitable for the further development of idealized models. The term perturbation is used instead of the more common term, gust. According to the conventional approach, a gust profile is calculated by applying a high pass digital filter to a Jimsphere profile; all the speeds in the filtered profile are defined as gusts. The high pass filtered profile is defined as a residual profile and the maximum residual in the vicinity of a specified reference height is defined as the gust. Gusts defined in this manner represent the perturbation peaks. A detailed discussion of the calculation of residual profiles and gusts is given. The meteorological coordinate system, the data sample, and Jimsphere profiles are also described. Recommendations and conclusions are presented.

  19. Sensor comparison study for load alleviating wind turbine pitch control

    DEFF Research Database (Denmark)

    Kragh, Knud Abildgaard; Hansen, Morten Hartvig; Henriksen, Lars Christian

    2014-01-01

    of angle of attack and relative velocity at a radial position of the blades, and upstream inflow measurements from a spinner mounted light detection and ranging (LiDAR) sensor that enables preview of the incoming flow field. The results show that for stationary inflow conditions, the three different......As the size of wind turbines increases, the load alleviating capabilities of the turbine controller are becoming increasingly important. Load alleviating control schemes have traditionally been based on feedback from load sensor; however, recent developments of measurement technologies have enabled...... control on the basis of preview measurements of the inflow acquired using, e.g., light detection and ranging. The potential of alleviating load variations that are caused by mean wind speed changes through feed-forward control have been demonstrated through both experiments and simulations in several...

  20. Inverse load calculation procedure for offshore wind turbines and application to a 5-MW wind turbine support structure: Inverse load calculation procedure for offshore wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Pahn, T. [Pahn Ingenieure, Am Seegraben 17b 03051 Cottbus Germany; Rolfes, R. [Institut f?r Statik und Dynamik, Leibniz Universit?t Hannover, Appelstra?e 9A 30167 Hannover Germany; Jonkman, J. [National Renewable Energy Laboratory, 15013 Denver West Parkway Golden Colorado 80401 USA

    2017-02-20

    A significant number of wind turbines installed today have reached their designed service life of 20 years, and the number will rise continuously. Most of these turbines promise a more economical performance if they operate for more than 20 years. To assess a continued operation, we have to analyze the load-bearing capacity of the support structure with respect to site-specific conditions. Such an analysis requires the comparison of the loads used for the design of the support structure with the actual loads experienced. This publication presents the application of a so-called inverse load calculation to a 5-MW wind turbine support structure. The inverse load calculation determines external loads derived from a mechanical description of the support structure and from measured structural responses. Using numerical simulations with the software fast, we investigated the influence of wind-turbine-specific effects such as the wind turbine control or the dynamic interaction between the loads and the support structure to the presented inverse load calculation procedure. fast is used to study the inverse calculation of simultaneously acting wind and wave loads, which has not been carried out until now. Furthermore, the application of the inverse load calculation procedure to a real 5-MW wind turbine support structure is demonstrated. In terms of this practical application, setting up the mechanical system for the support structure using measurement data is discussed. The paper presents results for defined load cases and assesses the accuracy of the inversely derived dynamic loads for both the simulations and the practical application.

  1. Model of analysis of maximum loads in wind generators produced by extreme winds

    International Nuclear Information System (INIS)

    Herrera – Sánchez, Omar; Schellong, Wolfgang; González – Fernández, Vladimir

    2010-01-01

    The use of the wind energy by means of the wind turbines in areas of high risk of occurrence of Hurricanes comes being an important challenge for the designers of wind farm at world for some years. The wind generator is not usually designed to support this type of phenomena, for this reason the areas of high incidence of tropical hurricanes of the planning are excluded, that which, in occasions disables the use of this renewable source of energy totally, either because the country is very small, or because it coincides the area of more potential fully with that of high risk. To counteract this situation, a model of analysis of maxims loads has been elaborated taken place the extreme winds in wind turbines of great behavior. This model has the advantage of determining, in a chosen place, for the installation of a wind farm, the micro-areas with higher risk of wind loads above the acceptable for the standard classes of wind turbines. (author)

  2. Wind Load Test of Earthbag Wall

    Directory of Open Access Journals (Sweden)

    Ryan Scott

    2013-08-01

    Full Text Available Earthbag construction is a sustainable, low-cost, housing option for developing countries. Earthbag structures are built of individual soil-filled fabric bags (i.e., sand bags stacked in a running bond pattern. Once stacked, earthbags are compacted and the soil inside the bags is dried in-place to form earthen bricks. Barbed wires are placed between each course to affect shear transfer within the wall. Results of an out-of-plane load test on a full-scale earthbag wall are presented in this paper. The wall was subjected to out-of-plane pressure up to 3.16 kPa, which resulted in plastic deformations up to 50 mm. The wall did not collapse during loading. Wall behavior and force transfer mechanisms are discussed.

  3. Potential load reductions on megawatt turbines exposed to wakes using individual-pitch wake compensator and trailing-edge flaps

    DEFF Research Database (Denmark)

    Markou, Helen; Andersen, Peter Bjørn; Larsen, Gunner Chr.

    2011-01-01

    Wind turbines located in wind farms experience inflow wind conditions that are substantially modified compared with the ambient wind field that applies for stand-alone wind turbines because of upstream emitted wakes. This has implications not only for the power production of a wind farm, but also...... that typically focus on either load or power prediction. As a consequence, the wake affected inflow field generated by the DWM formulation opens for control strategies for the individual turbine. Two different control approaches for load reduction on the individual turbines are implemented in the multi-body aero-servo-elastic...... tool HAWC2, developed at Risø-DTU in Denmark, and their potential load reduction capabilities compared: (1) full-blade ‘individual-pitch controllers’ acting as wake compensators and (2) controllers using trailing-edge flaps. Information on the wake inflow conditions, induced by upstream turbines...

  4. Analysis of extreme wind events at Høvsøre and the effect on wind turbine loads

    DEFF Research Database (Denmark)

    Hannesdóttir, Ásta; Kelly, Mark C.; Mann, Jakob

    used to simulate wind turbine response in time domain. The simulations are made for the DTU 10 MW reference wind turbine. Load analysis shows that the maximum tilt moment on the tower yaw bearing correlates well with the wind shear of the measurements. When these loads are compared with the extreme...... wind shear load case of the IEC standards, it is seen that they are of similar magnitude and in one case even higher....

  5. Comparison of analytical methods for calculation of wind loads

    Science.gov (United States)

    Minderman, Donald J.; Schultz, Larry L.

    1989-01-01

    The following analysis is a comparison of analytical methods for calculation of wind load pressures. The analytical methods specified in ASCE Paper No. 3269, ANSI A58.1-1982, the Standard Building Code, and the Uniform Building Code were analyzed using various hurricane speeds to determine the differences in the calculated results. The winds used for the analysis ranged from 100 mph to 125 mph and applied inland from the shoreline of a large open body of water (i.e., an enormous lake or the ocean) a distance of 1500 feet or ten times the height of the building or structure considered. For a building or structure less than or equal to 250 feet in height acted upon by a wind greater than or equal to 115 mph, it was determined that the method specified in ANSI A58.1-1982 calculates a larger wind load pressure than the other methods. For a building or structure between 250 feet and 500 feet tall acted upon by a wind rangind from 100 mph to 110 mph, there is no clear choice of which method to use; for these cases, factors that must be considered are the steady-state or peak wind velocity, the geographic location, the distance from a large open body of water, and the expected design life and its risk factor.

  6. Radar-cross-section reduction of wind turbines. part 1.

    Energy Technology Data Exchange (ETDEWEB)

    Brock, Billy C.; Loui, Hung; McDonald, Jacob J.; Paquette, Joshua A.; Calkins, David A.; Miller, William K.; Allen, Steven E.; Clem, Paul Gilbert; Patitz, Ward E.

    2012-03-05

    In recent years, increasing deployment of large wind-turbine farms has become an issue of growing concern for the radar community. The large radar cross section (RCS) presented by wind turbines interferes with radar operation, and the Doppler shift caused by blade rotation causes problems identifying and tracking moving targets. Each new wind-turbine farm installation must be carefully evaluated for potential disruption of radar operation for air defense, air traffic control, weather sensing, and other applications. Several approaches currently exist to minimize conflict between wind-turbine farms and radar installations, including procedural adjustments, radar upgrades, and proper choice of low-impact wind-farm sites, but each has problems with limited effectiveness or prohibitive cost. An alternative approach, heretofore not technically feasible, is to reduce the RCS of wind turbines to the extent that they can be installed near existing radar installations. This report summarizes efforts to reduce wind-turbine RCS, with a particular emphasis on the blades. The report begins with a survey of the wind-turbine RCS-reduction literature to establish a baseline for comparison. The following topics are then addressed: electromagnetic model development and validation, novel material development, integration into wind-turbine fabrication processes, integrated-absorber design, and wind-turbine RCS modeling. Related topics of interest, including alternative mitigation techniques (procedural, at-the-radar, etc.), an introduction to RCS and electromagnetic scattering, and RCS-reduction modeling techniques, can be found in a previous report.

  7. Application of Load Carrying Sandwich Elements in Wind Turbine Blades

    DEFF Research Database (Denmark)

    Jensen, Jacob Fisker; Schultz, Jacob Pagh; Berggreen, Carl Christian

    2005-01-01

    The present work investigates the possibilities and drawbacks when applying sandwich as opposed to single skin composites in the flanges of the load carrying spar in a future 180 m wind turbine rotor. FEA is applied to investigate two basic designs with single skin and sandwich flanges respectively...

  8. Aerodynamic load control strategy of wind turbine in microgrid

    Science.gov (United States)

    Wang, Xiangming; Liu, Heshun; Chen, Yanfei

    2017-12-01

    A control strategy is proposed in the paper to optimize the aerodynamic load of the wind turbine in micro-grid. In grid-connection mode, the wind turbine adopts a new individual variable pitch control strategy. The pitch angle of the blade is rapidly given by the controller, and the pitch angle of each blade is fine tuned by the weight coefficient distributor. In islanding mode, according to the requirements of energy storage system, a given power tracking control method based on fuzzy PID control is proposed. Simulation result shows that this control strategy can effectively improve the axial aerodynamic load of the blade under rated wind speed in grid-connection mode, and ensure the smooth operation of the micro-grid in islanding mode.

  9. Assessment of Load Extrapolation Methods for Wind Turbines

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard; Veldkamp, Dick

    2011-01-01

    threshold method with two different threshold values. The comparisons show that the goodness of fit for the local distribution has a significant influence on the results, but the peak over threshold method with a threshold value on the mean plus 1.4 standard deviations generally gives the best results......In the present paper, methods for statistical load extrapolation of wind-turbine response are studied using a stationary Gaussian process model, which has approximately the same spectral properties as the response for the out-of-plane bending moment of a wind-turbine blade. For a Gaussian process......, an approximate analytical solution for the distribution of the peaks is given by Rice. In the present paper, three different methods for statistical load extrapolation are compared with the analytical solution for one mean wind speed. The methods considered are global maxima, block maxima, and the peak over...

  10. Assessment of load extrapolation methods for wind turbines

    DEFF Research Database (Denmark)

    Toft, H.S.; Sørensen, John Dalsgaard; Veldkamp, D.

    2010-01-01

    threshold method with two different threshold values. The comparisons show that the goodness of fit for the local distribution has a significant influence on the results, but the peak over threshold method with a threshold value on the mean plus 1.4 standard deviations generally gives the best results......In the present paper methods for statistical load extrapolation of wind turbine response are studied using a stationary Gaussian process model which has approximately the same spectral properties as the response for the flap bending moment of a wind turbine blade. For a Gaussian process...... an approximate analytical solution for the distribution of the peaks is given by Rice. In the present paper three different methods for statistical load extrapolation are compared with the analytical solution for one mean wind speed. The methods considered are global maxima, block maxima and the peak over...

  11. Wind simulation for extreme and fatigue loads

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, M.; Larsen, G.C.; Mann, J.; Ott, S.; Hansen, K.S.; Pedersen, B.J.

    2004-01-01

    Measurements of atmospheric turbulence have been studied and found to deviate from a Gaussian process, in particular regarding the velocity increments over small time steps, where the tails of the pdf are exponential rather than Gaussian. Principles for extreme event counting and the occurrence of cascading events are presented. Empirical extreme statistics agree with Rices exceedence theory, when it is assumed that the velocity and its time derivative are independent. Prediction based on the assumption that the velocity is a Gaussian process underpredicts the rate of occurrence of extreme events by many orders of magnitude, mainly because the measured pdf is non-Gaussian. Methods for simulation of turbulent signals have been developed and their computational efficiency are considered. The methods are applicable for multiple processes with individual spectra and probability distributions. Non-Gaussian processes are simulated by the correlation-distortion method. Non-stationary processes are obtained by Bezier interpolation between a set of stationary simulations with identical random seeds. Simulation of systems with some signals available is enabled by conditional statistics. A versatile method for simulation of extreme events has been developed. This will generate gusts, velocity jumps, extreme velocity shears, and sudden changes of wind direction. Gusts may be prescribed with a specified ensemble average shape, and it is possible to detect the critical gust shape for a given construction. The problem is formulated as the variational problem of finding the most probable adjustment of a standard simulation of a stationary Gaussian process subject to relevant event conditions, which are formulated as linear combination of points in the realization. The method is generalized for multiple correlated series, multiple simultaneous conditions, and 3D fields of all velocity components. Generalization are presented for a single non-Gaussian process subject to relatively

  12. The Impact of Variable Wind Shear Coefficients on Risk Reduction of Wind Energy Projects

    Science.gov (United States)

    Thomson, Allan; Yoonesi, Behrang; McNutt, Josiah

    2016-01-01

    Estimation of wind speed at proposed hub heights is typically achieved using a wind shear exponent or wind shear coefficient (WSC), variation in wind speed as a function of height. The WSC is subject to temporal variation at low and high frequencies, ranging from diurnal and seasonal variations to disturbance caused by weather patterns; however, in many cases, it is assumed that the WSC remains constant. This assumption creates significant error in resource assessment, increasing uncertainty in projects and potentially significantly impacting the ability to control gird connected wind generators. This paper contributes to the body of knowledge relating to the evaluation and assessment of wind speed, with particular emphasis on the development of techniques to improve the accuracy of estimated wind speed above measurement height. It presents an evaluation of the use of a variable wind shear coefficient methodology based on a distribution of wind shear coefficients which have been implemented in real time. The results indicate that a VWSC provides a more accurate estimate of wind at hub height, ranging from 41% to 4% reduction in root mean squared error (RMSE) between predicted and actual wind speeds when using a variable wind shear coefficient at heights ranging from 33% to 100% above the highest actual wind measurement. PMID:27872898

  13. Wind effects on long-span bridges: Probabilistic wind data format for buffeting and VIV load assessments

    Science.gov (United States)

    Hoffmann, K.; Srouji, R. G.; Hansen, S. O.

    2017-12-01

    The technology development within the structural design of long-span bridges in Norwegian fjords has created a need for reformulating the calculation format and the physical quantities used to describe the properties of wind and the associated wind-induced effects on bridge decks. Parts of a new probabilistic format describing the incoming, undisturbed wind is presented. It is expected that a fixed probabilistic format will facilitate a more physically consistent and precise description of the wind conditions, which in turn increase the accuracy and considerably reduce uncertainties in wind load assessments. Because the format is probabilistic, a quantification of the level of safety and uncertainty in predicted wind loads is readily accessible. A simple buffeting response calculation demonstrates the use of probabilistic wind data in the assessment of wind loads and responses. Furthermore, vortex-induced fatigue damage is discussed in relation to probabilistic wind turbulence data and response measurements from wind tunnel tests.

  14. Active load reduction using individual pitch, based on local blade flow measurements

    DEFF Research Database (Denmark)

    Larsen, Torben J.; Aagaard Madsen, H.; Thomsen, K.

    2005-01-01

    -of-the-art load-reducing concepts. Since the new flow-based concept deviates significantly from previous published load-reducing strategies, a comparison of the performance based on aeroelastic simulations is included. Advantages and drawbacks of the systems are discussed. Copyright (C) 2004 John Wiley Sons, Ltd.......A new load-reducing control strategy for individual blade control of large pitch-controlled wind turbines is presented This control concept is based on local blade inflow measurements and offers the possibility of larger load reductions, without loss of power production, than seen in other state...

  15. Floating wind generators offshore wind farm: Implications for structural loads and control actions

    International Nuclear Information System (INIS)

    Garcia, E.; Morant F, Quiles E.; Correcher, A.

    2009-01-01

    This paper describes the work currently carried out in the design of floating wind generators and their involvement in the future development of power generation in marine farms in depths exceeding 20 m. We discuss the main issues to be taken into account in the design of floating platforms, including the involvement of structural loads they bear. Also from a standpoint of control engineering are discussed strategies to reduce structural loads such a system to ensure adequate durability and therefore ensuring their economic viability. Finally, the abstract modeling tools for floating wind turbines that can be used in both structural design and the design of appropriate control algorithms

  16. Device Loading of Modular Multilevel Converter in Wind Power

    DEFF Research Database (Denmark)

    Popova, L.; Ma, Ke; Blaabjerg, Frede

    2015-01-01

    of the MMC to wind energy systems is studied. The converters used to connect the wind turbine to the grid, which have rated active powers of 2MW and 10MW, are proposed and investigated. The electrical losses and thermal loading of the power devices in the proposed converter solutions are analyzed based...... applications, and the losses are evenly distributed between the submodules of the MMC. However, inside a submodule, the losses of the power devices are not equal, which may lead to the de-rating of the converter....

  17. AC-DC integrated load flow calculation for variable speed offshore wind farms

    DEFF Research Database (Denmark)

    Zhao, Menghua; Chen, Zhe; Blaabjerg, Frede

    2005-01-01

    This paper proposes a sequential AC-DC integrated load flow algorithm for variable speed offshore wind farms. In this algorithm, the variable frequency and the control strategy of variable speed wind turbine systems are considered. In addition, the losses of wind turbine systems and the losses...... of converters are also integrated into the load flow algorithm. As a general algorithm, it can be applied to different types of wind farm configurations, and the load flow is related to the wind speed....

  18. Dynamics and Control of High-Rise Buildings under Multidirectional Wind Loads

    Directory of Open Access Journals (Sweden)

    Aly Mousaad Aly

    2011-01-01

    Full Text Available This paper presents a procedure for the response prediction and reduction in high-rise buildings under multidirectional wind loads. The procedure is applied to a very slender tall building that is instructive. The structure is exposed to both cross-wind and along-wind loads obtained from pressure measurements on a rigid model (scaled 1 : 100 that was tested in a wind tunnel with two different configurations of the surroundings. In the theoretical formulation, dynamic equations of the structure are introduced by finite element and 3D lumped mass modeling. The lateral responses of the building in the two directions are controlled at the same time using tuned mass dampers (TMDs and active tuned mass dampers (ATMDs commanded by LQR and fuzzy logic controllers, while the effects of the uncontrolled torsional response of the structure are simultaneously considered. Besides their simplicity, fuzzy logic controllers showed similar trend as LQR controllers under multidirectional wind loads. Nevertheless, the procedure presented in this study can help decision makers, involved in the design process, to choose among innovative solutions like structural control, different damping techniques, modifying geometry, or even changing materials.

  19. Using wind speed from a blade-mounted flow sensor for power and load assessment on modern wind turbines

    Directory of Open Access Journals (Sweden)

    M. M. Pedersen

    2017-11-01

    Full Text Available In this paper an alternative method to evaluate power performance and loads on wind turbines using a blade-mounted flow sensor is investigated. The hypothesis is that the wind speed measured at the blades has a high correlation with the power and loads such that a power or load assessment can be performed from a few hours or days of measurements.In the present study a blade-mounted five-hole pitot tube is used as the flow sensor as an alternative to the conventional approach, where the reference wind speed is either measured at a nearby met mast or on the nacelle using lidar technology or cup anemometers. From the flow sensor measurements, an accurate estimate of the wind speed at the rotor plane can be obtained. This wind speed is disturbed by the presence of the wind turbine, and it is therefore different from the free-flow wind speed. However, the recorded wind speed has a high correlation with the actual power production as well as the flap-wise loads as it is measured close to the blade where the aerodynamic forces are acting.Conventional power curves are based on at least 180 h of 10 min mean values, but using the blade-mounted flow sensor both the observation average time and the overall assessment time can potentially be shortened. The basis for this hypothesis is that the sensor is able to provide more observations with higher accuracy, as the sensor follows the rotation of the rotor and because of the high correlation between the flow at the blades and the power production. This is the research question addressed in this paper.The method is first tested using aeroelastic simulations where the dependence of the radial position and effect of multiple blade-mounted flow sensors are also investigated. Next the method is evaluated on the basis of full-scale measurements on a pitch-regulated, variable-speed 3.6 MW wind turbine.It is concluded that the wind speed derived from the blade-mounted flow sensor is highly correlated with the

  20. On the wind speed reduction in the center of large clusters of wind turbines

    DEFF Research Database (Denmark)

    Frandsen, Sten Tronæs

    1992-01-01

    of the wind speed assuming the wind turbines effectively act as roughness elements. The model makes use of similarities to so-called canopy flows, where the surface drag and the drag on individual obstacles are added to form the total drag. Results are compared with existing models for reduction of efficiency...

  1. UWB Wind Turbine Blade Deflection Sensing for Wind Energy Cost Reduction

    DEFF Research Database (Denmark)

    Zhang, Shuai; Jensen, Tobias Lindstrøm; Franek, Ondrej

    2015-01-01

    A new application of utilizing ultra-wideband (UWB) technology to sense wind turbine blade deflections is introduced in this paper for wind energy cost reduction. The lower UWB band of 3.1–5.3 GHz is applied. On each blade, there will be one UWB blade deflection sensing system, which consists...

  2. Shear and Turbulence Estimates for Calculation of Wind Turbine Loads and Responses Under Hurricane Strength Winds

    Science.gov (United States)

    Kosovic, B.; Bryan, G. H.; Haupt, S. E.

    2012-12-01

    Schwartz et al. (2010) recently reported that the total gross energy-generating offshore wind resource in the United States in waters less than 30m deep is approximately 1000 GW. Estimated offshore generating capacity is thus equivalent to the current generating capacity in the United States. Offshore wind power can therefore play important role in electricity production in the United States. However, most of this resource is located along the East Coast of the United States and in the Gulf of Mexico, areas frequently affected by tropical cyclones including hurricanes. Hurricane strength winds, associated shear and turbulence can affect performance and structural integrity of wind turbines. In a recent study Rose et al. (2012) attempted to estimate the risk to offshore wind turbines from hurricane strength winds over a lifetime of a wind farm (i.e. 20 years). According to Rose et al. turbine tower buckling has been observed in typhoons. They concluded that there is "substantial risk that Category 3 and higher hurricanes can destroy half or more of the turbines at some locations." More robust designs including appropriate controls can mitigate the risk of wind turbine damage. To develop such designs good estimates of turbine loads under hurricane strength winds are essential. We use output from a large-eddy simulation of a hurricane to estimate shear and turbulence intensity over first couple of hundred meters above sea surface. We compute power spectra of three velocity components at several distances from the eye of the hurricane. Based on these spectra analytical spectral forms are developed and included in TurbSim, a stochastic inflow turbulence code developed by the National Renewable Energy Laboratory (NREL, http://wind.nrel.gov/designcodes/preprocessors/turbsim/). TurbSim provides a numerical simulation including bursts of coherent turbulence associated with organized turbulent structures. It can generate realistic flow conditions that an operating turbine

  3. Measuring footprints of wind turbine fatigue loads using monitoring methods. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Soeker Holger [ed.; Oestman, Anders; Thor, Sven-Erik [Aeronautical Research Inst. of Sweden, Bromma (Sweden)

    2001-03-01

    In the described research project the fatigue monitoring technique is applied on three 500kW wind turbines of the same type operating under different external conditions i.e. stand alone, wind farm and complex terrain conditions. Respective sites have been selected in Germany (stand alone and wind farm) and in Greece (complex terrain). During the measurement campaigns three new data bases have been created holding on-line monitoring data sets and time series data of the wind turbines' key loads. As a fourth data source time series measurements from the wind farm at Alsvik, Sweden, have been used for the project work. The central aspect of the work has been to establish 'footprints' of the measured load quantities for varying external conditions and to develop and accumulate skills and experience in reading the load information stored in such fatigue load 'footprints'. The term 'footprint' refers to the rainflow cycle frequency spectra of the observed load quantity recorded during a representative time interval together with a set of parameters describing the external and operational conditions during that time interval. In fatigue monitoring the rainflow counting data reduction technique is applied to the measured load samples on-line, reducing hardware memory and off-line evaluation demands. It has been attempted to introduce a framework of few statistic parameters that describe the fatigue load footprint and also relate to external physical conditions (s.a. average wind speed, turbulence etc.). In addition to the traditional formulations of statistic parameters in terms of time series statistics, special parameters adapted to on-line rainflow counted data sets have been examined. On-line fatigue footprint monitoring has so far been applied as a diagnostic tool. In the project the development of a scheme has been started that shall enable to normalise the footprinting results and furthermore to extrapolate them to external

  4. The determination of the extreme loads on wind turbines – some practical issues

    NARCIS (Netherlands)

    Bierbooms, W.A.A.M.

    2010-01-01

    The probabilistic method commonly applied to arrive at the ultimate loading is as follows: for several different mean wind speeds load simulations are performed. For each mean wind speed a conditional distribution can be fitted to the load maxima for that particular wind speed. The overall

  5. Load Sharing of Wind Based Microgrid in Autonomous Operation

    Directory of Open Access Journals (Sweden)

    Aarti Gupta

    2014-01-01

    Full Text Available Autonomous wind energy conversion systems sharing a common load consist of a number of voltage source converters operating in parallel. A suitable control system should ensure desired load sharing among these as a number of these sources operating in parallel are required to meet the load demand and load excursions should not lead to instability of the system. In absence of the grid there is no reference angle for synchronization. Hence, a control scheme for parallel-connected three-phase converters incorporating the desirable features needs to be developed in order to exploit the renewable energy sources, which are intermittent in nature as effectively as possible in case of an autonomous microgrid. A simple and effective droop control strategy without the use of conventional αβ technique incorporating only dq components has been proposed for load sharing among wind energy conversion systems connected by back to back voltage source converters in autonomous operation. The need for communication link should also be avoided, hence reducing the system cost. The system is modelled using Matlab and the control is authenticated by simulation results.

  6. Thermal loading and reliability of 10 MW multilevel wind power converter at different wind roughness classes

    DEFF Research Database (Denmark)

    Isidori, Andrea; Rossi, Fabio Mario; Blaabjerg, Frede

    2012-01-01

    This paper focuses on the design, thermal loading and reliability of a three-level Neutral Point Clamped (3-L NPC) back-to-back full scale converter for a 10 MW direct-drive wind turbine equipped with a Permanent Magnet Synchronous Generator (PMSG). The reliability performance of the three...

  7. Vertical Axis Wind Turbine Design Load Cases Investigation and Comparison with Horizontal Axis Wind Turbine

    DEFF Research Database (Denmark)

    Galinos, Christos; Larsen, Torben J.; Aagaard Madsen, Helge

    2016-01-01

    The paper studies the applicability of the IEC 61400-1 ed.3, 2005 International Standard of wind turbine minimum design requirements in the case of an onshore Darrieus VAWT and compares the results of basic Design Load Cases (DLCs) with those of a 3-bladed HAWT. The study is based on aeroelastic ...

  8. Active aerodynamic load control on wind turbines : Aeroservoelastic modeling and wind tunnel

    NARCIS (Netherlands)

    Barlas, A.

    2011-01-01

    This thesis investigates particular concepts and technologies that can alleviate fatigue loads on wind turbines by using distributed active aerodynamic devices on the blades, a concept briefly referred to as `smart blades'. Firstly, published research work on smart control devices is reviewed, and

  9. Effects of gain-scheduling methods in a classical wind turbine controller on wind turbine aeroservoelastic modes and loads

    DEFF Research Database (Denmark)

    Tibaldi, Carlo; Henriksen, Lars Christian; Hansen, Morten Hartvig

    2014-01-01

    The eects of dierent gain-scheduling methods for a classical wind turbine controller, operating in full load region, on the wind turbine aeroservoelastic modes and loads are investigated in this work. The dierent techniques are derived looking at the physical problem to take into account the chan......The eects of dierent gain-scheduling methods for a classical wind turbine controller, operating in full load region, on the wind turbine aeroservoelastic modes and loads are investigated in this work. The dierent techniques are derived looking at the physical problem to take into account...

  10. Reduction of radar cross-section of a wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, Jacob Jeremiah; Brock, Billy C.; Clem, Paul G.; Loui, Hung; Allen, Steven E.

    2016-08-02

    The various technologies presented herein relate to formation of a wind turbine blade having a reduced radar signature in comparison with a turbine blade fabricated using conventional techniques. Various techniques and materials are presented to facilitate reduction in radar signature of a wind turbine blade, where such techniques and materials are amenable for incorporation into existing manufacturing techniques without degradation in mechanical or physical performance of the blade or major alteration of the blade profile.

  11. Participation of Flexible Loads in Load Frequency Control to Support High Wind Penetration

    DEFF Research Database (Denmark)

    Uslu, Umur; Zhang, Boyang; Pillai, Jayakrishnan Radhakrishna

    2016-01-01

    The increasing amount of fluctuating wind power penetration in power systems presents many challenges to its operation and control. The new wind power plants are replacing many of the conventional large power plants that ensure power balancing and ancillary services for stable and reliable...... operation of the grid. Therefore, new solutions for power balancing reserves have to be explored and utilized by the grid utilities. To meet these challenges, large sizable loads like alkaline electrolysers, heat pumps and electric vehicles which are gaining popularity can provide system support to the grid...... through their inherent flexibility and energy storage characteristics. This paper investigates the possibilities and potential of such flexible loads to participate in power system frequency regulation in a wind dominated power system. The results show that these consumption units provide better...

  12. Fatigue of bridges with a horizontal rotation axle under random wind load

    NARCIS (Netherlands)

    Maljaars, J.; Steenbergen, R.D.J.M.

    2012-01-01

    The operating mechanisms of movable bridges are subjected to various types of fluctuating loads which may induce fatigue damage. Wind load acting on the bridge deck - when the bridge is open - is one of the important load types. A wind load model is proposed that can be used in the fatigue design

  13. Pervasive growth reduction in Norway spruce forests following wind disturbance.

    Directory of Open Access Journals (Sweden)

    Rupert Seidl

    Full Text Available BACKGROUND: In recent decades the frequency and severity of natural disturbances by e.g., strong winds and insect outbreaks has increased considerably in many forest ecosystems around the world. Future climate change is expected to further intensify disturbance regimes, which makes addressing disturbances in ecosystem management a top priority. As a prerequisite a broader understanding of disturbance impacts and ecosystem responses is needed. With regard to the effects of strong winds--the most detrimental disturbance agent in Europe--monitoring and management has focused on structural damage, i.e., tree mortality from uprooting and stem breakage. Effects on the functioning of trees surviving the storm (e.g., their productivity and allocation have been rarely accounted for to date. METHODOLOGY/PRINCIPAL FINDINGS: Here we show that growth reduction was significant and pervasive in a 6.79 million hectare forest landscape in southern Sweden following the storm Gudrun (January 2005. Wind-related growth reduction in Norway spruce (Picea abies (L. Karst. forests surviving the storm exceeded 10% in the worst hit regions, and was closely related to maximum gust wind speed (R(2 = 0.849 and structural wind damage (R(2 = 0.782. At the landscape scale, wind-related growth reduction amounted to 3.0 million m(3 in the three years following Gudrun. It thus exceeds secondary damage from bark beetles after Gudrun as well as the long-term average storm damage from uprooting and stem breakage in Sweden. CONCLUSIONS/SIGNIFICANCE: We conclude that the impact of strong winds on forest ecosystems is not limited to the immediately visible area of structural damage, and call for a broader consideration of disturbance effects on ecosystem structure and functioning in the context of forest management and climate change mitigation.

  14. Wind Turbine Control with Active Damage Reduction through Energy Dissipation

    NARCIS (Netherlands)

    Barradas Berglind, Jose de Jesus; Jayawardhana, Bayu; Wisniewski, Rafał

    2016-01-01

    In this paper we propose an active damage reduction control strategy for wind turbines based on dissipated energy. To this end we rely on the equivalences relating both damage in the rainflow counting sense and dissipated energy to the variations of Preisach hysteresis operators. Since dissipation

  15. Calculating the sensitivity of wind turbine loads to wind inputs using response surfaces

    DEFF Research Database (Denmark)

    Rinker, Jennifer M.

    2016-01-01

    at a low computational cost. Sobol sensitivity indices (SIs) can then be calculated with relative ease using the calibrated response surface. The proposed methodology is demonstrated by calculating the total sensitivity of the maximum blade root bending moment of the WindPACT 5 MW reference model to four......This paper presents a methodology to calculate wind turbine load sensitivities to turbulence parameters through the use of response surfaces. A response surface is a high-dimensional polynomial surface that can be calibrated to any set of input/output data and then used to generate synthetic data...... turbulence input parameters: a reference mean wind speed, a reference turbulence intensity, the Kaimal length scale, and a novel parameter reflecting the nonstationarity present in the inflow turbulence. The input/output data used to calibrate the response surface were generated for a previous project...

  16. A Wind Farm Controller for Load and Power Optimization in a Farm

    DEFF Research Database (Denmark)

    Soleimanzadeh, Maryam; Brand, Arno; Wisniewski, Rafal

    2011-01-01

    based on low and high wind speed. In low wind speed, the reference signals for rotor speed are adjusted, taking the trade-off between power maximization and load minimization into account. In high wind speed, the power and pitch angle reference signals are determined while structural loads are minimized....

  17. Ballistic Analysis of Capability to Parry the Wind Load at Initial Flight Path of Promising Aircrafts

    Directory of Open Access Journals (Sweden)

    S. N. Ilukhin

    2015-01-01

    Full Text Available The article describes a new approach to solving the problem of parrying the negative impact of the random wind loads at the initial stage of aircraft flight. Based on applied research and many years of practice is proved the usefulness of measures to eliminate the deviations caused by the wind at initial flight path.The paper provides a theoretical justification and formulates the basic law of control to parry the product reversal under the action of random wind. Via example of a modified ballistic target the logic of the functioning of a promising technique for correcting orbital speed is clearly illustrated. This study analyses the influence of the wind load on the dispersion characteristics of the product impact points. To identify the qualitative picture of the process under study was examined flight of the aircraft in the vertical plane. In comparison with uncorrectable case, a trivial example of a mathematical model is used to have an initial assessment of the proposed technique effectiveness. As a determining parameter, was considered a changing angle of the aircraft attack during flight. Using authors-developed algorithms, significant reduction in the dispersion of the product impact points was revealed upon performed calculations, thus bearing evidence of using this method in promising aircrafts of the class under consideration.

  18. Wind Tunnel Investigation of Ground Wind Loads for Ares Launch Vehicle

    Science.gov (United States)

    Keller, Donald F.; Ivanco, Thomas G.

    2010-01-01

    A three year program was conducted at the NASA Langley Research Center (LaRC) Aeroelasticity Branch (AB) and Transonic Dynamics Tunnel (TDT) with the primary objective to acquire scaled steady and dynamic ground-wind loads (GWL) wind-tunnel data for rollout, on-pad stay, and on-pad launch configurations for the Ares I-X Flight Test Vehicle (FTV). The experimental effort was conducted to obtain an understanding of the coupling of aerodynamic and structural characteristics that can result in large sustained wind-induced oscillations (WIO) on such a tall and slender launch vehicle and to generate a unique database for development and evaluation of analytical methods for predicting steady and dynamic GWL, especially those caused by vortex shedding, and resulting in significant WIO. This paper summarizes the wind-tunnel test program that employed two dynamically-aeroelastically scaled GWL models based on the Ares I-X Flight Test Vehicle. The first model tested, the GWL Checkout Model (CM), was a relatively simple model with a secondary objective of restoration and development of processes and methods for design, fabrication, testing, and data analysis of a representative ground wind loads model. In addition, parametric variations in surface roughness, Reynolds number, and protuberances (on/off) were investigated to determine effects on GWL characteristics. The second windtunnel model, the Ares I-X GWL Model, was significantly more complex and representative of the Ares I-X FTV and included the addition of simplified rigid geometrically-scaled models of the Kennedy Space Center (KSC) Mobile Launch Platform (MLP) and Launch Complex 39B primary structures. Steady and dynamic base bending moment as well as model response and steady and unsteady pressure data was acquired during the testing of both models. During wind-tunnel testing of each model, flow conditions (speed and azimuth) where significant WIO occurred, were identified and thoroughly investigated. Scaled data from

  19. Wind Energy and Air Emission Reduction Benefits: A Primer

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, D.; High, C.

    2008-02-01

    This document provides a summary of the impact of wind energy development on various air pollutants for a general audience. The core document addresses the key facts relating to the analysis of emission reductions from wind energy development. It is intended for use by a wide variety of parties with an interest in this issue, ranging from state environmental officials to renewable energy stakeholders. The appendices provide basic background information for the general reader, as well as detailed information for those seeking a more in-depth discussion of various topics.

  20. Wind Noise Reduction using Non-negative Sparse Coding

    DEFF Research Database (Denmark)

    Schmidt, Mikkel N.; Larsen, Jan; Hsiao, Fu-Tien

    2007-01-01

    We introduce a new speaker independent method for reducing wind noise in single-channel recordings of noisy speech. The method is based on non-negative sparse coding and relies on a wind noise dictionary which is estimated from an isolated noise recording. We estimate the parameters of the model ...... and discuss their sensitivity. We then compare the algorithm with the classical spectral subtraction method and the Qualcomm-ICSI-OGI noise reduction method. We optimize the sound quality in terms of signal-to-noise ratio and provide results on a noisy speech recognition task....

  1. Towards a reliable design of facade and roof elements against wind loading

    NARCIS (Netherlands)

    Geurts, C.P.W.; Staalduinen, P.C. van; Wit, M.S. de

    2004-01-01

    The most vulnerable parts of buildings with respect to wind loading are facades and roofs. Current standards on wind loading provide data to determine design loads for the elements in facades and roofs. These data are available for a limited number of simple building shapes. Up to now there is no

  2. 29 CFR 1919.76 - Safe working load reduction.

    Science.gov (United States)

    2010-07-01

    ... (CONTINUED) GEAR CERTIFICATION Certification of Shore-Based Material Handling Devices § 1919.76 Safe working load reduction. (a) If the operation in which equipment is engaged never utilizes more than a fraction of the safe working load rating, the owner of such equipment may, at his option, have the crane or...

  3. Investigation of UH-60A Rotor Structural Loads from Flight and Wind Tunnel Tests

    Science.gov (United States)

    2016-05-19

    Investigation of UH-60A Rotor Structural Loads From Flight and Wind Tunnel Tests Hyeonsoo Yeo Mark Potsdam US Army Aviation Development Directorate...NFAC) 40- by 80-Foot Wind Tunnel (Ref. 14) provides an- other set of airloads and structural loads measurements. Fig- ure 2 shows the UH-60A rotor ...blades installed on the NFAC Large Rotor Test Apparatus (LRTA) in the wind tunnel test section. One of the objectives of the wind tunnel test was to

  4. Implementing peak load reduction algorithms for household electrical appliances

    International Nuclear Information System (INIS)

    Dlamini, Ndumiso G.; Cromieres, Fabien

    2012-01-01

    Considering household appliance automation for reduction of household peak power demand, this study explored aspects of the interaction between household automation technology and human behaviour. Given a programmable household appliance switching system, and user-reported appliance use times, we simulated the load reduction effectiveness of three types of algorithms, which were applied at both the single household level and across all 30 households. All three algorithms effected significant load reductions, while the least-to-highest potential user inconvenience ranking was: coordinating the timing of frequent intermittent loads (algorithm 2); moving period-of-day time-flexible loads to off-peak times (algorithm 1); and applying short-term time delays to avoid high peaks (algorithm 3) (least accommodating). Peak reduction was facilitated by load interruptibility, time of use flexibility and the willingness of users to forgo impulsive appliance use. We conclude that a general factor determining the ability to shift the load due to a particular appliance is the time-buffering between the service delivered and the power demand of an appliance. Time-buffering can be ‘technologically inherent’, due to human habits, or realised by managing user expectations. There are implications for the design of appliances and home automation systems. - Highlights: ► We explored the interaction between appliance automation and human behaviour. ► There is potential for considerable load shifting of household appliances. ► Load shifting for load reduction is eased with increased time buffering. ► Design, human habits and user expectations all influence time buffering. ► Certain automation and appliance design features can facilitate load shifting.

  5. Effects of normal and extreme turbulence spectral parameters on wind turbine loads

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov; Natarajan, Anand; Mann, Jakob

    2017-01-01

    Loads simulations as performed to obtain design loads on wind turbines, requires wind turbulence as an input, characterized by parameters associated with the turbulence length scale, dissipation and anisotropy. The effect of variation in these turbulence spectral parameters on the magnitude...... the recommended values in the IEC 61400-1 Ed.3 that is used for wind turbine design. The present paper investigates the impact of Mann turbulence model parameter variations on the design loads envelope for 5 MW and 10 MW reference wind turbines. Specific focus is made on the blade root loads, tower top moments...

  6. Thermal Load Reduction System Development in a Hyundai Sonata PHEV

    Energy Technology Data Exchange (ETDEWEB)

    Kreutzer, Cory J.; Rugh, John; Tomerlin, Jeff

    2017-03-28

    Increased market penetration of electric drive vehicles (EDVs) requires overcoming a number of hurdles, including limited vehicle range and the elevated cost in comparison to conventional vehicles. Climate control loads have a significant impact on range, cutting it by over 50% in both cooling and heating conditions. To minimize the impact of climate control on EDV range, the National Renewable Energy Laboratory has partnered with Hyundai America and key industry partners to quantify the performance of thermal load reduction technologies on a Hyundai Sonata plug-in hybrid electric vehicle. Technologies that impact vehicle cabin heating in cold weather conditions and cabin cooling in warm weather conditions were evaluated. Tests included thermal transient and steady-state periods for all technologies, including the development of a new test methodology to evaluate the performance of occupant thermal conditioning. Heated surfaces demonstrated significant reductions in energy use from steady-state heating, including a 29%-59% reduction from heated surfaces. Solar control glass packages demonstrated significant reductions in energy use for both transient and steady-state cooling, with up to a 42% reduction in transient and 12.8% reduction in steady-state energy use for the packages evaluated. Technologies that demonstrated significant climate control load reduction were selected for incorporation into a complete thermal load reduction package. The complete package is set to be evaluated in the second phase of the ongoing project.

  7. Cost reduction potentials of offshore wind power in Germany

    International Nuclear Information System (INIS)

    Hobohm, Jens; Krampe, Leonard; Peter, Frank

    2014-01-01

    Offshore wind power is a major hope for the German energy turnaround. However, it will only be possible to tap its cost reduction potentials if industry, the political leadership and the administrative authorities join forces to create the necessary preconditions. An important requirement for this capital-intensive technology are stable legal and political framework conditions. A recent study on the future shows what needs to be done.

  8. Determining the impact of wind on system costs via the temporal patterns of load and wind generation

    International Nuclear Information System (INIS)

    Davis, Clay D.; Gotham, Douglas J.; Preckel, Paul V.; Liu, Andrew L.

    2013-01-01

    Ambitious targets have been set for expanding electricity generation from renewable sources, including wind. Expanding wind power impacts needs for other electricity generating resources. As states plan for increasing levels of wind generation in their portfolio of generation resources it is important to consider how this intermittent resource impacts the need for other generation resources. A case study for Indiana estimates the value of wind capacity and demonstrates how to optimize its level and the levels of other generation resources. Changes are driven by temporal patterns of wind power output and load. System wide impacts are calculated for energy, capacity, and costs under multiple wind expansion scenarios which highlight the geographic characteristics of a systems portfolio of wind generation. The impacts of carbon prices, as proposed in the Bingaman Bill, are considered. Finally, calculations showing the effect increasing levels of wind generation will have on end use Indiana retail rates are included. - Highlights: • We estimate the value of wind capacity. • We determine wind generation's impact on the optimal mix of non-wind generation. • Optimal levels of wind and non-wind generation are determined. • We consider the impact of a carbon price on the optimal mix of resources. • The impact of additional wind capacity on Indiana residential rates is calculated

  9. System Reduction in Nonlinear Multibody Dynamics of Wind Turbines

    DEFF Research Database (Denmark)

    Holm-Jørgensen, Kristian; Nielsen, Søren R.K.; Rubak, Rune

    2007-01-01

    In this paper the system reduction in nonlinear multibody dynamics of wind turbines is investigated for various updating schemes of the moving frame of reference. In one case, the moving frame of reference is updated to a stiff body, relative to which the elastic deformations are fixed at one end....... In the other case, the stiff body motion is defined as the chord line connecting the end points of the beam, and the elastic deformations are simply supported at the end points. The system reduction is performed by discretizing the spatial motion into a set of rigid body modes and linear elastic eigenmodes...

  10. On Small-Signal Stability of Wind Power System with Full-Load Converter Interfaced Wind Turbines

    DEFF Research Database (Denmark)

    Knüppel, Thyge; Akhmatov, Vladislav; Nielsen, Jørgen Nygård

    2010-01-01

    Small-signal stability analysis of power system oscillations is a well established field within power system analysis, but not much attention has yet been paid to systems with a high penetration of wind turbines and with large wind power plants. In this paper an analysis is presented which assess...... the impact of full-load converter interfaced wind turbines on power system small-signal stability. The study is based on a 7 generator network with lightly damped inter-area modes. A detailed wind turbine model with all grid relevant control functions is used in the study. Furthermore is the wind power plant...

  11. Determination of the wind power systems load to achieve operation in the maximum energy area

    Science.gov (United States)

    Chioncel, C. P.; Tirian, G. O.; Spunei, E.; Gillich, N.

    2018-01-01

    This paper analyses the operation of the wind turbine, WT, in the maximum power point, MPP, by linking the load of the Permanent Magnet Synchronous Generator, PMSG, with the wind speed value. The load control methods at wind power systems aiming an optimum performance in terms of energy are based on the fact that the energy captured by the wind turbine significantly depends on the mechanical angular speed of the wind turbine. The presented control method consists in determining the optimal mechanical angular speed, ωOPTIM, using an auxiliary low power wind turbine, WTAUX, operating without load, at maximum angular velocity, ωMAX. The method relies on the fact that the ratio ωOPTIM/ωMAX has a constant value for a given wind turbine and does not depend on the time variation of the wind speed values.

  12. Fully vs. Sequentially Coupled Loads Analysis of Offshore Wind Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Damiani, Rick; Wendt, Fabian; Musial, Walter; Finucane, Z.; Hulliger, L.; Chilka, S.; Dolan, D.; Cushing, J.; O' Connell, D.; Falk, S.

    2017-06-19

    The design and analysis methods for offshore wind turbines must consider the aerodynamic and hydrodynamic loads and response of the entire system (turbine, tower, substructure, and foundation) coupled to the turbine control system dynamics. Whereas a fully coupled (turbine and support structure) modeling approach is more rigorous, intellectual property concerns can preclude this approach. In fact, turbine control system algorithms and turbine properties are strictly guarded and often not shared. In many cases, a partially coupled analysis using separate tools and an exchange of reduced sets of data via sequential coupling may be necessary. In the sequentially coupled approach, the turbine and substructure designers will independently determine and exchange an abridged model of their respective subsystems to be used in their partners' dynamic simulations. Although the ability to achieve design optimization is sacrificed to some degree with a sequentially coupled analysis method, the central question here is whether this approach can deliver the required safety and how the differences in the results from the fully coupled method could affect the design. This work summarizes the scope and preliminary results of a study conducted for the Bureau of Safety and Environmental Enforcement aimed at quantifying differences between these approaches through aero-hydro-servo-elastic simulations of two offshore wind turbines on a monopile and jacket substructure.

  13. Wind Farm Active Power Dispatch for Output Power Maximizing Based on a Wind Turbine Control Strategy for Load Minimizing

    DEFF Research Database (Denmark)

    Zhang, Baohua; Hu, Weihao; Hou, Peng

    2015-01-01

    Inclusion of the wake effect in the wind farm control design (WF) can increase the total captured power by wind turbines (WTs), which is usually implemented by derating upwind WTs. However, derating the WT without a proper control strategy will increase the structural loads, caused by operation i...

  14. Wind farm electrical power production model for load flow analysis

    International Nuclear Information System (INIS)

    Segura-Heras, Isidoro; Escriva-Escriva, Guillermo; Alcazar-Ortega, Manuel

    2011-01-01

    The importance of renewable energy increases in activities relating to new forms of managing and operating electrical power: especially wind power. Wind generation is increasing its share in the electricity generation portfolios of many countries. Wind power production in Spain has doubled over the past four years and has reached 20 GW. One of the greatest problems facing wind farms is that the electrical power generated depends on the variable characteristics of the wind. To become competitive in a liberalized market, the reliability of wind energy must be guaranteed. Good local wind forecasts are therefore essential for the accurate prediction of generation levels for each moment of the day. This paper proposes an electrical power production model for wind farms based on a new method that produces correlated wind speeds for various wind farms. This method enables a reliable evaluation of the impact of new wind farms on the high-voltage distribution grid. (author)

  15. Wake Influence on Dynamic Load Characteristics of Offshore Floating Wind Turbines

    DEFF Research Database (Denmark)

    Jeon, Minu; Lee, Soogab; Kim, Taeseong

    2016-01-01

    Because the flow conditions of an offshore floating wind turbine and onshore fixed wind turbine differ, it is debatable whether the aerodynamic load predictions of an offshore floating wind turbine using the conventional blade-element momentum theory, which does not consider the dynamic wake effe...

  16. Mitigation of Fatigue Loads Using Individual Pitch Control of Wind Turbines Based on FAST

    DEFF Research Database (Denmark)

    Zhang, Yunqian; Chen, Zhe; Cheng, Ming

    2011-01-01

    With the increase of wind turbine dimension and capacity, the wind turbine structures are subjected to prominent loads and fatigue which would reduce the lifetime of wind turbines. Individual pitch control (IPC) is used in this paper to attenuate the blade root bending moment and the tilt and yaw...

  17. Comparison of blade loads of fixed and free yawing wind turbine

    Science.gov (United States)

    Cheney, M. C.; Bielawa, R. L.

    1978-01-01

    The self regulating composite bearingless wind turbine utilizes an automatic pitch control concept and a completely unrestrained yawing degree of freedom. Aerodynamic moments caused by skewed flow provide the control to align the wind turbine with the wind. Model tests demonstrated the feasibility of the concept and analytical studies showed the free system to experience lower blade loads compared to the fixed system.

  18. Controller design for a Wind Farm, Considering both Power and Load Aspects

    DEFF Research Database (Denmark)

    Soleimanzadeh, Maryam; Wisniewski, Rafal

    2011-01-01

    turbine. The control algorithm determines the reference signals for each individual wind turbine controller in two scenarios based on low and high wind speed. In low wind speed, the reference signals for rotor speed are adjusted, taking the trade-off between power maximization and load minimization...

  19. Fault Detection and Load Distribution for the Wind Farm Challenge

    DEFF Research Database (Denmark)

    Borchersen, Anders Bech; Larsen, Jesper Abildgaard; Stoustrup, Jakob

    2014-01-01

    In this paper a fault detection system and a fault tolerant controller for a wind farm model is designed and tested. The wind farm model is taken from the wind farm challenge which is a public available challenge where a wind farm consisting of nine turbines is proposed. The goal of the challenge...

  20. Comparison of computer codes for calculating dynamic loads in wind turbines

    Science.gov (United States)

    Spera, D. A.

    1978-01-01

    The development of computer codes for calculating dynamic loads in horizontal axis wind turbines was examined, and a brief overview of each code was given. The performance of individual codes was compared against two sets of test data measured on a 100 KW Mod-0 wind turbine. All codes are aeroelastic and include loads which are gravitational, inertial and aerodynamic in origin.

  1. An Optimization Framework for Load and Power Distribution in Wind Farms

    DEFF Research Database (Denmark)

    Soleimanzadeh, Maryam; Wisniewski, Rafal; Kanev, Stoyan

    2012-01-01

    by a system operator. Moreover, the reference signals are determined to reduce the load acting on wind turbines at low frequencies. Therefore, a trade-off is made for load and power control, which is formulated as an optimization problem. Afterwards, the optimization problem for the wind farm modeled...

  2. Minimum Thrust Load Control for Floating Wind Turbine

    DEFF Research Database (Denmark)

    Christiansen, Søren; Bak, Thomas; Knudsen, Torben

    2012-01-01

    — Offshore wind energy capitalizes on the higher and less turbulent wind at sea. Shallow water sites are profitable for deployment of monopile wind turbines at water depths of up to 30 meters. Beyond 30 meters, the wind is even stronger and less turbulent. At these depths, floating wind turbines...... become profitable, capable of accessing unexploited wind resources while reaching regions of new consumers. However, floating wind turbines are subject to reduced structural stiffness which results in instabilities when standard wind turbine control systems are applied. Based on optimal control, this paper...... presents a new minimum thrust control strategy capable of stabilizing a floating wind turbine. The new control strategy explores the freedom of variable generator speed above rated wind speed. A comparison to the traditional constant speed strategy, shows improvements in structural fore-aft oscillations...

  3. Crack retardation by load reduction during fatigue crack propagation

    International Nuclear Information System (INIS)

    Kim, Hyun Soo; Nam, Ki Woo; Ahn, Seok Hwan; Do, Jae Yoon

    2003-01-01

    Fracture life and crack retardation behavior were examined experimentally using CT specimens of aluminum alloy 5083. Crack retardation life and fracture life were a wide difference between 0.8 and 0.6 in proportion to ratio of load reduction. The wheeler model retardation parameter was used successfully to predict crack growth behavior. By using a crack propagation rule, prediction of fracture life can be evaluated quantitatively. A statistical approach based on Weibull distribution was applied to the test data to evaluate the dispersion in the retardation life and fracture life by the change of load reduction

  4. On Small-Signal Stability of Wind Power System with Full-Load Converter Interfaced Wind Turbines

    OpenAIRE

    Knüppel, Thyge; Akhmatov, Vladislav; Nielsen, Jørgen Nygård; Jensen, Kim H.; Dixon, Andrew; Østergaard, Jacob

    2010-01-01

    Small-signal stability analysis of power system oscillations is a well established field within power system analysis, but not much attention has yet been paid to systems with a high penetration of wind turbines and with large wind power plants. In this paper an analysis is presented which assess the impact of full-load converter interfaced wind turbines on power system small-signal stability. The study is based on a 7 generator network with lightly damped inter-area modes. A detailed wind tu...

  5. A Wind Power and Load Prediction Based Frequency Control Approach for Wind-Diesel-Battery Hybrid Power System

    Directory of Open Access Journals (Sweden)

    Chao Peng

    2015-01-01

    Full Text Available A frequency control approach based on wind power and load power prediction information is proposed for wind-diesel-battery hybrid power system (WDBHPS. To maintain the frequency stability by wind power and diesel generation as much as possible, a fuzzy control theory based wind and diesel power control module is designed according to wind power and load prediction information. To compensate frequency fluctuation in real time and enhance system disturbance rejection ability, a battery energy storage system real-time control module is designed based on ADRC (active disturbance rejection control. The simulation experiment results demonstrate that the proposed approach has a better disturbance rejection ability and frequency control performance compared with the traditional droop control approach.

  6. CFD-based design load analysis of 5MW offshore wind turbine

    Science.gov (United States)

    Tran, T. T.; Ryu, G. J.; Kim, Y. H.; Kim, D. H.

    2012-11-01

    The structure and aerodynamic loads acting on NREL 5MW reference wind turbine blade are calculated and analyzed based on advanced Computational Fluid Dynamics (CFD) and unsteady Blade Element Momentum (BEM). A detailed examination of the six force components has been carried out (three force components and three moment components). Structure load (gravity and inertia load) and aerodynamic load have been obtained by additional structural calculations (CFD or BEM, respectively,). In CFD method, the Reynolds Average Navier-Stokes approach was applied to solve the continuity equation of mass conservation and momentum balance so that the complex flow around wind turbines was modeled. Written in C programming language, a User Defined Function (UDF) code which defines transient velocity profile according to the Extreme Operating Gust condition was compiled into commercial FLUENT package. Furthermore, the unsteady BEM with 3D stall model has also adopted to investigate load components on wind turbine rotor. The present study introduces a comparison between advanced CFD and unsteady BEM for determining load on wind turbine rotor. Results indicate that there are good agreements between both present methods. It is importantly shown that six load components on wind turbine rotor is significant effect under Extreme Operating Gust (EOG) condition. Using advanced CFD and additional structural calculations, this study has succeeded to construct accuracy numerical methodology to estimate total load of wind turbine that compose of aerodynamic load and structure load.

  7. IDENTIFICATION OF WIND LOAD APPLIED TO THREE-DIMENSIONAL STRUCTURES BY VIRTUE OF ITS SIMULATION IN THE WIND TUNNEL

    Directory of Open Access Journals (Sweden)

    Doroshenko Sergey Aleksandrovich

    2012-10-01

    Full Text Available The authors discuss wind loads applied to a set of two buildings. The wind load is simulated with the help of the wind tunnel. In the Russian Federation, special attention is driven to the aerodynamics of high-rise buildings and structures. According to the Russian norms, identification of aerodynamic coefficients for high-rise buildings, as well as the influence of adjacent buildings and structures, is performed on the basis of models of structures exposed to wind impacts simulated in the wind tunnel. This article deals with the results of the wind tunnel test of buildings. The simulation was carried out with the involvement of a model of two twenty-three storied buildings. The experiment was held in a wind tunnel of the closed type at in the Institute of Mechanics of Moscow State University. Data were compared at the zero speed before and after the experiment. LabView software was used to process the output data. Graphs and tables were developed in the Microsoft Excel package. GoogleSketchUp software was used as a visualization tool. The three-dimensional flow formed in the wind tunnel can't be adequately described by solving the two-dimensional problem. The aerodynamic experiment technique is used to analyze the results for eighteen angles of the wind attack.

  8. Investigation of piezoelectric flaps for load alleviation using CFD; Wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Heinz, J.C.

    2010-03-15

    Cost efficient wind power generation demands for large wind turbines with a long lifetime. These demands place high interests on sophisticated load control techniques such as deformable trailing edge flaps. In this work a previously tested prototype airfoil was investigated by using the 2D incompressible RANS solver EllipSys2D. The prototype was built with a Risoe-B1-18 airfoil where piezoelectric actuators THUNDER TH-6R were attached at the trailing edge to realize a movable flap. The results of the simulation were compared to measurements of the previous wind tunnel test and comprehensive steady state computations were conducted to gain information about the general airfoil properties. The model was subsequently used to investigate aero-servo-elastic effects on the 2D airfoil section exposed to a fluctuating inflow. It is explained how a fluctuating inflow was simulated with EllipSys2D and how the CFD solver was coupled with a 3 DOF structural model and with two different control algorithms. Control 1 used the measured AOA in front of the LE as input, Control 2 used the pressure difference between suction and pressure side as input. The model showed a substantial load reduction potential for the present prototype airfoil. For a wind step from 10 m/s to 10.5 m/s the standard deviation of the structural deflection normal to the rotor plane could be reduced with up to 98 % (Control 1) and 96 % (Control 2). A 4 s turbulent inflow with TI=2.2 % could be reduced with up to 81 % (Control 1) and 82 % (Control 2). For a 12 s inflow with TI=2.4 % the standard deviation could be reduced with up to 68 % (Control 1) and 67 % (Control 2). The influence of possible time lags inside the control loop on the reduction potential of the prototype was also investigated. For a 12 s inflow with a tripled turbulence intensity of TI=7.7 % the prototype airfoil could still reach a reduction of up to 54 %. For an extended flap range of -6 to +6 degrees the reduction could be returned to 66

  9. Validation of SWAY Wind Turbine Response in FAST, with a Focus on the Influence of Tower Wind Loads: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Koh, J. H.; Robertson, A.; Jonkman, J.; Driscoll, R.; Yin Kwee Ng, E.

    2015-04-23

    Need to modify simulated system behavior to the measured data, but the tower wind loads improved the comparison for nonoperating conditions. the SWAY system in both turbine operating and nonoperating conditions. Mixed results were observed when comparing the simulated system behavior to the measured data, but the tower wind loads improved the comparison for nonoperating conditions. without the new tower-load capability to examine its influence on the response characteristics of the system. This is important in situations when the turbine is parked in survival conditions. The simulation results were then compared to measured data from the SWAY system in both turbine operating and nonoperating conditions. Mixed results were observed when comparing the simulated system behavior to the measured data, but the tower wind loads improved the comparison for nonoperating conditions.

  10. System Reduction in Multibody Dynamics of Wind Turbines

    DEFF Research Database (Denmark)

    Holm-Jørgensen, Kristian; Nielsen, Søren R.K.

    2009-01-01

    Abstract A system reduction scheme is devised related to a multibody formulation from which the dynamic response of a wind turbine is determined. In this formulation each substructure is described in its own frame of reference, which is moving freely in the vicinity of the moving substructure....... The Ritz bases spanning the reduced system comprises of rigid body modes and some dynamic low-frequency elastic eigenmodes compatible to the kinematic constraints of the related substructure. The high-frequency elastic modes are presumed to cause merely quasi-static displacements, and thus are included...... in the expansion via a quasi-static correction. The results show that by using the derived reduction scheme it is only necessary with 2 dynamical modes for the blade substructure when the remaining modes are treated as quasi-static. Moreover, it is shown that it has little to none effect if the gyroscopic...

  11. Calculation of PVC windows for wind loads in high-rise buildings

    Science.gov (United States)

    Konstantinov, Aleksandr; Lambias Ratnayake, Maya

    2018-03-01

    In the following article we examine problems faced when designing PVC windows for high-rise buildings, which are usually not considered when constructing objects for massive sites, using a high-rise residential complex as an example. We address the matters related to wind loads on windows & statistical calculation of the impact of wind loads on them. We have presented variants of installing load-bearing elements of PVC windows which accept wind loads. We conducted a laboratory experiment by simulating wind loads on the window design, which is actually used for glazing the examined high-rise building. In the course of the experiment we determined additional factors which need to be considered when constructing PVC window structures for glazing high-rise buildings. We can determine that the following calculation method for the impact of wind load on PVC windows gives higher values of the desired statistical characteristics of load-bearing elements of a window compared to the results of laboratory experiments. We provide prerequisites to improve the analytical method of calculating impact of wind loads on load-bearing elements of PVC windows.

  12. Tower Design Load Verification on a 1-kW Wind Turbine: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Prascher, D.; Huskey, A.

    2004-11-01

    Wind turbine testing at the National Wind Technology Center (NWTC) has been done to characterize both tower top loads and thrust loads for small wind turbines, which is part of an ongoing effort to model and predict small wind turbine behavior and the resulting stresses imposed on the supporting tower. To these ends, a 1-kW furling wind turbine mounted on a 10-meter tower was instrumented and monitored via a data acquisition system for nearly a year. This test was conducted to verify the design loads as predicted by the simple design equations provided in the draft revision of the International Electrotechnical Commission (IEC) Small Wind Turbine Safety Standard 61400-02 CDV (hereafter called ''the draft Standard''). Data were captured for several operating conditions covered by the draft Standard. This paper addresses the collected data and what conclusions can be made from it.

  13. Fatigue Load Sensitivity Based Optimal Active Power Dispatch For Wind Farms

    DEFF Research Database (Denmark)

    Zhao, Haoran; Wu, Qiuwei; Huang, Shaojun

    2017-01-01

    sensitivity are derived, which significantly improves the computation efficiency of the local WT controller. The proposed algorithm can be implemented in different active power control schemes. Case studies were conducted with a wind farm under balance control for both low and high wind conditions......This paper proposes an optimal active power dispatch algorithm for wind farms based on Wind Turbine (WT) load sensitivity. The control objectives include tracking power references from the system operator and minimizing fatigue loads experienced by WTs. The sensitivity of WT fatigue loads to power...... references is defined which simplifies the formulation of the optimal power dispatch problem. Since the sensitivity value is calculated at the local WT controller, the computation burden of the central wind farm controller is largely reduced. Moreover, explicit analytical equations of the fatigue load...

  14. Probabilistic model for multi-axial load combinations for wind turbines

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov

    2016-01-01

    The article presents a model describing the joint probability distribution of multiple load components acting on a wind turbine blade cross section. The problem of modelling the probability distribution of load time histories with large periodic components is addressed by dividing the signal...... for determining contemporaneous loads. Using examples with simulated loads on a 10 MW wind turbine,the behavior of the bending moments acting on a blade section is illustrated under different conditions.The loading direction most critical for material failure is determined using a finite-element model...... of the blade cross section on which load combinations with different directions but with equal probability are applied. By defining a joint probability distribution and return-period contours for multiple load components,the suggested procedure is applicable to different aspects of the design of wind turbine...

  15. Monitoring fatigue loads on wind turbines using cycle counting data acquisition systems

    Energy Technology Data Exchange (ETDEWEB)

    Soeker, H.; Seifert, H. [Deutsches Windenergie-Institut (Germany); Fragoulis, A.; Vionis, P.; Foussekis, D. [Center for Renewable Energy Sources (Greece); Dahlberg, J.A.; Poppen, M. [The Aeronautical Research Institue of Sweden (Sweden)

    1996-09-01

    As in any industrial application, the duration of a wind turbine`s life is a key parameter for the evaluation of its economic potential. Assuming a service life of 20 years, components of the turbine have to withstand a number of load cycles of up to 10{sup 8}. Such numbers of load cycles impose high demands on the fatigue characteristics of both, the used materials and the design. Nevertheless, fatigue loading of wind turbine components still remains a parameter of high uncertainty in the design of wind turbines. The specific features of these fatigue loads can be expected to vary with the type of turbine and the site of operation. In order to ensure the reliability of the next generation of larger scale wind turbines improved load assumptions will be of vital importance. Within the scope of the presented research program DEWI, C.R.E.S. and FFA monitored fatigue loads of serial produced wind turbines by means of a monitoring method that uses on-line cycle counting techniques. The blade root bending moments of two pitch controlled, variable speed wind turbines operating in the Hamswehrum wind farm, and also that of a stall controlled, fixed speed wind turbine operating in CRES` complex terrain test site, were measured by DEWI and CRES. In parallel FFA used their database of time series measurements of blade root bending moments on a stall controlled, fixed speed turbine at Alsvik Windfarm in order to derive semi-empirical fatigue load data. The experience gained from application of the on-line measurement technique is discussed with respect to performance, data quality, reliability and cost effectiveness. Investigations on the effects of wind farm and complex terrain operation on the fatigue loads of wind turbine rotor blades are presented. (au)

  16. Implementation of internal model based control and individual pitch control to reduce fatigue loads and tower vibrations in wind turbines

    Science.gov (United States)

    Mohammadi, Ebrahim; Fadaeinedjad, Roohollah; Moschopoulos, Gerry

    2018-05-01

    Vibration control and fatigue loads reduction are important issues in large-scale wind turbines. Identifying the vibration frequencies and tuning dampers and controllers at these frequencies are major concerns in many control methods. In this paper, an internal model control (IMC) method with an adaptive algorithm is implemented to first identify the vibration frequency of the wind turbine tower and then to cancel the vibration signal. Standard individual pitch control (IPC) is also implemented to compare the performance of the controllers in term of fatigue loads reduction. Finally, the performance of the system when both controllers are implemented together is evaluated. Simulation results demonstrate that using only IMC or IPC alone has advantages and can reduce fatigue loads on specific components. IMC can identify and suppress tower vibrations in both fore-aft and side-to-side directions, whereas, IPC can reduce fatigue loads on blades, shaft and yaw bearings. When both IMC and IPC are implemented together, the advantages of both controllers can be used. The aforementioned analysis and comparisons were not studied in literature and this study fills this gap. FAST, AreoDyn and Simulink are used to simulate the mechanical, aerodynamic and electrical aspects of wind turbine.

  17. Parametric Study of Tuned Mass Dampers for Long Span Transmission Tower-Line System under Wind Loads

    Directory of Open Access Journals (Sweden)

    Li Tian

    2016-01-01

    Full Text Available A parametric study of tuned mass dampers for a long span transmission tower-line system under wind loads is done in this paper. A three-dimensional finite element model of transmission tower-line system is established by SAP2000 software to numerically verify the effectiveness of the tuned mass damper device. The wind load time history is simulated based on Kaimal spectrum by the harmony superposition method. The equations of motion of a system with tuned mass damper under wind load excitation are proposed, and the schematic of tuned mass damper is introduced. The effects of mass ratio, frequency ratio, damping ratio, the change of the sag of transmission line, and the robustness of TMD are investigated, respectively. Results show that (1 the change of mass ratio has a greater effect on the vibration reduction ratio than those of frequency ratio and damping ratio, and the best vibration reduction ratio of TMD is not the frequency ratio of 1; (2 the sag-span ratio has an insignificant effect on the vibration reduction ratio of transmission tower when the change of sag-span ratio is not large; and (3 the effect of ice should be considered when the robustness study of TMD is carried out.

  18. Use of the WEST-1 wind turbine simulator to predict blade fatigue load distribution

    Science.gov (United States)

    Janetzke, D. C.

    1983-01-01

    To test the ability of WEST-1 to predict blade fatigue load distribution, actual wind signals were fed into the simulator and the response data were recorded and processed in the same manner as actual wind turbine data. The WEST-1 simulator was operated in a stable, unattended mode for six hours. The probability distribution of the cyclic flatwise bending moment for the blade was comparable to that for an actual wind turbine in winds with low turbulence. The input from a stationary anemometer was found to be inadequate for use in the prediction of fatigue load distribution for blade design purposes and modifications are necessary.

  19. Minimum load reduction for once-through boiler power plants

    International Nuclear Information System (INIS)

    Colombo, P.; Godina, G.; Manganelli, R.

    2001-01-01

    In Italy the liberalization process of energy market is giving particular importance to the optimization of power plants performances; especially for those that will be called to satisfy grid peak demands. On those plants some techniques have been experimented for the reduction of minimum load; these techniques, investigated and tested by an engineering dynamic simulator, have been sequentially tested on plant. The minimum load for up 320 MW of Tavazzano power plants has been diminished from 140 down to 80 MW without plant modification [it

  20. Harmonic Propagation and Interaction Evaluation between Small-Scale Wind Farms and Nonlinear Loads

    Directory of Open Access Journals (Sweden)

    Cheng-Xiong Mao

    2013-07-01

    Full Text Available Distributed generation is a flexible and effective way to utilize renewable energy. The dispersed generators are quite close to the load, and pose some power quality problems such as harmonic current emissions. This paper focuses on the harmonic propagation and interaction between a small-scale wind farm and nonlinear loads in the distribution grid. Firstly, by setting the wind turbines as P – Q(V nodes, the paper discusses the expanding Newton-Raphson power flow method for the wind farm. Then the generalized gamma mixture models are proposed to study the non-characteristic harmonic propagation of the wind farm, which are based on Gaussian mixture models, improved phasor clustering and generalized Gamma models. After the integration of the small-scale wind farm, harmonic emissions of nonlinear loads will become random and fluctuating due to the non-stationary wind power. Furthermore, in this paper the harmonic coupled admittance matrix model of nonlinear loads combined with a wind farm is deduced by rigorous formulas. Then the harmonic propagation and interaction between a real wind farm and nonlinear loads are analyzed by the harmonic coupled admittance matrix and generalized gamma mixture models. Finally, the proposed models and methods are verified through the corresponding simulation models in MATLAB/SIMULINK and PSCAD/EMTDC.

  1. Analysis of load reduction possibilities using a hydraulic soft yaw system for a 5-MW turbine and its sensitivity to yaw-bearing friction

    DEFF Research Database (Denmark)

    Stubkier, S.; Pedersen, H. C.; Jonkman, J. M.

    2014-01-01

    With the increasing size of wind turbines and with increasing lifetime demands, new methods for load reduction in the turbines need to be examined. One method is to make the yaw system of the turbine flexible, thereby dampening the loads to the system. This paper presents a hydraulic soft yaw...

  2. Estimation of Seismic Load Demand for a Wind Turbine in the Time Domain: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Prowell, I.; Elgamal, A.; Uang, C.; Jonkman, J.

    2010-03-01

    Turbines installed in seismically active regions such as the Pacific Rim or the Mediterranean must consider loads induced by base shaking from an earthquake. To account for this earthquake risk, current International Electrotechnical Commission (IEC) certification requirements provide a simplified method for calculating seismic loads which is intended to be conservative. Through the addition of capabilities, it is now possible to simulate earthquake loading of a wind turbine in conjunction other load sources such as wind and control system behavior using the FAST code. This paper presents a comparison of three earthquake loading scenarios of the National Renewable Energy Laboratory (NREL) offshore 5-MW baseline wind turbine: idling; continued operation through an earthquake; and an emergency shutdown initiated by an earthquake. Using a set of 22 earthquake records, simulations are conducted for each load case. A summary of the resulting tower moment demand is presented to assess the influence of operational state on the resulting structural demand.

  3. Ultimate Strength of Wind Turbine Blades under Multiaxial Loading

    DEFF Research Database (Denmark)

    Haselbach, Philipp Ulrich

    Modern wind turbine rotor blades are sophisticated lightweight structures, optimised towards achieving the best compromise between aerodynamic and structural design as well as a cost efficient manufacturing processes. They are usually designed for a lifetime of minimum 20 years, where they must...... endure a variety of weather conditions including uncontrollable, extreme winds without developing damage and fracture. The trend in the development of wind turbines is towards larger, more efficient wind turbines, placed offshore, where access is difficult and repairs costly. In consequence, failures...

  4. Ascent structural wind loads for the National Space Transportation System (NSTS)

    Science.gov (United States)

    Smith, O. E.; Adelfang, S. I.; Brown, R. P.

    1988-01-01

    An aerospace vehicle must withstand the design ascent structural load or be within any flight constraint to safely reach orbit. For the NSTS an assessment for flight readiness is made for each mission. This assessment for ascent loads and performance parameters is stated in terms of launch probability derived from samples of Jimsphere wind profiles. For the day of launch operations an allowance is made for the ascent load variability due to the wind profile variability over a 3.5-hour period. This is the current time period required to obtain a Jimsphere measurement and perform a complete load simulation prior to launch time. The load variability is derived from a sample of 3.5-hour Jimsphere wind profile pairs. It is applied as a conditional percentile value given the wind load at 3.5 hours prior to launch time. Probability models are used for these analyses. Application of the univariate, bivariate and conditional forms of the extreme value (Gumbel) probability distribution to the analysis of extreme wind speeds, wind shears and vehicle loads is described.

  5. UWB Wind Turbine Blade Deflection Sensing for Wind Energy Cost Reduction.

    Science.gov (United States)

    Zhang, Shuai; Jensen, Tobias Lindstrøm; Franek, Ondrej; Eggers, Patrick C F; Olesen, Kim; Byskov, Claus; Pedersen, Gert Frølund

    2015-08-12

    A new application of utilizing ultra-wideband (UWB) technology to sense wind turbine blade deflections is introduced in this paper for wind energy cost reduction. The lower UWB band of 3.1-5.3 GHz is applied. On each blade, there will be one UWB blade deflection sensing system, which consists of two UWB antennas at the blade root and one UWB antenna at the blade tip. The detailed topology and challenges of this deflection sensing system are addressed. Due to the complexity of the problem, this paper will first realize the on-blade UWB radio link in the simplest case, where the tip antenna is situated outside (and on the surface of) a blade tip. To investigate this case, full-blade time-domain measurements are designed and conducted under different deflections. The detailed measurement setups and results are provided. If the root and tip antenna locations are properly selected, the first pulse is always of sufficient quality for accurate estimations under different deflections. The measured results reveal that the blade tip-root distance and blade deflection can be accurately estimated in the complicated and lossy wireless channels around a wind turbine blade. Some future research topics on this application are listed finally.

  6. Behavior of a nuclear power plant ventilation stack for wind loads

    International Nuclear Information System (INIS)

    Venkatachalapathy, V.

    2012-01-01

    This paper describes behavior of self supporting tall reinforced concrete (RC) ventilation stack of a nuclear power plant (NPP) for wind loads. Since the static and equivalent dynamic wind loads are inter-dependant on overall size of the stack, proper sizing of the stack geometry is important for reducing wind loads. The present study investigated the influence of engineered backfill soil on lateral response of ventilation stack. Ignoring backfill soil stiffness up to ground height does not allow to predict actual critical wind velocity causing across wind oscillation. The results show that proposed modification in the stack geometry modeled using 2D beam-spring elements is economical than that of single tapered geometry. Shaft diameter reduced in the proposed geometry indicates that there is a scope for overall space savings in the NPP layout. (author)

  7. Load Reduction, Demand Response and Energy Efficient Technologies and Strategies

    Energy Technology Data Exchange (ETDEWEB)

    Boyd, Paul A.; Parker, Graham B.; Hatley, Darrel D.

    2008-11-19

    The Department of Energy’s (DOE’s) Pacific Northwest National Laboratory (PNNL) was tasked by the DOE Office of Electricity (OE) to recommend load reduction and grid integration strategies, and identify additional demand response (energy efficiency/conservation opportunities) and strategies at the Forest City Housing (FCH) redevelopment at Pearl Harbor and the Marine Corps Base Hawaii (MCBH) at Kaneohe Bay. The goal was to provide FCH staff a path forward to manage their electricity load and thus reduce costs at these FCH family housing developments. The initial focus of the work was at the MCBH given the MCBH has a demand-ratchet tariff, relatively high demand (~18 MW) and a commensurate high blended electricity rate (26 cents/kWh). The peak demand for MCBH occurs in July-August. And, on average, family housing at MCBH contributes ~36% to the MCBH total energy consumption. Thus, a significant load reduction in family housing can have a considerable impact on the overall site load. Based on a site visit to the MCBH and meetings with MCBH installation, FCH, and Hawaiian Electric Company (HECO) staff, recommended actions (including a "smart grid" recommendation) that can be undertaken by FCH to manage and reduce peak-demand in family housing are made. Recommendations are also made to reduce overall energy consumption, and thus reduce demand in FCH family housing.

  8. Application genetic algorithms for load management in refrigerated warehouses with wind power penetration

    DEFF Research Database (Denmark)

    Zong, Yi; Cronin, Tom; Gehrke, Oliver

    2009-01-01

    Wind energy is produced at random times, whereas the energy consumption pattern shows distinct demand peaks during day-time and low levels during the night. The use of a refrigerated warehouse as a giant battery for wind energy is a new possibility that is being studied for wind energy integration...... as well as a way to store electricity produced during night-time by wind turbines. The controller for load management in a refrigerated warehouse with wind power penetration by GA-based is introduced in this paper. The objective function is to minimize the energy consumption for operating the refrigerated...... warehouse. It can be seen that the GA-based control strategy achieves feasible results for operating the temperature in refrigerated warehouse. Balancing the wind power production with refrigerated warehouse load management promises to be a clean and cost effective method. For refrigerated warehouse owners...

  9. Performance Analysis of Doubly Fed Induction Generator Based Wind turbine under Faulty and RLC Load Conditions

    OpenAIRE

    Rekha Parashar; Shashikant

    2015-01-01

    This paper presents the performance of Doubly Fed Induction Generator based wind turbine system during different types of grid fault. The doubly fed induction generator (DFIG) based wind turbine (WT) system provides better power delivery towards the demand. The design and response of the DFIG based wind turbine system during different fault conditions, various load conditions and integrated system consisting of DFIG based WT system have been verified using MATLAB/ Simulink. The simulation re...

  10. Reducing Wind Turbine Load Simulation Uncertainties by Means of a Constrained Gaussian Turbulence Field

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov; Lazarov, Boyan Stefanov

    2015-01-01

    . A numerical study shows the application of the constrained turbulence method to load simulations on a 10MW wind turbine model, using two example lidar patterns – a 5-point pattern forming a square with a central point, and a circular one. Based on the results of this study, we assess the influence of applying...... the proposed method on the statistical uncertainty in wind turbine extreme and fatigue loads....

  11. The design of models for cryogenic wind tunnels. [mechanical properties and loads

    Science.gov (United States)

    Gillespie, V. P.

    1977-01-01

    Factors to be considered in the design and fabrication of models for cryogenic wind tunnels include high model loads imposed by the high operating pressures, the mechanical and thermodynamic properties of materials in low temperature environments, and the combination of aerodynamic loads with the thermal environment. Candidate materials are being investigated to establish criteria for cryogenic wind tunnel models and their installation. Data acquired from these tests will be provided to users of the National Transonic Facility.

  12. Wind loads for stability design of large multi-span duo-pitch greenhouses

    NARCIS (Netherlands)

    Bronkhorst, A.J.; Geurts, C.P.W.; Bentum, C.A. van; Knaap, L.P.M. van der; Pertermann, I.

    2017-01-01

    An atmospheric boundary layer wind tunnel study was performed to determine the overall horizontal wind load on multi-span duo-pitch greenhouses. The results of this study are intended for the stability design of inflexible Gladding system greenhouses (designated as Class A in EN 13031-1) with roof

  13. A simplified model predicting the weight of the load carrying beam in a wind turbine blade

    DEFF Research Database (Denmark)

    Mikkelsen, Lars Pilgaard

    2016-01-01

    Based on a simplified beam model, the loads, stresses and deflections experienced by a wind turbine blade of a given length is estimated. Due to the simplicity of the model used, the model is well suited for work investigating scaling effects of wind turbine blades. Presently, the model is used t...

  14. Assessment of the impact of frequency support on DFIG wind turbine loads

    DEFF Research Database (Denmark)

    Barahona Garzón, Braulio; You, Rui; Hansen, Anca Daniela

    2013-01-01

    This study presents models and tools for the assessment of the impact that providing frequency support has on doubly-fed generator (DFIG) wind turbine structural loads and drive train. The focus is on primary frequency support, aiming at quantifying the impact on wind turbines acting as frequency...

  15. Effect of blade flutter and electrical loading on small wind turbine noise

    Science.gov (United States)

    The effect of blade flutter and electrical loading on the noise level of two different size wind turbines was investigated at the Conservation and Production Research Laboratory (CPRL) near Bushland, TX. Noise and performance data were collected on two blade designs tested on a wind turbine rated a...

  16. The Load Level of Modern Wind Turbines according to IEC 61400-1

    International Nuclear Information System (INIS)

    Freudenreich, K; Argyriadis, K

    2007-01-01

    The paper describes some effects on the load level of state-of-the art multi megawatt wind turbines introduced by the new edition of the standard IEC 61400-1:2005 W ind Turbines - Part 1: Design requirements . Compared to the previous edition, especially the extreme load determination has been modified by applying stochastic and statistical analyses. Within this paper the effect on the overall load level of wind turbines is demonstrated and occurring problems are discussed. Load simulations have been carried out for four state-of-the-art multi-megawatt wind turbines of different design concepts and from different manufacturers. The blade root bending moments and tip deflection have been determined by applying different extrapolation methods. Advantages and disadvantages of these methods and tail fittings for different load components and wind turbine technologies are discussed and interpreted. Further on, the application of the extreme turbulence model is demonstrated. The dependence of the load level on the turbulence intensity and control system, as well as the interaction with extrapolated loads is discussed and limitations outlined. The obtained load level is compared to the overall load level of the turbines according to the previous edition of the standard, IEC 61400-1:1999

  17. Calibration procedures for improved accuracy of wind turbine blade load measurement

    Energy Technology Data Exchange (ETDEWEB)

    Dahlberg, J.Aa. [Aeronautical Research Inst. of Sweden, Bromma (Sweden); Johansson, Hjalmar [Teknikgruppen AB, Sollentuna (Sweden)

    1996-12-01

    External loads acting on wind turbine blades are mainly transferred via the hub to the rest of the structure. It is therefore a normal approach to measure the loads acting on the turbine by load measurements in the blade roots. The load measurement is often accomplished by measurements of strain on the surface of the blade or the hub. The strain signals are converted to loads by applying calibration factors to the measurements. This paper deals with difficulties associated with load measurements on two different wind turbines; one with strain gauges applied to a steel hub where a linear stress-load relationship is expected and the other with strain gauges applied to the GFRP blade close to the bearings where strong non-linearity`s and temperature effects are expected. This paper suggests calibration methods to overcome these problems. 2 refs, 11 figs

  18. Model-Based Load Estimation for Predictive Condition Monitoring of Wind Turbines

    DEFF Research Database (Denmark)

    Perisic, Nevena; Pederen, Bo Juul; Grunnet, Jacob Deleuran

    The main objective of this paper is to present a Load Observer Tool (LOT) for condition monitoring of structural extreme and fatigue loads on the main wind turbine (WTG) components. LOT uses well-known methods from system identification, state estimation and fatigue analysis in a novel approach...... for application in condition monitoring. Fatigue loads are estimated online using a load observer and grey box models which include relevant WTG dynamics. Identification of model parameters and calibration of observer are performed offline using measurements from WTG prototype. Signal processing of estimated load...... signal is performed online, and a Load Indicator Signal (LIS) is formulated as a ratio between current estimated accumulated fatigue loads and its expected value based only on a priori knowledge (WTG dynamics and wind climate). LOT initialisation is based on a priori knowledge and can be obtained using...

  19. Outlier robustness for wind turbine extrapolated extreme loads

    DEFF Research Database (Denmark)

    Natarajan, Anand; Verelst, David Robert

    2012-01-01

    . Stochastic identification of numerical artifacts in simulated loads is demonstrated using the method of principal component analysis. The extrapolation methodology is made robust to outliers through a weighted loads approach, whereby the eigenvalues of the correlation matrix obtained using the loads with its...

  20. Design of a wind tunnel scale model of an adaptive wind turbine blade for active aerodynamic load control experiments

    NARCIS (Netherlands)

    Hulskamp, A.W.; Beukers, A.; Bersee, H.E.N.; Van Wingerden, J.W.; Barlas, T.

    2007-01-01

    Within wind energy research there is a drive towards the development of a “smart rotor”; a rotor of which the loading can be measured and controlled through the application of a sensor system, a control system and an aerodynamic device. Most promising solutions from an aerodynamic point of view are

  1. Assessment of wind turbine drive-train fatigue loads under torsional excitation

    DEFF Research Database (Denmark)

    Gallego Calderon, Juan Felipe; Natarajan, Anand

    2015-01-01

    This paper establishes validated models that can accurately account for the dynamics of the gearbox, along with the external dynamics that excite the system. A drive-train model implementation is presented where the gearbox and generator are coupled to the wind turbine structure in a dynamic...... allows the computation of the bearing and gear-mesh loads. The proposed models are validated by experiments from a 750 kW test-rig. The drive-train model is configured for a 5 MW power capacity and coupled to the corresponding wind turbine and load simulations are carried out under turbulent wind...

  2. Grid Faults Impact on the Mechanical Loads of Active Stall Wind Turbine

    DEFF Research Database (Denmark)

    Iov, Florin; Cutululis, Nicolaos A.; Hansen, Anca D.

    2008-01-01

    Emphasis in this paper is on the fault ride-through operation impact on the wind turbines structural loads. Grid faults are typically simulated in power system simulation tools using simplified drive train mechanical model, approach which doesn't allow a thorough investigation of structural loads...... as the electrical design of the wind turbine response during grid faults. The two-step simulation procedure is assessed by means of a simulation example. The effect of a grid fault on the structural part of a typical fixed speed wind turbine, equipped with an induction generator, is assessed....

  3. Validation of Simplified Load Equations Through Loads Measurement and Modeling of a Small Horizontal-Axis Wind Turbine Tower

    Energy Technology Data Exchange (ETDEWEB)

    Dana, Scott [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Van Dam, Jeroen J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Damiani, Rick R [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-04-24

    As part of an ongoing effort to improve the modeling and prediction of small wind turbine dynamics, the National Renewable Energy Laboratory (NREL) tested a small horizontal-axis wind turbine in the field at the National Wind Technology Center. The test turbine was a 2.1-kW downwind machine mounted on an 18-m multi-section fiberglass composite tower. The tower was instrumented and monitored for approximately 6 months. The collected data were analyzed to assess the turbine and tower loads and further validate the simplified loads equations from the International Electrotechnical Commission (IEC) 61400-2 design standards. Field-measured loads were also compared to the output of an aeroelastic model of the turbine. In particular, we compared fatigue loads as measured in the field, predicted by the aeroelastic model, and calculated using the simplified design equations. Ultimate loads at the tower base were assessed using both the simplified design equations and the aeroelastic model output. The simplified design equations in IEC 61400-2 do not accurately model fatigue loads and a discussion about the simplified design equations is discussed.

  4. Impact of uncertainty in airfoil characteristics on wind turbine extreme loads

    DEFF Research Database (Denmark)

    Abdallah, Imad; Natarajan, Anand; Sørensen, John Dalsgaard

    2015-01-01

    Wind tunnel test measurements to characterize the static lift and drag coefficients of airfoils used in wind turbine blades are shown to possess large uncertainties, which leads to uncertainties in the aerodynamic loads on the rotor. In this paper a rational stochastic model is proposed to quantify...... the uncertainty in airfoil static lift and drag coefficients based on field and wind tunnel data, aero-servoelastic calculations and engineering judgment. The stochastic model is subsequently used to assess the effect of the uncertainty in airfoil static lift and drag coefficients on the prediction of extreme...... loads and structural reliability of large wind turbines. It is shown that the uncertainty in the static airfoil data has a significant impact on the prediction of extreme loads effects and structural reliability depending on the component, operating conditions (stand-still versus power production...

  5. Optimum Parameters of a Tuned Liquid Column Damper in a Wind Turbine Subject to Stochastic Load

    Science.gov (United States)

    Alkmim, M. H.; de Morais, M. V. G.; Fabro, A. T.

    2017-12-01

    Parameter optimization for tuned liquid column dampers (TLCD), a class of passive structural control, have been previously proposed in the literature for reducing vibration in wind turbines, and several other applications. However, most of the available work consider the wind excitation as either a deterministic harmonic load or random load with white noise spectra. In this paper, a global direct search optimization algorithm to reduce vibration of a tuned liquid column damper (TLCD), a class of passive structural control device, is presented. The objective is to find optimized parameters for the TLCD under stochastic load from different wind power spectral density. A verification is made considering the analytical solution of undamped primary system under white noise excitation by comparing with result from the literature. Finally, it is shown that different wind profiles can significantly affect the optimum TLCD parameters.

  6. Economic perspective of hybrid wind-diesel technology for commercial loads of Dhahran Saudi Arabia: A step towards sustainable future

    Directory of Open Access Journals (Sweden)

    Shaahid S.M.

    2015-01-01

    Full Text Available The governments world-wide are deliberating to promote renewable energy sources such as wind to mitigate increasing demand of energy and to overcome effects of pollution due to to use of fossil fuels. Integration of wind turbine generators (WTG with the diesel plants is pursued widely to reduce dependence on fossil-fuels and to reduce carbon emissions. Literature indicates that commercial/residential buildings in the Kingdom of Saudi Arabia (K.S.A consume an estimated 10 - 40% of the total electric energy generated. The aim of this study is to analyze wind-speed data of Dhahran (East-Coast, K.S.A. to assess the economic feasibility of utilizing hybrid wind-diesel power systems to meet the load requirements of a typical commercial building (with annual electrical energy demand of 620,000 kWh. The monthly average wind speeds range from 3.3 to 5.6 m/s. The hybrid systems simulated consist of different combinations of 100 kW commercial WTG supplemented with diesel generators. NREL’s (HOMER Energy’s HOMER software has been employed to perform the techno-economic analysis. The simulation results indicate that for a hybrid system comprising of 100 kW wind capacity together with 175 kW diesel system, the wind penetration (at 37 m hub-height, with 0% annual capacity shortage is 25%. The cost of generating energy (COE, $/kWh from this hybrid wind-diesel system has been found to be 0.121 $/kWh (assuming diesel fuel price of 0.1$/liter. The study exhibits that for a given hybrid configuration, the number of operational hours of diesel gensets decreases with increase in wind farm capacity. Emphasis has also been placed on wind penetration, un-met load, energy production and COE, excess electricity generation, percentage fuel savings and reduction in carbon emissions (relative to diesel-only situation of different hybrid systems, cost break-down of wind-diesel systems, COE of different hybrid systems, etc.

  7. Differential Effects of Cognitive Load on University Wind Students' Practice

    Science.gov (United States)

    Stambaugh, Laura A.

    2013-01-01

    The purpose of this study was to investigate the effects of cognitive load during practice on university wind students' learning. Cognitive load was manipulated through instrument family (woodwind or brass) and the amount of repetition used in practice (highly repetitive or random). University woodwind and valved-brass students (N = 46)…

  8. Approach to include load sequence effects in the design of an offshore wind turbine substructure

    NARCIS (Netherlands)

    Dragt, R.C.; Allaix, D.L.; Maljaars, J.; Tuitman, J.T.; Salman, Y.; Otheguy, M.E.

    2017-01-01

    Fatigue is one of the main design drivers for offshore wind substructures. Using Fracture Mechanics methods, load sequence effects such as crack growth retardation due to large load peaks can be included in the fatigue damage estimation. Due to the sequence dependency, a method is required that

  9. Reduction of horizontal wind speed in a boundary layer with obstacles

    DEFF Research Database (Denmark)

    Emeis, S.; Frandsen, S.

    1993-01-01

    The reduction of horizontal wind speed at hub height in an infinite cluster of wind turbines is computed from a balance between a loss of horizontal momentum due to the drag and replenishment from above by turbulent fluxes. This reduction is derived without assumptions concerning the vertical win...

  10. Unbalanced voltage faults: the impact on structural loads of doubly fed asynchronous generator wind turbines

    DEFF Research Database (Denmark)

    Barahona Garzón, Braulio; Cutululis, Nicolaos Antonio; Hansen, Anca Daniela

    2014-01-01

    , and control dynamics in an integrated simulation environment based on an aeroelastic code (HAWC2) and software for control design (Matlab/Simulink). In the present analysis, 1 Hz equivalent loads are used to compare fatigue loads, whereas maximum–minimum values are used to compare extreme loads. A control......This paper investigates the impact that unbalanced voltage faults have on wind turbine structural loads. In such cases, electromagnetic torque oscillations occur at two times the supply voltage frequency. The objectives of this work are to quantify wind turbine structural loads induced...... by unbalanced voltage faults relative to those during normal operation; and to evaluate the potential for reducing structural loads with the control of the generator. The method applied is integrated dynamic analysis. Namely, dynamic analysis with models that consider the most important aeroelastic, electrical...

  11. Structural investigation of composite wind turbine blade considering various load cases and fatigue life

    International Nuclear Information System (INIS)

    Kong, C.; Bang, J.; Sugiyama, Y.

    2005-01-01

    This study proposes a structural design for developing a medium scale composite wind turbine blade made of E-glass/epoxy for a 750 kW class horizontal axis wind turbine system. The design loads were determined from various load cases specified at the IEC61400-1 international specification and GL regulations for the wind energy conversion system. A specific composite structure configuration, which can effectively endure various loads such as aerodynamic loads and loads due to accumulation of ice, hygro-thermal and mechanical loads, was proposed. To evaluate the proposed composite wind turbine blade, structural analysis was performed by using the finite element method. Parametric studies were carried out to determine an acceptable blade structural design, and the most dominant design parameters were confirmed. In this study, the proposed blade structure was confirmed to be safe and stable under various load conditions, including the extreme load conditions. Moreover, the blade adapted a new blade root joint with insert bolts, and its safety was verified at design loads including fatigue loads. The fatigue life of a blade that has to endure for more than 20 years was estimated by using the well-known S-N linear damage theory, the service load spectrum, and the Spera's empirical equations. With the results obtained from all the structural design and analysis, prototype composite blades were manufactured. A specific construction process including the lay-up molding method was applied to manufacturing blades. Full-scale static structural test was performed with the simulated aerodynamic loads. From the experimental results, it was found that the designed blade had structural integrity. In addition, the measured results of deflections, strains, mass, and radial center of gravity agreed well with the analytical results. The prototype blade was successfully certified by an international certification institute, GL (Germanisher Lloyd) in Germany

  12. Research on Power System Scheduling Improving Wind Power Accommodation Considering Thermal Energy Storage and Flexible Load

    Science.gov (United States)

    Zou, Chenlu; Cui, Xue; Wang, Heng; Zhou, Bin; Liu, Yang

    2018-01-01

    In the case of rapid development of wind power and heavy wind curtailment, the study of wind power accommodation of combined heat and power system has become the focus of attention. A two-stage scheduling model contains of wind power, thermal energy storage, CHP unit and flexible load were constructed. This model with the objective function of minimizing wind curtailment and the operation cost of units while taking into account of the total coal consumption of units, constraint of thermal energy storage and electricity-heat characteristic of CHP. This paper uses MICA to solve the problem of too many constraints and make the solution more feasible. A numerical example showed that the two stage decision scheduling model can consume more wind power, and it could provide a reference for combined heat and power system short-term operation

  13. Power and loads for wind turbines in yawed conditions. Analysis of field measurements and aerodynamic predictions

    Energy Technology Data Exchange (ETDEWEB)

    Boorsma, K. [ECN Wind Energy, Petten (Netherlands)

    2012-11-15

    A description is given of the work carried out within the framework of the FLOW (Far and Large Offshore Wind) project on single turbine performance in yawed flow conditions. Hereto both field measurements as well as calculations with an aerodynamic code are analyzed. The rotors of horizontal axis wind turbines follow the changes in the wind direction for optimal performance. The reason is that the power is expected to decrease for badly oriented rotors. So, insight in the effects of the yaw angle on performance is important for optimization of the yaw control of each individual turbine. The effect of misalignment on performance and loads of a single 2.5 MW wind turbine during normal operation is investigated. Hereto measurements at the ECN Wind Turbine Test Site Wieringermeer (EWTW) are analyzed from December 2004 until April 2009. Also, the influence of yaw is studied using a design code and results from this design code are compared with wind tunnel measurements.

  14. Gearbox Fatigue Load Estimation for Condition Monitoring of Wind Turbines

    DEFF Research Database (Denmark)

    Perisic, Nevena; Pedersen, Bo Juul; Kirkegaard, Poul Henning

    2012-01-01

    control and data acquisition (SCADA) system. Estimated loads can be further used for prediction of remaining operating lifetime of turbine components, detection of high stress level or fault detection. An augmented Kalman filter is chosen as the fatigue load estimator because its characteristics well suit...

  15. Wind Energy Management System EMS Integration Project: Incorporating Wind Generation and Load Forecast Uncertainties into Power Grid Operations

    Energy Technology Data Exchange (ETDEWEB)

    Makarov, Yuri V.; Huang, Zhenyu; Etingov, Pavel V.; Ma, Jian; Guttromson, Ross T.; Subbarao, Krishnappa; Chakrabarti, Bhujanga B.

    2010-01-01

    The power system balancing process, which includes the scheduling, real time dispatch (load following) and regulation processes, is traditionally based on deterministic models. Since the conventional generation needs time to be committed and dispatched to a desired megawatt level, the scheduling and load following processes use load and wind and solar power production forecasts to achieve future balance between the conventional generation and energy storage on the one side, and system load, intermittent resources (such as wind and solar generation), and scheduled interchange on the other side. Although in real life the forecasting procedures imply some uncertainty around the load and wind/solar forecasts (caused by forecast errors), only their mean values are actually used in the generation dispatch and commitment procedures. Since the actual load and intermittent generation can deviate from their forecasts, it becomes increasingly unclear (especially, with the increasing penetration of renewable resources) whether the system would be actually able to meet the conventional generation requirements within the look-ahead horizon, what the additional balancing efforts would be needed as we get closer to the real time, and what additional costs would be incurred by those needs. To improve the system control performance characteristics, maintain system reliability, and minimize expenses related to the system balancing functions, it becomes necessary to incorporate the predicted uncertainty ranges into the scheduling, load following, and, in some extent, into the regulation processes. It is also important to address the uncertainty problem comprehensively by including all sources of uncertainty (load, intermittent generation, generators’ forced outages, etc.) into consideration. All aspects of uncertainty such as the imbalance size (which is the same as capacity needed to mitigate the imbalance) and generation ramping requirement must be taken into account. The latter

  16. Reduction of Dynamic Loads in Mine Lifting Installations

    Science.gov (United States)

    Kuznetsov, N. K.; Eliseev, S. V.; Perelygina, A. Yu

    2018-01-01

    Article is devoted to a problem of decrease in the dynamic loadings arising in transitional operating modes of the mine lifting installations leading to heavy oscillating motions of lifting vessels and decrease in efficiency and reliability of work. The known methods and means of decrease in dynamic loadings and oscillating motions of the similar equipment are analysed. It is shown that an approach based on the concept of the inverse problems of dynamics can be effective method of the solution of this problem. The article describes the design model of a one-ended lifting installation in the form of a two-mass oscillation system, in which the inertial elements are the mass of the lifting vessel and the reduced mass of the engine, reducer, drum and pulley. The simplified mathematical model of this system and results of an efficiency research of an active way of reduction of dynamic loadings of lifting installation on the basis of the concept of the inverse problems of dynamics are given.

  17. Toward Isolation of Salient Features in Stable Boundary Layer Wind Fields that Influence Loads on Wind Turbines

    Directory of Open Access Journals (Sweden)

    Jinkyoo Park

    2015-04-01

    Full Text Available Neutral boundary layer (NBL flow fields, commonly used in turbine load studies and design, are generated using spectral procedures in stochastic simulation. For large utility-scale turbines, stable boundary layer (SBL flow fields are of great interest because they are often accompanied by enhanced wind shear, wind veer, and even low-level jets (LLJs. The generation of SBL flow fields, in contrast to simpler stochastic simulation for NBL, requires computational fluid dynamics (CFD procedures to capture the physics and noted characteristics—such as shear and veer—that are distinct from those seen in NBL flows. At present, large-eddy simulation (LES is the most efficient CFD procedure for SBL flow field generation and related wind turbine loads studies. Design standards, such as from the International Electrotechnical Commission (IEC, provide guidance albeit with simplifying assumptions (one such deals with assuming constant variance of turbulence over the rotor and recommend standard target turbulence power spectra and coherence functions to allow NBL flow field simulation. In contrast, a systematic SBL flow field simulation procedure has not been offered for design or for site assessment. It is instructive to compare LES-generated SBL flow fields with stochastic NBL flow fields and associated loads which we evaluate for a 5-MW turbine; in doing so, we seek to isolate distinguishing characteristics of wind shear, wind veer, and turbulence variation over the rotor plane in the alternative flow fields and in the turbine loads. Because of known differences in NBL-stochastic and SBL-LES wind fields but an industry preference for simpler stochastic simulation in design practice, this study investigates if one can reproduce stable atmospheric conditions using stochastic approaches with appropriate corrections for shear, veer, turbulence, etc. We find that such simple tuning cannot consistently match turbine target SBL load statistics, even though

  18. Electromagnetic damper system for ground wind load studies

    Science.gov (United States)

    Scott, L. P.

    1972-01-01

    The design, fabrication, and adaptation of a model damper system to the 5.5% aeroelastic model of the Saturn 1B/Skylab launch vehicle are reported. The damper is dynamically calibrated over the desired range of additive damping for model conditions prior to wind tunnel testing.

  19. Simulation Of Probabilistic Wind Loads On A Building

    Science.gov (United States)

    Chamis, Christos C.; Shah, Ashwin R.

    1994-01-01

    Method of simulating probabilistic windloads on building developed. Numerical results of simulation used to assess reliability of building and risk associated with tendencies of large gusts or high steady winds to cause building to sway, buckle, and/or overturn. Using method to analyze proposed design in iterative design cycle, building designed for specified reliability.

  20. Forces and Moments on Flat Plates of Small Aspect Ratio with Application to PV Wind Loads and Small Wind Turbine Blades

    Directory of Open Access Journals (Sweden)

    Xavier Ortiz

    2015-03-01

    Full Text Available To improve knowledge of the wind loads on photovoltaic structures mounted on flat roofs at the high angles required in high latitudes, and to study starting flow on low aspect ratio wind turbine blades, a series of wind tunnel tests were undertaken. Thin flat plates of aspect ratios between 0.4 and 9.0 were mounted on a sensitive three-component instantaneous force and moment sensor. The Reynolds numbers varied from 6 × 104 to 2 × 105. Measurements were made for angles of attack between 0° and 90° both in the free stream and in wall proximity with increased turbulence and mean shear. The ratio of drag to lift closely follows the inverse tangent of the angle of incidence for virtually all measurements. This implies that the forces of interest are due largely to the instantaneous pressure distribution around the plate and are not significantly influenced by shear stresses. The instantaneous forces appear most complex for the smaller aspect ratios but the intensity of the normal force fluctuations is between 10% and 20% in the free-steam but can exceed 30% near the wall. As the wind tunnel floor is approached, the lift and drag reduce with increasing aspect ratio, and there is a reduction in the high frequency components of the forces. It is shown that the centre of pressure is closer to the centre of the plates than the quarter-chord position for nearly all cases.

  1. Mechanisms of Active Aerodynamic Load Reduction on a Rotorcraft Fuselage With Rotor Effects

    Science.gov (United States)

    Schaeffler, Norman W.; Allan, Brian G.; Jenkins, Luther N.; Yao, Chung-Sheng; Bartram, Scott M.; Mace, W. Derry; Wong, Oliver D.; Tanner, Philip E.

    2016-01-01

    The reduction of the aerodynamic load that acts on a generic rotorcraft fuselage by the application of active flow control was investigated in a wind tunnel test conducted on an approximately 1/3-scale powered rotorcraft model simulating forward flight. The aerodynamic mechanisms that make these reductions, in both the drag and the download, possible were examined in detail through the use of the measured surface pressure distribution on the fuselage, velocity field measurements made in the wake directly behind the ramp of the fuselage and computational simulations. The fuselage tested was the ROBIN-mod7, which was equipped with a series of eight slots located on the ramp section through which flow control excitation was introduced. These slots were arranged in a U-shaped pattern located slightly downstream of the baseline separation line and parallel to it. The flow control excitation took the form of either synthetic jets, also known as zero-net-mass-flux blowing, and steady blowing. The same set of slots were used for both types of excitation. The differences between the two excitation types and between flow control excitation from different combinations of slots were examined. The flow control is shown to alter the size of the wake and its trajectory relative to the ramp and the tailboom and it is these changes to the wake that result in a reduction in the aerodynamic load.

  2. Virginia Offshore Wind Cost Reduction Through Innovation Study (VOWCRIS) (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Maples, B.; Campbell, J.; Arora, D.

    2014-10-01

    The VOWCRIS project is an integrated systems approach to the feasibility-level design, performance, and cost-of-energy estimate for a notional 600-megawatt offshore wind project using site characteristics that apply to the Wind Energy Areas of Virginia, Maryland and North Carolina.

  3. Load inertia estimation using white and grey-box estimators for power systems with high wind penetration

    OpenAIRE

    Bank Tavakoli, M. Reza; Power, Michael; Ruttledge, Lisa; Flynn, Damian

    2012-01-01

    The increasing penetration of wind farms in power systems has increased concerns over the frequency behaviour and control of synchronous power systems due to a low contribution from modern wind turbines to overall system inertia. With this trend of conventional generators being displaced by variable speed wind turbines, the contribution from load inertia becomes more significant. The need for greater consideration towards load inertia estimation, or even on-line tracking of load inertia, seem...

  4. Decentralized & Adaptive Load-Frequency Control Scheme of Variable Speed Wind Turbines

    DEFF Research Database (Denmark)

    Hoseinzadeh, Bakhtyar; Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2014-01-01

    In power systems with high penetration of Wind Power (WP), transferring a part of Load Frequency Control (LFC) burden to variable speed Wind Turbines (WTs) is inevitable. The conventional LFC schemes merely rely on frequency information and since frequency is a common variable throughout the netw......In power systems with high penetration of Wind Power (WP), transferring a part of Load Frequency Control (LFC) burden to variable speed Wind Turbines (WTs) is inevitable. The conventional LFC schemes merely rely on frequency information and since frequency is a common variable throughout...... and therefore determining the contribution factor of each individual WT to gain an adaptive LFC approach. The Electrical Distance (ED) concept confirms that the locally measured voltage decay is a proper criterion of closeness to the disturbance place. Numerical simulations carried out in DigSilent Power...

  5. Wind Energy Management System Integration Project Incorporating Wind Generation and Load Forecast Uncertainties into Power Grid Operations

    Energy Technology Data Exchange (ETDEWEB)

    Makarov, Yuri V.; Huang, Zhenyu; Etingov, Pavel V.; Ma, Jian; Guttromson, Ross T.; Subbarao, Krishnappa; Chakrabarti, Bhujanga B.

    2010-09-01

    The power system balancing process, which includes the scheduling, real time dispatch (load following) and regulation processes, is traditionally based on deterministic models. Since the conventional generation needs time to be committed and dispatched to a desired megawatt level, the scheduling and load following processes use load and wind power production forecasts to achieve future balance between the conventional generation and energy storage on the one side, and system load, intermittent resources (such as wind and solar generation) and scheduled interchange on the other side. Although in real life the forecasting procedures imply some uncertainty around the load and wind forecasts (caused by forecast errors), only their mean values are actually used in the generation dispatch and commitment procedures. Since the actual load and intermittent generation can deviate from their forecasts, it becomes increasingly unclear (especially, with the increasing penetration of renewable resources) whether the system would be actually able to meet the conventional generation requirements within the look-ahead horizon, what the additional balancing efforts would be needed as we get closer to the real time, and what additional costs would be incurred by those needs. In order to improve the system control performance characteristics, maintain system reliability, and minimize expenses related to the system balancing functions, it becomes necessary to incorporate the predicted uncertainty ranges into the scheduling, load following, and, in some extent, into the regulation processes. It is also important to address the uncertainty problem comprehensively, by including all sources of uncertainty (load, intermittent generation, generators’ forced outages, etc.) into consideration. All aspects of uncertainty such as the imbalance size (which is the same as capacity needed to mitigate the imbalance) and generation ramping requirement must be taken into account. The latter unique

  6. Mean load effects on the fatigue life of offshore wind turbine monopile foundations

    DEFF Research Database (Denmark)

    Blasques, José Pedro Albergaria Amaral; Natarajan, Anand

    2013-01-01

    This paper discusses the importance of mean load effects on the estimation of the fatigue damage in offshore wind turbine monopile foundations. The mud line bending moment time series are generated using a fully coupled aero-hydro-elastic model accounting for non-linear water waves and sea current...... of the fatigue life of offshore wind turbine monopile foundations. Moreover, it is shown that a nonlinear hydrodynamic model is required in order to correctly account for the effect of the current....

  7. The Feasibility Study on Thermal Loading Control of Wind Power Converters with a Flexible Switching Frequency

    DEFF Research Database (Denmark)

    Qin, Zian; Wang, Huai; Blaabjerg, Frede

    2015-01-01

    of the IGBT modules, the power losses and thereby the thermal stresses can be controlled by varying the PWM switching frequency according to power loading conditions. This paper investigates the feasibility to apply this flexible modulation strategy in a 3 MW wind power converter application to reduce......Thermal loading of wind power converters is critical to their reliability performance. Especially for IGBT modules applied in a converter, both of the mean value and variation of the junction temperature have significant impact on the lifetime. Besides other strategies to reduce the thermal loading...... the temperature fluctuations due to wind speed variations. The trade-off between the reduced amplitude of temperature fluctuations and the additional power losses that may be introduced is quantitatively studied....

  8. Predicting the Extreme Loads on a Wind Turbine Considering Uncertainty in Airfoil Data

    DEFF Research Database (Denmark)

    Abdallah, Imad; Natarajan, Anand; Sørensen, John Dalsgaard

    2014-01-01

    The sources contributing to uncertainty in a wind turbine blade static airfoil data include wind tunnel testing, CFD calculations, 3D rotational corrections based on CFD or emprircal models, surface roughness corrections, Reynolds number corrections, expansion to the full 360-degree angle of attack...... range, validation by full scale measurements, and geometric distortions of the blade during manufacturing and under loading. In this paper a stochastic model of the static airfoil data is proposed to supplement the prediction of extreme loads effects for large wind turbines. It is shown...... that the uncertainty in airfoil data can have e significant impact on the prediction of extreme loads effects depending on the component, and the correlation along the span of the blade....

  9. Frequency-domain characteristics of aerodynamic loads of offshore floating vertical axis wind turbines

    DEFF Research Database (Denmark)

    Borg, Michael; Collu, M.

    2015-01-01

    The re-emerging interest in vertical axis wind turbines for floating offshore applications has led to a need to investigate the relatively complex dynamics of such floating offshore structures. Through the use of a coupled model of dynamics this article investigates the frequency-domain character......The re-emerging interest in vertical axis wind turbines for floating offshore applications has led to a need to investigate the relatively complex dynamics of such floating offshore structures. Through the use of a coupled model of dynamics this article investigates the frequency......-domain characteristics of floating vertical axis wind turbine aerodynamic loads. The impact of platform induced motion on aerodynamic loads is discussed in detail, with results indicating an increase in aerodynamic loads of several orders of magnitude over the range of frequencies usually containing significant wave...

  10. WISPER and WISPERX: Final definition of two standardised fatigue loading sequences for wind turbine blades

    Science.gov (United States)

    Tenhave, A. A.

    1992-09-01

    Relevant information used to develop WISPER (Wind turbine reference Spectrum) and WISPERX, standardized variable amplitude test loading histories for use in the fatigue design of horizontal axis wind turbine blades, is presented. WISPER and WISPERX are based on flap load service measurements on nine different horizontal axis wind turbines, covering a wide range of materials, rotor diameters and geographical locations. Their backgrounds are reported, basic data and associated data handling procedures are described, and quantitative data analysis results and statistical information on both standards are presented. The information given will enable fatigue specialists to judge whether the standard will suit their test objectives and to check for correct application of the load sequences on their test equipment.

  11. Experimental study of wind loads on unique buildings and structures in Russia

    Directory of Open Access Journals (Sweden)

    Poddaeva Olga

    2016-01-01

    Full Text Available Design and construction of unique buildings and structures (sports arenas, airport complexes, business centres, etc. from an engineering point of view is a very difficult task as in most cases these facilities have an original architectural form. Therefore, consideration of wind loads is an important part of the design. The paper presents the definition of wind load for two complex of airport. Researches was applied the combined calculation an experimental method. During the experimental study a wind tunnel architectural and construction type NRU MSUCE was used. Numerical simulations were performed using the software package ANSYS. The result of research on each object are integral aerodynamic loads on the object (coefficients Cx, Cy, Cmz and picture of the distribution of aerodynamic pressure coefficient Cp obtained in the numerical simulation. In conclusion, we discuss the possible formation of deposits of snow and recommendations to eliminate them from the roof of researched objects.

  12. A stochastic framework for the grid integration of wind power using flexible load approach

    International Nuclear Information System (INIS)

    Heydarian-Forushani, E.; Moghaddam, M.P.; Sheikh-El-Eslami, M.K.; Shafie-khah, M.; Catalão, J.P.S.

    2014-01-01

    Highlights: • This paper focuses on the potential of Demand Response Programs (DRPs) to contribute to flexibility. • A stochastic network constrained unit commitment associated with DR is presented. • DR participation levels and electricity tariffs are evaluated on providing a flexible load profile. • Novel quantitative indices for evaluating flexibility are defined to assess the success of DRPs. • DR types and customer participation levels are the main factors to modify the system load profile. - Abstract: Wind power integration has always been a key research area due to the green future power system target. However, the intermittent nature of wind power may impose some technical and economic challenges to Independent System Operators (ISOs) and increase the need for additional flexibility. Motivated by this need, this paper focuses on the potential of Demand Response Programs (DRPs) as an option to contribute to the flexible operation of power systems. On this basis, in order to consider the uncertain nature of wind power and the reality of electricity market, a Stochastic Network Constrained Unit Commitment associated with DR (SNCUCDR) is presented to schedule both generation units and responsive loads in power systems with high penetration of wind power. Afterwards, the effects of both price-based and incentive-based DRPs are evaluated, as well as DR participation levels and electricity tariffs on providing a flexible load profile and facilitating grid integration of wind power. For this reason, novel quantitative indices for evaluating flexibility are defined to assess the success of DRPs in terms of wind integration. Sensitivity studies indicate that DR types and customer participation levels are the main factors to modify the system load profile to support wind power integration

  13. A Cyber-Based Data-Enabled Virtual Organization for Wind Load Effects on Civil Infrastructures: VORTEX-Winds

    Directory of Open Access Journals (Sweden)

    Ahsan Kareem

    2017-08-01

    Full Text Available Despite many advances in the area of wind effects on structures in recent decades, research has been traditionally conducted within limited resources scattered geographically. With the trend toward increasingly complex designs of civil infrastructure combined with the escalating potential for losses by extreme wind events, a new culture of research needs to be established based on innovative and collaborative solutions for better management of the impact of extreme wind events. To address this change, this paper presents a new paradigm of a multiscale cyber-based laboratory framework for the analysis/design, modeling, and simulation of wind load effects based on an ongoing collaborative cyberinfrastructure-based platform, Virtual Organization for Reducing the Toll of EXtreme Winds (VORTEX-Winds, https://vortex-winds.org, and discusses its current status since its inception in 2007 and ongoing developments. This collaborative framework as it evolves would enable a paradigm shift by offering advanced cyber-enabled modules (e-modules for accelerating advances in research and education to achieve improved understanding and better modeling of wind effects on structures. Accordingly, it will enhance wind community’s analysis and design capabilities to address next-generation challenges posed by wind. Through empowering those without computational or experimental resources, the e-modules will encompass a large set of subject areas and topics categorized as Database-enabled design, Full-scale/Field site data repository, Statistical/Stochastic toolboxes, Tele-experimentation, Uncertainty modeling, Damage assessment, and Computational platforms. This prototype will allow access to the individual e-module, while it is envisaged that next level of development in VORTEX-Winds will have the capability for an automated and integrated analysis/design through a nexus of e-modules. A highlight of the e-modules currently completed or in development is presented

  14. Effects of rotor location, coning, and tilt on critical loads in large wind turbines

    Science.gov (United States)

    Spera, D. A.; Janetzke, D. C.

    1978-01-01

    Several large (1500 kW) horizontal rotor configurations were analyzed to determine the effects on dynamic loads of upwind downwind rotor locations, coned and radial blade positions, and tilted and horizontal rotor axis positions. Loads were calculated for a range of wind velocities at three locations in the structure: (1) the blade shank; (2) the hub shaft; and (3) the yaw drive. Blade axis coning and rotor axis tilt were found to have minor effects on loads. However, locating the rotor upwind of the tower significantly reduced loads at all locations analyzed.

  15. Load Coefficients on Grates used for Wind Turbine Access Platforms

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Rasmussen, Michael R.; Frigaard, Peter

    In this report is presented the results of tests carried out at Dept. of Civil Engineering, Aalborg University (AAU) on behalf of DONG Energy A/S and Vattenfall A/S, Denmark. The objective of the tests was to investigate the load coefficient on different platform grates and a solid plate for desi......In this report is presented the results of tests carried out at Dept. of Civil Engineering, Aalborg University (AAU) on behalf of DONG Energy A/S and Vattenfall A/S, Denmark. The objective of the tests was to investigate the load coefficient on different platform grates and a solid plate...

  16. Impacts of Providing Inertial Response on Dynamic Loads of Wind Turbine Drivetrains: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Girsang, I. P.; Dhupia, J.; Singh, M.; Gevorgian, V.; Muljadi, E.; Jonkman, J.

    2014-09-01

    There has been growing demand from the power industry for wind power plants to support power system operations. One such requirement is for wind turbines to provide ancillary services in the form of inertial response. When the grid frequency drops, it is essential for wind turbine generators (WTGs) to inject kinetic energy stored in their inertia into the grid to help arrest the frequency decline. However, the impacts of inertial response on the structural loads of the wind turbine have not been given much attention. To bridge this gap, this paper utilizes a holistic model for both fixed-speed and variable-speed WTGs by integrating the aeroelastic wind turbine model in FAST, developed by the National Renewable Energy Laboratory, with the electromechanical drivetrain model in SimDriveline and SimPowerSystems.

  17. Small-Signal Stability Analysis of Full-Load Converter Interfaced Wind Turbines

    DEFF Research Database (Denmark)

    Knüppel, Thyge; Akhmatov, Vladislav; Nielsen, Jørgen Nygård

    2009-01-01

    Power system stability investigations of wind farms often cover the tasks of low-voltage-fault-ride-through, voltage and reactive power control, and power balancing, but not much attention has yet been paid to the task of small-signal stability. Small-signal stability analysis needs increasing...... focus since the share of wind power increases substituting power generation from conventional power plants. Here, a study based on modal analysis is presented which investigate the effect of large scale integration of full-load converter interfaced wind turbines on inter-area oscillations in a three...... generator network. A detailed aggregated wind turbine model is employed which includes all necessary control functions. It is shown that the wind urbines have very low participation in the inter-area power oscillation....

  18. Thermal Loading and Lifetime Estimation for Power Device Considering Mission Profiles in Wind Power Converter

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2015-01-01

    As a key component in the wind turbine system, the power electronic converter and its power semiconductors suffer from complicated power loadings related to environment, and are proven to have high failure rates. Therefore, correct lifetime estimation of wind power converter is crucial for the re......As a key component in the wind turbine system, the power electronic converter and its power semiconductors suffer from complicated power loadings related to environment, and are proven to have high failure rates. Therefore, correct lifetime estimation of wind power converter is crucial....... Consequently, a relative more advanced approach is proposed in this paper, which is based on the loading and strength analysis of devices and takes into account different time constants of the thermal behaviors in power converter. With the established methods for loading and lifetime estimation for power...... devices, more detailed information of the lifetime-related performance in wind power converter can be obtained. Some experimental results are also included to validate the thermal behavior of power device under different mission profiles....

  19. Analyzing the Energy Performance, Wind Loading, and Costs of Photovoltaic Slat Modules on Commercial Rooftops

    Energy Technology Data Exchange (ETDEWEB)

    Van Geet, Otto D. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Fu, Ran [National Renewable Energy Lab. (NREL), Golden, CO (United States); Horowitz, Kelsey A. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kurup, Parthiv [National Renewable Energy Lab. (NREL), Golden, CO (United States); MacAlpine, Sara M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Silverman, Timothy J. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2018-02-13

    NREL studied a new type of photovoltaic (PV) module configuration wherein multiple narrow, tilted slats are mounted in a single frame. Each slat of the PV slat module contains a single row of cells and is made using ordinary crystalline silicon PV module materials and processes, including a glass front sheet and weatherproof polymer encapsulation. Compared to a conventional ballasted system, a system using slat modules offer higher energy production and lower weight at lower LCOE. The key benefits of slat modules are reduced wind loading, improved capacity factor and reduced installation cost. First, the individual slats allow air to flow through, which reduce wind loading. Using PV performance modeling software, we compared the performance of an optimized installation of slats modules to a typical installation of conventional modules in a ballasted rack mounting system. Based on the results of the performance modeling two different row tilt and spacing were tested in a wind tunnel. Scaled models of the PV Slat modules were wind tunnel tested to quantify the wind loading of a slat module system on a commercial rooftop, comparing the results to conventional ballasted rack mounted PV modules. Some commercial roofs do not have sufficient reserve dead load capacity to accommodate a ballasted system. A reduced ballast system design could make PV system installation on these roofs feasible for the first time without accepting the disadvantages of penetrating mounts. Finally, technoeconomic analysis was conducted to enable an economic comparison between a conventional commercial rooftop system and a reduced-ballast slat module installation.

  20. Extended onshore control of a floating wind turbine with wave disturbance reduction

    DEFF Research Database (Denmark)

    Christiansen, S.; Knudsen, T.; Bak, Thomas

    2014-01-01

    Reaching for higher wind resources floating wind turbines are being investigated. Wave induced loads significantly increase for floating wind turbines, and applying conventional onshore control strategies to floating wind turbines has been shown to impose negative damped oscillations in fore......-aft due to the low natural frequency of the floating structure. We suggest a control loop extension of the onshore controller which stabilizes the system and reduces the wave disturbance. The result is improved performance in power fluctuations, blade pitch activity, and platform oscillations...

  1. Space Shuttle Damper System for Ground Wind Load Tests

    Science.gov (United States)

    Robinson, G. D.; Holt, J. R.; Chang, C. S.

    1973-01-01

    An active damper system which was originally developed for a 5.5% Saturn IB/Skylab Ground Winds Model was modified and used for similar purposes in a Space Shuttle model. A second damper system which was originally used in a 3% Saturn V/Dry Workshop model was also modified and made compatible with the Space Shuttle model to serve as a back-up system. Included in this final report are descriptions of the modified damper systems and the associated control and instrumentation.

  2. Analysis of Oscillations in a Cableway: Wind Load Effects

    Directory of Open Access Journals (Sweden)

    Jan Gustincic

    2013-06-01

    Full Text Available The purpose of this paper is to develop and investigate a non-linear model for analysing the reaction of a self-detachable cabin monocable ropeway exposed to a sudden deceleration and wind forces. The First and Second Newton's Law and Differential Equations are the basic tools for building the model. Furthermore a few basic considerations have been made about the air “dragging and lifting" forces that induce oscillations and vibrations in mechanical systems alike. All the numerical data used for the simulation was taken from a ropeway in the skiing site of Ravascletto-Zoncolan in the North- East of Italy.

  3. Spatial reliability analysis of a wind turbine blade cross section subjected to multi-axial extreme loading

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov; Bitsche, Robert; Blasques, José Pedro Albergaria Amaral

    2017-01-01

    This paper presents a methodology for structural reliability analysis of wind turbine blades. The study introduces several novel elements by taking into account loading direction using a multiaxial probabilistic load model, considering random material strength, spatial correlation between materia...

  4. Loads on Entrance Platforms for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Frigaard, Peter; Andersen, Thomas Lykke; Ramirez, Jorge Robert Rodriguez

    2010-01-01

    The present paper gives an overview of the performed large scale tests in GWK, Hannover for studying wave run-up generated forces on wind turbine entrance platforms. The run-up height and velocity was measured by use of high speed video recordings supplemented by some wave gauges mounted at the p......The present paper gives an overview of the performed large scale tests in GWK, Hannover for studying wave run-up generated forces on wind turbine entrance platforms. The run-up height and velocity was measured by use of high speed video recordings supplemented by some wave gauges mounted...... at the pile. Hereafter, the run-up generated impact forces were measured on two types of grates and a solid plate. The pressure distribution was also measured for the solid plate. In addition to this the wave generated backfilling of an initial scour hole and the strength of the backfilling soil was studied....... The purpose of all the tests was to study scale effects related to the above items by comparison with small scale tests and also to present new guidelines for design....

  5. Investigation of potential extreme load reduction for a two-bladed upwind turbine with partial pitch

    DEFF Research Database (Denmark)

    Kim, Taeseong; Larsen, Torben J.; Yde, Anders

    2015-01-01

    This paper presents a wind turbine concept with an innovative design combining partial pitch with a two-bladed (PP-2B) turbine configuration. Special emphasis is on extreme load reduction during storm situations at standstill, but operational loads are also investigated. In order to compare...... the loads and dynamics of the PP-2B turbine, a partial pitch three-bladed (PP-3B) turbine and a normal pitch regulated three-bladed (3B) turbine are introduced on the basis of solidity similarity scaling. From the dynamic comparisons between two- and three-bladed turbines, it has been observed...... that the blade vibrations are transferred differently from the rotor to the tower. For a three-bladed turbine, blade vibrations seen in a fixed frame of reference are split with ±1P only. A two-bladed turbine has a similar split of ±1P but also includes contributions on higher harmonics (±2P, ±3P, … etc...

  6. Extreme Design Loads Calibration of Offshore Wind Turbine Blades through Real Time Measurements

    DEFF Research Database (Denmark)

    Natarajan, Anand; Vesth, Allan; Lamata, Rebeca Rivera

    2014-01-01

    moment is extrapolated. This is found to possess smaller scaling factors in measurements over six months as compared to both the flap and edge moments, indicating that the contemporaneous load component of an extrapolated load should possess much smaller magnitude than its maxima.......Blade Root flap and Edge moments are measured on the blades of a 3.6MW offshore wind turbine in normal operation. Ten minute maxima of the measurements are sampled to determine the extreme blade root flap moment, edge moment and resultant moment over six month duration. A random subset...... root flap moment, edge moment obtained by extrapolation. The validation yields valuable information on prescribing the slope of the local extrapolation curve at each mean wind speed. As an alternative to determining the contemporaneous loads for each primary extrapolated load, the blade root resultant...

  7. Comparison of Second-Order Loads on a Tension-Leg Platform for Wind Turbines: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Gueydon, S.; Wuillaume, P.; Jonkman, J.; Robertson, A.; Platt, A.

    2015-03-01

    The first objective of this work is to compare the two floating offshore wind turbine simulation packages {DIFFRAC+aNySIM} and {WAMIT+FAST}. The focus is on second-order wave loads, and so first- and second-order wave loads are applied to a structure sequentially for a detailed comparison and a more precise analysis of the effects of the second-order loads. aNySIM does not have the capability to model flexible bodies, and so the simulations performed in this tool are done assuming a rigid body. FAST also assumes that the platform is rigid, but can account for the flexibility of the tower. The second objective is to study the effects of the second-order loads on the response of a TLP floating wind turbine. The flexibility of the tower must be considered for this investigation, and therefore only FAST is used.

  8. Some aspects on wind turbines monitoring. General considerations and loads on horizontal wind turbines

    International Nuclear Information System (INIS)

    Cuerva, A.

    1996-01-01

    The concept Monitoring applied to the Wind Energy technology is similar to the definition used in other branches of Science or Engineering, this is knowing values of variables which have to do with a mechanic system, in our case a wind turbine. These mentioned parameters may have different relationships to our wind turbine; some of them come from the environment the machine is operating in, others, are a measure of how properly the machine is working, and finally, the rest are an assessment of the systems health during its life. In this chapter we will answer questions such as: What do we need to measure? Why is Monitoring mandatory (from the different points of view of people involved in this world)? How can we measure a wind turbine depending on our objectives (Technic, tools, guidance, recommendations, etc.)? And finally What can we expect in the near future? The author wants the reader to keep the idea in mind that Monitoring means the richest and most accurate knowledge on wind turbine's operation (Its environment, performances or health). This is the first step that allows us to optimize the operation mode of the machine and improve it (design, manufacturing, even the used modeling tools). When there is so much money involved, this fact becomes a must. (Author)

  9. Some aspects on wind turbines monitoring. General considerations and loads on horizontal wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Cuerva, A.

    1996-12-01

    The concept Monitoring applied to the Wind Energy technology is similar to the definition used in other branches of Science or Engineering, this is knowing values of variables which have to do with a mechanic system, in our case a wind turbine. These mentioned parameters may have different relationships to our wind turbine; some of them come from the environment the machine is operating in, others, are a measure of how properly the machine is working, and finally, the rest are an assessment of the ``system`s health`` during its ``life``. In this chapter we will answer questions such as: What do we need to measure? Why is Monitoring mandatory (from the different points of view of people involved in this world)? How can we measure a wind turbine depending on our objectives (Technic, tools, guidance, recommendations, etc)? And finally What can we expect in the near future?. The author wants the reader to keep the idea in mind that Monitoring means the richest and most accurate knowledge on wind turbine`s operation (Its environment, performances of health). This is the first step that allows us to optimize the operation mode of the machine and improve it (design, manufacturing, even the used modeling tools). When there is so much money involved, this fact becomes a must. (Author)

  10. South African wind loading specifications: the Euro way?

    CSIR Research Space (South Africa)

    Goliger, Adam M

    2007-10-01

    Full Text Available at the time, was undertaken towards the end of 1999 (Goliger, 2000). The code was assessed as being comprehensive, inclusive and detailed. However, at that stage the document was clearly unfinished and contained several discrepancies, inconsistencies... limit state and working stress ), as well as the principle of an average return period of 1000 years. t prepara iminary analysis of the Australian code revea An initial set of comparative calculations indicated the loads stipulated according...

  11. Estimation of the Unsteady Aerodynamic Load on Space Shuttle External Tank Protuberances from a Component Wind Tunnel Test

    Science.gov (United States)

    Panda, Jayatana; Martin, Fred W.; Sutliff, Daniel L.

    2008-01-01

    At the wake of the Columbia (STS-107) accident it was decided to remove the Protuberance Aerodynamic Load (PAL) Ramp that was originally intended to protect various protuberances outside of the Space Shuttle External Tank from high buffet load induced by cross-flows at transonic speed. In order to establish the buffet load without the PAL ramp, a wind tunnel test was conducted where segments of the protuberances were instrumented with dynamic pressure transducers; and power-spectra of sectional lift and drag forces at various span-wise locations between two adjacent support brackets were measured under different cross flow angles, Mach number and other conditions. Additionally, frequency-dependent spatial correlations between the sectional forces were also established. The sectional forces were then adjusted by the correlation length to establish span-averaged spectra of normal and lateral forces that can be suitably "added" to various other unsteady forces encountered by the protuberance. This paper describes the methodology used for calculating the correlation-adjusted power spectrum of the buffet load. A second part of the paper describes wind-tunnel results on the difference in the buffet load on the protuberances with and without the PAL ramp. In general when the ramp height is the same as that of the protuberance height, such as that found on the liquid Oxygen part of the tank, the ramp is found to cause significant reduction of the unsteady aerodynamic load. However, on the liquid Hydrogen part of the tank, where the Oxygen feed-line is far larger in diameter than the height of the PAL ramp, little protection is found to be available to all but the Cable Tray.

  12. Planetary Load Sharing in Three-Point Mounted Wind Turbine Gearboxes: A Design and Test Comparison

    Energy Technology Data Exchange (ETDEWEB)

    Keller, Jonathan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Guo, Yi [National Renewable Energy Lab. (NREL), Golden, CO (United States); Zhang, Zhiwei [Romax InSight, Nottingham, (United Kingdom); Lucas, Doug [The Timken Company, Jackson Township, OH (United States)

    2017-04-06

    This work compares the planetary load-sharing characteristics of wind turbine gearboxes supported by cylindrical roller bearings (CRBs) and preloaded tapered roller bearings (TRBs) when subjected to rotor moments. Planetary bearing loads were measured in field-representative dynamometer tests and compared to loads predicted by finite-element models. Preloaded TRBs significantly improved load sharing. In pure torque conditions, the upwind planet bearing load in the gearbox with preloaded TRBs was only 14% more than the assumed load compared to 47% more for the gearbox with CRBs. Consequently, the predicted fatigue life of the complete set of planetary bearings for the gearbox with preloaded TRBs is 3.5 times greater than that of the gearbox with CRBs.

  13. Predicting extreme loads effects on wind turbines considering uncertainty in airfoil data

    DEFF Research Database (Denmark)

    Abdallah, Imad; Natarajan, Anand; Sørensen, John Dalsgaard

    2013-01-01

    The sources contributing to uncertainty in a wind turbine blade static airfoil data include wind tunnel testing, CFD calculations, 3D rotational corrections based on CFD or empirical models, surface roughness corrections, Reynolds number corrections, expansion to the full 360-degree angle of atta...... that the uncertainty in airfoil data can have a significant impact on the prediction of extreme loads effects depending on the component, and the correlation along the span of the blade.......The sources contributing to uncertainty in a wind turbine blade static airfoil data include wind tunnel testing, CFD calculations, 3D rotational corrections based on CFD or empirical models, surface roughness corrections, Reynolds number corrections, expansion to the full 360-degree angle of attack...... range, validation by full scale measurements, and geometric distortions of the blade during manufacturing and under loading. In this paper a stochastic model of the static airfoil data is proposed to supplement the prediction of extreme loads effects for large wind turbines. It is shown...

  14. Correlated wind-power production and electric load scenarios for investment decisions

    International Nuclear Information System (INIS)

    Baringo, L.; Conejo, A.J.

    2013-01-01

    Highlights: ► Investment models require an accurate representation of the involved uncertainty. ► Demand and wind power production are correlated and uncertain parameters. ► Two methodologies are provided to represent uncertainty and correlation. ► An accurate uncertainty representation is crucial to get optimal results. -- Abstract: Stochastic programming constitutes a useful tool to address investment problems. This technique represents uncertain input data using a set of scenarios, which should accurately describe the involved uncertainty. In this paper, we propose two alternative methodologies to efficiently generate electric load and wind-power production scenarios, which are used as input data for investment problems. The two proposed methodologies are based on the load- and wind-duration curves and on the K-means clustering technique, and allow representing the uncertainty of and the correlation between electric load and wind-power production. A case study pertaining to wind-power investment is used to show the interest of the proposed methodologies and to illustrate how the selection of scenarios has a significant impact on investment decisions.

  15. Including load sequence effects in the fatigue damage estimation of an offshore wind turbine substructure

    NARCIS (Netherlands)

    Dragt, R.C.; Maljaars, J.; Tuitman, J.T.; Salman, Y.; Otheguy, M.E.

    2016-01-01

    Retardation is a load sequence effect, which causes a reduced fatigue crack growth rate after an overload is encountered. Retardation can be cancelled when the overload is followed by an underload. The net effect is beneficial to the fatigue lifetime of Offshore Wind Turbines (OWTs). To be able to

  16. Device loading of modular multilevel converter MMC in wind power application

    DEFF Research Database (Denmark)

    Popova, L.; Pyrhönen, J.; Ma, Ke

    2014-01-01

    . The converters used to connect the wind turbine to the grid having the rated active powers of 2MW and 10MW are designed and investigated. Electrical losses and thermal loading of the power devices in the proposed converter solutions are analyzed. The efficiency of the MMC converter under different P/Q boundaries...

  17. Inflow characteristics associated with high-blade-loading events in a wind farm

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, N.D.

    1993-07-01

    The stochastic characteristics of the turbulent inflow have been shown to be of major significance in the accumulation of fatigue in wind turbines. Because most of the wind turbine installations in the US have taken place in multi-turbine or wind farm configurations, the fatigue damage associated with the higher turbulence levels within such arrangements must be taken into account when making estimates of component service lifetimes. The simultaneous monitoring of two adjacent wind turbines over a wide range of turbulent inflow conditions has given the authors more confidence in describing the structural load distributions that can be expected in such an environment. The adjacent testing of the two turbines allowed the authors to postulate that observed similarities in the response dynamics and load distributions could be considered quasi-universal, while the dissimilarities could be considered to result from the differing design of the rotors. The format has also allowed them to begin to define appropriate statistical load distribution models for many of the critical components in which fatigue is a major driver of the design. In addition to the adjacent turbine measurements, they also briefly discuss load distributions measured on a teetered-hub turbine.

  18. Wind loads on stand-off photovoltaic systems on pitched roofs

    NARCIS (Netherlands)

    Geurts, C.P.W.; Blackmore, P.

    2013-01-01

    Stand-off photovoltaic systems are a popular measure for retrofitting of existing pitched roofs.Panels are generally mounted parallel to the existing roof coverings,usually roofing tiles.Full scale and wind tunnel experiments have been performed to determine the net uplift loads on these systems,

  19. Analysis of wind driven self-excited induction generator supplying isolated DC loads

    Directory of Open Access Journals (Sweden)

    Khaled S. Sakkoury

    2017-05-01

    Full Text Available This paper presents the analysis, modelling and simulation of wind-driven self-excited induction generator (SEIG. The three-phase SEIG is driven by a variable-speed prime mover to represent a wind turbine. Also, the paper investigates the dynamic performance of the SEIG during start-up, increasing or decreasing the load or rotor speed. The value of the excitation capacitance required for the SEIG is calculated to give suitable saturation level to assure self-excitation and to avoid heavy saturation levels. Matching of the maximum power available from the wind turbine is performed through varying the load value. The effect of AC–DC power conversion on the generator is investigated. The system simulation is carried out using MATLAB/SIMULINK toolbox program.

  20. Impact of fault ride-through requirements on fixed-speed wind turbine structural loads

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Cutululis, Nicolaos Antonio; Markou, Helen

    2011-01-01

    simulation tools, which have expertise in different specialized wind turbines design areas. Two complimentary simulation tools are considered i.e. the detailed power system simulation tool PowerFactory from DIgSILENT and the advanced aeroelastic computer code HAWC2, in order to assess of the dynamic response...... by performing a rainflow and a statistical analysis for fatigue and ultimate structural loads, respectively. Two cases are compared i.e. one where the turbine is immediately disconnected from the grid when a grid fault occurs and one where the turbine is equipped with a fault ride-through controller...... faults. This article proposes a computer approach for the quantification of the wind turbines structural loads caused by the fault ride-through grid requirements. This approach, exemplified for the case of a 2MW active stall wind turbine, relies on the combination of knowledge from complimentary...

  1. Full load estimation of an offshore wind turbine based on SCADA and accelerometer data

    Science.gov (United States)

    Noppe, N.; Iliopoulos, A.; Weijtjens, W.; Devriendt, C.

    2016-09-01

    As offshore wind farms (OWFs) grow older, the optimal use of the actual fatigue lifetime of an offshore wind turbine (OWT) and predominantly its foundation will get more important. In case of OWTs, both quasi-static wind/thrust loads and dynamic loads, as induced by turbulence, waves and the turbine's dynamics, contribute to its fatigue life progression. To estimate the remaining useful life of an OWT, the stresses acting on the fatigue critical locations within the structure should be monitored continuously. Unfortunately, in case of the most common monopile foundations these locations are often situated below sea-level and near the mud line and thus difficult or even impossible to access for existing OWTs. Actual strain measurements taken at accessible locations above the sea level show a correlation between thrust load and several SCADA parameters. Therefore a model is created to estimate the thrust load using SCADA data and strain measurements. Afterwards the thrust load acting on the OWT is estimated using the created model and SCADA data only. From this model the quasi static loads on the foundation can be estimated over the lifetime of the OWT. To estimate the contribution of the dynamic loads a modal decomposition and expansion based virtual sensing technique is applied. This method only uses acceleration measurements recorded at accessible locations on the tower. Superimposing both contributions leads to a so-called multi-band virtual sensing. The result is a method that allows to estimate the strain history at any location on the foundation and thus the full load, being a combination of both quasi-static and dynamic loads, acting on the entire structure. This approach is validated using data from an operating Belgian OWF. An initial good match between measured and predicted strains for a short period of time proofs the concept.

  2. Full scale investigation of the wind loads on a light-weight building-integrated photovoltaic system

    NARCIS (Netherlands)

    Geurts, C.P.W.; Bronkhorst, A.J.; Bentum, C.A. van

    2017-01-01

    The wind loads on solar energy systems are crucial for the engineering of the panels, substructure and fixings. There is a demand for aesthetically more acceptable solutions such as frameless solar systems. For these frameless systems, the wind loads are carried by the panels themselves. Combined

  3. An index guiding temporal planting policies for wind erosion reduction

    NARCIS (Netherlands)

    Zhao, C.X.; Zheng, D.W.; Stigter, C.J.; He, W.Q.; Tuo, D.B.; Zhao, P.

    2006-01-01

    Vegetation cover has spatial as well as temporal characteristics, but the latter are often neglected. Temporal cover characteristics were explored to recommend planting policies for returning arable land into land better protected from serious wind erosion during late autumn, winter, and

  4. Validated Loads Prediction Models for Offshore Wind Turbines for Enhanced Component Reliability

    DEFF Research Database (Denmark)

    Koukoura, Christina

    are used for the modification of the sub-structure/foundation design for possible material savings. First, the background of offshore wind engineering, including wind-wave conditions, support structure, blade loading and wind turbine dynamics are presented. Second, a detailed description of the site...... is given and the metocean conditions are analyzed. The joint wind-wave distribution and the probability of the misalignment angles are estimated. Third, the calibration process of the different components is thoroughly depicted. The turbulence intensity implemented in the simulations is extracted from...... response of a boat impact. The first and second modal damping of the system during normal operation both from measurements and simulations are identified with the implementation of the Enhanced Frequency Domain Decomposition technique. The effect of damping on the side-side fatigue of the support structure...

  5. Investigation of the dependency of wind turbine loads on the simulation time

    DEFF Research Database (Denmark)

    Tibaldi, Carlo; Henriksen, Lars Christian; Bak, Christian

    2014-01-01

    In this work the dependency of several wind turbine parameters with respect to the length of simulations used for their evaluation is investigated. The analysis is performed by computing the parameters with a different number of turbulent wind simulations, therefore simulation time, and repeating...... the computation with different turbulence realizations. The repetition of the computation is performed to identify the scatter of the parameters for a given number of turbulent seeds due to the different turbulence realization. The dependency on the simulation time of load variations due to changes...... in the collective pitch controller tuning is also investigated. Results show a significantly high dependency of the parameters and their variations on the turbulent wind realization. This dependency makes the use of turbulent wind simulation results not reliable for numerical optimization purposes....

  6. Simulation of Mechanical Behavior and Damage of a Large Composite Wind Turbine Blade under Critical Loads

    Science.gov (United States)

    Tarfaoui, M.; Nachtane, M.; Khadimallah, H.; Saifaoui, D.

    2018-04-01

    Issues such as energy generation/transmission and greenhouse gas emissions are the two energy problems we face today. In this context, renewable energy sources are a necessary part of the solution essentially winds power, which is one of the most profitable sources of competition with new fossil energy facilities. This paper present the simulation of mechanical behavior and damage of a 48 m composite wind turbine blade under critical wind loads. The finite element analysis was performed by using ABAQUS code to predict the most critical damage behavior and to apprehend and obtain knowledge of the complex structural behavior of wind turbine blades. The approach developed based on the nonlinear FE analysis using mean values for the material properties and the failure criteria of Tsai-Hill to predict failure modes in large structures and to identify the sensitive zones.

  7. Evaluating the risk-reduction benefits of wind energy

    Energy Technology Data Exchange (ETDEWEB)

    Brower, M.C.; Bell, K.; Spinney, P. [and others

    1997-05-01

    The question of uncertainty and risk in electric utility resource planning has received considerable attention in recent years. During the 1980s, many utilities suffered financial losses because of unexpectedly high plant construction costs and low growth in electricity demand. In addition, the introduction of competition to the electric industry is creating new risks for power companies. No longer will utilities be able to count on regulatory protections and a base of captive consumers to provide a stable market and adequate return on their investments. Alternative risk management strategies will have to be considered instead. One approach to managing risk is for a utility company to invest in diverse power sources such as wind power plants. Since wind plants consume no fuel, can be built in relatively small increments with short construction lead times, and generate no pollutants, it is often said that they offer significant protection from risks associated with conventional fossil-fuel power plants. So far there have been few efforts to quantify these benefits, however. The study compares the costs and risks of two competing resource options, a gas-fired combined cycle plant and a wind plant, both utility-owned, through decision analysis. The case study utility is Texas Utilities Electric, a very large investor-owned company serving an area with substantial, high-quality wind resources. The authors chose a specific moment in the future - the year 2003 - when the utility currently plans to build a large fossil-fueled power plant, and examined the implications for the utility`s expected revenues, costs, and profits if a wind plant were to be built instead.

  8. Validation of the dynamic wake meander model for loads and power production in the Egmond aan Zee wind farm

    DEFF Research Database (Denmark)

    Larsen, Torben J.; Aagaard Madsen, Helge; Larsen, Gunner Chr.

    2013-01-01

    is excellent regarding power production in both free and wake sector, and a very good agreement is seen for the load comparisons too. This enables the conclusion that wake meandering, caused by large scale ambient turbulence, is indeed an important contribution to wake loading in wind farms. Copyright © 2012......This paper investigates wake effects on load and power production by using the dynamic wake meander (DWM) model implemented in the aeroelastic code HAWC2. The instationary wind farm flow characteristics are modeled by treating the wind turbine wakes as passive tracers transported downstream using...... a meandering process driven by the low frequent cross-wind turbulence components. The model complex is validated by comparing simulated and measured loads for the Dutch Egmond aan Zee wind farm consisting of 36 Vestas V90 turbine located outside the coast of the Netherlands. Loads and production are compared...

  9. Scaling Issues in the Determination of Wind loads on Lattice Masts

    DEFF Research Database (Denmark)

    Koss, Holger; Srouji, Robin G.

    2015-01-01

    The paper presents a study conducted to investigate the influence of geometric scale and flow condition on the wind load coefficients for lattice masts structures. An initial study in 2008 on a full size mast section indicated a possible contingency, which could be used to add equipment...... reflecting model scale behavior than full scale aerodynamics. This reveals the main challenge if for reasons of economic production and operation of telecommunication towers and masts a more accurate wind load description is required: full size testing....... on telecommunication towers without further structural strengthening. This study focuses on the role of scaling. A 1:6 scaled mast model was tested in two different flow conditions and in three layout variations. It was found that scaling does play a large role and that some of the codified loads are in fact more...

  10. Artificial bee colony algorithm for economic load dispatch with wind power energy

    Directory of Open Access Journals (Sweden)

    Safari Amin

    2016-01-01

    Full Text Available This paper presents an efficient Artificial Bee Colony (ABC algorithm for solving large scale economic load dispatch (ELD problems in power networks. To realize the ELD, the valve-point loading effect, system load demand, power losses, ramp rate limits and prohibited operation zones are considered here. Simulations were performed on four different power systems with 3, 6, 15 and 40 generating units and the results are compared with two forms of power systems, one power system is with a wind power generator and other power system is without a wind power generator. The results of this study reveal that the proposed approach is able to find appreciable ELD solutions than those of previous algorithms.

  11. Performance and load data from Mod-0A and Mod-1 wind turbine generators

    Science.gov (United States)

    Spera, D. A.; Janetzke, D. C.

    1982-01-01

    Experimental data, together with supporting analysis, are presented on the power conversion performance and blade loading of large, horizontal-axis wind turbines tested at electric utility sites in the U.S. Four turbine rotor configurations, from 28 to 61 meters in diameter, and data from five test sites are included. Performance data are presented in the form of graphs of power and system efficiency versus free-stream wind speed. Deviations from theoretical performance are analyzed statistically. Power conversion efficiency averaged 0.34 for all tests combined, compared with 0.31 predicted. Round blade tips appeared to improve performance significantly. Cyclic blade loads were normalized to develop load factors which can be used in the design of rotors with rigid hubs.

  12. Linear parameter varying control of wind turbines covering both partial load and full load conditions

    DEFF Research Database (Denmark)

    Østergaard, Kasper Zinck; Stoustrup, Jakob; Brath, Per

    2009-01-01

    This paper considers the design of linear parameter varying (LPV) controllers for wind turbines in order to obtain a multivariable control law that covers the entire nominal operating trajectory.The paper first presents a controller structure for selecting a proper operating trajectory as a funct......This paper considers the design of linear parameter varying (LPV) controllers for wind turbines in order to obtain a multivariable control law that covers the entire nominal operating trajectory.The paper first presents a controller structure for selecting a proper operating trajectory...... as a function of estimated wind speed. The dynamic control law is based on LPV controller synthesis with general parameter dependency by gridding the parameter space.The controller construction can, for medium- to large-scale systems, be difficult from a numerical point of view, because the involved matrix...... operations tend to be ill-conditioned. The paper proposes a controller construction algorithm together with various remedies for improving the numerical conditioning the algorithm.The proposed algorithm is applied to the design of a LPV controller for wind turbines, and a comparison is made with a controller...

  13. Short-Term Forecasting of Loads and Wind Power for Latvian Power System: Accuracy and Capacity of the Developed Tools

    Directory of Open Access Journals (Sweden)

    Radziukynas V.

    2016-04-01

    Full Text Available The paper analyses the performance results of the recently developed short-term forecasting suit for the Latvian power system. The system load and wind power are forecasted using ANN and ARIMA models, respectively, and the forecasting accuracy is evaluated in terms of errors, mean absolute errors and mean absolute percentage errors. The investigation of influence of additional input variables on load forecasting errors is performed. The interplay of hourly loads and wind power forecasting errors is also evaluated for the Latvian power system with historical loads (the year 2011 and planned wind power capacities (the year 2023.

  14. Planetary Load Sharing in Three-Point-Mounted Wind Turbine Gearboxes: A Design and Test Comparison

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yi; Keller, Jonathan; Zhang, Zhiwei; Lucas, Doug

    2017-03-08

    The planetary load sharing characteristics of wind turbine gearboxes supported by cylindrical roller bearings (CRBs) and preloaded tapered roller bearings (TRBs) when subjected to rotor moments are compared in this work. Planetary bearing loads were measured in field-representative dynamometer tests and compared to loads predicted by finite-element models. Load sharing was significantly improved with preloaded TRBs. In pure torque conditions, the upwind planet bearing loads in the gearbox with preloaded TRBs were a maximum of 1.14 compared to 1.47 in the gearbox with CRBs. Consequently, the predicted fatigue life of the complete set of planetary bearings for the gearbox with preloaded TRBs is 3.5 times greater than that of the gearbox with CRBs.

  15. Detailed Load Analysis of the baseline 5MW DeepWind Concept

    DEFF Research Database (Denmark)

    Verelst, David Robert; Aagaard Madsen, Helge; Kragh, Knud Abildgaard

    that is reported here will be called version 2.2.0. The numbering system has just been introduced at the present design version, but the rst 5MW design called the "baseline design" [1] was developed in 2011 and this will therefore be called version 1.0.0. In this report, the design loads of the DeepWind 5 MW...... turbine are presented. The loads are calculated using Hawc2 (ver 11.8). The turbine controller is implemented according to principles outlined in work package 4 (Turbine operational control), only the normal production part of the controller is implemented. Hence, the calculated design loads only covers...... normal operations. In the Chapter 3 and 2 the modelled design is and simulation scenarios are introduced. In Chapter 5 the estimated loads are presented in the form of plots. In Appendix A the simulated loads are tabulated, and the input data for the numerical HAWC2 model is given in Appendix B....

  16. Determination of brace forces caused by construction loads and wind loads during bridge construction.

    Science.gov (United States)

    2014-04-01

    The first objective of this study was to develop procedures for determining bracing forces during bridge construction. : Numerical finite element models and analysis techniques were developed for evaluating brace forces induced by construction loads ...

  17. Short-term load and wind power forecasting using neural network-based prediction intervals.

    Science.gov (United States)

    Quan, Hao; Srinivasan, Dipti; Khosravi, Abbas

    2014-02-01

    Electrical power systems are evolving from today's centralized bulk systems to more decentralized systems. Penetrations of renewable energies, such as wind and solar power, significantly increase the level of uncertainty in power systems. Accurate load forecasting becomes more complex, yet more important for management of power systems. Traditional methods for generating point forecasts of load demands cannot properly handle uncertainties in system operations. To quantify potential uncertainties associated with forecasts, this paper implements a neural network (NN)-based method for the construction of prediction intervals (PIs). A newly introduced method, called lower upper bound estimation (LUBE), is applied and extended to develop PIs using NN models. A new problem formulation is proposed, which translates the primary multiobjective problem into a constrained single-objective problem. Compared with the cost function, this new formulation is closer to the primary problem and has fewer parameters. Particle swarm optimization (PSO) integrated with the mutation operator is used to solve the problem. Electrical demands from Singapore and New South Wales (Australia), as well as wind power generation from Capital Wind Farm, are used to validate the PSO-based LUBE method. Comparative results show that the proposed method can construct higher quality PIs for load and wind power generation forecasts in a short time.

  18. Analysis of Damage in Laminated Architectural Glazing Subjected to Wind Loading and Windborne Debris Impact

    Directory of Open Access Journals (Sweden)

    Daniel S. Stutts

    2013-05-01

    Full Text Available Wind loading and windborne debris (missile impact are the two primary mechanisms that result in window glazing damage during hurricanes. Wind-borne debris is categorized into two types: small hard missiles; such as roof gravel; and large soft missiles representing lumber from wood-framed buildings. Laminated architectural glazing (LAG may be used in buildings where impact resistance is needed. The glass plies in LAG undergo internal damage before total failure. The bulk of the published work on this topic either deals with the stress and dynamic analyses of undamaged LAG or the total failure of LAG. The pre-failure damage response of LAG due to the combination of wind loading and windborne debris impact is studied. A continuum damage mechanics (CDM based constitutive model is developed and implemented via an axisymmetric finite element code to study the failure and damage behavior of laminated architectural glazing subjected to combined loading of wind and windborne debris impact. The effect of geometric and material properties on the damage pattern is studied parametrically.

  19. Wind Turbine Pitch Control and Load Mitigation Using an L1 Adaptive Approach

    Directory of Open Access Journals (Sweden)

    Danyong Li

    2014-01-01

    Full Text Available We present an application of L1 adaptive output feedback control design to wind turbine collective pitch control and load mitigation. Our main objective is the design of an L1 output feedback controller without wind speed estimation, ensuring that the generator speed tracks the reference trajectory with robustness to uncertain parameters and time-varying disturbances (mainly the uniform wind disturbance across the wind turbine rotor. The wind turbine model CART (controls advanced research turbine developed by the national renewable energy laboratory (NREL is used to validate the performance of the proposed L1 adaptive controller using the FAST (fatigue, aerodynamics, structures, and turbulence code. A comparative study is also conducted between the proposed controller and the most popular methods in practice: gain scheduling PI (GSPI controls and disturbance accommodating control (DAC methods. The results show better performance of L1 output feedback controller over the other two methods. Moreover, based on the FAST software and LQR analysis in the reference model selection of L1 adaptive controller, tradeoff can be achieved between control performance and loads mitigation.

  20. Wind-induced transmission tower foundation loads. A field study-design code comparison

    Energy Technology Data Exchange (ETDEWEB)

    Savory, E. [Department of Mechanical and Materials Engineering, University of Western Ontario, London, Ont. (Canada); Parke, G.A.R.; Disney, P.; Toy, N. [School of Engineering, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

    2008-06-15

    This paper presents a comparison between the wind-induced foundation loads measured on a type L6 transmission line tower during a field study in the UK and those computed using the UK Code of Practice for lattice tower and transmission line design (BS8100). In this work, the Code provisions have been generalised to give the wind-induced strain in each of the tower legs immediately above the foundation as a function of wind direction and wind speed at the top of the tower. The complete data set from the field monitoring has been decomposed to provide a similar formulation for comparison purposes. The analysis shows excellent agreement between the Code calculations and the measured results, within the overall accuracy of the field data. This indicates that, at least for the tower type examined here, the existing design Code provides a reliable transformation of the local wind speed at the top of the tower into tension and compression loads on the foundations. (author)

  1. Calculation of design load for the MOD-5A 7.3 mW wind turbine system

    Science.gov (United States)

    Mirandy, L.; Strain, J. C.

    1995-01-01

    Design loads are presented for the General Electric MOD-SA wind turbine. The MOD-SA system consists of a 400 ft. diameter, upwind, two-bladed, teetered rotor connected to a 7.3 mW variable-speed generator. Fatigue loads are specified in the form of histograms for the 30 year life of the machine, while limit (or maximum) loads have been derived from transient dynamic analysis at critical operating conditions. Loads prediction was accomplished using state of the art aeroelastic analyses developed at General Electric. Features of the primary predictive tool - the Transient Rotor Analysis Code (TRAC) are described in the paper. Key to the load predictions are the following wind models: (1) yearly mean wind distribution; (2) mean wind variations during operation; (3) number of start/shutdown cycles; (4) spatially large gusts; and (5) spatially small gusts (local turbulence). The methods used to develop statistical distributions from load calculations represent an extension of procedures used in past wind programs and are believed to be a significant contribution to Wind Turbine Generator analysis. Test/theory correlations are presented to demonstrate code load predictive capability and to support the wind models used in the analysis. In addition MOD-5A loads are compared with those of existing machines. The MOD-5A design was performed by the General Electric Company, Advanced Energy Program Department, under Contract DEN3-153 with NASA Lewis Research Center and sponsored by the Department of Energy.

  2. Alternative wind power modeling methods using chronological and load duration curve production cost models

    Energy Technology Data Exchange (ETDEWEB)

    Milligan, M R

    1996-04-01

    As an intermittent resource, capturing the temporal variation in windpower is an important issue in the context of utility production cost modeling. Many of the production cost models use a method that creates a cumulative probability distribution that is outside the time domain. The purpose of this report is to examine two production cost models that represent the two major model types: chronological and load duration cure models. This report is part of the ongoing research undertaken by the Wind Technology Division of the National Renewable Energy Laboratory in utility modeling and wind system integration.

  3. Short-term fatigue analysis for tower base of a spar-type wind turbine under stochastic wind-wave loads

    Directory of Open Access Journals (Sweden)

    Haoran Li

    2018-01-01

    Full Text Available Due to integrated stochastic wind and wave loads, the supporting platform of a Floating Offshore Wind Turbine (FOWT has to bear six Degrees of Freedom (DOF motion, which makes the random cyclic loads acting on the structural components, for instance the tower base, more complicated than those on bottom-fixed or land-based wind turbines. These cyclic loads may cause unexpected fatigue damages on a FOWT. This paper presents a study on short-term fatigue damage at the tower base of a 5 MW FOWT with a spar-type platform. Fully coupled time-domain simulations code FAST is used and realistic environment conditions are considered to obtain the loads and structural stresses at the tower base. Then the cumulative fatigue damage is calculated based on rainflow counting method and Miner's rule. Moreover, the effects of the simulation length, the wind-wave misalignment, the wind-only condition and the wave-only condition on the fatigue damage are investigated. It is found that the wind and wave induced loads affect the tower base's axial stress separately and in a decoupled way, and the wave-induced fatigue damage is greater than that induced by the wind loads. Under the environment conditions with rated wind speed, the tower base experiences the highest fatigue damage when the joint probability of the wind and wave is included in the calculation. Moreover, it is also found that 1 h simulation length is sufficient to give an appropriate fatigue damage estimated life for FOWT.

  4. How Expensive Is Expensive Enough? Opportunities for Cost Reductions in Offshore Wind Energy Logistics

    DEFF Research Database (Denmark)

    Poulsen, Thomas; Hasager, Charlotte Bay

    2016-01-01

    to, and produced, a number of possible opportunities for offshore wind cost reductions through logistics innovation; however, within the case study company, no company-wide logistics organization existed to focus horizontally on reducing logistics costs in general. Logistics was not well defined......This paper reveals that logistics may conservatively amount to 18% of the levelized cost of energy for offshore wind farms. This is the key finding from an extensive case study carried out within the organization of the world’s leading offshore wind farm developer and operator. The case study aimed...... within the case study company, and a logistics strategy did not exist. With full life-cycle costs of offshore wind farms still high enough to present a political challenge within the European Union in terms of legislation to ensure offshore wind diffusion beyond 2020, our research presents logistics...

  5. Should we build wind farms close to load or invest in transmission to access better wind resources in remote areas? A case study in the MISO region

    International Nuclear Information System (INIS)

    Lamy, Julian V.; Jaramillo, Paulina; Azevedo, Inês L.; Wiser, Ryan

    2016-01-01

    Wind speeds in remote areas are sometimes very high, but transmission costs to access these locations can be prohibitive. We present a conceptual model to estimate the economics of accessing high quality wind resources in remote areas to comply with renewable energy policy targets, and apply the model to the Midwestern grid (MISO) as a case study. We assess the goal of providing 40 TWh of new wind generation while minimizing costs, and include temporal aspects of wind power (variability costs and correlation to market prices) as well as total wind power produced from different farms. We find that building wind farms in North/South Dakota (windiest states) compared to Illinois (less windy, but close to load) would only be economical if the incremental transmission costs to access them were below $360/kW of wind capacity (break-even value). Historically, the incremental transmission costs for wind development in North/South Dakota compared to in Illinois are about twice this value. However, the break-even incremental transmission cost for wind farms in Minnesota/Iowa (also windy states) is $250/kW, which is consistent with historical costs. We conclude that wind development in Minnesota/Iowa is likely more economical to meet MISO renewable targets compared to North/South Dakota or Illinois. - Highlights: •We evaluate the economics of building wind farms in remote areas in MISO. •We present a conceptual wind site selection model to meet 40 TWh of new wind. •We use the model to compare remote windy sites to less windy ones closer to load. •We show break-even transmission costs that would justify remote wind development. •Comparing break-even values to historical costs, MN/IA sites are most economical.

  6. On the Use of Coupled Wind, Wave, and Current Fields in the Simulation of Loads on Bottom-Supported Offshore Wind Turbines during Hurricanes: March 2012 - September 2015

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eungsoo [Univ. of Texas, Austin, TX (United States); Manuel, Lance [Univ. of Texas, Austin, TX (United States); Curcic, Milan [Univ. of Miami, Coral Gables, FL (United States); Chen, Shuyi S. [Univ. of Miami, Coral Gables, FL (United States); Phillips, Caleb [National Renewable Energy Lab. (NREL), Golden, CO (United States); Veers, Paul [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-06-01

    In the United States, potential offshore wind plant sites have been identified along the Atlantic seaboard and in the Gulf of Mexico. It is imperative that we define external conditions associated with hurricanes and severe winter storms and consider load cases for which wind turbines may need to be designed. We selected two hurricanes, Ike (2008) and Sandy (2012), and investigated the effect these tropical storms would have on bottom-supported offshore wind turbines that were hypothetically in or close to their path as they made landfall. For realistic turbine loads assessment, it is important that the coupled influences of the changing wind, wave, and current fields are simulated throughout the evolution of the hurricanes. We employed a coupled model--specifically, the University of Miami Coupled Model (UMCM)--that integrates atmospheric, wave, and ocean components to produce needed wind, wave, and current data. The wind data are used to generate appropriate vertical wind profiles and full wind velocity fields including turbulence; the current field over the water column is obtained by interpolated discrete output current data; and short-crested irregular second-order waves are simulated using output directional wave spectra from the coupled model. We studied two monopile-supported offshore wind turbines sited in 20 meters of water in the Gulf of Mexico to estimate loads during Hurricane Ike, and a jacket space-frame platform-supported offshore wind turbine sited in 50 meters of water in the mid-Atlantic region to estimate loads during Hurricane Sandy. In this report we discuss in detail how the simulated hurricane wind, wave, and current output data are used in turbine loads studies. In addition, important characteristics of the external conditions are studied, including the relative importance of swell versus wind seas, aerodynamic versus hydrodynamic forces, current velocity effects, yaw control options for the turbine, hydrodynamic drag versus inertia forces

  7. Comparison of Speed-Up Over Hills Derived from Wind-Tunnel Experiments, Wind-Loading Standards, and Numerical Modelling

    Science.gov (United States)

    Safaei Pirooz, Amir A.; Flay, Richard G. J.

    2018-03-01

    We evaluate the accuracy of the speed-up provided in several wind-loading standards by comparison with wind-tunnel measurements and numerical predictions, which are carried out at a nominal scale of 1:500 and full-scale, respectively. Airflow over two- and three-dimensional bell-shaped hills is numerically modelled using the Reynolds-averaged Navier-Stokes method with a pressure-driven atmospheric boundary layer and three different turbulence models. Investigated in detail are the effects of grid size on the speed-up and flow separation, as well as the resulting uncertainties in the numerical simulations. Good agreement is obtained between the numerical prediction of speed-up, as well as the wake region size and location, with that according to large-eddy simulations and the wind-tunnel results. The numerical results demonstrate the ability to predict the airflow over a hill with good accuracy with considerably less computational time than for large-eddy simulation. Numerical simulations for a three-dimensional hill show that the speed-up and the wake region decrease significantly when compared with the flow over two-dimensional hills due to the secondary flow around three-dimensional hills. Different hill slopes and shapes are simulated numerically to investigate the effect of hill profile on the speed-up. In comparison with more peaked hill crests, flat-topped hills have a lower speed-up at the crest up to heights of about half the hill height, for which none of the standards gives entirely satisfactory values of speed-up. Overall, the latest versions of the National Building Code of Canada and the Australian and New Zealand Standard give the best predictions of wind speed over isolated hills.

  8. Effect of load eccentricity and stress level on monopile support for offshore wind turbines

    DEFF Research Database (Denmark)

    Klinkvort, Rasmus Tofte; Hededal, Ole

    2014-01-01

    on which load is applied with a large eccentricity. With centrifuge tests as the basis, this paper investigates the behaviour of a rigid pile loaded with a high eccentricity. A test series was carried out to simulate idealized monotonic load cases for monopiles supporting an offshore wind turbine...... analysis and Rankine’s passive earth pressure coefficient as a normalization parameter. The normalized ultimate soil resistance was unaffected by acceleration level and load eccentricity, indicating that the failure mechanism was the same for all tests. Based on the centrifuge tests, a reformulation...... of soil–pile interaction curves is presented. The normalized initial stiffness of the soil–pile resistance curves was seen to increase linearly with depth in the centrifuge tests. The reformulation differs from current guidelines in terms of the shape of the interaction curve and magnitude of ultimate...

  9. Development of SMA Actuated Morphing Airfoil for Wind Turbine Load Alleviation

    Science.gov (United States)

    Karakalas, A.; Machairas, T.; Solomou, A.; Riziotis, V.; Saravanos, D.

    Wind turbine rotor upscaling has entered a range of rotor diameters where the blade structure cannot sustain the increased aerodynamic loads without novel load alleviation concepts. Research on load alleviation using morphing blade sections is presented. Antagonistic shape memory alloy (SMA) actuators are implemented to deflect the section trailing edge (TE) to target shapes and target time-series relating TE movement with changes in lift coefficient. Challenges encountered by the complex thermomechanical response of morphing section and the enhancement of SMA transient response to achieve frequencies meaningful for aerodynamic load alleviation are addressed. Using a recently developed finite element for SMA actuators [1], actuator configurations are considered for fast cooling and heating cycles. Numerical results quantify the attained ranges of TE angle movement, the moving time period and the developed stresses. Estimations of the attained variations of lift coefficient vs. time are also presented to assess the performance of the morphing section.

  10. Load consequences when sweeping blades - A case study of a 5 MW pitch controlled wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Verelst, D.R.S.; Larsen, Torben J.

    2010-08-15

    The generic 5 MW NREL wind turbine model is used in Risoe's aeroelastic simulator HAWC2 to investigate 120 different swept blade configurations (forward and backward sweep). Sensitivity for 2 different controllers is considered as well. Backward sweep results in a pitch to feather torsional moment of the blade, effectively reducing blade twist angles under increased loading. This behaviour results in decreased flap-wise fatigue and extreme loads, an increase for edge-wise fatigue loading and status quo or slight decrease in extreme loads (depending on the controller). Tower base and shaft-end bending moments are reduced as well. Forward sweep leads to an increase in angle of attack under loading. For a pitch controlled turbine this leads to an increase in fatigue and extreme loading in all cases. A controller inflicted instability is present for the more extreme forward swept cases. Due to the shape of considered sweep curves, an inherent and significant increase in torsional blade root bending moment is noted. A boomerang shaped sweep curve is proposed to counteract this problematic increased loading. Controller sensitivity shows that adding sweep affects some loadings differently. Power output is reduced for backward sweep since the blade twist is optimized as a rigid structure, ignoring the torsional deformations which for a swept blade can be significant. (author)

  11. Modeling nitrate-nitrogen load reduction strategies for the Des Moines River, Iowa using SWAT.

    Science.gov (United States)

    Schilling, Keith E; Wolter, Calvin F

    2009-10-01

    The Des Moines River that drains a watershed of 16,175 km(2) in portions of Iowa and Minnesota is impaired for nitrate-nitrogen (nitrate) due to concentrations that exceed regulatory limits for public water supplies. The Soil Water Assessment Tool (SWAT) model was used to model streamflow and nitrate loads and evaluate a suite of basin-wide changes and targeting configurations to potentially reduce nitrate loads in the river. The SWAT model comprised 173 subbasins and 2,516 hydrologic response units and included point and nonpoint nitrogen sources. The model was calibrated for an 11-year period and three basin-wide and four targeting strategies were evaluated. Results indicated that nonpoint sources accounted for 95% of the total nitrate export. Reduction in fertilizer applications from 170 to 50 kg/ha achieved the 38% reduction in nitrate loads, exceeding the 34% reduction required. In terms of targeting, the most efficient load reductions occurred when fertilizer applications were reduced in subbasins nearest the watershed outlet. The greatest load reduction for the area of land treated was associated with reducing loads from 55 subbasins with the highest nitrate loads, achieving a 14% reduction in nitrate loads achieved by reducing applications on 30% of the land area. SWAT model results provide much needed guidance on how to begin implementing load reduction strategies most efficiently in the Des Moines River watershed.

  12. Structural Load Alleviation Applied to Next Generation Aircraft and Wind Turbines

    Science.gov (United States)

    Frost, Susan

    2011-01-01

    Reducing the environmental impact of aviation is a goal of the Subsonic Fixed Wing Project under the Fundamental Aeronautics Program of NASAs Aeronautics Research Mission Directorate. Environmental impact of aviation is being addressed by novel aircraft configurations and materials that reduce aircraft weight and increase aerodynamic efficiency. NASA is developing tools to address the challenges of increased airframe flexibility created by wings constructed with reduced structural material and novel light-weight materials. This talk will present a framework and demonstration of a flight control system using optimal control allocation with structural load feedback and constraints to achieve safe aircraft operation. As wind turbines age, they become susceptible to many forms of blade degradation. Results will be presented on work in progress that uses adaptive contingency control for load mitigation in a wind turbine simulation with blade damage progression modeled.

  13. Assessment of extreme design loads for modern wind turbines using the probabilistic approach

    DEFF Research Database (Denmark)

    Abdallah, Imad

    as necessary, but no stronger [Veldkamp, 2006]. The original contributions of this research were:  • A comprehensive list of sources of uncertainties affecting the prediction of extreme loads on a wind turbine. Such a list is indeed subjective and subject to scrutiny and updating depending on a researcher......’s, scientist’s and engineer’s background, know-how and experiences.  • A fully encompassing stochastic model of aerofoil aerodynamic lift and drag coefficients, followed by a quantification of the effect of aerodynamic uncertainties on the extreme loads and an optimization of the partial safety factors...

  14. Optimized Power Dispatch in Wind Farms for Power Maximizing Considering Fatigue Loads

    DEFF Research Database (Denmark)

    Zhang, Baohua; N. Soltani, Mohsen; Hu, Weihao

    2018-01-01

    load of the shafts and the towers within a certain range from the values using traditional strategy, which adopts maximum power point tracking (MPPT) control for each WT. A WT derating control strategy is included in the WT controller and the fatigue load for the tower and shaft is evaluated offline...... at a series of turbulence intensity, mean wind speed and active power reference to form a lookup table, which is used for the WF control. The proposed strategy is compared with WT MPPT control strategy and WF MPPT control strategy. The simulation results show the effectiveness of the proposed strategy....

  15. Reduction of the Random Variables of the Turbulent Wind Field

    DEFF Research Database (Denmark)

    Sichani, Mahdi Teimouri; Nielsen, Søren R.K.

    2012-01-01

    Applicability of the Probability Density Evolution Method (PDEM) for realizing evolution of the probability density for the wind turbines has rather strict bounds on the basic number of the random variables involved in the model. The efficiency of most of the Advanced Monte Carlo (AMC) methods, i...... of the integral domain; this becomes increasingly difficult as the dimensions of the integral domain increase. On the other hand efficiency of the AMC methods is closely dependent on the design points of the problem. Presence of many random variables may increase the number of the design points, hence affects.......e. Importance Sampling (IS) or Subset Simulation (SS), will be deteriorated on problems with many random variables. The problem with PDEM is that a multidimensional integral has to be carried out over the space defined by the random variables of the system. The numerical procedure requires discretization...

  16. Wind, waves, and wing loading: Morphological specialization may limit range expansion of endangered albatrosses

    Science.gov (United States)

    Suryan, R.M.; Anderson, D.J.; Shaffer, S.A.; Roby, D.D.; Tremblay, Y.; Costa, D.P.; Sievert, P.R.; Sato, F.; Ozaki, K.; Balogh, G.R.; Nakamura, N.

    2008-01-01

    Among the varied adaptations for avian flight, the morphological traits allowing large-bodied albatrosses to capitalize on wind and wave energy for efficient long-distance flight are unparalleled. Consequently, the biogeographic distribution of most albatrosses is limited to the windiest oceanic regions on earth; however, exceptions exist. Species breeding in the North and Central Pacific Ocean (Phoebastria spp.) inhabit regions of lower wind speed and wave height than southern hemisphere genera, and have large intrageneric variation in body size and aerodynamic performance. Here, we test the hypothesis that regional wind and wave regimes explain observed differences in Phoebastria albatross morphology and we compare their aerodynamic performance to representatives from the other three genera of this globally distributed avian family. In the North and Central Pacific, two species (short-tailed P. albatrus and waved P. irrorata) are markedly larger, yet have the smallest breeding ranges near highly productive coastal upwelling systems. Short-tailed albatrosses, however, have 60% higher wing loading (weight per area of lift) compared to waved albatrosses. Indeed, calculated aerodynamic performance of waved albatrosses, the only tropical albatross species, is more similar to those of their smaller congeners (black-footed P. nigripes and Laysan P. immutabilis), which have relatively low wing loading and much larger foraging ranges that include central oceanic gyres of relatively low productivity. Globally, the aerodynamic performance of short-tailed and waved albatrosses are most anomalous for their body sizes, yet consistent with wind regimes within their breeding season foraging ranges. Our results are the first to integrate global wind and wave patterns with albatross aerodynamics, thereby identifying morphological specialization that may explain limited breeding ranges of two endangered albatross species. These results are further relevant to understanding past and

  17. Wind, waves, and wing loading: morphological specialization may limit range expansion of endangered albatrosses.

    Directory of Open Access Journals (Sweden)

    Robert M Suryan

    Full Text Available Among the varied adaptations for avian flight, the morphological traits allowing large-bodied albatrosses to capitalize on wind and wave energy for efficient long-distance flight are unparalleled. Consequently, the biogeographic distribution of most albatrosses is limited to the windiest oceanic regions on earth; however, exceptions exist. Species breeding in the North and Central Pacific Ocean (Phoebastria spp. inhabit regions of lower wind speed and wave height than southern hemisphere genera, and have large intrageneric variation in body size and aerodynamic performance. Here, we test the hypothesis that regional wind and wave regimes explain observed differences in Phoebastria albatross morphology and we compare their aerodynamic performance to representatives from the other three genera of this globally distributed avian family. In the North and Central Pacific, two species (short-tailed P. albatrus and waved P. irrorata are markedly larger, yet have the smallest breeding ranges near highly productive coastal upwelling systems. Short-tailed albatrosses, however, have 60% higher wing loading (weight per area of lift compared to waved albatrosses. Indeed, calculated aerodynamic performance of waved albatrosses, the only tropical albatross species, is more similar to those of their smaller congeners (black-footed P. nigripes and Laysan P. immutabilis, which have relatively low wing loading and much larger foraging ranges that include central oceanic gyres of relatively low productivity. Globally, the aerodynamic performance of short-tailed and waved albatrosses are most anomalous for their body sizes, yet consistent with wind regimes within their breeding season foraging ranges. Our results are the first to integrate global wind and wave patterns with albatross aerodynamics, thereby identifying morphological specialization that may explain limited breeding ranges of two endangered albatross species. These results are further relevant to

  18. Lifetime prediction of towers with respect to lateral and longitudinal wind load

    Czech Academy of Sciences Publication Activity Database

    Pospíšil, Stanislav; Hračov, Stanislav; Lahodný, J.; Janata, V.; Urushadze, Shota

    2014-01-01

    Roč. 55, č. 2 (2014), s. 117-126 ISSN 1028-365X R&D Projects: GA MPO(CZ) FR-TI3/654; GA ČR(CZ) GA103/09/0094; GA ČR(CZ) GP13-41574P Institutional support: RVO:68378297 Keywords : lifetime prediction * spectrum * towers * wind load * fatigue Subject RIV: JM - Building Engineering http://www.iass-structures.org/index.cfm/journal.article?aID=702

  19. Wind Load Assessment of a Large Radar Antenna using Measurements and Simulation

    Science.gov (United States)

    Weerasinghe, Rohitha; Bunn, Thomas

    2017-11-01

    Radar structures are subject to heavy wind loads due to the physical size of such structures. This paper contains the methodology and assessment of a project which set out to accomplish an improved method for modelling wind loads on a radar structure. The new method employs the use of computational fluid dynamics (CFD) to create a simulation of the conditions. Several studies on the approach to CFD testing were undertaken to optimise the process. Dimensions of domain volume and mesh density were examined for their effect on the computed solutions, as well as run time. Once an efficient set-up had been found, a scale model of the radar was analysed. Pressure distributions across the antenna face were studied from four cases, in which the prevailing wind approached from a different direction relative to the system (0°, 45°,90° and 180°). To validate the results from the CFD, a low-speed wind tunnel test was conducted. The experimental measurements were compared to the computed results and common trends were shown to exist between both sets of data.

  20. Influence of Wind Strength and Duration on Relative Hypoxia Reductions by Opposite Wind Directions in an Estuary with an Asymmetric Channel

    Directory of Open Access Journals (Sweden)

    Ping Wang

    2016-09-01

    Full Text Available Computer model experiments are applied to analyze hypoxia reductions for opposing wind directions under various speeds and durations in the north–south oriented, two-layer-circulated Chesapeake estuary. Wind’s role in destratification is the main mechanism in short-term reduction of hypoxia. Hypoxia can also be reduced by wind-enhanced estuarine circulation associated with winds that have down-estuary straining components that promote bottom-returned oxygen-rich seawater intrusion. The up-bay-ward along-channel component of straining by the southerly or easterly wind induces greater destratification than the down-bay-ward straining by the opposite wind direction, i.e., northerly or westerly winds. While under the modulation of the west-skewed asymmetric cross-channel bathymetry in the Bay’s hypoxic zone, the westward cross-channel straining by easterly or northerly winds causes greater destratification than its opposite wind direction. The wind-induced cross-channel circulation can be completed much more rapidly than the wind-induced along-channel circulation, and the former is usually more effective than the latter in destratification and hypoxia reduction in an early wind period. The relative importance of cross-channel versus along-channel circulation for a particular wind direction can change with wind speed and duration. The existence of month-long prevailing unidirectional winds in the Chesapeake is explored, and the relative hypoxia reductions among different prevailing directions are analyzed. Scenarios of wind with intermittent calm or reversing directions on an hourly scale are also simulated and compared.

  1. Study of Flexible Load Dispatch to Improve the Capacity of Wind Power Absorption

    Science.gov (United States)

    Yunlei, Yang; Shifeng, Zhang; Xiao, Chang; Da, Lei; Min, Zhang; Jinhao, Wang; Shengwen, Li; Huipeng, Li

    2017-05-01

    The dispatch method which track the trend of load demand by arranging the generation scheme of controllable hydro or thermal units faces great difficulties and challenges. With the increase of renewable energy sources such as wind power and photovoltaic power introduced to grid, system has to arrange much more spinning reserve units to compensate the unbalanced power. How to exploit the peak-shaving potential of flexible load which can be shifted with time or storage energy has become many scholars’ research direction. However, the modelling of different kinds of load and control strategy is considerably difficult, this paper choose the Air Conditioner with compressor which can storage energy in fact to study. The equivalent thermal parameters of Air Conditioner has been established. And with the use of “loop control” strategies, we can predict the regulated power of Air Conditioner. Then we established the Gen-Load optimal scheduling model including flexible load based on traditional optimal scheduling model. At last, an improved IEEE-30 case is used to verify. The result of simulation shows that flexible load can fast-track renewable power changes. More than that, with flexible load and reasonable incentive method to consumers, the operating cost of the system can be greatly cut down.

  2. Analysis of the effect of curtailment on power and fatigue loads of two aligned wind turbines using an actuator disc approach

    International Nuclear Information System (INIS)

    Martinen, Silke; Nilsson, Karl; Breton, Simon-Philippe; Ivanell, Stefan; Carlén, Ingemar

    2014-01-01

    To study the effects of curtailment on both power production and fatigue loading, actuator disc (ACD) simulations of two turbines aligned in the wind direction are performed with the EllipSys3D code developed at DTU/Risø. A simple non-aeroelastic fatigue load evaluation method for ACD simulations is developed. Blade loads, extracted along a line that rotates in the rotor plane with the rotational velocity of the respective turbine, are used to calculate flapwise bending moments. After applying a rainflow counting algorithm an equivalent moment is calculated. Power curtailment is introduced by increasing the blade pitch angle of the first turbine. Evaluation is made with regards to fatigue load reduction at the second turbine and the change in the total production. Further parameters investigated are the spacing between the two turbines and the level of imposed pre-generated turbulence. The aeroelastic code Vidyn, Ganander [1], is used for validation of the ACD load evaluation method. For this purpose, the EllipSys3D simulations are rerun without the second turbine. Time series of cross sectional velocity fields are extracted at positions corresponding to the former placement of the downstream turbine and used as input for aeroelastic turbine load calculations in Vidyn. The results from Vidyn and the results based on the ACD loads show similar trends. Fatigue loads at the downwind turbine are clearly decreasing as the blade pitch angle of the upstream turbine is increasing. The achievable amount of fatigue load reduction depends on the level of the imposed pre-generated turbulence as well as the spacing between the turbines. The presented method is intended for further development of wind park optimization strategies

  3. Numerical Investigation of Aerodynamic Performance and Loads of a Novel Dual Rotor Wind Turbine

    Directory of Open Access Journals (Sweden)

    Behnam Moghadassian

    2016-07-01

    Full Text Available The objective of this paper is to numerically investigate the effects of the atmospheric boundary layer on the aerodynamic performance and loads of a novel dual-rotor wind turbine (DRWT. Large eddy simulations are carried out with the turbines operating in the atmospheric boundary layer (ABL and in a uniform inflow. Two stability conditions corresponding to neutral and slightly stable atmospheres are investigated. The turbines are modeled using the actuator line method where the rotor blades are modeled as body forces. Comparisons are drawn between the DRWT and a comparable conventional single-rotor wind turbine (SRWT to assess changes in aerodynamic efficiency and loads, as well as wake mixing and momentum and kinetic energy entrainment into the turbine wake layer. The results show that the DRWT improves isolated turbine aerodynamic performance by about 5%–6%. The DRWT also enhances turbulent axial momentum entrainment by about 3.3 %. The highest entrainment is observed in the neutral stability case when the turbulence in the ABL is moderately high. Aerodynamic loads for the DRWT, measured as out-of-plane blade root bending moment, are marginally reduced. Spectral analyses of ABL cases show peaks in unsteady loads at the rotor passing frequency and its harmonics for both rotors of the DRWT.

  4. Wave loads on foundations for wind turbines. A literature survey; Vaaglaster paa fundament till vindkraftverk - systemdynamik och utmattning: Litteraturstudie

    Energy Technology Data Exchange (ETDEWEB)

    Carlen, Ingemar

    2001-05-01

    This report is an overview of literature covering the influence of wave loads on foundations for wind power plants. Relevant subjects are wave motion, wave forces on slender structures, wave statistics for the Swedish coast together with planning and certification.

  5. Real-time POD-CFD Wind-Load Calculator for PV Systems

    Energy Technology Data Exchange (ETDEWEB)

    Huayamave, Victor [Centecorp; Divo, Eduardo [Centecorp; Ceballos, Andres [Centecorp; Barriento, Carolina [Centecorp; Stephen, Barkaszi [FSEC; Hubert, Seigneur [FSEC

    2014-03-21

    The primary objective of this project is to create an accurate web-based real-time wind-load calculator. This is of paramount importance for (1) the rapid and accurate assessments of the uplift and downforce loads on a PV mounting system, (2) identifying viable solutions from available mounting systems, and therefore helping reduce the cost of mounting hardware and installation. Wind loading calculations for structures are currently performed according to the American Society of Civil Engineers/ Structural Engineering Institute Standard ASCE/SEI 7; the values in this standard were calculated from simplified models that do not necessarily take into account relevant characteristics such as those from full 3D effects, end effects, turbulence generation and dissipation, as well as minor effects derived from shear forces on installation brackets and other accessories. This standard does not include provisions that address the special requirements of rooftop PV systems, and attempts to apply this standard may lead to significant design errors as wind loads are incorrectly estimated. Therefore, an accurate calculator would be of paramount importance for the preliminary assessments of the uplift and downforce loads on a PV mounting system, identifying viable solutions from available mounting systems, and therefore helping reduce the cost of the mounting system and installation. The challenge is that although a full-fledged three-dimensional computational fluid dynamics (CFD) analysis would properly and accurately capture the complete physical effects of air flow over PV systems, it would be impractical for this tool, which is intended to be a real-time web-based calculator. CFD routinely requires enormous computation times to arrive at solutions that can be deemed accurate and grid-independent even in powerful and massively parallel computer platforms. This work is expected not only to accelerate solar deployment nationwide, but also help reach the SunShot Initiative goals

  6. Evaluation of MOSTAS computer code for predicting dynamic loads in two-bladed wind turbines

    Science.gov (United States)

    Kaza, K. R. V.; Janetzke, D. C.; Sullivan, T. L.

    1979-01-01

    Calculated dynamic blade loads are compared with measured loads over a range of yaw stiffnesses of the DOE/NASA Mod-0 wind turbine to evaluate the performance of two versions of the MOSTAS computer code. The first version uses a time-averaged coefficient approximation in conjunction with a multiblade coordinate transformation for two-bladed rotors to solve the equations of motion by standard eigenanalysis. The results obtained with this approximate analysis do not agree with dynamic blade load amplifications at or close to resonance conditions. The results of the second version, which accounts for periodic coefficients while solving the equations by a time history integration, compare well with the measured data.

  7. Effect of Coupled Non linear Wave Kinematics and Soil Flexibility on the Design Loads of Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Kim, Taeseong; Natarajan, Anand

    2013-01-01

    The design driving loads on offshore wind turbine monopile support structures at water depths of 35m, which are beyond current monopile installation depths, are derived based on fully coupled aerohydroelastic simulations of the wind turbine in normal operation and in storm conditions in the prese...

  8. Advancing Development and Greenhouse Gas Reductions in Vietnam's Wind Sector

    Energy Technology Data Exchange (ETDEWEB)

    Bilello, D.; Katz, J.; Esterly, S.; Ogonowski, M.

    2014-09-01

    Clean energy development is a key component of Vietnam's Green Growth Strategy, which establishes a target to reduce greenhouse gas (GHG) emissions from domestic energy activities by 20-30 percent by 2030 relative to a business-as-usual scenario. Vietnam has significant wind energy resources, which, if developed, could help the country reach this target while providing ancillary economic, social, and environmental benefits. Given Vietnam's ambitious clean energy goals and the relatively nascent state of wind energy development in the country, this paper seeks to fulfill two primary objectives: to distill timely and useful information to provincial-level planners, analysts, and project developers as they evaluate opportunities to develop local wind resources; and, to provide insights to policymakers on how coordinated efforts may help advance large-scale wind development, deliver near-term GHG emission reductions, and promote national objectives in the context of a low emission development framework.

  9. Assessment of the Uniqueness of Wind Tunnel Strain-Gage Balance Load Predictions

    Science.gov (United States)

    Ulbrich, N.

    2016-01-01

    A new test was developed to assess the uniqueness of wind tunnel strain-gage balance load predictions that are obtained from regression models of calibration data. The test helps balance users to gain confidence in load predictions of non-traditional balance designs. It also makes it possible to better evaluate load predictions of traditional balances that are not used as originally intended. The test works for both the Iterative and Non-Iterative Methods that are used in the aerospace testing community for the prediction of balance loads. It is based on the hypothesis that the total number of independently applied balance load components must always match the total number of independently measured bridge outputs or bridge output combinations. This hypothesis is supported by a control volume analysis of the inputs and outputs of a strain-gage balance. It is concluded from the control volume analysis that the loads and bridge outputs of a balance calibration data set must separately be tested for linear independence because it cannot always be guaranteed that a linearly independent load component set will result in linearly independent bridge output measurements. Simple linear math models for the loads and bridge outputs in combination with the variance inflation factor are used to test for linear independence. A highly unique and reversible mapping between the applied load component set and the measured bridge output set is guaranteed to exist if the maximum variance inflation factor of both sets is less than the literature recommended threshold of five. Data from the calibration of a six{component force balance is used to illustrate the application of the new test to real-world data.

  10. Input Shaping for Helicopter Slung Load Swing Reduction

    DEFF Research Database (Denmark)

    Bisgaard, Morten; la Cour-Harbo, Anders; Bendtsen, Jan Dimon

    2008-01-01

    This chapter presents a feedforward swing reducing control system for augmenting already existing helicopter controllers and enables slung load flight with autonomous helicopters general cargo transport. The feedforward controller is designed to avoid excitation of the lightly damped modes of the...

  11. Advances in the Assessment of Wind Turbine Operating Extreme Loads via More Efficient Calculation Approaches

    Energy Technology Data Exchange (ETDEWEB)

    Graf, Peter; Damiani, Rick R.; Dykes, Katherine; Jonkman, Jason M.

    2017-01-09

    A new adaptive stratified importance sampling (ASIS) method is proposed as an alternative approach for the calculation of the 50 year extreme load under operational conditions, as in design load case 1.1 of the the International Electrotechnical Commission design standard. ASIS combines elements of the binning and extrapolation technique, currently described by the standard, and of the importance sampling (IS) method to estimate load probability of exceedances (POEs). Whereas a Monte Carlo (MC) approach would lead to the sought level of POE with a daunting number of simulations, IS-based techniques are promising as they target the sampling of the input parameters on the parts of the distributions that are most responsible for the extreme loads, thus reducing the number of runs required. We compared the various methods on select load channels as output from FAST, an aero-hydro-servo-elastic tool for the design and analysis of wind turbines developed by the National Renewable Energy Laboratory (NREL). Our newly devised method, although still in its infancy in terms of tuning of the subparameters, is comparable to the others in terms of load estimation and its variance versus computational cost, and offers great promise going forward due to the incorporation of adaptivity into the already powerful importance sampling concept.

  12. Planetary Load Sharing in Three-Point- Mounted Wind Turbine Gearboxes: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yi [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Keller, Jonathan A [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-09-15

    Wind turbine gearboxes do not achieve their expected design life. The cost of gearbox replacements and rebuilds and the downtime associated with these failures increase the cost of wind energy. In 2007, the U.S. Department of Energy established the National Renewable Energy Laboratory (NREL) Gearbox Reliability Collaborative (GRC). Its goals are to understand the root causes of premature gearbox failures and improve their reliability. To date, the GRC has focused on a 750-kW drivetrain with a three-stage, three-point-mounted gearbox. A nonproprietary version of the gearbox containing CRBs with C3 clearances in the planetary stage was customized. Two of these gearboxes, GB1 and GB2, were manufactured and then tested in the National Wind Technology Center's 2.5-MW dynamometer and in the field. Major GRC findings include the detrimental effect of rotor moments on planetary load sharing and predicted fatigue, and the risk of bearing sliding in low-torque conditions for three-point configuration drivetrains. Based on the knowledge gained from testing and analysis of the original design, the GRC gearbox was redesigned to improve its load-sharing characteristics and predicted fatigue. This new gearbox is named GB3. As shown in Figure 1, its key improvement is the incorporation of preloaded TRBs that support the planet carrier and planets. Roller loads can be optimized and bearing life maximized with a small preload [4]. These preloaded bearings, along with interference-fitted planet pins, improve alignments and load-sharing characteristics. A semi-integrated planet bearing design also increases capacity and eliminates outer race fretting. Romax Technology, with Powertrain Engineers and the Timken Company (Timken), completed the redesign. Timken manufactured and instrumented the planet gears and bearings. Brad Foote Gearing manufactured the other gearing and assembled the gearbox.

  13. Load reduction test method of similarity theory and BP neural networks of large cranes

    Science.gov (United States)

    Yang, Ruigang; Duan, Zhibin; Lu, Yi; Wang, Lei; Xu, Gening

    2016-01-01

    Static load tests are an important means of supervising and detecting a crane's lift capacity. Due to space restrictions, however, there are difficulties and potential danger when testing large bridge cranes. To solve the loading problems of large-tonnage cranes during testing, an equivalency test is proposed based on the similarity theory and BP neural networks. The maximum stress and displacement of a large bridge crane is tested in small loads, combined with the training neural network of a similar structure crane through stress and displacement data which is collected by a physics simulation progressively loaded to a static load test load within the material scope of work. The maximum stress and displacement of a crane under a static load test load can be predicted through the relationship of stress, displacement, and load. By measuring the stress and displacement of small tonnage weights, the stress and displacement of large loads can be predicted, such as the maximum load capacity, which is 1.25 times the rated capacity. Experimental study shows that the load reduction test method can reflect the lift capacity of large bridge cranes. The load shedding predictive analysis for Sanxia 1200 t bridge crane test data indicates that when the load is 1.25 times the rated lifting capacity, the predicted displacement and actual displacement error is zero. The method solves the problem that lifting capacities are difficult to obtain and testing accidents are easily possible when 1.25 times related weight loads are tested for large tonnage cranes.

  14. Energy Coordinative Optimization of Wind-Storage-Load Microgrids Based on Short-Term Prediction

    Directory of Open Access Journals (Sweden)

    Changbin Hu

    2015-02-01

    Full Text Available According to the topological structure of wind-storage-load complementation microgrids, this paper proposes a method for energy coordinative optimization which focuses on improvement of the economic benefits of microgrids in the prediction framework. First of all, the external characteristic mathematical model of distributed generation (DG units including wind turbines and storage batteries are established according to the requirements of the actual constraints. Meanwhile, using the minimum consumption costs from the external grid as the objective function, a grey prediction model with residual modification is introduced to output the predictive wind turbine power and load at specific periods. Second, based on the basic framework of receding horizon optimization, an intelligent genetic algorithm (GA is applied to figure out the optimum solution in the predictive horizon for the complex non-linear coordination control model of microgrids. The optimum results of the GA are compared with the receding solution of mixed integer linear programming (MILP. The obtained results show that the method is a viable approach for energy coordinative optimization of microgrid systems for energy flow and reasonable schedule. The effectiveness and feasibility of the proposed method is verified by examples.

  15. Time Accurate Unsteady Pressure Loads Simulated for the Space Launch System at a Wind Tunnel Condition

    Science.gov (United States)

    Alter, Stephen J.; Brauckmann, Gregory J.; Kleb, Bil; Streett, Craig L; Glass, Christopher E.; Schuster, David M.

    2015-01-01

    Using the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics code, an unsteady, time-accurate flow field about a Space Launch System configuration was simulated at a transonic wind tunnel condition (Mach = 0.9). Delayed detached eddy simulation combined with Reynolds Averaged Naiver-Stokes and a Spallart-Almaras turbulence model were employed for the simulation. Second order accurate time evolution scheme was used to simulate the flow field, with a minimum of 0.2 seconds of simulated time to as much as 1.4 seconds. Data was collected at 480 pressure taps at locations, 139 of which matched a 3% wind tunnel model, tested in the Transonic Dynamic Tunnel (TDT) facility at NASA Langley Research Center. Comparisons between computation and experiment showed agreement within 5% in terms of location for peak RMS levels, and 20% for frequency and magnitude of power spectral densities. Grid resolution and time step sensitivity studies were performed to identify methods for improved accuracy comparisons to wind tunnel data. With limited computational resources, accurate trends for reduced vibratory loads on the vehicle were observed. Exploratory methods such as determining minimized computed errors based on CFL number and sub-iterations, as well as evaluating frequency content of the unsteady pressures and evaluation of oscillatory shock structures were used in this study to enhance computational efficiency and solution accuracy. These techniques enabled development of a set of best practices, for the evaluation of future flight vehicle designs in terms of vibratory loads.

  16. A zero torsional stiffness twist morphing blade as a wind turbine load alleviation device

    International Nuclear Information System (INIS)

    Lachenal, X; Daynes, S; Weaver, P M

    2013-01-01

    This paper presents the design, analysis and realization of a zero stiffness twist morphing wind turbine blade. The morphing blade is designed to actively twist as a means of alleviating the gust loads which reduce the fatigue life of wind turbine blades. The morphing structure exploits an elastic strain energy balance within the blade to enable large twisting deformations with modest actuation requirements. While twist is introduced using the warping of the blade skin, internal pre-stressed members ensure that a constant strain energy balance is achieved throughout the deformation, resulting in a zero torsional stiffness structure. The torsional stability of the morphing blade is characterized by analysing the elastic strain energy in the device. Analytical models of the skin, the pre-stressed components and the complete blade are compared to their respective finite element models as well as experimental results. The load alleviation potential of the adaptive structure is quantified using a two-dimensional steady flow aerodynamic model which is experimentally validated with wind tunnel measurements. (paper)

  17. Flight Load Assessment for Light Aircraft Landing Trajectories in Windy Atmosphere and Near Wind Farms

    Directory of Open Access Journals (Sweden)

    Carmine Varriale

    2018-04-01

    Full Text Available This work focuses on the wake encounter problem occurring when a light, or very light, aircraft flies through or nearby a wind turbine wake. The dependency of the aircraft normal load factor on the distance from the turbine rotor in various flight and environmental conditions is quantified. For this research, a framework of software applications has been developed for generating and controlling a population of flight simulation scenarios in presence of assigned wind and turbulence fields. The JSBSim flight dynamics model makes use of several autopilot systems for simulating a realistic pilot behavior during navigation. The wind distribution, calculated with OpenFOAM, is a separate input for the dynamic model and is considered frozen during each flight simulation. The aircraft normal load factor during wake encounters is monitored at different distances from the rotor, aircraft speeds, rates of descent and crossing angles. Based on these figures, some preliminary guidelines and recommendations on safe encounter distances are provided for general aviation aircraft, with considerations on pilot comfort and flight safety. These are needed, for instance, when an accident risk assessment study is required for flight in proximity of aeolic parks. A link to the GitHub code repository is provided.

  18. Preliminary study of inphase gusts and moment force wind loads over the first 150 meters at KSC, Florida

    Science.gov (United States)

    Kaufman, J. W.

    1985-01-01

    A mathematical/statistical analysis of inphase gusts and wind velocity moment forces over the first 150 m at the Kennedy Space Center (KSC) is presented. The wind velocity profile data were acquired at the KSC 150 m ground wind tower. The results show that planetary boundary layer (PBL) winds can sustain near peak speeds for periods up to 60 sec and longer. This is proven from calculating the autocorrelation functions of moment forces for several 10 min cases of wind profile data. The results show that lower atmospheric planetary boundary layer winds have periodic variations for long periods of time. This flow characteristic is valuable as aerospace vehicle engineering and design criteria where wind loading must be determined.

  19. Stochastic Unit Commitment of Wind-Integrated Power System Considering Air-Conditioning Loads for Demand Response

    Directory of Open Access Journals (Sweden)

    Xiao Han

    2017-11-01

    Full Text Available As a result of extensive penetration of wind farms into electricity grids, power systems face enormous challenges in daily operation because of the intermittent characteristics of wind energy. In particular, the load peak-valley gap has been dramatically widened in wind energy-integrated power systems. How to quickly and efficiently meet the peak-load demand has become an issue to practitioners. Previous literature has illustrated that the demand response (DR is an important mechanism to direct customer usage behaviors and reduce the peak load at critical times. This paper introduces air-conditioning loads (ACLs as a load shedding measure in the DR project. On the basis of the equivalent thermal parameter model for ACLs and the state-queue control method, a compensation cost calculation method for the ACL to shift peak load is proposed. As a result of the fluctuation and uncertainty of wind energy, a two-stage stochastic unit commitment (UC model is developed to analyze the ACL users’ response in the wind-integrated power system. A simulation study on residential and commercial ACLs has been performed on a 10-generator test system. The results illustrate the feasibility of the proposed stochastic programming strategy and that the system peak load can be effectively reduced through the participation of ACL users in DR projects.

  20. Effective Method for Determining Environmental Loads on Supporting Structures for Offshore Wind Turbines

    Directory of Open Access Journals (Sweden)

    Dymarski Paweł

    2016-01-01

    Full Text Available This paper presents a description of an effective method for determining loads due to waves and current acting on the supporting structures of the offshore wind turbines. This method is dedicated to the structures consisting of the cylindrical or conical elements as well as (truncates pyramids of polygon with a large number of sides (8 or more. The presented computational method is based on the Morison equation, which was originally developed only for cylindrically shaped structures. The new algorithm shown here uses the coefficients of inertia and drag forces that were calculated for non-cylindrical shapes. The analysed structure consists of segments which are truncated pyramids on the basis of a hex decagon. The inertia coefficients, CM, and drag coefficients, CD, were determined using RANSE-CFD calculations. The CFD simulations were performed for a specific range of variation of the period, and for a certain range of amplitudes of the velocity. In addition, the analysis of influence of the surface roughness on the inertia and drag coefficients was performed. In the next step, the computations of sea wave, current and wind load on supporting structure for the fifty-year storm were carried out. The simulations were performed in the time domain and as a result the function of forces distribution along the construction elements was obtained. The most unfavourable distribution of forces will be used, to analyse the strength of the structure, as the design load.

  1. Turbulence descriptors for scaling fatigue loading spectra of wind turbine structural components

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, N D

    1994-07-01

    The challenge for the designer in developing a new wind turbine is to incorporate sufficient strength in its components to safely achieve a 20- or 30-year service life. To accomplish this, the designer must understand the load and stress distributions (in a statistical sense at least) that the turbine is likely to encounter during its operating life. Sources of loads found in the normal operating environment include start/stop cycles, emergency shutdowns, the turbulence environment associated with the specific site and turbine location, and extreme or ``rare`` events that can challenge the turbine short-term survivability. Extreme events can result from an operational problem (e.g., controller failure) or violent atmospheric phenomena (tornadic circulations, strong gust fronts). For the majority of the operating time, however, the character of the turbulent inflow is the dominant source of the alternating stress distributions experienced by the structural components. Methods of characterizing or scaling the severity of the loading spectra (or the rate of fatigue damage accumulation) must be applicable to a wide range of turbulent inflow environments -- from solitary isolation to the complex flows associated with multi-row wind farms. The metrics chosen must be related to the properties of the turbulent inflow and independent of the nature of local terrain features.

  2. Renewable Generation (Wind/Solar and Load Modeling through Modified Fuzzy Prediction Interval

    Directory of Open Access Journals (Sweden)

    Syed Furqan Rafique

    2018-01-01

    Full Text Available The accuracy of energy management system for renewable microgrid, either grid-connected or isolated, is heavily dependent on the forecasting precision such as wind, solar, and load. In this paper, an improved fuzzy prediction horizon forecasting method is developed to address the issue of intermittence and uncertainty problem related to renewable generation and load forecast. In the first phase, a Takagi-Sugeno type fuzzy system is trained with many evolutionary optimization algorithms and established coverage grade indicator to check the accuracy of interval forecast. Secondly, a wind, solar, and load forecaster is developed for renewable microgrid test bed which is located in Beijing, China. One day and one step ahead results for the proposed forecaster are expressed with lowest RMSE and training time. In order to check the efficiency of the proposed method, a comparison is carried out with the existing models. The fuzzy interval-based model for the microgrid test bed will help to formulate the energy management problem with more accuracy and robustness.

  3. Long-Haul Truck Sleeper Heating Load Reduction Package for Rest Period Idling: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Lustbader, Jason; Kekelia, Bidzina; Tomerlin, Jeff; Kreutzer, Cory; Adelman, Steve; Yeakel, Skip; Luo, Zhiming; Zehme, John

    2016-03-24

    Annual fuel use for sleeper cab truck rest period idling is estimated at 667 million gallons in the United States, or 6.8% of long-haul truck fuel use. Truck idling during a rest period represents zero freight efficiency and is largely done to supply accessory power for climate conditioning of the cab. The National Renewable Energy Laboratory's CoolCab project aims to reduce heating, ventilating, and air conditioning (HVAC) loads and resulting fuel use from rest period idling by working closely with industry to design efficient long-haul truck thermal management systems while maintaining occupant comfort. Enhancing the thermal performance of cab/sleepers will enable smaller, lighter, and more cost-effective idle reduction solutions. In addition, if the fuel savings provide a one- to three-year payback period, fleet owners will be economically motivated to incorporate them. For candidate idle reduction technologies to be implemented by original equipment manufacturers and fleets, their effectiveness must be quantified. To address this need, several promising candidate technologies were evaluated through experimentation and modeling to determine their effectiveness in reducing rest period HVAC loads. Load reduction strategies were grouped into the focus areas of solar envelope, occupant environment, conductive pathways, and efficient equipment. Technologies in each of these focus areas were investigated in collaboration with industry partners. The most promising of these technologies were then combined with the goal of exceeding a 30% reduction in HVAC loads. These technologies included 'ultra-white' paint, advanced insulation, and advanced curtain design. Previous testing showed more than a 35.7% reduction in air conditioning loads. This paper describes the overall heat transfer coefficient testing of this advanced load reduction technology package that showed more than a 43% reduction in heating load. Adding an additional layer of advanced insulation

  4. Long-Haul Truck Sleeper Heating Load Reduction Package for Rest Period Idling

    Energy Technology Data Exchange (ETDEWEB)

    Lustbader, Jason Aaron; Kekelia, Bidzina; Tomerlin, Jeff; Kreutzer, Cory J.; Yeakel, Skip; Adelman, Steven; Luo, Zhiming; Zehme, John

    2016-04-05

    Annual fuel use for sleeper cab truck rest period idling is estimated at 667 million gallons in the United States, or 6.8% of long-haul truck fuel use. Truck idling during a rest period represents zero freight efficiency and is largely done to supply accessory power for climate conditioning of the cab. The National Renewable Energy Laboratory's CoolCab project aims to reduce heating, ventilating, and air conditioning (HVAC) loads and resulting fuel use from rest period idling by working closely with industry to design efficient long-haul truck thermal management systems while maintaining occupant comfort. Enhancing the thermal performance of cab/sleepers will enable smaller, lighter, and more cost-effective idle reduction solutions. In addition, if the fuel savings provide a one- to three-year payback period, fleet owners will be economically motivated to incorporate them. For candidate idle reduction technologies to be implemented by original equipment manufacturers and fleets, their effectiveness must be quantified. To address this need, several promising candidate technologies were evaluated through experimentation and modeling to determine their effectiveness in reducing rest period HVAC loads. Load reduction strategies were grouped into the focus areas of solar envelope, occupant environment, conductive pathways, and efficient equipment. Technologies in each of these focus areas were investigated in collaboration with industry partners. The most promising of these technologies were then combined with the goal of exceeding a 30% reduction in HVAC loads. These technologies included 'ultra-white' paint, advanced insulation, and advanced curtain design. Previous testing showed more than a 35.7% reduction in air conditioning loads. This paper describes the overall heat transfer coefficient testing of this advanced load reduction technology package that showed more than a 43% reduction in heating load. Adding an additional layer of advanced insulation

  5. Integrity of reinforced concrete cooling towers under extreme loads: Wind and earthquake

    International Nuclear Information System (INIS)

    Louhi, Amine

    2015-01-01

    The authorities have planned to increase the lifetime of currently operating nuclear power plants. The ageing of reinforced concrete structures such as cooling towers should be evaluated and its impact on the bearing capacity calculated. In the case of significant damage, the strengthening must be considered to ensure the sustainability of these towers facing the risk of storms and earthquakes becoming more and more frequent. This work aims to quantify the adverse effects that can generate concrete cracks and rebar section loss induced by corrosion, especially on the bearing capacity of nuclear power plant cooling towers under monotonic or cyclic extreme load conditions (wind and earthquake). These loads are certainly the most severe, since they take the structure into the nonlinear domain and can induce or amplify cracking damage. Numerical simulations are proposed to determine the quasi-static or dynamic response of the structure, taking into account appearance of concrete cracks and their evolution via an appropriate material concrete law and rebar's yielding. In the case of a seismic load, the responses are evaluated by three different methods; the nonlinear response history analysis (NLRHA), the response spectrum analysis and the modal response history analysis (MRHA) in order to compare the earthquake modeling approaches and to evaluate the robustness of the results. Parametric studies on damping, load combinations and structural configurations, are also performed. In the case of a wind load, the strengthening technique using composite materials, such as carbon fiber reinforced plastic (CFRP) is modeled. The behavior of the damaged structure with an advanced corrosion rate is estimated in the pre- and post-cracking regime, compared to the undamaged structure. The drop of bearing capacity is quantified, a reinforcement designed is proposed to restore the integrity and thus increase the lifetime of the structure. (author)

  6. Directionality Effects of Aligned Wind and Wave Loads on a Y-Shape Semi-Submersible Floating Wind Turbine under Rated Operational Conditions

    Directory of Open Access Journals (Sweden)

    Shengtao Zhou

    2017-12-01

    Full Text Available The Y-shape (triangular semi-submersible foundation has been adopted by most of the built full-scale floating wind turbines, such as Windfloat, Fukushima Mirai and Shimpuu. Considering the non-fully-symmetrical shape and met-ocean condition, the foundation laying angle relative to wind/wave directions will not only influence the downtime and power efficiency of the floating turbine, but also the strength and fatigue safety of the whole structure. However, the dynamic responses induced by various aligned wind and wave load directions have scarcely been investigated comparatively before. In our study, the directionality effects are investigated by means of combined wind and wave tests and coupled multi-body simulations. By comparing the measured data in three load directions, it is found that the differences of platform motions are mainly derived from the wave loads and larger pitch motion can always be observed in one of the directions. To make certain the mechanism underlying the observed phenomena, a coupled multi-body dynamic model of the floating wind turbine is established and validated. The numerical results demonstrate that the second-order hydrodynamic forces contribute greatly to the directionality distinctions for surge and pitch, and the first-order hydrodynamic forces determine the variations of tower base bending moments and nacelle accelerations. These findings indicate the directionality effects should be predetermined comprehensively before installation at sea, which is important for the operation and maintenance of the Y-shape floating wind turbines.

  7. Structure Optimal Design of Electromagnetic Levitation Load Reduction Device for Hydroturbine Generator Set

    Directory of Open Access Journals (Sweden)

    Qingyan Wang

    2015-01-01

    Full Text Available Thrust bearing is one part with the highest failure rate in hydroturbine generator set, which is primarily due to heavy axial load. Such heavy load often makes oil film destruction, bearing friction, and even burning. It is necessary to study the load and the reduction method. The dynamic thrust is an important factor to influence the axial load and reduction design of electromagnetic device. Therefore, in the paper, combined with the structure features of vertical turbine, the hydraulic thrust is analyzed accurately. Then, take the turbine model HL-220-LT-550, for instance; the electromagnetic levitation load reduction device is designed, and its mathematical model is built, whose purpose is to minimize excitation loss and total quality under the constraints of installation space, connection layout, and heat dissipation. Particle swarm optimization (PSO is employed to search for the optimum solution; finally, the result is verified by finite element method (FEM, which demonstrates that the optimized structure is more effective.

  8. Simplified rotor load models and fatigue damage estimates for offshore wind turbines.

    Science.gov (United States)

    Muskulus, M

    2015-02-28

    The aim of rotor load models is to characterize and generate the thrust loads acting on an offshore wind turbine. Ideally, the rotor simulation can be replaced by time series from a model with a few parameters and state variables only. Such models are used extensively in control system design and, as a potentially new application area, structural optimization of support structures. Different rotor load models are here evaluated for a jacket support structure in terms of fatigue lifetimes of relevant structural variables. All models were found to be lacking in accuracy, with differences of more than 20% in fatigue load estimates. The most accurate models were the use of an effective thrust coefficient determined from a regression analysis of dynamic thrust loads, and a novel stochastic model in state-space form. The stochastic model explicitly models the quasi-periodic components obtained from rotational sampling of turbulent fluctuations. Its state variables follow a mean-reverting Ornstein-Uhlenbeck process. Although promising, more work is needed on how to determine the parameters of the stochastic model and before accurate lifetime predictions can be obtained without comprehensive rotor simulations. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  9. Design Loads on Platforms on Offshore wind Turbine Foundations with Respect to Vertical Wave Run-up

    DEFF Research Database (Denmark)

    Damsgaard, Mathilde L.; Gravesen, Helge; Andersen, Thomas Lykke

    2007-01-01

    Experiences have shown that the vertical run-up generated by waves meeting the offshore wind turbine foundations, can result in rather vigorous loads on appurtenances and platform structures. This study aims to provide a qualitative method of determining run-up height and the following loads...

  10. Modelling the drained response of bucket foundations for offshore wind turbines under general monotonic and cyclic loading

    DEFF Research Database (Denmark)

    Foglia, Aligi; Gottardi, Guido; Govoni, Laura

    2015-01-01

    the typical conditions of offshore wind turbines: very large cyclic overturning moment, large cyclic horizontal load and comparatively little, self-weight induced, vertical load. The experimental soil-foundation response is interpreted within the macro-element approach, using an existing analytical model...

  11. Optimal control of a fuel cell/wind/PV/grid hybrid system with thermal heat pump load

    CSIR Research Space (South Africa)

    Sichilalu, S

    2016-10-01

    Full Text Available This paper presents an optimal energy management strategy for a grid-tied photovoltaic–wind-fuel cell hybrid power supply system. The hybrid system meets the load demand consisting of an electrical load and a heat pump water heater supplying thermal...

  12. Coordination of Voltage and Frequency Feedback in Load-Frequency Control Capability of Wind Turbine

    DEFF Research Database (Denmark)

    Hoseinzadeh, Bakhtyar; Silva, Filipe Faria Da; Bak, Claus Leth

    2014-01-01

    , sufficient reserve capacity should be procured. This paper addresses the Load-Frequency Control (LFC) scheme offered by VSWT. Feedback loop of locally measured voltage and frequency data is employed to improve transient and permanent response to achieve faster and more efficient LFC action and voltage...... regulation. The proposed scheme demonstrates remarkable improvement transient state of both voltage and frequency profiles in comparison with conventional LFC designs provided by Central Power Plants (CPP) or Wind Power Plants (WPP). Numerical simulations carried out in DigSilent Power- Factory confirm...

  13. Reduction Assessment of Agricultural Non-Point Source Pollutant Loading

    OpenAIRE

    Fu, YiCheng; Zang, Wenbin; Zhang, Jian; Wang, Hongtao; Zhang, Chunling; Shi, Wanli

    2018-01-01

    NPS (Non-point source) pollution has become a key impact element to watershed environment at present. With the development of technology, application of models to control NPS pollution has become a very common practice for resource management and Pollutant reduction control in the watershed scale of China. The SWAT (Soil and Water Assessment Tool) model is a semi-conceptual model, which was put forward to estimate pollutant production & the influences on water quantity-quality under different...

  14. Evaluation of MOSTAS computer code for predicting dynamic loads in two bladed wind turbines

    Science.gov (United States)

    Kaza, K. R. V.; Janetzke, D. C.; Sullivan, T. L.

    1979-01-01

    Calculated dynamic blade loads were compared with measured loads over a range of yaw stiffnesses of the DOE/NASA Mod-O wind turbine to evaluate the performance of two versions of the MOSTAS computer code. The first version uses a time-averaged coefficient approximation in conjunction with a multi-blade coordinate transformation for two bladed rotors to solve the equations of motion by standard eigenanalysis. The second version accounts for periodic coefficients while solving the equations by a time history integration. A hypothetical three-degree of freedom dynamic model was investigated. The exact equations of motion of this model were solved using the Floquet-Lipunov method. The equations with time-averaged coefficients were solved by standard eigenanalysis.

  15. Fusing Simulation Results From Multifidelity Aero-servo-elastic Simulators - Application To Extreme Loads On Wind Turbine

    DEFF Research Database (Denmark)

    Abdallah, Imad; Sudret, Bruno; Lataniotis, Christos

    2015-01-01

    Fusing predictions from multiple simulators in the early stages of the conceptual design of a wind turbine results in reduction in model uncertainty and risk mitigation. Aero-servo-elastic is a term that refers to the coupling of wind inflow, aerodynamics, structural dynamics and controls. Fusing...

  16. Time-Accurate Unsteady Pressure Loads Simulated for the Space Launch System at Wind Tunnel Conditions

    Science.gov (United States)

    Alter, Stephen J.; Brauckmann, Gregory J.; Kleb, William L.; Glass, Christopher E.; Streett, Craig L.; Schuster, David M.

    2015-01-01

    A transonic flow field about a Space Launch System (SLS) configuration was simulated with the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics (CFD) code at wind tunnel conditions. Unsteady, time-accurate computations were performed using second-order Delayed Detached Eddy Simulation (DDES) for up to 1.5 physical seconds. The surface pressure time history was collected at 619 locations, 169 of which matched locations on a 2.5 percent wind tunnel model that was tested in the 11 ft. x 11 ft. test section of the NASA Ames Research Center's Unitary Plan Wind Tunnel. Comparisons between computation and experiment showed that the peak surface pressure RMS level occurs behind the forward attach hardware, and good agreement for frequency and power was obtained in this region. Computational domain, grid resolution, and time step sensitivity studies were performed. These included an investigation of pseudo-time sub-iteration convergence. Using these sensitivity studies and experimental data comparisons, a set of best practices to date have been established for FUN3D simulations for SLS launch vehicle analysis. To the author's knowledge, this is the first time DDES has been used in a systematic approach and establish simulation time needed, to analyze unsteady pressure loads on a space launch vehicle such as the NASA SLS.

  17. A Case for Including Atmospheric Thermodynamic Variables in Wind Turbine Fatigue Loading Parameter Identification

    International Nuclear Information System (INIS)

    Kelley, Neil D.

    1999-01-01

    This paper makes the case for establishing efficient predictor variables for atmospheric thermodynamics that can be used to statistically correlate the fatigue accumulation seen on wind turbines. Recently, two approaches to this issue have been reported. One uses multiple linear-regression analysis to establish the relative causality between a number of predictors related to the turbulent inflow and turbine loads. The other approach, using many of the same predictors, applies the technique of principal component analysis. An examination of the ensemble of predictor variables revealed that they were all kinematic in nature; i.e., they were only related to the description of the velocity field. Boundary-layer turbulence dynamics depends upon a description of the thermal field and its interaction with the velocity distribution. We used a series of measurements taken within a multi-row wind farm to demonstrate the need to include atmospheric thermodynamic variables as well as velocity-related ones in the search for efficient turbulence loading predictors in various turbine-operating environments. Our results show that a combination of vertical stability and hub-height mean shearing stress variables meet this need over a period of 10 minutes

  18. Capacitive top-loading of a mobile phone antenna for size reduction

    DEFF Research Database (Denmark)

    Thaysen, Jesper; Jakobsen, Kaj Bjarne

    2004-01-01

    Capacitive top loading for size reduction of the Planar Inverted F Antenna (PIFA) is presented in this paper. A measured 39% reduction from 1.8 to 1.22 GHz of the resonant frequency is accomplished by using a 1.1 pF distributed capacitor. The simulated –6 dB bandwidth is 9% with a peak radiation ...

  19. Design and Implementation of a Thermal Load Reduction System in a Hyundai PHEV

    Energy Technology Data Exchange (ETDEWEB)

    Kreutzer, Cory J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rugh, John P [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-08-08

    Increased market penetration of electric drive vehicles (EDVs) requires overcoming a number of hurdles including limited vehicle range and the elevated cost of EDVs as compared to conventional vehicles. Climate control loads have a significant impact on range, cutting it by over 50% in both cooling and heating conditions. In order to minimize the impact of climate control on EDV range, the National Renewable Energy Laboratory has partnered with Hyundai America and key industry partners to quantify the performance of thermal load reduction technologies on a Hyundai Sonata PHEV. Technologies that impact vehicle cabin heating in cold weather conditions and cabin cooling in warm weather conditions were evaluated. Tests included thermal transient and steady-state periods for all technologies, including the development of a new test methodology to evaluate the performance of occupant thermal conditioning. Heated surfaces and increased insulation demonstrated significant reductions in energy use from steady-state heating, including a 29% - 59% reduction from heated surfaces. Solar control glass packages demonstrated significant reductions in energy use for both transient and steady-state cooling, with up to a 42% reduction in transient and 12.8% reduction in steady-state energy use for the packages evaluated. Technologies that demonstrated significant climate control load reduction were selected for incorporation into a complete thermal load reduction package. The complete package is set to be evaluated in the second phase of the ongoing project.

  20. Research of Short-range Missile Motion in Terms of Different Wind Loads

    Directory of Open Access Journals (Sweden)

    A. N. Klishin

    2015-01-01

    Full Text Available When modeling the aircraft motion it is advisable to choose a particular model of the Earth, depending both on the task and on the required accuracy of calculation. The article describes various models of the Earth, such as the flat Earth with a plane-parallel field of gravity, spherical and non-rotating Earth with a plane-parallel field of gravity, spherical and non-rotating Earth with a central gravitational field, spherical and non-rotating Earth, taking into account the polar flattening of the Earth, spherical Earth based compression and polar daily rotation. The article also considers the influence of these models on the motion of the selected aircraft.To date, there is technical equipment to provide highly accurate description of the Earthshape, gravitational field, etc. The improved accuracy of the Earth model description results in more correct description of the trajectory and motion parameters of a ballistic missile. However, for short ranges (10-20 km this accuracy is not essential, and, furthermore, it increases time of calculation. Therefore, there is a problem of choosing the optimal description of the Earth parameters.The motion in the model of the Earth, which takes into account a daily rotation of the planet and polar flattening, is discussed in more detail, and the geographical latitude impact on coordinates of the points of fall of a ballistic missile is analyzed on the basis of obtained graphs.The article individually considers a problem of the wind effect on the aircraft motion and defines dependences of the missile motion on the parameters of different wind loads, such as wind speed and height of its action.A mathematical model of the missile motion was built and numerically integrated, using the Runge-Kutta 4th order method, for implementation and subsequent analysis.Based on the analysis of the calculation results in the abovementioned models of the Earth, differences in impact of these models on the parameters of the

  1. Climate Control Load Reduction Strategies for Electric Drive Vehicles in Warm Weather

    Energy Technology Data Exchange (ETDEWEB)

    Jeffers, M. A.; Chaney, L.; Rugh, J. P.

    2015-04-30

    Passenger compartment climate control is one of the largest auxiliary loads on a vehicle. Like conventional vehicles, electric vehicles (EVs) require climate control to maintain occupant comfort and safety, but cabin heating and air conditioning have a negative impact on driving range for all electric vehicles. Range reduction caused by climate control and other factors is a barrier to widespread adoption of EVs. Reducing the thermal loads on the climate control system will extend driving range, thereby reducing consumer range anxiety and increasing the market penetration of EVs. Researchers at the National Renewable Energy Laboratory have investigated strategies for vehicle climate control load reduction, with special attention toward EVs. Outdoor vehicle thermal testing was conducted on two 2012 Ford Focus Electric vehicles to evaluate thermal management strategies for warm weather, including solar load reduction and cabin pre-ventilation. An advanced thermal test manikin was used to assess a zonal approach to climate control. In addition, vehicle thermal analysis was used to support testing by exploring thermal load reduction strategies, evaluating occupant thermal comfort, and calculating EV range impacts. Through stationary cooling tests and vehicle simulations, a zonal cooling configuration demonstrated range improvement of 6%-15%, depending on the drive cycle. A combined cooling configuration that incorporated thermal load reduction and zonal cooling strategies showed up to 33% improvement in EV range.

  2. Variation of Loads on Offshore Wind Turbine Drivetrains During Measured Shutdown Events

    DEFF Research Database (Denmark)

    Natarajan, Anand

    2016-01-01

    -megawatt wind turbine located at an offshore wind farm are correlated with corresponding observations of shutdowns on surrounding wind turbines. The observed wind turbines have multiple shutdowns at high mean wind speeds due to wind speed variations near cut-out. Through the use of an Inverse First Order...

  3. Analytical aeroelastic stability considerations and conversion loads for an XV-15 tilt-rotor in a wind tunnel simulation

    Science.gov (United States)

    Kottapalli, Sesi; Meza, Victor

    1992-01-01

    A rotorcraft analysis is conducted to assess tilt-rotor stability and conversion loads for the XV-15 rotor with metal blades within its specified test envelope. A 38-DOF flutter analysis based on the code by Johnson (1988) is developed to simulate a wind-tunnel test in which the rotor torque is constant and thereby study stability. The same analytical model provides the simulated loads including hub loads, blade loads, and oscillatory pitch-link loads with attention given to the nonuniform inflow through the proprotor in the presence of the wing. Tilt-rotor stability during the cruise mode is found to be sensitive to coupling effects in the control system stiffness, and a stability problem is identified in the XV-15 Advanced Technology Blades. The present analysis demonstrates that the tilt-rotor is stable within the specified test envelope of the NASA 40 x 80-ft wind tunnel.

  4. Wind Load Design of Hangar-Type Closed Steel Structures with Different Roof Pitches Using Abaqus CAE Software

    Directory of Open Access Journals (Sweden)

    Aybike Özyüksel Çiftçioğlu

    2017-05-01

    Full Text Available Structures convert the kinetic energy available in the air into potential energy which is in the form of pressure and suction forces reducing or fully stopping its motion. The potential impact of the wind depends on the geometric properties and pertinacity of a building, the angle of the wind flow, its strength and velocity. Design gains importance for tall buildings against the impact of the resonance along with the force based on pressure. Relevant calculations are made in Turkey based on the TS 498 Wind Load Velocity Criterion and this standard is currently being updated. This study develops the wind load design of hangar-type closed steel structures with different roof pitches using Abaqus CAE software.

  5. Computer-aided optimization of an offshore jacket for a wind turbine with a simplified load model

    OpenAIRE

    Bakkom, Ole Edvard

    2015-01-01

    In this report the jacket structure of a 5MW reference offshore wind turbine has been explored in terms of structural redundancy and for optimisation of the node locations. This has been done by the creation and utilisation of fully parametric scripts that creates input and post processes results from Abaqus CAE. The dynamic nature of offshore wind turbine forms a basis for complex loading of the jacket structure. This makes the analysis work needed to fully understand such structures substan...

  6. Operating and Loading Conditions of a Three-Level Neutral-Point-Clamped Wind Power Converter Under Various Grid Faults

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2014-01-01

    In order to fulfill the growing demands from the grid side, full-scale power converters are becoming popular in the wind turbine system. The low-voltage ride-through (LVRT) requirements may not only cause control problems but also result in overstressed components for the power converter. However...... are analytically solved and simulated. It has been found that the operating and loading conditions of the converter under LVRT strongly depend on the types/severity values of grid voltage dips and also the chosen control algorithms. The thermal distribution among the three phases of the converter may be quite......, the thermal loading of the wind power converter under various grid faults is still not yet clarified, particularly at megawatt power level. In this paper, the impacts by three types of grid faults to a three-level neutral-point-clamped (3L-NPC) wind power converter in terms of operating and loading conditions...

  7. Sliding mode load frequency control for multi-area time-delay power system with wind power integration

    DEFF Research Database (Denmark)

    Mi, Yang; Hao, Xuezhi; Liu, Yongjuan

    2017-01-01

    The interconnected time-delay power system has become an important issue for the open communication network. Meanwhile, due to the output power fluctuation of integrated wind energy, load frequency control (LFC) for power system with variable sources and loads has become more complicated. The novel...... the hitting condition. At last, the SM controller is proved by using the real-time digital simulator device under different case of time delay, wind penetration, load disturbance and operating point. The test results show that the proposed SM LFC can reduce frequency deviation and tie-line power fluctuation...... decentralised sliding mode (SM) LFC strategy is proposed for multi-area time-delay power system with significant wind power penetration. The appropriate switching surface gain is selected to assure the stability of power system with mismatched uncertainties. The SM controller is constructed to satisfy...

  8. Fastener load tests and retention systems tests for cryogenic wind-tunnel models

    Science.gov (United States)

    Wallace, J. W.

    1984-01-01

    A-286 stainless steel screws were tested to determine the tensile load capability and failure mode of various screw sizes and types at both cryogenic and room temperature. Additionally, five fastener retention systems were tested by using A-286 screws with specimens made from the primary metallic alloys that are currently used for cryogenic models. The locking system effectiveness was examined by simple no-load cycling to cryogenic temperatures (-275 F) as well as by dynamic and static loading at cryogenic temperatures. In general, most systems were found to be effective retention devices. There are some differences between the various devices with respect to ease of application, cleanup, and reuse. Results of tests at -275 F imply that the cold temperatures act to improve screw retention. The improved retention is probably the result of differential thermal contraction and/or increased friction (thread-binding effects). The data provided are useful in selecting screw sizes, types, and locking devices for model systems to be tested in cryogenic wind tunnels.

  9. A Method to Exchange Air Nitrogen Emission Reductions for Watershed Nitrogen Load Reductions

    Science.gov (United States)

    Presentation of the method developed for the Chesapeake Bay Program to estimate changes in nitrogen loading to Chesapeake due to changes in Bay State state-level nitrogen oxide emissions to support air-water trading by the Bay States. Type for SticsUnder AMAD Application QAPP, QA...

  10. [Suspension-sedimentation of sediment and release amount of internal load in Lake Taihu affected by wind].

    Science.gov (United States)

    Pang, Yong; Yan, Run-run; Yu, Zhong-bo; Li, Yi-ping; Li, Rui-ling

    2008-09-01

    The water quality in Meiliang Bay of the Taihu Lake was totally tested five times in the four seasons. The suspension samples were obtained by using a sediment trap. The sediment settling flux and resuspended flux were calculated according to the observation data by using Gansith formula, and the relationships between these fluxes and wind speeds were established. Seven experiments were conducted in Laboratory for hydrostatic settling behavior of suspended matter affected by different wind speeds in Lake Taihu. The hydrostatic settling fluxes of suspended matter were calculated and the relationships between the fluxes and suspended matter concentrations were established. Base on these works, the suspension-sedimentation process was decomposed and generalized according to the critical wind speed of 3.7 m/s. Daily sediment resuspended amount and settling amount of the year 2005 was calculated and annual average release amount of internal load in Lake Taihu was estimated using the wind data of nearly 10 years. The results indicate that daily release amount of internal load in Lake Taihu significantly influenced by wind and have the same trend of change with wind, while the release amount of different nutrients in the same condition are different. The Lake Taihu has an annual average release amount of internal load with COD 49,600 t, TN 7773.0 t and TP 275.5 t, of which summer has the markedly highest release amount than other seasons.

  11. Effect of vortex generators on the power conversion performance and structural dynamic loads of the Mod-2 wind turbine

    Science.gov (United States)

    Sullivan, T. L.

    1984-01-01

    Applying vortex generators from 20 to 100 percent span of the Mod-2 rotor resulted in a projected increase in annual energy capture of 20 percent and reduced the wind speed at which rated power is reached by nearly 3 m/sec. Application of vortex generators from 20 to 70 percent span, the fixed portion of the Mod-2 rotor, resulted in a projected increase in annual energy capture of about half this. This improved performance came at the cost of a small increase in cyclic blade loads in below rated power conditions. Cyclic blade loads were found to correlate well with the change in wind speed during one rotor revolution.

  12. Influence of Rigid Body Motions on Rotor Induced Velocities and Aerodynamic Loads of a Floating Horizontal Axis Wind Turbine

    DEFF Research Database (Denmark)

    de Vaal, Jacobus B.; Hansen, Martin Otto Laver; Moan, Torgeir

    2014-01-01

    This paper discusses the influence of rigid body motions on rotor induced velocities and aerodynamic loads of a floating horizontal axis wind turbine. Analyses are performed with a simplified free wake vortex model specifically aimed at capturing the unsteady and non-uniform inflow typically......, and captures the essential influences of rigid body motions on the rotor loads, induced velocities and wake influence....... experienced by a floating wind turbine. After discussing the simplified model in detail, comparisons are made to a state of the art free wake vortex code, using test cases with prescribed platform motion. It is found that the simplified model compares favourably with a more advanced numerical model...

  13. Multi-Temporal Decomposed Wind and Load Power Models for Electric Energy Systems

    Science.gov (United States)

    Abdel-Karim, Noha

    This thesis is motivated by the recognition that sources of uncertainties in electric power systems are multifold and may have potentially far-reaching effects. In the past, only system load forecast was considered to be the main challenge. More recently, however, the uncertain price of electricity and hard-to-predict power produced by renewable resources, such as wind and solar, are making the operating and planning environment much more challenging. The near-real-time power imbalances are compensated by means of frequency regulation and generally require fast-responding costly resources. Because of this, a more accurate forecast and look-ahead scheduling would result in a reduced need for expensive power balancing. Similarly, long-term planning and seasonal maintenance need to take into account long-term demand forecast as well as how the short-term generation scheduling is done. The better the demand forecast, the more efficient planning will be as well. Moreover, computer algorithms for scheduling and planning are essential in helping the system operators decide what to schedule and planners what to build. This is needed given the overall complexity created by different abilities to adjust the power output of generation technologies, demand uncertainties and by the network delivery constraints. Given the growing presence of major uncertainties, it is likely that the main control applications will use more probabilistic approaches. Today's predominantly deterministic methods will be replaced by methods which account for key uncertainties as decisions are made. It is well-understood that although demand and wind power cannot be predicted at very high accuracy, taking into consideration predictions and scheduling in a look-ahead way over several time horizons generally results in more efficient and reliable utilization, than when decisions are made assuming deterministic, often worst-case scenarios. This change is in approach is going to ultimately require new

  14. Wind Farms: Modeling and Control

    DEFF Research Database (Denmark)

    Soleimanzadeh, Maryam

    2012-01-01

    is minimized. The controller is practically feasible. Yet, the results on load reduction in this approach are not very significant. In the second strategy, the wind farm control problem has been divided into below rated and above rated wind speed conditions. In the above rated wind speed pitch angle and power....... Distributed controller design commences with formulating the problem, where a structured matrix approach has been put in to practice. Afterwards, an H2 control problem is implemented to obtain the controller dynamics for a wind farm such that the structural loads on wind turbines are minimized.......The primary purpose of this work is to develop control algorithms for wind farms to optimize the power production and augment the lifetime of wind turbines in wind farms. In this regard, a dynamical model for wind farms was required to be the basis of the controller design. In the first stage...

  15. Flow field and load characteristics of the whole MEXICO wind turbine

    DEFF Research Database (Denmark)

    Xu, Haoran; Yang, Hua; Liu, Chao

    2017-01-01

    CFD(Computational Fluid Dynamics) method was used to perform steady numerical simulation investigation on the flow field and load characteristics of MEXICO(Model EXperiment In Controlled cOnditions) wind turbine under non-yawed condition. Circumferentially-Averaged method was used to extract...... the calculated axial, radial and tangential components of velocity along the axial direction, then these components were compared with the experimental data, the compared results show that the computational components agree well with the experimental data and the computational results are reliable. The flow...... characteristics around the blade was analyzed and the points of flow separation were found along the blade, the results show that the points of flow separation move towards trailing edge with the increase of radius. The distribution of vorticity in the wake of MEXICO rotor was also analyzed. The distribution...

  16. Framing Failures in Wood-Frame Hip Roofs under Extreme Wind Loads

    Directory of Open Access Journals (Sweden)

    Sarah A. Stevenson

    2018-02-01

    Full Text Available Wood-frame residential roof failures are among the most common and expensive types of wind damage. Hip roofs are commonly understood to be more resilient during extreme wind in relation to gable roofs. However, inspection of damage survey data from recent tornadoes has revealed a previously unstudied failure mode in which hip roofs suffer partial failure of the framing structure. In the current study, evidence of partial framing failures and statistics of their occurrence are explored and discussed, while the common roof design and construction practice are reviewed. Two-dimensional finite element models are developed to estimate the element-level load effects on hip roof trusses and stick-frame components. The likelihood of failure in each member is defined based on relative demand-to-capacity ratios. Trussed and stick-frame structures are compared to assess the relative performance of the two types of construction. The present analyses verify the common understanding that toenailed roof-to-wall connections are likely to be the most vulnerable elements in the structure of a wood-frame hip roof. However, the results also indicate that certain framing members and connections display significant vulnerability under the same wind uplift, and the possibility of framing failure is not to be discounted. Furthermore, in the case where the roof-to-wall connection uses hurricane straps, certain framing members and joints become the likely points of failure initiation. The analysis results and damage survey observations are used to expand the understanding of wood-frame residential roof failures, as they relate to the Enhanced Fujita Scale and provide assessment of potential gaps in residential design codes.

  17. Climate Control Load Reduction Strategies for Electric Drive Vehicles in Cold Weather: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Jeffers, Matthew; Chaney, Lawrence; Rugh, John

    2016-03-31

    When operated, the climate control system is the largest auxiliary load on a vehicle. This load has significant impact on fuel economy for conventional and hybrid vehicles, and it drastically reduces the driving range of all electric vehicles (EVs). Heating is even more detrimental to EV range than cooling because no engine waste heat is available. Reducing the thermal loads on the heating, ventilating, and air conditioning system will extend driving range and increase the market penetration of EVs. Researchers at the National Renewable Energy Laboratory have evaluated strategies for vehicle climate control load reduction with special attention toward grid connected electric vehicles. Outdoor vehicle thermal testing and computational modeling were used to assess potential strategies for improved thermal management and to evaluate the effectiveness of thermal load reduction technologies. A human physiology model was also used to evaluate the impact on occupant thermal comfort. Experimental evaluations of zonal heating strategies demonstrated a 5.5% to 28.5% reduction in cabin heating energy over a 20-minute warm-up. Vehicle simulations over various drive cycles show a 6.9% to 18.7% improvement in EV range over baseline heating using the most promising zonal heating strategy investigated. A national-level analysis was conducted to determine the overall national impact. If all vehicles used the best zonal strategy, the range would be improved by 7.1% over the baseline heating range. This is a 33% reduction in the range penalty for heating.

  18. Comparison of calculated and measured blade loads on a full-scale tilting proprotor in a wind tunnel

    Science.gov (United States)

    Johnson, W.

    1980-01-01

    The loads measured in a wind tunnel on a full-scale tilting proprotor are compared with calculated results. The data consists primarily of oscillatory beamwise bending moments at 35% radial station, oscillatory spindle chord bending moments, and oscillatory pitch link loads. The measured and calculated results as a function of thrust are compared over a range of nacelle angles from 0 to 75 deg, and a range of speeds from 80 to 185 knots.

  19. The Role of Logistics in Practical Levelized Cost of Energy Reduction Implementation and Government Sponsored Cost Reduction Studies: Day and Night in Offshore Wind Operations and Maintenance Logistics

    DEFF Research Database (Denmark)

    Poulsen, Thomas; Hasager, Charlotte Bay; Jensen, Christian Munk

    2017-01-01

    contrast to the shore-based office personnel who develop studies directing cost reduction efforts. This paper details the company motivation to join industry-wide cost reduction initiatives. A business case for offshore wind operations and maintenance logistics yielding 1% savings in levelized cost...

  20. Loads Correlation of a Full-Scale UH-60A Airloads Rotor in a Wind Tunnel

    Science.gov (United States)

    Yeo, Hyeonsoo; Romander, Ethan A.

    2012-01-01

    Wind tunnel measurements of the rotor trim, blade airloads, and structural loads of a full-scale UH-60A Black Hawk main rotor are compared with calculations obtained using the comprehensive rotorcraft analysis CAMRAD II and a coupled CAMRAD II/OVERFLOW 2 analysis. A speed sweep at constant lift up to an advance ratio of 0.4 and a thrust sweep at constant speed into deep stall are investigated. The coupled analysis shows significant improvement over comprehensive analysis. Normal force phase is better captured and pitching moment magnitudes are better predicted including the magnitude and phase of the two stall events in the fourth quadrant at the deeply stalled condition. Structural loads are, in general, improved with the coupled analysis, but the magnitude of chord bending moment is still significantly underpredicted. As there are three modes around 4 and 5/rev frequencies, the structural responses to the 5/rev airloads due to dynamic stall are magnified and thus care must be taken in the analysis of the deeply stalled condition.

  1. Wind-Tunnel Investigations of Blunt-Body Drag Reduction Using Forebody Surface Roughness

    Science.gov (United States)

    Whitmore, Stephen A.; Sprague, Stephanie; Naughton, Jonathan W.; Curry, Robert E. (Technical Monitor)

    2001-01-01

    This paper presents results of wind-tunnel tests that demonstrate a novel drag reduction technique for blunt-based vehicles. For these tests, the forebody roughness of a blunt-based model was modified using micomachined surface overlays. As forebody roughness increases, boundary layer at the model aft thickens and reduces the shearing effect of external flow on the separated flow behind the base region, resulting in reduced base drag. For vehicle configurations with large base drag, existing data predict that a small increment in forebody friction drag will result in a relatively large decrease in base drag. If the added increment in forebody skin drag is optimized with respect to base drag, reducing the total drag of the configuration is possible. The wind-tunnel tests results conclusively demonstrate the existence of a forebody dragbase drag optimal point. The data demonstrate that the base drag coefficient corresponding to the drag minimum lies between 0.225 and 0.275, referenced to the base area. Most importantly, the data show a drag reduction of approximately 15% when the drag optimum is reached. When this drag reduction is scaled to the X-33 base area, drag savings approaching 45,000 N (10,000 lbf) can be realized.

  2. Application of a new method to determine the modal parameters of tall buildings under random wind loading

    NARCIS (Netherlands)

    Steenbergen, R.D.J.M.; Lentzen, S.S.K.

    2011-01-01

    Modal properties of high rise buildings are mostly derived from measurements on existing buildings under dynamic random wind loading. Measured accelerometer signals are translated into values for the natural frequency and damping. In order to obtain reliable values for the modal properties, the

  3. Modeling of quasi-static thrust load of wind turbines based on 1 s SCADA data

    Directory of Open Access Journals (Sweden)

    N. Noppe

    2018-03-01

    Full Text Available A reliable load history is crucial for a fatigue assessment of wind turbines. However, installing strain sensors on every wind turbine is not economically feasible. In this paper, a technique is proposed to reconstruct the thrust load history of a wind turbine based on high-frequency Supervisory Control and Data Acquisition (SCADA data. Strain measurements recorded during a short period of time are used to train a neural network. The selection of appropriate input parameters is performed based on Pearson correlation and mutual information. Once the training is done, the model can be used to predict the thrust load based on SCADA data only. The technique is validated on two different datasets, one consisting of simulation data (using the software FAST v8, created by Jonkman and Jonkman, 2016 obtained in a controllable environment and one consisting of measurements taken at an offshore wind turbine. In general, the relative error between simulated or measured and predicted thrust load barely exceeds 15 % during normal operation.

  4. Design of DC-DC Converter and its Control for a Wind Generation System Connected to an Isolated Load

    Directory of Open Access Journals (Sweden)

    Carlos A. Ramírez Gómez

    2013-11-01

    Full Text Available A method to design a Buck converter and its control, which are associated to a wind generation system that is feeding an isolated load, is presented in this paper. To design the converter a Thevenin equivalent is deduced, which represents the behavior of the wind turbine, the permanent magnet synchronous generator, and the rectifier. The design of the converter elements guarantees input/output voltages and inductor current ripples of 5 % or less. The output voltage control is developed with a proportional-integral-derivative controller and as design criteria a damping of 0,707 and cutoff frequency of 1/5 converter commutation frequency are selected. The designed controller regulates the output voltage faced load perturbations and wind speed variations. 

  5. Wind Loads on Ships and Offshore Structures Determined by Model Tests, CFD and Full-Scale Measurements

    DEFF Research Database (Denmark)

    Aage, Christian

    1998-01-01

    Wind loads on ships and offshore structures have until recently been determined only by model tests, or by statistical methods based on model tests. By the development of Computational Fluid Dynamics or CFD there is now a realistic computational alternative. In principle, both methods should...... be validated systematically against full-scale measurements, but due to the great practical difficulties involved, this is almost never done. In this investigation, wind loads on a seagoing ferry and on a semisubmersible platform have been determined by model tests and by CFD. On the ferry, full......-scale measurements have been carried out as well. The CFD method also offers the possibility of a computational estimate of scale effects related to wind tunnel model testing. An example of such an estimate on the ferry is discussed. This work has been published in more details in Proceedings of BOSS'97, Aage et al...

  6. Mechanical Loads Test Report for the U.S. Department of Energy 1.5-Megawatt Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Rick [Santos Wind Engineering Technologies, Inc., Portland, ME (United States); van Dam, Jeroen [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2015-07-16

    The objective of the test was to obtain a baseline characterization of the mechanical loads of the DOE 1.5 wind turbine located at NREL. The test was conducted in accordance with the International Electrotechnical Commission (IEC) Technical Specification, IEC 61400-13 Wind Turbine Generator Systems – Part 13: Measurement of mechanical loads; First Edition 2001-06 [1]. The National Wind Technology Center (NWTC) at NREL conducted this test in accordance with its quality system procedures so that the final test report meets the full requirements of its accreditation by the American Association for Laboratory Accreditation (A2LA). NREL’s quality system requires that all applicable requirements specified by A2LA and International Standards Organization/IEC 17025 be met or to note any exceptions in the test report.

  7. Air-Loads Prediction of a UH-60A Rotor inside the 40- by 80-Foot Wind Tunnel

    Science.gov (United States)

    Chang, I-Chung; Romander, Ethan A.; Potsdam, Mark; Yeo, Hyeonsoo

    2010-01-01

    The presented research extends the capability of a loose coupling computational fluid dynamics (CFD) and computational structure dynamics (CSD) code to calculate the flow-field around a rotor and test stand mounted inside a wind tunnel. Comparison of predicted air-load results for a full-scale UH-60A rotor recently tested inside the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel at Ames Research Center and in free-air flight are made for three challenging flight data points from the earlier conducted UH-60A Air-loads Program. Overall results show that the extension of the coupled CFD/CSD code to the wind-tunnel environment is generally successful.

  8. SIMULATION OF FRICTIONAL DISSIPATION UNDER BIAXIAL TANGENTIAL LOADING WITH THE METHOD OF DIMENSIONALITY REDUCTION

    Directory of Open Access Journals (Sweden)

    Andrey V. Dimaki

    2017-08-01

    Full Text Available The paper is concerned with the contact between the elastic bodies subjected to a constant normal load and a varying tangential loading in two directions of the contact plane. For uni-axial in-plane loading, the Cattaneo-Mindlin superposition principle can be applied even if the normal load is not constant but varies as well. However, this is generally not the case if the contact is periodically loaded in two perpendicular in-plane directions. The applicability of the Cattaneo-Mindlin superposition principle guarantees the applicability of the method of dimensionality reduction (MDR which in the case of a uni-axial in-plane loading has the same accuracy as the Cattaneo-Mindlin theory. In the present paper we investigate whether it is possible to generalize the procedure used in the MDR for bi-axial in-plane loading. By comparison of the MDR-results with a complete three-dimensional numeric solution, we arrive at the conclusion that the exact mapping is not possible. However, the inaccuracy of the MDR solution is on the same order of magnitude as the inaccuracy of the Cattaneo-Mindlin theory itself. This means that the MDR can be also used as a good approximation for bi-axial in-plane loading.

  9. Update on the Comparison of Second-Order Loads on a Tension Leg Platform for Wind Turbines: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Gueydon, Sebastien; Jonkman, Jason

    2016-08-01

    In comparison to other kinds of floaters (like a spar or a semisubmersible), the tension leg platform has several notable advantages: its vertical motions are negligible, its weight is lighter, and its mooring system's footprint is smaller. Although a tension leg platform has a negligible response to first-order vertical wave loads, the second-order wave loads need to be addressed. This paper follows up on a verification study of second-order wave loads on a tension leg platform for wind turbines done by the Maritime Research Institute of The Netherlands and National Renewable Energy Laboratory and it brings some corrections to its conclusions.

  10. Wind Tunnel Analysis of the Aerodynamic Loads on Rolling Stock over Railway Embankments: The Effect of Shelter Windbreaks

    Science.gov (United States)

    Avila-Sanchez, Sergio; Lopez-Garcia, Oscar; Sanz-Andres, Angel

    2014-01-01

    Wind-flow pattern over embankments involves an overexposure of the rolling stock travelling on them to wind loads. Windbreaks are a common solution for changing the flow characteristic in order to decrease unwanted effects induced by the presence of cross-wind. The shelter effectiveness of a set of windbreaks placed over a railway twin-track embankment is experimentally analysed. A set of two-dimensional wind tunnel tests are undertaken and results corresponding to pressure tap measurements over a section of a typical high-speed train are herein presented. The results indicate that even small-height windbreaks provide sheltering effects to the vehicles. Also, eaves located at the windbreak tips seem to improve their sheltering effect. PMID:25544954

  11. Economic emission dispatching with variations of wind power and loads using multi-objective optimization by learning automata

    International Nuclear Information System (INIS)

    Liao, H.L.; Wu, Q.H.; Li, Y.Z.; Jiang, L.

    2014-01-01

    Highlights: • Apply multi-objective optimization by learning automata to power system. • Sequentially dimensional search and state memory are incorporated. • Track dispatch under significant variations of wind power and load demand. • Good performance in terms of accuracy, distribution and computation time. - Abstract: This paper is concerned with using multi-objective optimization by learning automata (MOLA) for economic emission dispatching in the environment where wind power and loads vary. With its capabilities of sequentially dimensional search and state memory, MOLA is able to find accurate solutions while satisfying two objectives: fuel cost coupled with environmental emission and voltage stability. Its searching quality and efficiency are measured using the hypervolume indicator for investigating the quality of Pareto front, and demonstrated by tracking the dispatch solutions under significant variations of wind power and load demand. The simulation studies are carried out on the modified midwestern American electric power system and the IEEE 118-bus test system, in which wind power penetration and load variations present. Evaluated on these two power systems, MOLA is fully compared with multi-objective evolutionary algorithm based on decomposition (MOEA/D) and non-dominated sorting genetic algorithm II (NSGA-II). The simulation results have shown the superiority of MOLA over NAGA-II and MOEA/D, as it is able to obtain more accurate and widely distributed Pareto fronts. In the dynamic environment where the operation condition of both wind speed and load demand varies, MOLA outperforms the other two algorithms, with respect to the tracking ability and accuracy of the solutions

  12. Spatial optimization of watershed management practices for nitrogen load reduction using a modeling-optimization framework.

    Science.gov (United States)

    Yang, Guoxiang; Best, Elly P H

    2015-09-15

    Best management practices (BMPs) can be used effectively to reduce nutrient loads transported from non-point sources to receiving water bodies. However, methodologies of BMP selection and placement in a cost-effective way are needed to assist watershed management planners and stakeholders. We developed a novel modeling-optimization framework that can be used to find cost-effective solutions of BMP placement to attain nutrient load reduction targets. This was accomplished by integrating a GIS-based BMP siting method, a WQM-TMDL-N modeling approach to estimate total nitrogen (TN) loading, and a multi-objective optimization algorithm. Wetland restoration and buffer strip implementation were the two BMP categories used to explore the performance of this framework, both differing greatly in complexity of spatial analysis for site identification. Minimizing TN load and BMP cost were the two objective functions for the optimization process. The performance of this framework was demonstrated in the Tippecanoe River watershed, Indiana, USA. Optimized scenario-based load reduction indicated that the wetland subset selected by the minimum scenario had the greatest N removal efficiency. Buffer strips were more effective for load removal than wetlands. The optimized solutions provided a range of trade-offs between the two objective functions for both BMPs. This framework can be expanded conveniently to a regional scale because the NHDPlus catchment serves as its spatial computational unit. The present study demonstrated the potential of this framework to find cost-effective solutions to meet a water quality target, such as a 20% TN load reduction, under different conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Reduction of Thermal Loss in HTS Windings by Using Magnetic Flux Deflection

    Science.gov (United States)

    Tsuzuki, K.; Miki, M.; Felder, B.; Koshiba, Y.; Izumi, M.; Umemoto, K.; Aizawa, K.; Yanamoto, T.

    Efforts on the generation of intensified magnetic flux have been made for the optimized shape of HTS winding applications. This contributes to the high efficiency of the rotating machines using HTS windings. Heat generation from the HTS windings requires to be suppressed as much as possible, when those coils are under operation with either direct or alternative currents. Presently, the reduction of such thermal loss generated by the applied currents on the HTS coils is reported with a magnetic flux deflection system. The HTS coils are fixed together with flattened magnetic materials to realize a kind of redirection of the flux pathway. Eventually, the magnetic flux density perpendicular to the tape surface (equivalent to the a-b plane) of the HTS tape materials is reduced to the proximity of the HTS coil. To verify the new geometry of the surroundings of the HTS coils with magnetic materials, a comparative study of the DC coil voltage was done for different applied currents in prototype field-pole coils of a ship propulsion motor.

  14. Simulation of Irregular Waves and Wave Induced Loads on Wind Power Plants in Shallow Water

    Energy Technology Data Exchange (ETDEWEB)

    Trumars, Jenny [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Water Environment Transport

    2004-05-01

    The essay gives a short introduction to waves and discusses the problem with non-linear waves in shallow water and how they effect an offshore wind energy converter. The focus is on the realisation of non-linear waves in the time domain from short-term statistics in the form of a variance density spectrum of the wave elevation. For this purpose the wave transformation from deep water to the near to shore site of a wind energy farm at Bockstigen has been calculated with the use of SWAN (Simulating Waves Near Shore). The result is a wave spectrum, which can be used as input to the realisation. The realisation of waves is done by perturbation theory to the first and second-order. The properties calculated are the wave elevation, water particle velocity and acceleration. The wave heights from the second order perturbation equations are higher than those from the first order perturbation equations. This is also the case for the water particle kinematics. The increase of variance is significant between the first order and the second order realisation. The calculated wave elevation exhibits non-linear features as the peaks become sharper and the troughs flatter. The resulting forces are calculated using Morison's equation. For second order force and base moment there is an increase in the maximum values. The force and base moment are largest approximately at the zero up and down crossing of the wave elevation. This indicates an inertia dominated wave load. So far the flexibility and the response of the structure have not been taken into account. They are, however, of vital importance. For verification of the wave model the results will later on be compared with measurements at Bockstigen off the coast of Gotland in the Baltic Sea.

  15. Research and analysis on response characteristics of bracket-line coupling system under wind load

    Science.gov (United States)

    Jiayu, Zhao; Qing, Sun

    2018-01-01

    In this paper, a three-dimensional finite element model of bracket-line coupling system is established based on ANSYS software. Using the wind velocity time series which is generated by MATLAB as a power input, by comparing and analyzing the influence of different wind speeds and different wind attack angles, it is found that when 0 degree wind acts on the structure, wires have a certain damping effect in the bracket-line coupling system and at the same wind speed, the 90 degree direction is the most unfavorable wind direction for the whole structure according to the three kinds of angle wind calculated at present. In the bracket-line coupling system, the bracket structure is more sensitive to the increase of wind speed while the conductors are more sensitive to the change of wind attack angle.

  16. Aeroservoelastic Testing of Free Flying Wind Tunnel Models Part 2: A Centerline Supported Fullspan Model Tested for Gust Load Alleviation

    Science.gov (United States)

    Scott, Robert C.; Vetter, Travis K.; Penning, Kevin B.; Coulson, David A.; Heeg, Jennifer

    2014-01-01

    This is part 2 of a two part document. Part 1 is titled: "Aeroservoelastic Testing of Free Flying Wind Tunnel Models Part 1: A Sidewall Supported Semispan Model Tested for Gust Load Alleviation and Flutter Suppression." A team comprised of the Air Force Research Laboratory (AFRL), Boeing, and the NASA Langley Research Center conducted three aeroservoelastic wind tunnel tests in the Transonic Dynamics Tunnel to demonstrate active control technologies relevant to large, flexible vehicles. In the first of these three tests, a full-span, aeroelastically scaled, wind tunnel model of a joined wing SensorCraft vehicle was mounted to a force balance to acquire a basic aerodynamic data set. In the second and third tests, the same wind tunnel model was mated to a new, two degree of freedom, beam mount. This mount allowed the full-span model to translate vertically and pitch. Trimmed flight at10 percent static margin and gust load alleviation were successfully demonstrated. The rigid body degrees of freedom required that the model be flown in the wind tunnel using an active control system. This risky mode of testing necessitated that a model arrestment system be integrated into the new mount. The safe and successful completion of these free-flying tests required the development and integration of custom hardware and software. This paper describes the many systems, software, and procedures that were developed as part of this effort. The balance and free flying wind tunnel tests will be summarized. The design of the trim and gust load alleviation control laws along with the associated results will also be discussed.

  17. Induced Torques on Synchronous Generators from Operation of Wind Power Plant based on Full-Load Converter Interfaced Wind Turbines

    DEFF Research Database (Denmark)

    Knüppel, Thyge; Nielsen, Jørgen N.; Jensen, Kim H.

    2011-01-01

    It is expected that large wind power plants (WPP) contribute to stable and reliable operation of the electric power system. This includes participation with delivery of system services such as voltage and frequency support. With variable-speed WPPs this can be achieved by adding auxiliary control...... be predicted with the presented method. The work is based on a nonlinear, dynamic model of the 3.6 MW Siemens Wind Power wind turbine....... properties from the closed-loop system. A method based on induced torque coefficients (ITC) is here presented for assessing the closed-loop behavior from the open-loop system. Results are presented using both modal analysis and ITC prediction, which demonstrate that the dominant closed-loop behavior can...

  18. Detection and Use of Load and Gage Output Repeats of Wind Tunnel Strain-Gage Balance Data

    Science.gov (United States)

    Ulbrich, N.

    2017-01-01

    Criteria are discussed that may be used for the detection of load and gage output repeats of wind tunnel strain-gage balance data. First, empirical thresholds are introduced that help determine if the loads or electrical outputs of a pair of balance calibration or check load data points match. A threshold of 0.01 percent of the load capacity is suggested for the identification of matching loads. Similarly, a threshold of 0.1 microV/V is recommended for the identification of matching electrical outputs. Two examples for the use of load and output repeats are discussed to illustrate benefits of the implementation of a repeat point detection algorithm in a balance data analysis software package. The first example uses the suggested load threshold to identify repeat data points that may be used to compute pure errors of the balance loads. This type of analysis may reveal hidden data quality issues that could potentially be avoided by making calibration process improvements. The second example uses the electrical output threshold for the identification of balance fouling. Data from the calibration of a six-component force balance is used to illustrate the calculation of the pure error of the balance loads.

  19. Fusing Simulation Results From Multifidelity Aero-servo-elastic Simulators - Application To Extreme Loads On Wind Turbine

    DEFF Research Database (Denmark)

    Abdallah, Imad; Sudret, Bruno; Lataniotis, Christos

    2015-01-01

    Fusing predictions from multiple simulators in the early stages of the conceptual design of a wind turbine results in reduction in model uncertainty and risk mitigation. Aero-servo-elastic is a term that refers to the coupling of wind inflow, aerodynamics, structural dynamics and controls. Fusing...... the response data from multiple aero-servo-elastic simulators could provide better predictive ability than using any single simulator. The co-Kriging approach to fuse information from multifidelity aero-servo-elastic simulators is presented. We illustrate the co-Kriging approach to fuse the extreme flapwise...... bending moment at the blade root of a large wind turbine as a function of wind speed, turbulence and shear exponent in the presence of model uncertainty and non-stationary noise in the output. The extreme responses are obtained by two widely accepted numerical aero-servo-elastic simulators, FAST...

  20. Synthetic jet actuation for load control

    NARCIS (Netherlands)

    de Vries, Hein; van der Weide, Edwin Theodorus Antonius; Hoeijmakers, Hendrik Willem Marie

    2014-01-01

    The reduction of wind turbine blade loads is an important issue in the reduction of the costs of energy production. Reduction of the loads of a non-cyclic nature requires so-called smart rotor control, which involves the application of distributed actuators and sensors to provide fast and local

  1. Structural Reliability Aspects in Design of Wind Turbines

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2007-01-01

    Reliability assessment, optimal design and optimal operation and maintenance of wind turbines are an area of significant interest for the fast growing wind turbine industry for sustainable production of energy. Offshore wind turbines in wind farms give special problems due to wake effects inside...... the farm. Reliability analysis and optimization of wind turbines require that the special conditions for wind turbine operation are taken into account. Control of the blades implies load reductions for large wind speeds and parking for high wind speeds. In this paper basic structural failure modes for wind...

  2. Iterative data-driven load control for flexible wind turbine rotors

    NARCIS (Netherlands)

    Navalkar, S.T.

    2016-01-01

    Wind energy has reached a high degree ofmaturity: for wind-rich onshore locations, it is already competitive with conventional energy sources. However, for low-wind, remote and offshore regions, research efforts are still required to enhance its economic viability. While it is possible to reduce the

  3. Review of climatic input data for wind load design in accordance with SANS 10160-3

    CSIR Research Space (South Africa)

    Goliger, Adam MW

    2017-12-01

    Full Text Available background information on South African conditions. The need for updating the map for the free field wind speed is related also to the improved representation of the mixed and complex strong wind climate of the country. Furthermore, strong wind probability...

  4. Adding concentrated solar power plants to wind farms to achieve a good utility electrical load match

    Science.gov (United States)

    Texas has the greatest installed wind turbine capacity of any state in the United States, the percentage of wind capacity approaches 10% of the utilities capacity (in 2010 the total wind generated capacity in Texas was 8%). It is becomimg increasingly difficult for the utility to balance the elec...

  5. Wind Turbine Loads Induced by Terrain and Wakes: An Experimental Study through Vibration Analysis and Computational Fluid Dynamics

    Directory of Open Access Journals (Sweden)

    Francesco Castellani

    2017-11-01

    Full Text Available A wind turbine is a very well-known archetype of energy conversion system working at non-stationary regimes. Despite this, a deep mechanical comprehension of wind turbines operating in complicated conditions is still challenging, especially as regards the analysis of experimental data. In particular, wind turbines in complex terrain represent a very valuable testing ground because of the possible combination of wake effects among nearby turbines and flow accelerations caused by the terrain morphology. For these reasons, in this work, a cluster of four full-scale wind turbines from a very complex site is studied. The object of investigation is vibrations, at the level of the structure (tower and drive-train. Data collected by the on-board condition monitoring system are analyzed and interpreted in light of the knowledge of wind conditions and operating parameters collected by the Supervisory Control And Data Acquisition (SCADA. A free flow Computational Fluid Dynamics (CFD simulation is also performed, and it allows one to better interpret the vibration analysis. The main outcome is the interpretation of how wakes and flow turbulences appear in the vibration signals, both at the structural level and at the drive-train level. Therefore, this wind to gear approach builds a connection between flow phenomena and mechanical phenomena in the form of vibrations, representing a precious tool for assessing loads in different working conditions.

  6. INCA Modelling of the Lee System: strategies for the reduction of nitrogen loads

    Science.gov (United States)

    Flynn, N. J.; Paddison, T.; Whitehead, P. G.

    The Integrated Nitrogen Catchment model (INCA) was applied successfully to simulate nitrogen concentrations in the River Lee, a northern tributary of the River Thames for 1995-1999. Leaching from urban and agricultural areas was found to control nitrogen dynamics in reaches unaffected by effluent discharges and abstractions; the occurrence of minimal flows resulted in an upward trend in nitrate concentration. Sewage treatment works (STW) discharging into the River Lee raised nitrate concentrations substantially, a problem which was compounded by abstractions in the Lower Lee. The average concentration of nitrate (NO3) for the simulation period 1995-96 was 7.87 mg N l-1. Ammonium (NH4) concentrations were simulated less successfully. However, concentrations of ammonium rarely rose to levels which would be of environmental concern. Scenarios were run through INCA to assess strategies for the reduction of nitrate concentrations in the catchment. The conversion of arable land to ungrazed vegetation or to woodland would reduce nitrate concentrations substantially, whilst inclusion of riparian buffer strips would be unsuccessful in reducing nitrate loading. A 50% reduction in nitrate loading from Luton STW would result in a fall of up to 5 mg N l-1 in the reach directly affected (concentrations fell from maxima of 13 to 8 mg N l-1 , nearly a 40 % reduction), whilst a 20% reduction in abstractions would reduce maximum peaks in concentration in the lower Lee by up to 4 mg l-1 (from 17 to 13 mg N l-1, nearly a 25 % reduction),.

  7. Load and Flicker Mitigation of Grid-Connected Wind Turbines with DFIG

    DEFF Research Database (Denmark)

    Zhang, Yunqian

    , such as loss of a small amount of wind energy at low wind speeds and high demand of the pitch actuation system (PAS), are also pointed out. Taking advantage of the large inertia of the wind turbine rotor, a simple and effective method of Flicker mitigation by generator torque control of DFIG is proposed......, such that the power oscillation is stored as the kinetic energy of the wind turbine. Based on the flickermeter model, flicker level of the DFIG based wind turbine is investigated during continuous operation....

  8. Advanced Load Alleviation for Wind Turbines using Adaptive Trailing Edge Flaps: Sensoring and Control

    DEFF Research Database (Denmark)

    Andersen, Peter Bjørn

    The purpose of wind turbines and their predecessors the windmill, is to convert the energy in the wind to usable energy forms. Whereas windmills of the past focused on the conversion of wind power to torque for grinding, pumping and winching, modern wind turbines convert the wind energy into elec...... control. Active control is often considered costly but if the lifespan of the components can be increased it could be justifiable. This thesis covers various aspects of ‘smart control’ such as control theory, sensoring, optimization, experiments and numerical modeling....

  9. An error reduction algorithm to improve lidar turbulence estimates for wind energy

    Directory of Open Access Journals (Sweden)

    J. F. Newman

    2017-02-01

    Full Text Available Remote-sensing devices such as lidars are currently being investigated as alternatives to cup anemometers on meteorological towers for the measurement of wind speed and direction. Although lidars can measure mean wind speeds at heights spanning an entire turbine rotor disk and can be easily moved from one location to another, they measure different values of turbulence than an instrument on a tower. Current methods for improving lidar turbulence estimates include the use of analytical turbulence models and expensive scanning lidars. While these methods provide accurate results in a research setting, they cannot be easily applied to smaller, vertically profiling lidars in locations where high-resolution sonic anemometer data are not available. Thus, there is clearly a need for a turbulence error reduction model that is simpler and more easily applicable to lidars that are used in the wind energy industry. In this work, a new turbulence error reduction algorithm for lidars is described. The Lidar Turbulence Error Reduction Algorithm, L-TERRA, can be applied using only data from a stand-alone vertically profiling lidar and requires minimal training with meteorological tower data. The basis of L-TERRA is a series of physics-based corrections that are applied to the lidar data to mitigate errors from instrument noise, volume averaging, and variance contamination. These corrections are applied in conjunction with a trained machine-learning model to improve turbulence estimates from a vertically profiling WINDCUBE v2 lidar. The lessons learned from creating the L-TERRA model for a WINDCUBE v2 lidar can also be applied to other lidar devices. L-TERRA was tested on data from two sites in the Southern Plains region of the United States. The physics-based corrections in L-TERRA brought regression line slopes much closer to 1 at both sites and significantly reduced the sensitivity of lidar turbulence errors to atmospheric stability. The accuracy of machine

  10. Advanced load alleviation for wind turbines using adaptive trailing edge flaps: Sensoring and control

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, Peter Bjoern

    2010-02-15

    The purpose of wind turbines and their predecessors the windmill, is to convert the energy in the wind to usable energy forms. Whereas windmills of the past focused on the conversion of wind power to torque for grinding, pumping and winching, modern wind turbines convert the wind energy into electric power. They do so through incorporation of generators, which convert mechanical torque into electricity. Wind turbines are designed to keep the overall cost per produced Kilo Watt hour as low as possible. One way of improving the performance and lifetime of the wind turbine is through active flow control. Active control is often considered costly but if the lifespan of the components can be increased it could be justifiable. This thesis covers various aspects of 'smart control' such as control theory, sensoring, optimization, experiments and numerical modeling. (author)

  11. Sleeper Cab Climate Control Load Reduction for Long-Haul Truck Rest Period Idling

    Energy Technology Data Exchange (ETDEWEB)

    Lustbader, J. A.; Kreutzer, C.; Adelman, S.; Yeakel, S.; Zehme, J.

    2015-04-29

    Annual fuel use for long-haul truck rest period idling is estimated at 667 million gallons in the United States. The U.S. Department of Energy’s National Renewable Energy Laboratory’s CoolCab project aims to reduce heating, ventilating, and air conditioning (HVAC) loads and resulting fuel use from rest period idling by working closely with industry to design efficient long-haul truck climate control systems while maintaining occupant comfort. Enhancing the thermal performance of cab/sleepers will enable smaller, lighter, and more cost-effective idle reduction solutions. In order for candidate idle reduction technologies to be implemented at the original equipment manufacturer and fleet level, their effectiveness must be quantified. To address this need, a number of promising candidate technologies were evaluated through experimentation and modeling to determine their effectiveness in reducing rest period HVAC loads. For this study, load reduction strategies were grouped into the focus areas of solar envelope, occupant environment, and conductive pathways. The technologies selected for a complete-cab package of technologies were “ultra-white” paint, advanced insulation, and advanced curtains. To measure the impact of these technologies, a nationally-averaged solar-weighted reflectivity long-haul truck paint color was determined and applied to the baseline test vehicle. Using the complete-cab package of technologies, electrical energy consumption for long-haul truck daytime rest period air conditioning was reduced by at least 35% for summer weather conditions in Colorado. The National Renewable Energy Laboratory's CoolCalc model was then used to extrapolate the performance of the thermal load reduction technologies nationally for 161 major U.S. cities using typical weather conditions for each location over an entire year.

  12. Implementation and Assessment of a Decentralized Load Frequency Control: Application to Power Systems with High Wind Energy Penetration

    Directory of Open Access Journals (Sweden)

    Irene Muñoz-Benavente

    2017-01-01

    Full Text Available This paper describes and assesses a decentralized solution based on a wireless sensor-actuator network to provide primary frequency control from demand response in power systems with high wind energy penetration and, subsequently, with relevant frequency excursions. The proposed system is able to modify the electrical power demand of a variety of thermostatically-controlled loads, maintaining minimum comfort levels and minimizing both infrastructure requirements and primary reserves from the supply side. This low-cost hardware solution avoids any additional wiring, extending the wireless sensor-actuator network technology towards small customers, which account for over a 30% share of the current power demand. Frequency excursions are collected by each individual load controller, considering not only the magnitude of the frequency deviation, but also their evolution over time. Based on these time-frequency excursion characteristics, controllers are capable of modifying the power consumption of thermostatically-controlled loads by switching them off and on, thus contributing to primary frequency control in power systems with higher generation unit oscillations as a consequence of relevant wind power integration. Field tests have been carried out in a laboratory environment to assess the load controller performance, as well as to evaluate the electrical and thermal response of individual loads under frequency deviations. These frequency deviations are estimated from power systems with a high penetration of wind energy, which are more sensitive to frequency oscillations and where demand response can significantly contribute to mitigate these frequency excursions. The results, also included in the paper, evaluate the suitability of the proposed load controllers and their suitability to decrease frequency excursions from the demand side in a decentralized manner.

  13. Simulation of Moving Loads in Elastic Multibody Systems With Parametric Model Reduction Techniques

    Directory of Open Access Journals (Sweden)

    Fischer Michael

    2014-08-01

    Full Text Available In elastic multibody systems, one considers large nonlinear rigid body motion and small elastic deformations. In a rising number of applications, e.g. automotive engineering, turning and milling processes, the position of acting forces on the elastic body varies. The necessary model order reduction to enable efficient simulations requires the determination of ansatz functions, which depend on the moving force position. For a large number of possible interaction points, the size of the reduced system would increase drastically in the classical Component Mode Synthesis framework. If many nodes are potentially loaded, or the contact area is not known a-priori and only a small number of nodes is loaded simultaneously, the system is described in this contribution with the parameter-dependent force position. This enables the application of parametric model order reduction methods. Here, two techniques based on matrix interpolation are described which transform individually reduced systems and allow the interpolation of the reduced system matrices to determine reduced systems for any force position. The online-offline decomposition and description of the force distribution onto the reduced elastic body are presented in this contribution. The proposed framework enables the simulation of elastic multibody systems with moving loads efficiently because it solely depends on the size of the reduced system. Results in frequency and time domain for the simulation of a thin-walled cylinder with a moving load illustrate the applicability of the proposed method.

  14. Experimental data on load test and performance parameters of a LENZ type vertical axis wind turbine in open environment condition.

    Science.gov (United States)

    Sivamani, Seralathan; T, Micha Premkumar; Sohail, Mohammed; T, Mohan; V, Hariram

    2017-12-01

    Performance and load testing data of a three bladed two stage LENZ type vertical axis wind turbine from the experiments conducted in an open environment condition at Hindustan Institute of Technology and Science, Chennai (location 23.2167°N, 72.6833°E) are presented here. Low-wind velocity ranging from 2 to 11 m/s is available everywhere irrespective of climatic seasons and this data provides the support to the researchers using numerical tool to validate and develop an enhanced Lenz type design. Raw data obtained during the measurements are processed and presented in the form so as to compare with other typical outputs. The data is measured at different wind speeds prevalent in the open field condition ranging from 3 m/s to 9 m/s.

  15. Assessment of the Dynamic Behaviour of Saturated Soil Subjected to Cyclic Loading from Offshore Monopile Wind Turbine Foundations

    DEFF Research Database (Denmark)

    Damgaard, Mads; Bayat, Mehdi; Andersen, Lars Vabbersgaard

    2014-01-01

    The fatigue life of offshore wind turbines strongly depends on the dynamic behaviour of the structures including the underlying soil. To diminish dynamic amplification and avoid resonance, the eigenfrequency related to the lowest eigenmode of the wind turbine should not coalesce with excitation...... frequencies related to strong wind, wave and ice loading. Typically, lateral response of monopile foundations is analysed using a beam on a nonlinear Winkler foundation model with soil-pile interaction recommended by the design regulations. However, as it will be shown in this paper, the guideline approaches...... consequently underestimate the eigenfrequency compared to full-scale measurements. This discrepancy leads the authors to investigate the influence of pore water pressure by utilising a numerical approach and consider the soil medium as a two-phase system consisting of a solid skeleton and a single pore fluid...

  16. Dynamic Reliability Analysis of Gear Transmission System of Wind Turbine in Consideration of Randomness of Loadings and Parameters

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2014-01-01

    Full Text Available A dynamic model of gear transmission system of wind turbine is built with consideration of randomness of loads and parameters. The dynamic response of the system is obtained using the theory of random sampling and the Runge-Kutta method. According to rain flow counting principle, the dynamic meshing forces are converted into a series of luffing fatigue load spectra. The amplitude and frequency of the equivalent stress are obtained using equivalent method of Geber quadratic curve. Moreover, the dynamic reliability model of components and system is built according to the theory of probability of cumulative fatigue damage. The system reliability with the random variation of parameters is calculated and the influence of random parameters on dynamic reliability of components is analyzed. In the end, the results of the proposed method are compared with that of Monte Carlo method. This paper can be instrumental in the design of wind turbine gear transmission system with more advantageous dynamic reliability.

  17. Reduction of Cogging Torque in Dual Rotor Permanent Magnet Generator for Direct Coupled Wind Energy Systems

    Directory of Open Access Journals (Sweden)

    Sivachandran Paulsamy

    2014-01-01

    Full Text Available In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG for direct coupled stand alone wind energy systems (SAWES. Three methods were applied to reduce the cogging torque in DRFPMG. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA using MagNet Software. The cogging torque of DRFPMG has been reduced without major change in induced emf. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The test results have good agreement with the simulation predictions.

  18. Reduction of cogging torque in dual rotor permanent magnet generator for direct coupled wind energy systems.

    Science.gov (United States)

    Paulsamy, Sivachandran

    2014-01-01

    In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG) for direct coupled stand alone wind energy systems (SAWES). Three methods were applied to reduce the cogging torque in DRFPMG. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA) using MagNet Software. The cogging torque of DRFPMG has been reduced without major change in induced emf. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The test results have good agreement with the simulation predictions.

  19. Is There a Future for Nuclear Power? Wind and Emission Reduction Targets in Fossil-Fuel Alberta.

    Science.gov (United States)

    van Kooten, G Cornelis; Duan, Jun; Lynch, Rachel

    2016-01-01

    This paper explores the viability of relying on wind power to replace upwards of 60% of electricity generation in Alberta that would be lost if coal-fired generation is phased out. Using hourly wind data from 17 locations across Alberta, we are able to simulate the potential wind power output available to the Alberta grid when modern, 3.5 MW-capacity wind turbines are spread across the province. Using wind regimes for the years 2006 through 2015, we find that available wind power is less than 60% of installed capacity 98% of the time, and below 30% of capacity 74% of the time. There is only a small amount of correlation between wind speeds at different locations, but yet it remains necessary to rely on fossil fuel generation. Then, based on the results from a grid allocation model, we find that CO2 emissions can be reduced by about 30%, but only through a combination of investment in wind energy and reliance on purchases of hydropower from British Columbia. Only if nuclear energy is permitted into the generation mix would Alberta be able to meet its CO2-emissions reduction target in the electricity sector. With nuclear power, emissions can be reduced by upwards of 85%.

  20. Is There a Future for Nuclear Power? Wind and Emission Reduction Targets in Fossil-Fuel Alberta

    Science.gov (United States)

    Duan, Jun; Lynch, Rachel

    2016-01-01

    This paper explores the viability of relying on wind power to replace upwards of 60% of electricity generation in Alberta that would be lost if coal-fired generation is phased out. Using hourly wind data from 17 locations across Alberta, we are able to simulate the potential wind power output available to the Alberta grid when modern, 3.5 MW-capacity wind turbines are spread across the province. Using wind regimes for the years 2006 through 2015, we find that available wind power is less than 60% of installed capacity 98% of the time, and below 30% of capacity 74% of the time. There is only a small amount of correlation between wind speeds at different locations, but yet it remains necessary to rely on fossil fuel generation. Then, based on the results from a grid allocation model, we find that CO2 emissions can be reduced by about 30%, but only through a combination of investment in wind energy and reliance on purchases of hydropower from British Columbia. Only if nuclear energy is permitted into the generation mix would Alberta be able to meet its CO2-emissions reduction target in the electricity sector. With nuclear power, emissions can be reduced by upwards of 85%. PMID:27902712

  1. Coordination Between Wind Power, Hydro Storage Facility and Conventional Generating Units According to the Annual Growth Load

    Directory of Open Access Journals (Sweden)

    Shahrokh Shojaeean

    2013-04-01

    Full Text Available Considering the growing trend of the consumption of the electric power and the global tendency to substitute new renewable sources of energy, this paper proposes a Monte Carlo based method to determine an optimal level of this change. Considering the limitation of the wind farms in continuous supply of electric power, hydrostatic power storage facilities are used beside wind farms so that the electric power could be stored and fed in a continuous flow into power systems. Due to the gradual exclusion of conventional generators and 5 percent annual load increments, LOLE index was used in order to calculate the amount of the wind power and the capacity of the necessary power storage facility. To this end, LOLE index was calculated for the first year as the reference index for the estimation of the amount of wind power and the capacity of the storage facility in consequent years. For the upcoming years, calculations have been made to account for the gradual exclusion of conventional generators in proportion to load increments. The proposed method has been implemented and simulated on IEEE-RTS test system.

  2. Pitch link loads reduction of variable speed rotors by variable tuning frequency fluidlastic isolators

    Directory of Open Access Journals (Sweden)

    Han Dong

    2015-10-01

    Full Text Available To reduce the pitch link loads of variable speed rotors, variable tuning frequency fluidlastic isolators are proposed. This isolator utilizes the variation of centrifugal force due to the change of rotor speed to change the tuning port area ratio, which can change the tuning frequency of the isolator. A rotor model including the model of fluidlastic isolator is coupled with a fuselage model to predict the steady responses of the rotor system in forward flight. The aeroelastic analyses indicate that distinct performance improvement in pitch link load control can be achieved by the utilization of variable frequency isolators compared with the constant tuning frequency isolators. The 4/rev (per revolution pitch link load is observed to be reduced by 87.6% compared with the increase of 56.3% by the constant frequency isolator, when the rotor speed is reduced by 16.7%. The isolation ability at different rotor speeds in different flight states is investigated. To achieve overall load reduction within the whole range of rotor speed, the strategy of the variation of tuning frequency is adjusted. The results indicate that the 4/rev pitch link load within the whole rotor speed range is decreased.

  3. Power load reduction due to impurity radiation in ITER-like reactor

    International Nuclear Information System (INIS)

    Stankiewicz, R.; Zagorski, R.

    2001-01-01

    The reduction of power load to divertor target plates is a critical issue for long pulse and high power operation regime for magnetic confinement fusion devices. Thus additional losses are required to spread the power load over a wider area. Significant reduction of the heat load to the divertor plates can be achieved by strong impurities radiation in the SOL (Scrape-off Layer) and the core region. In order to asses correctly the heat load to the divertor plates the core region and SOL have to be treated self-consistently. In recent years the necessity of the self-consistent modelling of the plasma dynamics in the core and the scrape-off layer (SOL) has been widely recognised. In the paper the simple self-consistent model for the core and the SOL has been used. The model consists of 1-D analytical model for SOL plasma and 1-D core radial transport model for heat, bulk ions and impurities and is suitable to fast scans of the parameter space of the tokamak type reactor. The SOL model takes into account the strong variation of plasma parameters along the magnetic fields lines. The energy losses due to Bremsstrahlung and line radiation of sputtered and added impurities as well as alpha particles heating are included into the model. The sputtering phenomena and radiation cooling in the SOL and the core are treated in self-consistent way in the model. The heat transport has been described by the simple local transport model proposed by Mandrekas and Stacey reproducing the global confinement predictions or by the simple mixed Bohm and gyro Bohm model. Calculations have been performed to analyse the influence of the core-SOL coupling due to the production of sputtered impurities and its cooling effect in the new ITER-FEAT design. The problem of the choice of suitable materials for the plasma facing components in the ITER type reactor is also addressed. Analysis have been performed to investigate operating regimes of the reactor with deferent diverter plate materials and

  4. Framework for Testing the Effectiveness of Bat and Eagle Impact-Reduction Strategies at Wind Energy Projects

    Energy Technology Data Exchange (ETDEWEB)

    Sinclair, Karin [National Renewable Energy Lab. (NREL), Golden, CO (United States); DeGeorge, Elise [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-04-13

    The objectives of this framework are to facilitate the study design and execution to test the effectiveness of bat and eagle impact-reduction strategies at wind energy sites. Through scientific field research, the wind industry and its partners can help determine if certain strategies are ready for operational deployment or require further development. This framework should be considered a living document to be improved upon as fatality-reduction technologies advance from the initial concepts to proven readiness (through project- and technology-specific testing) and as scientific field methods improve.

  5. Uncertainty reduction as a measure of cognitive load in sentence comprehension.

    Science.gov (United States)

    Frank, Stefan L

    2013-07-01

    The entropy-reduction hypothesis claims that the cognitive processing difficulty on a word in sentence context is determined by the word's effect on the uncertainty about the sentence. Here, this hypothesis is tested more thoroughly than has been done before, using a recurrent neural network for estimating entropy and self-paced reading for obtaining measures of cognitive processing load. Results show a positive relation between reading time on a word and the reduction in entropy due to processing that word, supporting the entropy-reduction hypothesis. Although this effect is independent from the effect of word surprisal, we find no evidence that these two measures correspond to cognitively distinct processes. Copyright © 2013 Cognitive Science Society, Inc.

  6. Proportional resonant individual pitch control for mitigation of wind turbines loads

    DEFF Research Database (Denmark)

    Zhang, Yunqian; Chen, Zhe; Cheng, Ming

    2013-01-01

    coordinate frame. The new strategy can attenuate the 1p and higher harmonics on the wind turbine blades as well as 3p on the hub without any filters. The wind turbine code fatigue, aerodynamics, structures and turbulence is applied to a doubly fed induction generator-based wind power generation system....... The simulations are performed on the National Renewable Energy Laboratory 1.5 MW upwind reference wind turbine model. The simulation results are presented and discussed to demonstrate the capability and effectiveness of the proposed PR IPC method....

  7. An investigation of drag reduction for tractor trailer vehicles with air deflector and boattail. [wind tunnel tests

    Science.gov (United States)

    Muirhead, V. U.

    1981-01-01

    A wind tunnel investigation was conducted to determine the influence of several physical variables on the aerodynamic drag of a trailer model. The physical variables included: a cab mounted wind deflector, boattail on trailer, flow vanes on trailer front, forced transition on trailer, and decreased gap between tractor and trailer. Tests were conducted at yaw angles (relative wind angles) of 0, 5, 10, 20, and 30 degrees and Reynolds numbers of 3.58 x 10 to the 5th power 6.12 x 10 to the 5th power based upon the equivalent diameter of the vehicles. The wind deflector on top of the cab produced a calculated reduction in fuel consumption of about 5 percent of the aerodynamic portion of the fuel budget for a wind speed of 15.3 km/hr (9.5 mph) over a wind angle range of 0 deg to 180 deg and for a vehicle speed of 88.5 km/hr (55 mph). The boattail produced a calculated 7 percent to 8 percent reduction in fuel consumption under the same conditions. The decrease in gap reduced the calculated fuel consumption by about 5 percent of the aerodynamic portion of the fuel budget.

  8. The Role of Logistics in Practical Levelized Cost of Energy Reduction Implementation and Government Sponsored Cost Reduction Studies: Day and Night in Offshore Wind Operations and Maintenance Logistics

    Directory of Open Access Journals (Sweden)

    Thomas Poulsen

    2017-04-01

    Full Text Available This paper reveals that logistics make up at least 17% of annual operational expenditure costs for offshore wind farms. Annual operational expenditure is found to vary by a factor of 9.5, making its share of levelized cost of energy for offshore wind range from 13% to 57%. These are key findings of a 20-month research project targeting cost reduction initiatives for offshore wind systems. The findings reveal that cost-out measures are difficult to implement due to cultural differences. Implementation efforts are rendered by personnel located offshore in a harsh sea environment which is in stark contrast to the shore-based office personnel who develop studies directing cost reduction efforts. This paper details the company motivation to join industry-wide cost reduction initiatives. A business case for offshore wind operations and maintenance logistics yielding 1% savings in levelized cost of energy is included on how to expand working hours from daytime to also work at night.

  9. Analysis of 7- X 10-foot high speed wind tunnel shaft loads in support of fan blade failure investigation

    Science.gov (United States)

    Faison, Richard W.

    1987-01-01

    This is a report of the investigation of the High-Speed 7- X 10-Foot Wind Tunnel at NASA Langley Research Center, which experienced a catastrophic failure of all 18 Sitka spruce fan blades during operation at 0.8 Mach number on 2 July 1985. The High-Speed Tunnel, a closed-circuit/single-return atmospheric wind tunnel, had been operated since 1945 to support a wide range of subsonic aerodynamic tests and studies. The failed blade set had been in use since 1975. In addition to blade loss, the most significant damage was a bent main drive shaft for a total estimated damage loss of 1.7 million dollars. An analysis of the natural frequency characteristics as well as loads, reactions, stresses, and deflections of the fan drive system resulting from steady-state and dynamic loads due to unbalance was performed. Transient load cases were simulated by step input and ramp input loading functions intended to simulate the loss of one to nine blades (maximum unbalance forces).

  10. Wind pressure loading for tall buidings: a case study of Warsaw Trade Tower

    CSIR Research Space (South Africa)

    Cwik, M

    2012-12-01

    Full Text Available This paper presents an overview of wind-tunnel tests of one of the highest buildings in Poland - Warsaw Trade Tower. The aim of the tests was to evaluate the extreme values of wind pressure over building facade. In the first part, the development...

  11. Analysis of proton exchange membrane fuel cell catalyst layers for reduction of platinum loading at Nissan

    International Nuclear Information System (INIS)

    Ohma, Atsushi; Mashio, Tetsuya; Sato, Kazuyuki; Iden, Hiroshi; Ono, Yoshitaka; Sakai, Kei; Akizuki, Ken; Takaichi, Satoshi; Shinohara, Kazuhiko

    2011-01-01

    The biggest issue that must be addressed in promoting widespread use of fuel cell vehicles (FCVs) is to reduce the cost of the fuel cell system. Especially, it is of vital importance to reduce platinum (Pt) loading of catalyst layers (CLs) in the membrane electrode assembly (MEA) of a proton exchange membrane fuel cell (PEMFC). In order to lower the Pt loading of the MEA, mass transport of reactants related to the performance in high current density should be enhanced significantly as well as kinetics of the catalyst, which can result in the better Pt utilization and effectiveness. In this study, we summarized our analytical approach and methods for reduction of Pt loading in CLs. Microstructure, mass transport properties of the reactants, and their relation in CLs were elucidated by applying experimental analyses and computational methods. A simple CL model for I–V performance prediction was then established, where experimentally elucidated parameters of the microstructure and the properties in CLs were taken into account. Finally, we revealed the impact of lowering the Pt loading on the transport properties, polarization, and the I–V performance.

  12. Cogging Torque Reduction in a Permanent Magnet Wind Turbine Generator: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, E.; Green, J.

    2002-01-01

    In this paper, we investigate three design options to minimize cogging torque: uniformity of air gap, pole width, and skewing. Although the design improvement is intended for small wind turbines, it is also applicable to larger wind turbines.

  13. Wind reduction patterns around isolated biomass for wind erosion control in a desertified area of Central Sudan

    NARCIS (Netherlands)

    Nasr Al-amin, N.K.; Stigter, C.J.; El-Tayeb Mohammed, A.

    2010-01-01

    The aim of this study was to assess the effectiveness of sparse vegetation, feature common in arid zone, to reduce wind force (velocity) and hence protect the surface and regions downwind from drifting sand and their consequences. Respectively 4 (with heights h of 4, 3.2, 2 and 1.66 m), 2 (with h of

  14. Comoving frame models of hot star winds II. Reduction of O star wind mass-loss rates in global models

    Czech Academy of Sciences Publication Activity Database

    Krtička, J.; Kubát, Jiří

    2017-01-01

    Roč. 606, October (2017), A31/1-A31/12 E-ISSN 1432-0746 R&D Projects: GA ČR GA13-10589S Institutional support: RVO:67985815 Keywords : stars * winds * outflows Subject RIV: BN - Astronomy , Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 5.014, year: 2016

  15. Induced Torques on Synchronous Generators from Operation of Wind Power Plant based on Full-Load Converter Interfaced Wind Turbines

    DEFF Research Database (Denmark)

    Knüppel, Thyge; Nielsen, Jørgen N.; Jensen, Kim H.

    2011-01-01

    controllers that control the active and reactive power output accordingly. While being designed for a given system service, any feedback control affects the closed-loop behavior of the overall system and thereby its small-signal stability properties. Eigenvalue analysis conveniently determines the stability......It is expected that large wind power plants (WPP) contribute to stable and reliable operation of the electric power system. This includes participation with delivery of system services such as voltage and frequency support. With variable-speed WPPs this can be achieved by adding auxiliary...... properties from the closed-loop system. A method based on induced torque coefficients (ITC) is here presented for assessing the closed-loop behavior from the open-loop system. Results are presented using both modal analysis and ITC prediction, which demonstrate that the dominant closed-loop behavior can...

  16. An experimental study on the effect of wind load around tall towers of square and hexagonal shapes in staggered form

    Science.gov (United States)

    Anwar, Proma; Islam, Md. Quamrul; Ali, Mohammad

    2017-06-01

    In this research work an experiment is conducted to observe the effect of wind load around square and hexagonal shaped cylinders in staggered form. The experiment is performed in an open circuit wind tunnel at a Reynolds number of 4.23×104 based on the face width of the cylinder across the flow direction. The flow velocity has been kept uniform at 14.3 m/s throughout the experiment. The test is conducted for single cylinders first and then in staggered form. The cylinders are rotated to create different angles of attack and the angles are chosen at a definite interval. The static pressure readings are taken at different locations of the cylinder by inclined multi-manometers. From the surface static pressure readings pressure coefficients, drag coefficients and lift coefficients are calculated using numerical integration method. These results will surely help engineers to design buildings more stable against wind load. All the results are expressed in non-dimensional form, so that they can be applied for prototype structures.

  17. Investigation of the load reduction potential of two trailing edge flap controls using CFD

    DEFF Research Database (Denmark)

    Heinz, Joachim Christian; Sørensen, Niels N.; Zahle, Frederik

    2011-01-01

    In this work, a 2D aero‐servo‐elastic model of an airfoil section with 3 degrees of freedom (DOF) based on the 2D CFD solver EllipSys2D to calculate the aerodynamic forces is utilized to calculate the load reduction potential of an airfoil equipped with an adaptive trailing edge flap (ATEF......) and subjected to a turbulent inflow signal. The employed airfoil model corresponds to a successfully tested prototype airfoil where piezoelectric actuators were used for the flapping. In the present investigation two possible control methods for the flap are compared in their ability to reduce the fluctuating...

  18. Valence of wind power, photovoltaic and peak-load power plants as a part of the entire electricity system

    International Nuclear Information System (INIS)

    Schüppel, A.

    2014-01-01

    The transition to a higher share of renewable energy sources in the electricity sector leads to a multitude of challenges for the current electricity system. Within this thesis, the development of wind power and photovoltaics generation capacities in Germany is analysed based on the evaluation of technical and economic criteria. In order to derive those criteria, different scenarios with a separated and combined increase of wind and photovoltaics capacity are simulated using the model ATLANTIS. The results are compared to a reference scenario without additional wind and PV capacities. Furthermore, the value and functionality of the energy only market based on economic methods, as well as the value of peak load power plants based on opportunity costs are determined. The results of this thesis show, that the current market system is able to gain an additional annual welfare of four to six billion Euro at the best. This result shows that the task of optimising the power plant dispatch is well fulfilled by the current market design. However, the effects, e.g. fuel costs, which may influence this margin. The value of wind power and photovoltaics within the overall electricity system can be derived from the effort which is necessary to integrate these generation technologies into the existing system, and the changes in total costs of electricity generation. Based on the evaluation of time dependencies (seasonality of energy yield from wind and PV) as well as the development of total generation costs, the conclusion can be drawn that wind power is the more suitable RES generation technology for Germany. However, when it comes to grid integration measures, PV shows better results due to a higher generation potential in Southern Germany, which leads to a higher degree of utilisation. Therefore, there is no need to transport electricity from Northern to Southern Germany as it is the case with wind power. A common expansion of wind power and photovoltaics even shows slight

  19. Extreme Value Predictions for Wave- and Wind-induced Loads on Floating Offshore Wind Turbines using FORM

    DEFF Research Database (Denmark)

    Joensen, Sunvard; Jensen, Jørgen Juncher; Mansour, Alaa E.

    2007-01-01

    The aim of the present paper is to advocate for a very effective stochastic procedure, based on the First Order Reliability Method (FORM), for extreme value predic-tions related to wave induced loads. Due to the efficient optimisation procedures implemented in standard FORM codes and the short...... duration of the time domain simulations needed (typically 60-300s to cover the hy-drodynamic memory effects in the response) the calcu-lation of the mean out-crossing rates of a given response are very fast. Thus complicated non-linear effects can be included. The FORM analysis also identifies the most...

  20. Using wind speed from a blade-mounted flow sensor for power and load assessment on modern wind turbines

    DEFF Research Database (Denmark)

    Pedersen, Mads M.; Larsen, Torben J.; Madsen, Helge Aa

    2017-01-01

    with the actual power production as well as the flap-wise loads as it is measured close to the blade where the aerodynamic forces are acting. Conventional power curves are based on at least 180 h of 10 min mean values, but using the blade-mounted flow sensor both the observation average time and the overall...... assessment time can potentially be shortened. The basis for this hypothesis is that the sensor is able to provide more observations with higher accuracy, as the sensor follows the rotation of the rotor and because of the high correlation between the flow at the blades and the power production...

  1. Long-term global response analysis of a vertical axis wind turbine supported on a semi-submersible floating platform: Comparison between operating and non-operating wind turbine load cases

    DEFF Research Database (Denmark)

    Collu, Maurizio; Manuel, Lance; Borg, Michael

    2015-01-01

    is adopted, as well as also taking into account the drag generated by the wind turbine tower. Short-term turbine load and platform motion statistics are established for individual sea states that are analysed. The long-term reliability yields estimates of 50-year loads and platform motions that takes......This study continues [1] the examination of the long-term global response of a floating vertical axis wind turbine (VAWT) situated off the Portuguese coast in the Atlantic Ocean. The VAWT, which consists of a 5-MW 3-bladed H-type rotor developed as part of the EU-FP7 H2OCEAN project, is assumed...... into consideration response statistics from the simulations as well as the metocean (wind-wave) data and distributions. The results show that it is not necessarily the load cases associated with the highest wind speed that lead to the highest displacements and tensions in the mooring lines; differences among...

  2. Direct Embedding of Fiber-Optical Load Sensors into Wind Turbine Blades

    DEFF Research Database (Denmark)

    Glavind, Lars; Buggy, Stephen; Olesen, Ib S.

    Long Period Gratings were embedded into the adhesive utilized in the matrix of a wind turbine blade. The LPGs were subsequently subjected to temperature-testing in order to assess their performance, which illustrates good embedding capabilities....

  3. Investigation of the dependency of wind turbine loads on the simulation time

    OpenAIRE

    Tibaldi, Carlo; Henriksen, Lars Christian; Bak, Christian

    2014-01-01

    In this work the dependency of several wind turbine parameters with respect to the length of simulations used for their evaluation is investigated. The analysis is performed by computing the parameters with a different number of turbulent wind simulations, therefore simulation time, and repeating the computation with different turbulence realizations. The repetition of the computation is performed to identify the scatter of the parameters for a given number of turbulent seeds due to the diffe...

  4. Long-period gratings for selective monitoring of loads on a wind turbine blade.

    Science.gov (United States)

    Glavind, L; Buggy, S; Canning, J; Gao, S; Cook, K; Luo, Y; Peng, G D; Skipper, B F; Kristensen, M

    2014-06-20

    An optical fiber sensor based on long-period gratings (LPG) for selective measurements of flap- and edge-wise bending of a wind turbine blade is presented. Two consecutive LPGs separated by 40 mm interfere to improve resolution and reduce noise in a D-shaped fiber. The mode profile of the device was characterized experimentally to provide a model describing the mode couplings. The sensor was tested on a wind turbine blade.

  5. Small-Signal Stability Analysis of Full-Load Converter Interfaced Wind Turbines

    OpenAIRE

    Knüppel, Thyge; Akhmatov, Vladislav; Nielsen, Jørgen Nygård; Jensen, Kim H.; Dixon, Andrew; Østergaard, Jacob

    2009-01-01

    Power system stability investigations of wind farms often cover the tasks of low-voltage-fault-ride-through, voltage and reactive power control, and power balancing, but not much attention has yet been paid to the task of small-signal stability. Small-signal stability analysis needs increasing focus since the share of wind power increases substituting power generation from conventional power plants. Here, a study based on modal analysis is presented which investigate the effect of large scale...

  6. Water Quality Improvement through Reductions of Pollutant Loads on Small Scale of Bioretention System

    Science.gov (United States)

    Elyza Muha, Norshafa; Mohd Sidek, Lariyah; Jajarmizadeh, Milad

    2016-03-01

    Bioretention system is introduced as an important topic namely Urban Storm Water Management Manual for Malaysia (MSMA) by the Department of Irrigation and Drainage Malaysia (DID) in May 2012. The main objective of this paper is to evaluate the performance of water quality for small scale bioretention system under tropical climate via MUSIC model. Two bioretention systems 1 and 2 are observed based on the difference media depth. The result of bioretention system is compared with a reference model which has infrastructure with Urban Stormwater Improvement Conceptualisation (MUSIC) for pollutants load reduction and water quality results. Assessment of results via MUSIC software indicates a significant percentage of reduction for Total Suspended Solid (TSS), Total Phosphorus (TP) and Total Nitrogen (TN). The prediction of pollutant reduction via using MUSIC has the harmony for requirement in MSMA. TSS pollutant reduction is more than 80%, while for TP and TN more than 50%. The outcome of this study can be helpful for improvement of the existing MSMA guidelines for application of bioretention systems in Malaysia.

  7. Study on load-bearing characteristics of a new pile group foundation for an offshore wind turbine.

    Science.gov (United States)

    Lang, Ruiqing; Liu, Run; Lian, Jijian; Ding, Hongyan

    2014-01-01

    Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect.

  8. Study on Load-Bearing Characteristics of a New Pile Group Foundation for an Offshore Wind Turbine

    Science.gov (United States)

    Liu, Run; Lian, Jijian; Ding, Hongyan

    2014-01-01

    Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect. PMID:25250375

  9. Performance Evaluation of a Thermal Load Reduction System in a Hyundai Sonata PHEV

    Energy Technology Data Exchange (ETDEWEB)

    Kreutzer, Cory J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rugh, John P [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Titov, Eugene V [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Gallagher, James [Gentherm, Inc.; Scott, Matthew [Hyundai America Technical Center, Inc.

    2017-11-28

    Increased adoption of electric-drive vehicles (EDVs) requires overcoming hurdles including limited vehicle range. Vehicle cabin heating and cooling demand for occupant climate control requires energy from the main battery and has been shown to significantly degrade vehicle range. During peak cooling and heating conditions, climate control can require as much or more energy as propulsion. As part of an ongoing project, NREL and project partners Hyundai America Technical Center, Inc. (HATCI), Gentherm , Pittsburgh Glass Works (PGW), PPG Industries, Sekisui, 3M, and Hanon Systems developed a thermal load reduction system in order to reduce the range penalty associated with electric vehicle climate control. Solar reflective paint, solar control glass, heated and cooled/ventilated seats, heated surfaces, and heated windshield with door demisters were integrated into a Hyundai Sonata plug-in hybrid electric vehicle (PHEV). Cold weather field-testing was conducted in Fairbanks, Alaska while warm weather testing was conducted in Death Valley, California to assess the system performance in comparison to the baseline production vehicle. In addition, environmental chamber testing at peak heating and cooling conditions was performed to assess the performance of the system in standardized conditions compared to the baseline. Experimental results are presented in this paper providing quantitative data to automobile manufacturers on the impact of climate control thermal load reduction technologies to increase the advanced thermal technology adoption and market penetration of electric drive vehicles.

  10. Modelling reduction of urban heat load in Vienna by modifying surface properties of roofs

    Science.gov (United States)

    Žuvela-Aloise, Maja; Andre, Konrad; Schwaiger, Hannes; Bird, David Neil; Gallaun, Heinz

    2018-02-01

    The study examines the potential of urban roofs to reduce the urban heat island (UHI) effect by changing their reflectivity and implementing vegetation (green roofs) using the example of the City of Vienna. The urban modelling simulations are performed based on high-resolution orography and land use data, climatological observations, surface albedo values from satellite imagery and registry of the green roof potential in Vienna. The modelling results show that a moderate increase in reflectivity of roofs (up to 0.45) reduces the mean summer temperatures in the densely built-up environment by approximately 0.25 °C. Applying high reflectivity materials (roof albedo up to 0.7) leads to average cooling in densely built-up area of approximately 0.5 °C. The green roofs yield a heat load reduction in similar order of magnitude as the high reflectivity materials. However, only 45 % of roof area in Vienna is suitable for greening and the green roof potential mostly applies to industrial areas in city outskirts and is therefore not sufficient for substantial reduction of the UHI effect, particularly in the city centre which has the highest heat load. The strongest cooling effect can be achieved by combining the green roofs with high reflectivity materials. In this case, using 50 or 100 % of the green roof potential and applying high reflectivity materials on the remaining surfaces have a similar cooling effect.

  11. Estimated Pollution Reduction from Wind Farms in Oklahoma and Associated Economic and Human Health Benefits

    Directory of Open Access Journals (Sweden)

    J. Scott Greene

    2013-01-01

    Full Text Available Over the past few decades, there has been a recognition of the growing need for different forms of energy outside of fossil fuels. Since the latter half of the twentieth century individuals, corporations, and governments have become increasingly aware of the effects of the emissions of carbon and other harmful pollutants on the environment. With this greater concern has come increasing activity to combat these harmful emissions by using alternative fuel sources to power homes, businesses, and cities. As can be seen from recent trends in their installed capacity, it is clear that renewable energy resources will continue to be more commonly used in the future. As renewable energy increases, a decrease in a range of harmful pollutants from the energy sector will also occur. This paper provides a case study to estimate the potential environmental and health benefits of an increased shift from fossil fuels to renewable fuels for electrical production in Oklahoma. Results illustrate and quantify the specific reduction that wind energy can and will have on air quality, as well as provide a quantification of the associated potential health benefits.

  12. Application of microwaves for microbial load reduction in black pepper (Piper nigrum L.).

    Science.gov (United States)

    Jeevitha, G Chengaiyan; Sowbhagya, H Bogegowda; Hebbar, H Umesh

    2016-09-01

    Black pepper (Piper nigrum L.) is exposed to microbial contamination which could potentially create public health risk and also rejection of consignments in the export market due to non-adherance to microbial safety standards. The present study investigates the use of microwave (MW) radiation for microbial load reduction in black pepper and analyses the effect on quality. Black pepper was exposed to MWs at two different power levels (663 and 800 W) at an intensity of 40 W g(-1) for different time intervals (1-15 min) and moisture content (110 and 260 g kg(-1) on a wet basis). The exposure of black pepper to MWs at 663 W for 12.5 min was found to be sufficient to reduce the microbial load to the permissible level suggested by the International Commission on Microbiological Specifications for Foods and the European Spice Association. The retention of volatile oil, piperine and resin was 91.3 ± 0.03, 87.6 ± 0.02 and 90.7 ± 0.05%, respectively, in MW-treated black pepper. The final moisture content after MW treatment was found to be 100 ± 1 g kg(-1) for black pepper containing initial moisture of 260 ± 3 g kg(-1) . These results suggest that MW heating can be effectively used for microbial load reduction of black pepper without a significant loss in product quality. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  13. Dynamic programming for reduction of fuel consumption in a photovoltaic/wind/diesel generating system; Doteki keikakuho ni yoru taiyoko/furyoku/diesel hatsuden system no nenryo shohiryo no sakugen

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, K.; Kenmoku, Y.; Sakakibara, T. [Toyohashi University of Technology, Aichi (Japan); Nakagawa, S. [Maizuru National College of Technology, Kyoto (Japan); Kawamoto, T. [Shizuoka University, Shizuoka (Japan)

    1997-11-25

    Dynamic programming is employed in the study of the operation of the diesel engine in a photovoltaic/wind-force/diesel-engine power generating system, which aims at reduction in the system fuel consumption and at determining an optimum system constitution. The parameters set in this system are the photovoltaic/wind-force supply rate, photovoltaic/wind-force power generation ratio, and battery capacity. An island in Ise Bay, with an annual load power of approximately 1.59-million kWh and mean daily load power of approximately 4336kWh is assumed as the location for the system. Observation data of Ommaezaki Weather Station are utilized for the calculation of the amount of photovoltaic/wind-force power generation. It is found as the result that the fuel consumption of the diesel engine in this system decreases to 82-84% when the natural energy supply rate is 20%. It is also found that the fuel consumption of the system records the minimum at a photovoltaic/wind-force ratio of 60/40, irrespective of the battery capacity or natural energy supply rate, and this ratio is the optimum ratio. 3 refs., 9 figs., 1 tab.

  14. Active Aerodynamic Load Reduction on a Rotorcraft Fuselage With Rotor Effects: A CFD Validation Effort

    Science.gov (United States)

    Allan, Brian G.; Schaeffler, Norman W.; Jenkins, Luther N.; Yao, Chung-Sheng; Wong, Oliver D.; Tanner, Philip E.

    2015-01-01

    A rotorcraft fuselage is typically designed with an emphasis on operational functionality with aerodynamic efficiency being of secondary importance. This results in a significant amount of drag during high-speed forward flight that can be a limiting factor for future high-speed rotorcraft designs. To enable higher speed flight, while maintaining a functional fuselage design (i.e., a large rear cargo ramp door), the NASA Rotary Wing Project has conducted both experimental and computational investigations to assess active flow control as an enabling technology for fuselage drag reduction. This paper will evaluate numerical simulations of a flow control system on a generic rotorcraft fuselage with a rotor in forward flight using OVERFLOW, a structured mesh Reynolds-averaged Navier-Stokes flow solver developed at NASA. The results are compared to fuselage forces, surface pressures, and PN flow field data obtained in a wind tunnel experiment conducted at the NASA Langley 14-by 22-Foot Subsonic Tunnel where significant drag and download reductions were demonstrated using flow control. This comparison showed that the Reynolds-averaged Navier-Stokes flow solver was unable to predict the fuselage forces and pressure measurements on the ramp for the baseline and flow control cases. While the CFD was able to capture the flow features, it was unable to accurately predict the performance of the flow control.

  15. Combined Load Diagram for a Wind Tunnel Strain-Gage Balance

    Science.gov (United States)

    Ulbrich, N.

    2010-01-01

    Combined Load Diagrams for Direct-Read, Force, and Moment Balances are discussed in great detail in the paper. The diagrams, if compared with a corresponding combined load plot of a balance calibration data set, may be used to visualize and interpret basic relationships between the applied balance calibration loads and the load components at the forward and aft gage of a strain-age balance. Lines of constant total force and moment are identified in the diagrams. In addition, the lines of pure force and pure moment are highlighted. Finally, lines of constant moment arm are depicted. It is also demonstrated that each quadrant of a Combined Load Diagram has specific regions where the applied total calibration force is at, between, or outside of the balance gage locations. Data from the manual calibration of a Force Balance is used to illustrate the application of a Combined Load Diagram to a realistic data set.

  16. Measurements and simulations for peak electrical load reduction in cooling dominated climate

    International Nuclear Information System (INIS)

    Sadineni, Suresh B.; Boehm, Robert F.

    2012-01-01

    Peak electric demand due to cooling load in the Desert Southwest region of the US has been an issue for the electrical energy suppliers. To address this issue, a consortium has been formed between the University of Nevada Las Vegas, Pulte Homes (home builder) and NV Energy (local utility) in order to reduce the peak load by more than 65%. The implemented strategies that were used to accomplish that goal consist of energy efficiency in homes, onsite electricity generation through roof integrated PV, direct load control, and battery storage at the substation level. The simulation models developed using building energy analysis software were validated against measured data. The electrical energy demand for the upgraded home during peak period (1:00–7:00 PM) decreased by approximately 37% and 9% compared to a code standard home of the same size, due to energy efficiency and PV generation, respectively. The total decrease in electrical demand due to energy efficiency and PV generation during the peak period is 46%. Additionally, a 2.2 °C increase in thermostat temperature from 23.9 °C to 26.1 °C between 4:00 PM and 7:00 PM has further decreased the average demand during the peak period by 69% of demand from a standard home. -- Highlights: ► A study to demonstrate peak load reductions of 65% at the substation. ► A new residential energy efficient community named Villa Trieste is being developed. ► The peak demand from the homes has decreased by 37% through energy efficiency. ► A 1.8 kWp system along with energy efficiency measures decreased peak by 46%.

  17. Reduction of load-bearing capacity of all-ceramic crowns due to cement aging.

    Science.gov (United States)

    Lu, Chenglin; Wang, Raorao; Mao, Shuangshuang; Arola, Dwayne; Zhang, Dongsheng

    2013-01-01

    The purpose of this study was to investigate how water aging of the resin cement influences the stress distribution in all-ceramic crowns and if there is an increase in the propensity for crown failure. The failure of all-ceramic crowns attributed to cement degradation was explored using a combination of experimental and numerical methods. Sectioned all-ceramic crown specimens were fabricated of IPS e.max Ceram/e.max Press (CP) and Vita VM9/Cercon zirconia (VZ), and then stored in either air or distilled water for 30 days. Monotonic contact loads were applied to fracture near the buccal cusp ridge of each sample. Deformation within the crown layers during loading was analyzed by means of Digital Image Correlation (DIC). A 3D finite element model of the restoration including veneer, core, cement and tooth substrate was developed to evaluate the stress distribution in the crowns before and after cement degradation. There was a significant decrease (pcement water absorption in the CP crowns. In contrast, there was no significant influence of cement aging on fracture modes and fracture loads (p>0.05) in the VZ crowns. Finite element analysis showed that regardless of the crown types, the stress distribution is identical by degradation in Young's modulus of the cement. However, core/substrate debonding results in a change of the stress distribution and a significant increase in the magnitude. Water aging causes reduction of stiffness and bonding strength of cement agents. Degradation in bonding strength and stiffness could potentially lead to stress redistribution in the restored crown and reduce the load-bearing capacity of all-ceramic restorations after years of service. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Effect of Coupled Non linear Wave Kinematics and Soil Flexibility on the Design Loads of Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Kim, Taeseong; Natarajan, Anand

    2013-01-01

    in the presence of flexible soil conditions. The impact of moving to 35m water depths on monopile sub structure loads is quantified using irregular non linear wave kinematics interactions with the reduced natural frequencies of the sub structure resulting from soil flexibility. The wave kinematics is modeled...... without the need for geometric stretching methods. The effect of the nonlinear wave interaction sum frequencies on the support structure is investigated when the structural natural frequencies are reduced due to soil flexibility. The impact of the wave sum frequencies during the occurrence of extreme...... in soil properties and adequate damping in the support structure during wind/wave misalignment, without which monopile sub structural loading is highly amplified at 35m water depths compared to the design conditions at 20 m depths....

  19. Reduction method for residual stress of welded joint using harmonic vibrational load

    International Nuclear Information System (INIS)

    Aoki, Shigeru; Nishimura, Tadashi; Hiroi, Tetsumaro; Hirai, Seiji

    2007-01-01

    Welding is widely used for construction of many structures. Since welding is a process using locally given heat, residual stress is generated near the bead. Tensile residual stress degrades fatigue strength. Some reduction methods of residual stress have been presented and, for example, heat treatment and shot peening are practically used. However, those methods need special tools and are time consuming. In this paper, a new method for reduction of residual stress using harmonic vibrational load during welding is proposed. The proposed method is examined experimentally for some conditions. Two thin plates are supported on the supporting device and butt-welded using an automatic CO 2 gas shielded arc welding machine. Residual stress in the direction of the bead is measured by using a paralleled beam X-ray diffractometer with scintillation counter after removing quenched scale chemically. First, the welding of rolled steel for general structure for some excitation frequencies is examined. Specimens are welded along the groove on both sides. For all frequencies, tensile residual stress near the bead is significantly reduced. Second, welding of the specimen made of high tensile strength steel is examined. In this case, tensile residual stress near the bead is also reduced. Finally, the proposed method is examined by an analytical method. An analytical model which consists of mass and preloaded springs with elasto-plastic characteristic is used. Reduction of residual stress is demonstrated using this model

  20. The Reduction of Partitioned Wind and Water Erosion by Conservation Agriculture

    Science.gov (United States)

    Soil loss due to wind and water erosion degrades the soil and results in environmental problems downstream and downwind of the source field. Wind and water erosion may both occur to varying extents particularly in semi-arid environments. Soil conservation strategies require information about the p...

  1. An Error-Reduction Algorithm to Improve Lidar Turbulence Estimates for Wind Energy

    Energy Technology Data Exchange (ETDEWEB)

    Newman, Jennifer F.; Clifton, Andrew

    2016-08-01

    Currently, cup anemometers on meteorological (met) towers are used to measure wind speeds and turbulence intensity to make decisions about wind turbine class and site suitability. However, as modern turbine hub heights increase and wind energy expands to complex and remote sites, it becomes more difficult and costly to install met towers at potential sites. As a result, remote sensing devices (e.g., lidars) are now commonly used by wind farm managers and researchers to estimate the flow field at heights spanned by a turbine. While lidars can accurately estimate mean wind speeds and wind directions, there is still a large amount of uncertainty surrounding the measurement of turbulence with lidars. This uncertainty in lidar turbulence measurements is one of the key roadblocks that must be overcome in order to replace met towers with lidars for wind energy applications. In this talk, a model for reducing errors in lidar turbulence estimates is presented. Techniques for reducing errors from instrument noise, volume averaging, and variance contamination are combined in the model to produce a corrected value of the turbulence intensity (TI), a commonly used parameter in wind energy. In the next step of the model, machine learning techniques are used to further decrease the error in lidar TI estimates.

  2. Coupled vibrations of rectangular buildings subjected to normally-incident random wind loads

    Science.gov (United States)

    Safak, E.; Foutch, D.A.

    1987-01-01

    A method for analyzing the three-directional coupled dynamic response of wind-excited buildings is presented. The method is based on a random vibration concept and is parallel to those currently used for analyzing alongwind response. Only the buildings with rectangular cross-section and normally-incident wind are considered. The alongwind pressures and their correlations are represented by the well-known expressions that are available in the literature. The acrosswind forces are assumed to be mainly due to vortex shedding. The torque acting on the building is taken as the sum of the torque due to random alongwind forces plus the torque due to asymmetric acrosswind forces. The study shows the following: (1) amplitude of acrosswind vibrations can be several times greater than that of alongwind vibrations; (2) torsional vibrations are significant if the building has large frontal width, and/or it is asymmetric, and/or its torsional natural frequency is low; (3) even a perfectly symmetric structure with normally incident wind can experience significant torsional vibrations due to the randomness of wind pressures. ?? 1987.

  3. Direct load control for electricity supply and demand matching : increasing reliability of wind energy

    NARCIS (Netherlands)

    Hoeve ten, Marieke

    2009-01-01

    In Sweden as well as in The Netherlands energy policy is increasingly aiming at extending the use of renew-able sources. In accordance with the targets of the European Union, both countries have formulated national targets for the year 2020. For wind ener

  4. Spectral tensor parameters for wind turbine load modeling from forested and agricultural landscapes

    DEFF Research Database (Denmark)

    Chougule, Abhijit S.; Mann, Jakob; Segalini, A.

    2015-01-01

    A velocity spectral tensor model was evaluated from the single-point measurements of wind speed. The model contains three parameters representing the dissipation rate of specific turbulent kinetic energy, a turbulence length scale and the turbulence anisotropy. Sonic anemometer measurements taken...

  5. Use of Three-Level Power Converters in Wind-Driven Permanent-Magnet Synchronous Generators with Unbalanced Loads

    Directory of Open Access Journals (Sweden)

    Ming-Hung Chen

    2015-06-01

    Full Text Available This paper describes the design and implementation of three-level power converters for wind-driven permanent-magnet synchronous generators with unbalanced loads. To increase voltage stress and reduce current harmonics in the electrical power generated by a wind generator, a three-phase, three-level rectifier is used. Because a synchronous rotating frame is used on the AC-input side, the use of a neutral-point-clamped controller is proposed to increase the power factor to unity and reduce current harmonics. Furthermore, a novel six-leg inverter is proposed for transferring energy from the DC voltage to a three-phase, four-wire AC source with a constant voltage and a constant frequency. The power converters also contain output transformers and filters for power buffering and filtering, respectively. All three output phase voltages are fed back to control the inverter output during load variations. A digital signal processor is used as the core control device for implementing a 1.5 kV, 75 kW drive system. Experimental data show that the power factor is successfully increased to unity and the total current harmonic distortion is 3.2% on the AC-input side. The entire system can attain an efficiency of 91%, and the voltage error between the upper and lower capacitors is approximately zero. Experimental results that confirm the high performance of the proposed system are presented.

  6. Reduction of teat skin mastitis pathogen loads: differences between strains, dips, and contact times.

    Science.gov (United States)

    Enger, B D; Fox, L K; Gay, J M; Johnson, K A

    2015-02-01

    The purpose of these experiments was to (1) assess differences in mastitis pathogen strain sensitivities to teat disinfectants (teat dips), and (2) determine the optimum time for premilking teat dips to remain in contact with teat skin to reduce pathogen loads on teat skin. Two experiments were conducted using the excised teat model. In experiment 1, the differences in mastitis pathogen strain sensitivities to 4 commercially available dips (dip A: 1% H2O2; dip B: 1% chlorine dioxide; dip C: 1% iodophor; and dip D: 0.5% iodophor) were evaluated. Four strains of 11 common mastitis pathogens (Staphylococcus aureus, Streptococcus agalactiae, Mycoplasma bovis, Streptococcus dysgalactiae, Streptococcus uberis, Escherichia coli, Staphylococcus chromogenes, Staphylococcus epidermidis, Staphylococcus hyicus, Staphylococcus xylosus, and Staphylococcus haemolyticus) were tested. In experiment 2, the percentage log reduction of mastitis pathogens (Escherichia coli, Streptococcus uberis, Streptococcus dysgalactiae, Klebsiella species, Staphylococcus chromogenes, Staphylococcus haemolyticus, Staphylococcus xylosus, and Staphylococcus epidermidis) on teat skin with 3 commercially available teat dips: dip A; dip D; and dip E: 0.25% iodophor, using dip contact times of 15, 30, and 45 s, was evaluated. Experiment 1 results indicated significant differences in strain sensitivities to dips within pathogen species: Staphylococcus aureus, Staphylococcus chromogenes, and Streptococcus uberis. Species differences were also found where Mycoplasma bovis (97.9% log reduction) was the most sensitive to tested teat dips and Staphylococcus haemolyticus (71.4% log reduction) the most resistant. Experiment 2 results indicated that contact times of 30 and 45 s were equally effective in reducing recovered bacteria for dips D and E and were also significantly more effective than a 15-s contact time. No differences were seen in recovered bacteria between tested contact times after treatment with dip

  7. Full scale testing of wind turbine blade to failure - flapwise loading

    DEFF Research Database (Denmark)

    Jørgensen, E.R.; Borum, Kaj Kvisgaard; McGugan, Malcolm

    2004-01-01

    for the detection of damages in the blade during the test. The report contains measurements of the total deflection of the blade, the local deflection of the skinand the load carrying main spar and also measurement of strain all as a function of the applied load and up to failure of the blade. The “post mortem......” analysis and description of how the damages propagate du-ring the tests are reported in a separatereport....

  8. Load Flow Analysis of Hybrid AC-DC Power System with Offshore Wind Power

    DEFF Research Database (Denmark)

    Dhua, Debasish; Huang, Shaojun; Wu, Qiuwei

    2017-01-01

    is to model such hybrid AC-DC systems including the interfacing converters, which have several control parameters that can change the load flow of the hybrid systems. Then, the paper proposes a Load Flow algorithm based on the Newton-Raphson method, which covers three different section types...... of the transmission system: the AC parts, the DC parts and the interfacing converters. Finally, this paper validates this algorithm through a detailed case study with a typical hybrid network...

  9. Computer subroutine for estimating aerodynamic blade loads on Darrieus vertical axis wind turbines. [FORCE code

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, W. N.; Leonard, T. M.

    1980-11-01

    An important aspect of structural design of the Darrieus rotor is the determination of aerodynamic blade loads. This report describes a load generator which has been used at Sandia for quasi-static and dynamic rotor analyses. The generator is based on the single streamtube aerodynamic flow model and is constructed as a FORTRAN IV subroutine to facilitate its use in finite element structural models. Input and output characteristics of the subroutine are described and a complete listing is attached as an appendix.

  10. The role of wind field induced flow velocities in destratification and hypoxia reduction at Meiling Bay of large shallow Lake Taihu, China.

    Science.gov (United States)

    Jalil, Abdul; Li, Yiping; Du, Wei; Wang, Wencai; Wang, Jianwei; Gao, Xiaomeng; Khan, Hafiz Osama Sarwar; Pan, Baozhu; Acharya, Kumud

    2018-01-01

    Wind induced flow velocity patterns and associated thermal destratification can drive to hypoxia reduction in large shallow lakes. The effects of wind induced hydrodynamic changes on destratification and hypoxia reduction were investigated at the Meiling bay (N 31° 22' 56.4″, E 120° 9' 38.3″) of Lake Taihu, China. Vertical flow velocity profile analysis showed surface flow velocities consistency with the wind field and lower flow velocity profiles were also consistent (but with delay response time) when the wind speed was higher than 6.2 m/s. Wind field and temperature found the control parameters for hypoxia reduction and for water quality conditions at the surface and bottom profiles of lake. The critical temperature for hypoxia reduction at the surface and the bottom profile was ≤24.1C° (below which hypoxic conditions were found reduced). Strong prevailing wind field (onshore wind directions ESE, SE, SSE and E, wind speed ranges of 2.4-9.1 m/s) reduced the temperature (22C° to 24.1C°) caused reduction of hypoxia at the near surface with a rise in water levels whereas, low to medium prevailing wind field did not supported destratification which increased temperature resulting in increased hypoxia. Non-prevailing wind directions (offshore) were not found supportive for the reduction of hypoxia in study area due to less variable wind field. Daytime wind field found more variable (as compared to night time) which increased the thermal destratification during daytime and found supportive for destratification and hypoxia reduction. The second order exponential correlation found between surface temperature and Chlorophyll-a (R 2 : 0.2858, Adjusted R-square: 0.2144 RMSE: 4.395), Dissolved Oxygen (R 2 : 0.596, Adjusted R-square: 0.5942, RMSE: 0.3042) concentrations. The findings of the present study reveal the driving mechanism of wind induced thermal destratification and hypoxic conditions, which may further help to evaluate the wind role in eutrophication

  11. Vibration reduction of beams under successive traveling loads by means of linear and nonlinear dynamic absorbers

    Science.gov (United States)

    Samani, Farhad S.; Pellicano, Francesco

    2012-05-01

    The goal of the present work is to assess the performances of dynamic vibration absorbers (DVA) in suppressing the vibrations of a simply supported beam subjected to an infinite sequence of regularly spaced concentrated moving loads. In particular, several types of DVA are considered: linear, cubic, higher odd-order monomials and piecewise linear stiffness; linear, cubic and linear-quadratic viscous damping. The purpose is to clarify if nonlinear DVAs show improvements with respect to the classical linear devices. The dynamic scenario is deeply investigated in a wide range of operating conditions, spanning the parameter space of the DVA (damping, stiffness). Nonlinear stiffness can lead to complex dynamics such as quasi-periodic, chaotic and sub-harmonic responses; moreover, acting on the stiffness nonlinearity no improvement is found with respect to the linear DVA. A nonlinear non-symmetric dissipation in the DVA leads to a great reduction of the beam response, the reduction is larger with respect to the linear DVA.

  12. Rate bounded linear parameter varying control of a wind turbine in full load operation

    DEFF Research Database (Denmark)

    Østergaard, Kasper Zinck; Stoustrup, Jakob; Brath, Per

    2008-01-01

    This paper considers the control of wind turbines using an LPV design technique. The controller design is done by a combination of a method that uses elimination of controller variables and a method using a congruent transformation followed by a change of variables. An investigation is performed...... to understand the gap between zero rate of variation and arbitrary fast rate of variation for the selected scheduling variable. In particular it is analysed for which rate of variation, the local performance level starts to deteriorate from the performance level that can be obtained locally by LTI controllers....... A rate of variation is selected which is expected only to be exceeded outside the normal wind turbine operating conditions. For this rate of variation a controller has been designed and simulations show a performance level over the operating region which is very similar to what can be obtained by LTI...

  13. ASSESSMENT OF A WIND TURBINE INTELLIGENT CONTROLLER FOR ENHANCED ENERGY PRODUCTION AND POLLUTION REDUCTION

    Science.gov (United States)

    This study assessed the enhanced energy production which is possible when variable-speed wind turbines are electronically controlled by an intelligent controller for efficiency optimization and performance improvement. The control system consists of three fuzzy- logic controllers...

  14. Model Development and Loads Analysis of an Offshore Wind Turbine on a Tension Leg Platform with a Comparison to Other Floating Turbine Concepts: April 2009

    Energy Technology Data Exchange (ETDEWEB)

    Matha, D.

    2010-02-01

    This report presents results of the analysis of a 5-MW wind turbine located on a floating offshore tension leg platform (TLP) that was conducted using the fully coupled time-domain aero-hydro-servo-elastic design code FAST with AeroDyn and HydroDyn. The report also provides a description of the development process of the TLP model. The model has been verified via comparisons to frequency-domain calculations. Important differences have been identified between the frequency-domain and time-domain simulations, and have generated implications for the conceptual design process. An extensive loads and stability analysis for ultimate and fatigue loads according to the procedure of the IEC 61400-3 offshore wind turbine design standard was performed with the verified TLP model. This report compares the loads for the wind turbine on the TLP to those of an equivalent land-based turbine. Major instabilities for the TLP are identified and described.

  15. The impacts of electricity dispatch protocols on the emission reductions due to wind power and carbon tax.

    Science.gov (United States)

    Yu, Yang; Rajagopal, Ram

    2015-02-17

    Two dispatch protocols have been adopted by electricity markets to deal with the uncertainty of wind power but the effects of the selection between the dispatch protocols have not been comprehensively analyzed. We establish a framework to compare the impacts of adopting different dispatch protocols on the efficacy of using wind power and implementing a carbon tax to reduce emissions. We suggest that a market has high potential to achieve greater emission reduction by adopting the stochastic dispatch protocol instead of the static protocol when the wind energy in the market is highly uncertain or the market has enough adjustable generators, such as gas-fired combustion generators. Furthermore, the carbon-tax policy is more cost-efficient for reducing CO2 emission when the market operates according to the stochastic protocol rather than the static protocol. An empirical study, which is calibrated according to the data from the Electric Reliability Council of Texas market, confirms that using wind energy in the Texas market results in a 12% CO2 emission reduction when the market uses the stochastic dispatch protocol instead of the 8% emission reduction associated with the static protocol. In addition, if a 6$/ton carbon tax is implemented in the Texas market operated according to the stochastic protocol, the CO2 emission is similar to the emission level from the same market with a 16$/ton carbon tax operated according to the static protocol. Correspondingly, the 16$/ton carbon tax associated with the static protocol costs 42.6% more than the 6$/ton carbon tax associated with the stochastic protocol.

  16. Derivation of a new parametric impulse response matrix utilized for nodal wind load identification by response measurement.

    Science.gov (United States)

    Kazemi Amiri, A; Bucher, C

    2015-05-26

    This paper provides new formulations to derive the impulse response matrix, which is then used in the problem of load identification with application to wind induced vibration. The applied loads are inversely identified based on the measured structural responses by solving the associated discrete ill-posed problem. To this end - based on an existing parametric structural model - the impulse response functions of acceleration, velocity and displacement have been computed. Time discretization of convolution integral has been implemented according to an existing and a newly proposed procedure, which differ in the numerical integration methods. The former was evaluated based on a constant rectangular approximation of the sampled data and impulse response function in a number of steps corresponding to the sampling rate, while the latter interpolates the sampled data in an arbitrary number of sub-steps and then integrates over the sub-steps and steps. The identification procedure was implemented for a simulation example as well as an experimental laboratory case. The ill-conditioning of the impulse response matrix made it necessary to use Tikhonov regularization to recover the applied force from noise polluted measured response. The optimal regularization parameter has been obtained by L-curve and GCV method. The results of simulation represent good agreement between identified and measured force. In the experiments the identification results based on the measured displacement as well as acceleration are provided. Further it is shown that the accuracy of experimentally identified load depends on the sensitivity of measurement instruments over the different frequency ranges.

  17. A New Load Residual Threshold Definition for the Evaluation of Wind Tunnel Strain-Gage Balance Data

    Science.gov (United States)

    Ulbrich, N.; Volden, T.

    2016-01-01

    A new definition of a threshold for the detection of load residual outliers of wind tunnel strain-gage balance data was developed. The new threshold is defined as the product between the inverse of the absolute value of the primary gage sensitivity and an empirical limit of the electrical outputs of a strain{gage. The empirical limit of the outputs is either 2.5 microV/V for balance calibration or check load residuals. A reduced limit of 0.5 microV/V is recommended for the evaluation of differences between repeat load points because, by design, the calculation of these differences removes errors in the residuals that are associated with the regression analysis of the data itself. The definition of the new threshold and different methods for the determination of the primary gage sensitivity are discussed. In addition, calibration data of a six-component force balance and a five-component semi-span balance are used to illustrate the application of the proposed new threshold definition to different types of strain{gage balances. During the discussion of the force balance example it is also explained how the estimated maximum expected output of a balance gage can be used to better understand results of the application of the new threshold definition.

  18. Conference 'onshore and offshore wind energy cost reduction: challenges and opportunities for the industry in France and in Germany'

    International Nuclear Information System (INIS)

    Abadie, Pierre-Marie; Hinsch, Thomas; Wallasch, Anna-Kathrin; Giese, Norbert; Guyet, Quentin; Lenhardt, Edouard; Beinke, Thies; Bodenstab, Marc; Wolff, Nicolas; Burkhardt, Claus; Lessmeister, Andreas L.

    2012-01-01

    The French-German office for Renewable energies (OFAEnR) organised a conference on cost reduction in onshore and offshore wind energy. In the framework of this French-German exchange of experience, about 140 participants exchanged views on the cost allocation in onshore wind energy projects, on their financing, and on the transport and logistics profitability challenges. Concrete examples of operating and maintenance cost reductions in offshore wind energy projects were presented as well. This document brings together the available presentations (slides) made during this event: 1 - Overview of France's onshore and offshore wind support policies (Pierre-Marie Abadie); 2 - Keynote: Framework conditions for cost reductions in the German wind energy sector (Thomas Hinsch); 3 - Cost of onshore wind energy projects in Germany - Status and experience feedback (Anna-Kathrin Wallasch); 4 - Crown estate's Offshore Wind Cost Reduction Pathways Study: how to transpose the conclusions to the German case (Norbert Giese); 5 - Combined Forces for Reliable Supply Chain - French-German Convergence of expertise: strategic partnerships for offshore projects implementation (Quentin Guyet, Edouard Lenhardt); 6 - Reducing costs of onshore and offshore wind energy. Mon2Sea research project - Real-time monitoring of transport and cargo handling of components for the offshore installation of wind turbines (Thies Beinke, Marc Bodenstab); 7 - expertise, Innovation and reduction of cost of energy: Vestas experience (Nicolas Wolff); 8 - Far-Offshore-Wind projects. Results of the First German Offshore Windpark alpha ventus (Claus Burkhardt); 9 - Maintenance for Offshore-Wind parks: examples and good practices for the future (Andreas L. Lessmeister)

  19. Lidar-Enhanced Wind Turbine Control: Past, Present, and Future

    Energy Technology Data Exchange (ETDEWEB)

    Scholbrock, Andrew; Fleming, Paul; Schlipf, David; Wright, Alan; Johnson, Kathryn; Wang, Na

    2016-08-01

    The main challenges in harvesting energy from the wind arise from the unknown incoming turbulent wind field. Balancing the competing interests of reduction in structural loads and increasing energy production is the goal of a wind turbine controller to reduce the cost of producing wind energy. Conventional wind turbines use feedback methods to optimize these goals, reacting to wind disturbances after they have already impacted the wind turbine. Lidar sensors offer a means to provide additional inputs to a wind turbine controller, enabling new techniques to improve control methods, allowing a controller to actuate a wind turbine in anticipation of an incoming wind disturbance. This paper will look at the development of lidar-enhanced controls and how they have been used for various turbine load reductions with pitch actuation, as well as increased energy production with improved yaw control. Ongoing work will also be discussed to show that combining pitch and torque control using feedforward nonlinear model predictive control can lead to both reduced loads and increased energy production. Future work is also proposed on extending individual wind turbine controls to the wind plant level and determining how lidars can be used for control methods to further lower the cost of wind energy by minimizing wake impacts in a wind farm.

  20. Gaussian vs non-Gaussian turbulence: impact on wind turbine loads

    DEFF Research Database (Denmark)

    Berg, Jacob; Natarajan, Anand; Mann, Jakob

    2016-01-01

    taking into account the safety factor for extreme moments. Other extreme load moments as well as the fatigue loads are not affected because of the use of non-Gaussian turbulent inflow. It is suggested that the turbine thus acts like a low-pass filter that averages out the non-Gaussian behaviour, which......From large-eddy simulations of atmospheric turbulence, a representation of Gaussian turbulence is constructed by randomizing the phases of the individual modes of variability. Time series of Gaussian turbulence are constructed and compared with its non-Gaussian counterpart. Time series from the two...

  1. Response Load Extrapolation for Wind Turbines during Operation Based on Average Conditional Exceedance Rates

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Naess, Arvid; Saha, Nilanjan

    2011-01-01

    within a hierarchical model where the variables that influence the loading are divided into ergodic variables and time-invariant non-ergodic variables. The presented method for statistical response load extrapolation was compared with the existing methods based on peak extrapolation for the blade out...... to cases where the Gumbel distribution is the appropriate asymptotic extreme value distribution. However, two extra parameters are introduced by which a more general and flexible class of extreme value distributions is obtained with the Gumbel distribution as a subclass. The general method is implemented...

  2. Impact of load management on the energy management strategy of a wind-short hydro hybrid system in frequency based pricing

    International Nuclear Information System (INIS)

    Malakar, T.; Goswami, S.K.; Sinha, A.K.

    2014-01-01

    Highlights: • This paper presents a new profit centric operating strategy of a hybrid power system under market environment. • The profit is ensured by optimal coordination of RES and load management approach. • The problem is formulated as dynamic optimization problem and solved using ABC algorithm. • Comparison shows that the proposed approach results more profit for the hybrid system. - Abstract: In the post restructuring era of electrical power system, each of the generating farm or utility has its own business strategy in terms of generation planning, load management and for other decisions. The basic objective of the utility is to maximize the operational profit for a given period of time. Generation scheduling for a utility with wind farm largely depends on the accuracy of wind power prediction. Therefore, it is important to explore the suitability of load management approach in coordination with the use of energy storage facility to compensate the uncertainty in wind power generation. This paper focuses mainly the operating strategy of a grid connected small hybrid power system to maximize its profit by adopting coordination between load management technique and utilization of storage plant under frequency based pricing. The optimum load scheduling has been implemented to utilities own local load. An hourly-discretized optimization algorithm is proposed and solved using artificial bee colony algorithm. To verify the effectiveness of the proposed method, the optimization problem is solved for varied wind power scenarios with different demand expectations cases in a day ahead Indian electricity market. It is noted that the proposed load management approach results more profit for the hybrid system because of better power management compared to the case when load scheduling has not been incorporated. The solution of the proposed optimization algorithm gives the strategies to be followed by the hybrid system how to operate its pump storage unit and to

  3. Fatigue and extreme wave loads on bottom fixed offshore wind turbines. Effects from fully nonlinear wave forcing on the structural dynamics

    DEFF Research Database (Denmark)

    Schløer, Signe

    2013-01-01

    are investigated. Focus is on the sectional moments in the tower and monopile. The equivalent loads and accumulated equivalent load due to the six wind and sea states are further calculated and compared. The wind forcing and the aerodynamic damping are often dominating over the effects from the waves...... response is an important parameter, when the nonlinearity of the waves is investigated. Besides aerodynamic damping other damping effects also exist which affect the structural dynamics. The magnitude of the hydrodynamic damping is therefore also investigated in the thesis. To investigate the effects...

  4. Use of MODIS Data in Dynamic SPARROW Analysis of Watershed Loading Reductions

    Science.gov (United States)

    Smith, R. A.; Schwarz, G. E.; Brakebill, J. W.; Hoos, A.; Moore, R. B.; Nolin, A. W.; Shih, J. S.; Journey, C. A.; Macauley, M.

    2014-12-01

    Predicting the temporal response of stream water quality to a proposed reduction in contaminant loading is a major watershed management problem due to temporary storage of contaminants in groundwater, vegetation, snowpack, etc. We describe the response of dynamically calibrated SPARROW models of total nitrogen (TN) flux to hypothetical reductions in reactive nitrogen inputs in three sub-regional watersheds: Potomac River Basin (Chesapeake Bay drainage), Long Island Sound drainage, and South Carolina coastal drainage. The models are based on seasonal water quality and watershed input data from 170 monitoring stations for the period 2002 to 2008.The spatial reference frames of the three models are stream networks containing an average 38,000 catchments and the time step is seasonal. We use MODIS Enhanced Vegetation Index (EVI) and snow/ice cover data to parameterize seasonal uptake and release of nitrogen from vegetation and snowpack. The model accounts for storage of total nitrogen inputs from fertilized cropland, pasture, urban land, and atmospheric deposition. Model calibration is by non-linear regression. Model source terms based on previous season export allow for recursive simulation of stream flux and can be used to estimate the approximate residence times of TN in the watersheds. Catchment residence times in the Long Island Sound Basin are shorter (typically 1 year), in part, because a significant fraction of nitrogen flux derives from snowmelt and occurs within one season of snowfall. We use the calibrated models to examine the response of TN flux to hypothetical step reductions in source inputs at the beginning of the 2002-2008 period and the influence of observed fluctuations in precipitation, temperature, vegetation growth and snow melt over the period. Following non-point source reductions of up to 100%, stream flux was found to continue to vary greatly for several years as a function of seasonal conditions, with high values in both winter (January

  5. Mud, models, and managers: Reaching consensus on a watershed strategy for sediment load reduction

    Science.gov (United States)

    Wilcock, P. R.; Cho, S. J.; Gran, K.; Belmont, P.; Hobbs, B. F.; Heitkamp, B.; Marr, J. D.

    2017-12-01

    Agricultural nonpoint source sediment pollution is a leading cause of impairment of U.S. waters. Sediment sources are often on private land, such that solutions require not only considerable investment, but broad acceptance among landowners. We present the story of a participatory modeling exercise whose goal was to develop a consensus strategy for reducing sediment loading from the Greater Blue Earth River Basin, a large (9,200 km2) watershed in southern Minnesota dominated by row crop agriculture. The Collaborative for Sediment Source Reduction was a stakeholder group of farmers, industry representatives, conservation groups, and regulatory agencies. We used a participatory modeling approach to promote understanding of the problem, to define the scope of solutions acceptable to farmers, to develop confidence in a watershed model, and to reach consensus on a watershed strategy. We found that no existing watershed model could provide a reliable estimate of sediment response to management actions and developed a purpose-built model that could provide reliable, transparent, and fast answers. Because increased stream flow was identified as an important driver of sediment loading, the model and solutions included both hydrologic and sediment transport components. The model was based on an annual sediment budget with management actions serving to proportionally reduce both sediment sources and sediment delivery. Importantly, the model was developed in collaboration with stakeholders, such that a shared understanding emerged regarding of the modeling challenges and the reliability of information used to strongly constrain model output. The simplicity of the modeling approach supported stakeholder engagement and understanding, thereby lowering the social barrier between expert modeler and concerned stakeholder. The consensus strategy focused on water storage higher in the watershed in order to reduce river discharge and the large supply of sediment from near

  6. Load Measurements

    DEFF Research Database (Denmark)

    Kock, Carsten Weber; Vesth, Allan

    The report describes Load measurements carried out on a given wind turbine. The aim of the measurement program regarding the loads on the turbine is to verify the basic characteristics of the wind turbine and loads on the blades, the rotor and the tower, using [Ref 1], [Ref2] and [Ref 3]. Regarding...... the fatigue loads, the rotor, blades and tower moments are presented. The fatigue loads are evaluated using rainflow counting described in detail in Ref. [1]. The 1Hz equivalent load ranges are calculated at different wind speeds. All information regarding the instrumentation is collected in [ref 4] and [ref...

  7. Power Devices Loading in Multilevel Converters for 10 MW Wind Turbines

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede; Xu, Dehong

    2011-01-01

    Several promising multilevel converter solutions for 10 MW wind turbines using permanent magnet synchronous generators are proposed, designed and compared both with one-stage gear-box drive and direct drive systems. The current and loss distributions, as well as the utilization of power devices...... in each converter are analyzed based on simulation results. Finally, the total loss and efficiency comparison are given. It is concluded that five-level and three-level H-bridge topologies show higher efficiency either in the power conversion or in the device utilization compared to the three...

  8. Stohastic Model for Loads on Offshore Structures from Wave, Wind, Current and Water Elevation

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Sterndorff, M.J.

    2002-01-01

    For code-based LRFD and for reliability-based assessment of offshore structures such as steel platforms it is essential that consistent stochastic models for the main metocean parameters are available. The most important metocean parameters are the significant wave height, maximum individual wave...... height, maximum crest height, wind speed, current speed and water elevation. In this paper a consistent stochastic model for these parameters is formulated, where the relevant directional dependence is included. For code-based LRFD assessment it is shown how the stochastic models can be used to determine...

  9. Stochastic model for joint wave and wind loads on offshore structures

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager

    2002-01-01

    The stochastic wave load environment of offshore structures is of such a complicated nature that any engineering analysis requires extensive simplifications. This concerns both the transformation of the wave field velocities and accelerations to forces on the structure and the probabilistic descr...

  10. Elastic deformations of floaters for offshore wind turbines: Dynamic modelling and sectional load calculations

    DEFF Research Database (Denmark)

    Borg, Michael; Bredmose, Henrik; Hansen, Anders Melchior

    2017-01-01

    is considered through a reduced set of modes, selected based on their relevance to the external load frequency range, and represented with a superelement. The implementation of this method in aeroelastic simulation tool HAWC2 and wavestructure analysis programWAMIT is described, highlighting the practical...

  11. Material matters: Controllable rubber trailing edge flap regulates load on wind turbine blades

    DEFF Research Database (Denmark)

    Aagaard Madsen, Helge

    2010-01-01

    trailing edge flap, known as CRTEF. The trailing edge blade design is expected to help mitigate localized loading, and its molded rubber design, the sharp trailing edge, produces less noise and greater output. With CRTEF, the blade automatically has a completely sharp edge. The elastic flap tested...

  12. The Role of Overloading on the Reduction of Residual Stress by Cyclic Loading in Cold-Drawn Prestressing Steel Wires

    Directory of Open Access Journals (Sweden)

    Jesús Toribio

    2017-01-01

    Full Text Available Prestressing steel wires are commonly used as reinforcement elements in structures bearing fatigue loads. These wires are obtained by a conforming process called cold drawing, where a progressive reduction of the wire diameter is produced, causing residual stress in the commercial wire. The aim of this paper is to analyze the effect of diverse in-service cyclic loading conditions (cyclic loading and cyclic loading with overload on such a residual stress field. To achieve this goal, firstly, a numerical simulation of the wire drawing process of a commercial prestressing steel wire was carried out to reveal the residual stress state induced by the manufacture technique. Afterwards, a numerical simulation was performed of the in-service loading conditions of a prestressing steel wire in which the previously calculated residual stress state is included. The analysis of the obtained results shows a significant reduction of the residual stress state of about 50% for common in-service loadings and as high as 90% for certain cases undergoing overloads during cyclic loading. Therefore, an improvement of the mechanical performance of these structural components during their life in-service can be achieved.

  13. Effect of Fe Loading Condition and Reductants on CO2 Reduction Performance with Fe/TiO2 Photocatalyst

    Directory of Open Access Journals (Sweden)

    Akira Nishimura

    2017-01-01

    Full Text Available Fe-doped TiO2 (Fe/TiO2 film photocatalyst was prepared by sol-gel and dip-coating process and pulse arc plasma method. The effect of pulse number on the CO2 reduction performance with the Fe/TiO2 was investigated in this study. In addition, the effect of reductants such as H2O, H2, and NH3/H2O on the CO2 reduction performance with the Fe/TiO2 photocatalyst was also investigated. The characteristics of the prepared Fe/TiO2 film coated on a netlike glass fiber which is a base material were analyzed by SEM, EPMA, EDX, and EPMA. Furthermore, the CO2 reduction performance of the Fe/TiO2 film was tested under a Xe lamp with or without ultraviolet (UV light. The results show that the CO2 reduction performance with the pulse number of 100 is the best with H2O and/or H2 as reductant under UV light illumination, while that with the pulse number of 500 is the best when NH3/H2O is used as reductant. On the other hand, the CO2 reduction performance with the pulse number of 500 is the best under every reductant condition without UV light illumination. The highest CO2 reduction performance with the Fe/TiO2 is obtained under H2 + H2O/CO2 condition, and the best moral ratio of total reductants to CO2 is 1.5 : 1.

  14. Wind-Tunnel Evaluation of the Effect of Blade Nonstructural Mass Distribution on Helicopter Fixed-System Loads

    Science.gov (United States)

    Wilbur, Matthew L.; Yeager, Jr, William T.; Singleton, Jeffrey D.; Mirick, Paul H.; Wilkie, W K.

    1998-01-01

    This report provides data obtained during a wind-tunnel test conducted to investigate parametrically the effect of blade nonstructural mass on helicopter fixed-system vibratory loads. The data were obtained with aeroelastically scaled model rotor blades that allowed for the addition of concentrated nonstructural masses at multiple locations along the blade radius. Testing was conducted for advance ratios ranging from 0.10 to 0.35 for 10 blade-mass configurations. Three thrust levels were obtained at representative full-scale shaft angles for each blade-mass configuration. This report provides the fixed-system forces and moments measured during testing. The comprehensive database obtained is well-suited for use in correlation and development of advanced rotorcraft analyses.

  15. Hover test of a full-scale hingeless helicopter rotor: Aeroelastic stability, performance and loads data. [wind tunnel tests

    Science.gov (United States)

    Peterson, R. L.; Warmbrodt, W.

    1984-01-01

    A hover test of a full-scale, hingeless rotor system was conducted in the NASA Ames 40- by 80-foot wind tunnel. The rotor was tested on the Ames rotor test apparatus. Rotor aeroelastic stability, performance, and loads at various rotational speeds and thrust coefficients were investigated. The primary objective was to determine the inplane stability characteristics of the rotor system. Rotor inplane damping data were obtained for operation between 350 and 425 rpm (design speed), and for thurst coefficients between 0.0 and 0.12. The rotor was stable for all conditions tested. At constant rotor rotational speed, a minimum inplane dampling level was obtained at a thrust coefficient approximately = 0.02. At constant rotor lift, a minimum in rotor inplane damping was measured at 400 rpm.

  16. Optimal power flow based TU/CHP/PV/WPP coordination in view of wind speed, solar irradiance and load correlations

    International Nuclear Information System (INIS)

    Azizipanah-Abarghooee, Rasoul; Niknam, Taher; Malekpour, Mostafa; Bavafa, Farhad; Kaji, Mahdi

    2015-01-01

    Highlights: • Formulate probabilistic OPF with VPE, multi-fuel options, POZs, FOR of CHP units. • Propose a new powerful optimization method based on enhanced black hole algorithm. • Coordinate of TUs, WPPs, PVs and CHP units together in the proposed problem. • Evaluate the impacts of inputs’ uncertainties and their correlations on the POPF. • Use the 2m + 1 point estimated method. - Abstract: This paper addresses a novel probabilistic optimisation framework for handling power system uncertainties in the optimal power flow (OPF) problem that considers all the essential factors of great impact in the OPF problem. The object is to study and model the correlation and fluctuation of load demands, photovoltaic (PV) and wind power plants (WPPs) which have an important influence on transmission lines and bus voltages. Moreover, as an important tool of saving waste heat energy in the thermoelectric power plant, the power networks share of combined heat and power (CHP) has increased dramatically in the past decade. So, the probabilistic OPF (POPF) problem considering valve point effects, multi-fuel options and prohibited zones of thermal units (TUs) is firstly formulated. The PV, WPP and CHP units are also modeled. Then, a new method utilizing enhanced binary black hole (EBBH) algorithm and 2m + 1 point estimated method is proposed to solve this problem and to handle the random nature of solar irradiance, wind speed and load of consumers. The correlation between input random variables is considered using a correlation matrix. Finally, numerical results are presented and considered regarding the IEEE 118-busses, including PV, WPP, CHP and TU at several busses. The simulation and comparison results obtained demonstrate the broad advantages and feasibility of the suggested framework in the presence of dependent non-Gaussian distribution of random variables

  17. Load-Direction-Derived Support Structures for Wind Turbines: A Lattice Tower Concept and Preparations for Future Certifications: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Jonkman, Jason [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Damiani, Rick R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Struve, Achim [University of Applied Sciences Flensburg; Faber, Torsten [University of Applied Sciences Flensburg; Ummenhofer, Thomas [Karlsruhe Institute of Technology

    2017-11-07

    The call for more cost-effective and environmentally friendly tower concepts is motivated by tower costs [1] and tower CO2-emission contributions [2], which are high relative to the whole wind turbine system. The proposed rotatable tower concept with yaw bearing at the bottom instead of the top of the tower will provide beneficial economic and environmental impacts to the turbine system. This wind alignment capability indicates a load-direction-derived tower design. By combining this approach with a lattice concept, large material and cost savings for the tower can be achieved. This paper presents a way to analyze and verify the proposed design through aero-servo-elastic simulations, which make future certifications of rotatable tower concepts viable. For this reason, the state-of-the-art, open-source lattice-tower finite-element-method (FEM) module SubDyn [10], developed by the National Renewable Energy Laboratory, has been modified to account for arbitrary member cross-sections. Required changes in the beam element stiffness and mass matrix formulation took place according to an energy method [13]. All validated adaptions will be usable within the aero-servo-elastic simulation framework FAST and are also beneficial for other nonrotatable lattice structures.

  18. Prediction and Reduction of Noise from a 2.3 MW Wind Turbine

    International Nuclear Information System (INIS)

    Leloudas, G; Zhu, W J; Soerensen, J N; Shen, W Z; Hjort, S

    2007-01-01

    We address the issue of noise emission from a 2.3 MW SWT-2.3-93 wind turbine and compare simulations from a semi-empirical acoustic model with measurements. The noise measurements were taken at the Hoevsoere test site for large wind turbines. The acoustic model is based on the Blade-Element Momentum (BEM) technique and various semi-empirical acoustic relations. The comparison demonstrates a generally good agreement between predicted and measured noise levels. The acoustic model is further employed to carry out a parametrical study to optimize the performance/noise of the wind turbine by changing tip speed and pitch setting. We show that it is possible to reduce the noise level up to 2 dB(A) without sacrificing too much the power yield

  19. Full-scale S-76 rotor performance and loads at low speeds in the NASA Ames 80- by 120-Foot Wind Tunnel. Vol. 1

    Science.gov (United States)

    Shinoda, Patrick M.

    1996-01-01

    A full-scale helicopter rotor test was conducted in the NASA Ames 80- by 120-Foot Wind Tunnel with a four-bladed S-76 rotor system. Rotor performance and loads data were obtained over a wide range of rotor shaft angles-of-attack and thrust conditions at tunnel speeds ranging from 0 to 100 kt. The primary objectives of this test were (1) to acquire forward flight rotor performance and loads data for comparison with analytical results; (2) to acquire S-76 forward flight rotor performance data in the 80- by 120-Foot Wind Tunnel to compare with existing full-scale 40- by 80-Foot Wind Tunnel test data that were acquired in 1977; (3) to evaluate the acoustic capability of the 80- by 120- Foot Wind Tunnel for acquiring blade vortex interaction (BVI) noise in the low speed range and compare BVI noise with in-flight test data; and (4) to evaluate the capability of the 80- by 120-Foot Wind Tunnel test section as a hover facility. The secondary objectives were (1) to evaluate rotor inflow and wake effects (variations in tunnel speed, shaft angle, and thrust condition) on wind tunnel test section wall and floor pressures; (2) to establish the criteria for the definition of flow breakdown (condition where wall corrections are no longer valid) for this size rotor and wind tunnel cross-sectional area; and (3) to evaluate the wide-field shadowgraph technique for visualizing full-scale rotor wakes. This data base of rotor performance and loads can be used for analytical and experimental comparison studies for full-scale, four-bladed, fully articulated rotor systems. Rotor performance and structural loads data are presented in this report.

  20. Bone Reduction to Facilitate Immediate Implant Placement and Loading Using CAD/CAM Surgical Guides for Patients With Terminal Dentition.

    Science.gov (United States)

    Alzoubi, Fawaz; Massoomi, Nima; Nattestad, Anders

    2016-10-01

    The aim of this study is to present a method, using 3 computer-aided design/computer-aided manufacturing (CAD/CAM) surgical guides, to accurately obtain the desired bone reduction followed by immediate implant placements and loading for patients diagnosed with terminal dentition. Patients who had bone reduction, implants placed, and immediate loading using Anatomage Invivo 5 CAD/CAM surgical guides between the period 2013 and 2015 were evaluated retrospectively. Patients diagnosed with terminal dentition and treated using the "3-guide technique" were identified. Pre- and postsurgical images were superimposed to evaluate deviations of the bone reduction and deviations at the crest, apex, and angle of implants placed. Twenty-six implants placed in 5 patients were included in this study. The overall deviation means measured for bone reduction was 1.98 mm. The overall deviation means measured for implant placement at the crest, apex, and angle were 1.43 mm, 1.90 mm, and 4.14°, respectively. The CAD/CAM surgical guide fabrication is an emerging tool that may facilitate the surgical process and aid in safe and predictable execution of bone reduction and immediate implant placement. Using 3 CAD/CAM surgical guides, a method is presented to obtain the desired bone reduction followed by immediate implant placement and loading for patients diagnosed with terminal dentition. This method may improve guide stability for patients with terminal dentition undergoing complete implant-supported treatment by taking advantage of the teeth to be extracted.

  1. Vibratory Loads Data from a Wind-Tunnel Test of Structurally Tailored Model Helicopter Rotors

    Science.gov (United States)

    Yeager, William T., Jr.; Hamouda, M-Nabil H.; Idol, Robert F.; Mirick, Paul H.; Singleton, Jeffrey D.; Wilbur, Matthew L.

    1991-01-01

    An experimental study was conducted in the Langley Transonic Dynamics Tunnel to investigate the use of a Bell Helicopter Textron (BHT) rotor structural tailoring concept, known as rotor nodalization, in conjunction with advanced blade aerodynamics as well as to evaluate rotor blade aerodynamic design methodologies. A 1/5-size, four-bladed bearingless hub, three sets of Mach-scaled model rotor blades were tested in forward flight from transition up to an advance ratio of 0.35. The data presented pertain only to the evaluation of the structural tailoring concept and consist of fixed-system and rotating system vibratory loads. These data will be useful for evaluating the effects of tailoring blade structural properties on fixed-system vibratory loads, as well as validating analyses used in the design of advanced rotor systems.

  2. Loads and Performance Data from a Wind-Tunnel Test of Generic Model Helicopter Rotor Blades

    Science.gov (United States)

    Yeager, William T., Jr.; Wilbur, Matthew L.

    2005-01-01

    An investigation was conducted in the NASA Langley Transonic Dynamics Tunnel to acquire data for use in assessing the ability of current and future comprehensive analyses to predict helicopter rotating-system and fixed-system vibratory loads. The investigation was conducted with a generic model helicopter rotor system using blades with rectangular planform, no built-in twist, uniform radial distribution of mass and stiffnesses, and a NACA 0012 airfoil section. Rotor performance data, as well as mean and vibratory components of blade bending and torsion moments, fixed-system forces and moments, and pitch link loads were obtained at advance ratios up to 0.35 for various combinations of rotor shaft angle-of-attack and collective pitch. The data are presented without analysis.

  3. Fatigue behaviour of fiberglass wind turbine blade material under variable amplitude loading

    Energy Technology Data Exchange (ETDEWEB)

    Delft, D.R.V. Van; Winkel, G.D. de [Delft Univ. of Technology, STEVIN Lab., Delft (Netherlands); Joosse, P.A. [Stork Product Engineering b.v., Amsterdam (Netherlands)

    1996-09-01

    In the work presented here fatigue tests with the WISPER and WISPERX load sequence have been carried out and analysed. The test programme includes tests at low stress levels which results in fatigue lives of 50 millions of cycles. The results are compared with constant amplitude tests in the very high cycle range, carried out in a previous programme. The results are also compared with ECN results in the lower cycle range (on identical specimens). It appeared, that the difference between the fatigue life of the specimens tested with the WISPER and the WISPERX load sequence is larger than can be expected from the theoretical damage rates. Moreover, the slope of the S-N data differs from theoretical values obtained by using commonly applied design rules. (au)

  4. Probabilistic Constrained Load Flow Considering Integration of Wind Power Generation and Electric Vehicles

    DEFF Research Database (Denmark)

    Vlachogiannis, Ioannis (John)

    2009-01-01

    are incorporated into load flow studies. In the resulted PCLF formulation, discrete and continuous control parameters are engaged. Therefore, a hybrid learning automata system (HLAS) is developed to find the optimal offline control settings over a whole planning period of power system. The process of HLAS...... integration of WT generation in correlation with EV demand/supply into the electricity grids are also introduced, resulting in the first benchmark. Novel conclusions for EV portfolio management are drawn....

  5. Cost optimization of wind turbines for large-scale offshore wind farms

    International Nuclear Information System (INIS)

    Fuglsang, P.; Thomsen, K.

    1998-02-01

    This report contains a preliminary investigation of site specific design of off-shore wind turbines for a large off-shore wind farm project at Roedsand that is currently being proposed by ELKRAFT/SEAS. The results were found using a design tool for wind turbines that involve numerical optimization and aeroelastic calculations of response. The wind climate was modeled in detail and a cost function was used to estimate costs from manufacture and installation. Cost of energy is higher for off-shore installations. A comparison of an off-shore wind farm site with a typical stand alone on-shore site showed an increase of the annual production of 28% due to the difference in wind climate. Extreme loads and blade fatigue loads were nearly identical, however,fatigue loads on other main components increased significantly. Optimizations were carried out to find the optimum overall off-shore wind turbine design. A wind turbine for the off-shore wind farm should be different compared with a stand-alone on-shore wind turbine. The overall design changed were increased swept area and rated power combined with reduced rotor speed and tower height. Cost was reduced by 12% for the final 5D/14D off-shore wind turbine from 0.306 DKr/kWh to 0.270 DKr/kWh. These figures include capital costs from manufacture and installation but not on-going costs from maintenance. These results make off-shore wind farms more competitive and comparable to the reference on-shore stand-alone wind turbine. A corresponding reduction of cost of energy could not be found for the stand alone on-shore wind turbine. Furthermore the fatigue loads on wind turbines in on-shore wind farms will increase and cost of energy will increase in favor of off-shore wind farms. (au) EFP-95; EU-JOULE-3; 21 tabs., 7 ills., 8 refs

  6. Impact of modulation strategies on power devices loading for 10 MW multilevel wind power converter

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Isidori, Andrea; Rossi, Fabio Mario

    2012-01-01

    the dynamics of the system using different kinds of modulation strategies, identifying which methods can improve the converter efficiency. It is concluded that 60° discontinuous PWM modulation strategies show less power losses in the semiconductor devices and will increase the overall efficiency......This paper focuses on the control and modulation of a three-level Neutral Point Clamped (3L-NPC) back-to-back full scale converter for a 10 MW direct-drive wind turbine, equipped with a Permanent Magnet Synchronous Generator (PMSG). Emphasis is oriented towards the investigation of the power losses...... in the semiconductor devices of three-level converter adopting continuous and discontinuous PWM modulation strategies. This aspect strongly influences the operation of the converter and directly affects its efficiency. Therefore, a simulation platform is developed in Matlab/Simulink and PLECS environment to analyse...

  7. Reliability assessment of Wind turbines

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2015-01-01

    Wind turbines can be considered as structures that are in between civil engineering structures and machines since they consist of structural components and many electrical and machine components together with a control system. Further, a wind turbine is not a one-of-a-kind structure...... but manufactured in series production based on many component tests, some prototype tests and zeroseries wind turbines. These characteristics influence the reliability assessment where focus in this paper is on the structural components. Levelized Cost Of Energy is very important for wind energy, especially when...... comparing to other energy sources. Therefore much focus is on cost reductions and improved reliability both for offshore and onshore wind turbines. The wind turbine components should be designed to have sufficient reliability level with respect to both extreme and fatigue loads but also not be too costly...

  8. Design Load Case Analysis tools for aeroelastic wind turbine simulations with HAWC2

    DEFF Research Database (Denmark)

    2014-01-01

    , prepost and cluster tools are created by David R.S. Verelst. This repository holds a series of scripts and small libraries that aim to help with the process of creating, managing, and post processing design load cases (DLC's) simulations. Note that the work presented here has not been streamlined......, and is not easy to use nor easy installable. During the course of 2015 a library will be released with proper build, install and usage documentation. The version that is included in this repository was extensively used within the INDUFLAP project....

  9. Development of a variable loading switch for wind turbines. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Pinkston, L.C.; Harris, C.F.

    1980-11-01

    The objective of this project was to design and build an electrical switch system which could sense excess power production and direct the power to an alternative load. The first attempt to design the system resulted in a faulty design because it was discovered that the phase angle of the excess power was a significant factor in the functioning of the system instead of the power output being the major factor. As a result, a new system was designed that accounted for the effects of the phase angle. This subsequent system was bench and field tested and was found to be an acceptable system.

  10. Conditions Contributing to Adverse Loading of Wind Turbines In the Nocturnal Boundary Layer: Final Report, November 15, 2003 -- December 31, 2004

    Energy Technology Data Exchange (ETDEWEB)

    Fritts, D.C.

    2005-07-01

    This report summarizes the development of a methodology to describe the characteristics of coherent turbulence in the nocturnal boundary layer that are known to induce excessive structural loads and component vibration in operating wind turbines and suggestions for applying those results in the development of techniques of real-time detection and prediction that can be used for mitigation purposes.

  11. Pultrusion of a vertical axis wind turbine blade part-II: combining the manufacturing process simulation with a subsequent loading scenario

    NARCIS (Netherlands)

    Baran, Ismet; Hattel, Jesper H.; Tutum, Cem C.; Akkerman, Remko

    2015-01-01

    This paper in particular deals with the integrated modeling of a pultruded NACA0018 blade profile being a part of EU funded DeepWind project. The manufacturing aspects of the pultrusion process are associated with the preliminary subsequent service loading scenario. A 3D thermo-chemical analysis of

  12. Medium fidelity modelling of loads in wind farms under non-neutral ABL stability conditions – a full-scale validation study

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Larsen, Torben J.; Chougule, A.

    2017-01-01

    The aim of the present paper is to demonstrate the capability of medium fidelity modelling of wind turbine component fatigue loading, when the wind turbines are subjected to wake affected non-stationary flow fields under non-neutral atmospheric stability conditions. To accomplish this we combine...... the classical Dynamic Wake Meandering model with a fundamental conjecture stating: Atmospheric boundary layer stability affects primary wake meandering dynamics driven by large turbulent scales, whereas wake expansion in the meandering frame of reference is hardly affected. Inclusion of stability (i.e. buoyancy......) in description of both large- and small scale atmospheric boundary layer turbulence is facilitated by a generalization of the classical Mann spectral tensor, which consistently includes buoyancy effects. With non-stationary wind turbine inflow fields modelled as described above, fatigue loads are obtained using...

  13. Reliability-oriented multi-objective optimal decision-making approach for uncertainty-based watershed load reduction

    International Nuclear Information System (INIS)

    Dong, Feifei; Liu, Yong; Su, Han; Zou, Rui; Guo, Huaicheng

    2015-01-01

    Water quality management and load reduction are subject to inherent uncertainties in watershed systems and competing decision objectives. Therefore, optimal decision-making modeling in watershed load reduction is suffering due to the following challenges: (a) it is difficult to obtain absolutely “optimal” solutions, and (b) decision schemes may be vulnerable to failure. The probability that solutions are feasible under uncertainties is defined as reliability. A reliability-oriented multi-objective (ROMO) decision-making approach was proposed in this study for optimal decision making with stochastic parameters and multiple decision reliability objectives. Lake Dianchi, one of the three most eutrophic lakes in China, was examined as a case study for optimal watershed nutrient load reduction to restore lake water quality. This study aimed to maximize reliability levels from considerations of cost and load reductions. The Pareto solutions of the ROMO optimization model were generated with the multi-objective evolutionary algorithm, demonstrating schemes representing different biases towards reliability. The Pareto fronts of six maximum allowable emission (MAE) scenarios were obtained, which indicated that decisions may be unreliable under unpractical load reduction requirements. A decision scheme identification process was conducted using the back propagation neural network (BPNN) method to provide a shortcut for identifying schemes at specific reliability levels for decision makers. The model results indicated that the ROMO approach can offer decision makers great insights into reliability tradeoffs and can thus help them to avoid ineffective decisions. - Highlights: • Reliability-oriented multi-objective (ROMO) optimal decision approach was proposed. • The approach can avoid specifying reliability levels prior to optimization modeling. • Multiple reliability objectives can be systematically balanced using Pareto fronts. • Neural network model was used to

  14. Mechanisms of basin-scale nitrogen load reductions under intensified irrigated agriculture.

    Directory of Open Access Journals (Sweden)

    Rebecka Törnqvist

    Full Text Available Irrigated agriculture can modify the cycling and transport of nitrogen (N, due to associated water diversions, water losses, and changes in transport flow-paths. We investigate dominant processes behind observed long-term changes in dissolved inorganic nitrogen (DIN concentrations and loads of the extensive (465,000 km2 semi-arid Amu Darya River basin (ADRB in Central Asia. We specifically considered a 40-year period (1960-2000 of large irrigation expansion, reduced river water flows, increased fertilizer application and net increase of N input into the soil-water system. Results showed that observed decreases in riverine DIN concentration near the Aral Sea outlet of ADRB primarily were due to increased recirculation of irrigation water, which extends the flow-path lengths and enhances N attenuation. The observed DIN concentrations matched a developed analytical relation between concentration attenuation and recirculation ratio, showing that a fourfold increase in basin-scale recirculation can increase DIN attenuation from 85 to 99%. Such effects have previously only been observed at small scales, in laboratory experiments and at individual agricultural plots. These results imply that increased recirculation can have contributed to observed increases in N attenuation in agriculturally dominated drainage basins in different parts of the world. Additionally, it can be important for basin scale attenuation of other pollutants, including phosphorous, metals and organic matter. A six-fold lower DIN export from ADRB during the period 1981-2000, compared to the period 1960-1980, was due to the combined result of drastic river flow reduction of almost 70%, and decreased DIN concentrations at the basin outlet. Several arid and semi-arid regions around the world are projected to undergo similar reductions in discharge as the ADRB due to climate change and agricultural intensification, and may therefore undergo comparable shifts in DIN export as shown here

  15. Mechanisms of Basin-Scale Nitrogen Load Reductions under Intensified Irrigated Agriculture

    Science.gov (United States)

    Törnqvist, Rebecka; Jarsjö, Jerker; Thorslund, Josefin; Rao, P. Suresh C.; Basu, Nandita B.; Destouni, Georgia

    2015-01-01

    Irrigated agriculture can modify the cycling and transport of nitrogen (N), due to associated water diversions, water losses, and changes in transport flow-paths. We investigate dominant processes behind observed long-term changes in dissolved inorganic nitrogen (DIN) concentrations and loads of the extensive (465,000 km2) semi-arid Amu Darya River basin (ADRB) in Central Asia. We specifically considered a 40-year period (1960–2000) of large irrigation expansion, reduced river water flows, increased fertilizer application and net increase of N input into the soil-water system. Results showed that observed decreases in riverine DIN concentration near the Aral Sea outlet of ADRB primarily were due to increased recirculation of irrigation water, which extends the flow-path lengths and enhances N attenuation. The observed DIN concentrations matched a developed analytical relation between concentration attenuation and recirculation ratio, showing that a fourfold increase in basin-scale recirculation can increase DIN attenuation from 85 to 99%. Such effects have previously only been observed at small scales, in laboratory experiments and at individual agricultural plots. These results imply that increased recirculation can have contributed to observed increases in N attenuation in agriculturally dominated drainage basins in different parts of the world. Additionally, it can be important for basin scale attenuation of other pollutants, including phosphorous, metals and organic matter. A six-fold lower DIN export from ADRB during the period 1981–2000, compared to the period 1960–1980, was due to the combined result of drastic river flow reduction of almost 70%, and decreased DIN concentrations at the basin outlet. Several arid and semi-arid regions around the world are projected to undergo similar reductions in discharge as the ADRB due to climate change and agricultural intensification, and may therefore undergo comparable shifts in DIN export as shown here for the

  16. Wave Disturbance Reduction of a Floating Wind Turbine Using a Reference Model-based Predictive Control

    DEFF Research Database (Denmark)

    Christiansen, Søren; Tabatabaeipour, Seyed Mojtaba; Bak, Thomas

    2013-01-01

    a controller designed for an onshore wind turbine yields instability in the fore-aft rotation. In this paper, we propose a general framework, where a reference model models the desired closed-loop behavior of the system. Model predictive control combined with a state estimator finds the optimal rotor blade...... pitch such that the state trajectories of the controlled system tracks the reference trajectories. The framework is demonstrated with a reference model of the desired closed-loop system undisturbed by the incident waves. This allows the wave-induced motion of the platform to be damped significantly...... compared to a baseline floating wind turbine controller at the cost of more pitch action....

  17. Wind-Tunnel Investigation of Wind Loads on a Post-Panamax Container Ship as a Function of the Container Configuration on Deck

    DEFF Research Database (Denmark)

    Andersen, Ingrid Marie Vincent

    2012-01-01

    An investigation of the wind forces acting on a 9,000+ TEU container ship has been carried out through a series of wind tunnel tests. It was investigated how the wind forces depend on the container configuration on the deck using a 1:450 scale model and a series of appropriate container...... are presented as nondimensional coefficients. It is concluded, that the measured forces and moment depend on the container configuration on deck, and the results may provide a general idea of how the magnitude of the wind forces is affected by a given container stacking configuration on a similar container ship....

  18. Transient voltage control of a DFIG-based wind power plant for suppressing overvoltage using a reactive current reduction loop

    Directory of Open Access Journals (Sweden)

    Geon Park

    2016-01-01

    Full Text Available This paper proposes a transient voltage control scheme of a doubly fed induction generator (DFIG-based wind power plant (WPP using a reactive current reduction loop to suppress the overvoltage at a point of interconnection (POI and DFIG terminal after a fault clearance. The change of terminal voltage of a DFIG is monitored at every predefined time period to detect the fault clearance. If the voltage change exceeds a set value, then the reactive current reduction loop reduces the reactive current reference in the DFIG controller using the step function. The reactive current injection of DFIGs in a WPP is rapidly reduced, and a WPP can rapidly suppress the overvoltage at a fault clearance because the reactive current reference is reduced. Using an electromagnetic transients program–released version (EMTP–RV simulator, the performance of the proposed scheme was validated for a model system comprising 20 units of a 5-MW DFIG considering various scenarios, such as fault and wind conditions. Test results show that the proposed scheme enables a WPP to suppress the overvoltage at the POI and DFIG terminal within a short time under grid fault conditions.

  19. Torque- and Speed Control of a Pitch Regulated Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Rasila, Mika

    2003-07-01

    Variable speed operated wind turbines has the potential to reduce fatigue loads, compared to fixed speed wind turbines. With pitch controllable rotor blades limitation of the power at high wind speeds is obtained. The thesis describes different controlling aspects concerning wind turbines and how these together can be used to optimize the system's performance. Torque control is used in order to achieve reduction on the mechanical loads on the drive-train for low wind speeds and limitation of power output for high wind speeds. In the high wind speed interval torque control is effective in order to limit the output power if a sufficiently fast pitch actuator is used. In the middle wind speed interval filter utilization can be used to give a reference signal to the controller in order to reduce speed and torque variations.

  20. Plasma volume reduction and hematological fluctuations in high-level athletes after an increased training load

    DEFF Research Database (Denmark)

    Bejder, Jacob; Andersen, Andreas Breenfeldt; Goetze, J P

    2017-01-01

    to baseline training load in week 3. PV and hematological variables were determined frequently during all weeks. The higher training load in week 2 increased (P..., demonstrating the importance of knowledge on naturally occurring hematological fluctuations. Finally, concentrations of albumin, sTfR, and proANP could not explain PV fluctuations....