Resolving Nonstationary Spectral Information in Wind Speed Time Series Using the Hilbert-Huang Transform

DEFF Research Database (Denmark)

Vincent, Claire Louise; Giebel, Gregor; Pinson, Pierre

2010-01-01

a 4-yr time series of 10-min wind speed observations. An adaptive spectral analysis method called the Hilbert–Huang transform is chosen for the analysis, because the nonstationarity of time series of wind speed observations means that they are not well described by a global spectral analysis method...... such as the Fourier transform. The Hilbert–Huang transform is a local method based on a nonparametric and empirical decomposition of the data followed by calculation of instantaneous amplitudes and frequencies using the Hilbert transform. The Hilbert–Huang transformed 4-yr time series is averaged and summarized...

A new Markov-chain-related statistical approach for modelling synthetic wind power time series

International Nuclear Information System (INIS)

Pesch, T; Hake, J F; Schröders, S; Allelein, H J

2015-01-01

The integration of rising shares of volatile wind power in the generation mix is a major challenge for the future energy system. To address the uncertainties involved in wind power generation, models analysing and simulating the stochastic nature of this energy source are becoming increasingly important. One statistical approach that has been frequently used in the literature is the Markov chain approach. Recently, the method was identified as being of limited use for generating wind time series with time steps shorter than 15–40 min as it is not capable of reproducing the autocorrelation characteristics accurately. This paper presents a new Markov-chain-related statistical approach that is capable of solving this problem by introducing a variable second lag. Furthermore, additional features are presented that allow for the further adjustment of the generated synthetic time series. The influences of the model parameter settings are examined by meaningful parameter variations. The suitability of the approach is demonstrated by an application analysis with the example of the wind feed-in in Germany. It shows that—in contrast to conventional Markov chain approaches—the generated synthetic time series do not systematically underestimate the required storage capacity to balance wind power fluctuation. (paper)

Design, operation and control of series-connected power converters for offshore wind parks

Energy Technology Data Exchange (ETDEWEB)

Ruiz, Alejandro Garces

2012-07-01

Offshore wind farms need to develop technologies that fulfill three main objectives:Efficiency, power density and reliability. The purpose of this thesis is to study an HVDC transmission system based on series connection of the turbines which theoretically meet these three objectives. A new topology of matrix converter operated at high frequency is proposed. This converter is studied using different modulation algorithms. Simulation and experimental results demonstrated that the converter can be operated as a current source converter with high efficiency. An optimal control based on a linear quadratic regulator is propose dto control the matrix converter as well as the converter placed on shore. Results demonstrated the high performance of this type of control and its simplicity for implementation. An stationary state study based on non-linear programming and Montecarlo simulation was carried out to determine the performance of the concept for long-term operation. Series connection is an efficient technology if and only if the differences in the effective wind velocity are small. This aspect limits the number of wind turbines that can be connected in series, since a numerous number of turbines will lead to high covariances in the distribution of the wind. A complementary study about active filter and reactive power compensation was carried out using an optimization-based algorithm. (Author)

Comparison of methods for the identification of mesoscale wind speed fluctuations

Directory of Open Access Journals (Sweden)

Anna Rieke Mehrens

2017-06-01

Full Text Available Mesoscale wind speed fluctuations influence the characteristics of offshore wind energy. These recurring wind speed changes on time scales between tens of minutes and six hours lead to power output fluctuations. In order to investigate the meteorological conditions associated with mesoscale wind speed fluctuations, a measure is needed to detect these situations in wind speed time series. Previous studies used the empirical Hilbert-Huang Transform to determine the energy in the mesoscale frequency range or calculated the standard deviation of a band-pass filtered wind speed time series. The aim of this paper is to introduce newly developed empirical mesoscale fluctuation measures and to compare them with existing measures in regard to their sensitivity to recurring wind speed changes. One of the methods is based on the Hilbert-Huang Transform, two on the Fast Fourier Transform and one on wind speed increments. It is found that despite various complexity of the methods, all methods can identify days with highly variable mesoscale wind speeds equally well.

Detecting and characterising ramp events in wind power time series

International Nuclear Information System (INIS)

Gallego, Cristóbal; Cuerva, Álvaro; Costa, Alexandre

2014-01-01

In order to implement accurate models for wind power ramp forecasting, ramps need to be previously characterised. This issue has been typically addressed by performing binary ramp/non-ramp classifications based on ad-hoc assessed thresholds. However, recent works question this approach. This paper presents the ramp function, an innovative wavelet- based tool which detects and characterises ramp events in wind power time series. The underlying idea is to assess a continuous index related to the ramp intensity at each time step, which is obtained by considering large power output gradients evaluated under different time scales (up to typical ramp durations). The ramp function overcomes some of the drawbacks shown by the aforementioned binary classification and permits forecasters to easily reveal specific features of the ramp behaviour observed at a wind farm. As an example, the daily profile of the ramp-up and ramp-down intensities are obtained for the case of a wind farm located in Spain

Adaptive modelling and forecasting of offshore wind power fluctuations with Markov-switching autoregressive models

DEFF Research Database (Denmark)

Pinson, Pierre; Madsen, Henrik

optimized is based on penalized maximum-likelihood, with exponential forgetting of past observations. MSAR models are then employed for 1-step-ahead point forecasting of 10-minute resolution time-series of wind power at two large offshore wind farms. They are favourably compared against persistence and Auto......Wind power production data at temporal resolutions of a few minutes exhibits successive periods with fluctuations of various dynamic nature and magnitude, which cannot be explained (so far) by the evolution of some explanatory variable. Our proposal is to capture this regime-switching behaviour......Regressive (AR) models. It is finally shown that the main interest of MSAR models lies in their ability to generate interval/density forecasts of significantly higher skill....

Two Machine Learning Approaches for Short-Term Wind Speed Time-Series Prediction.

Science.gov (United States)

Ak, Ronay; Fink, Olga; Zio, Enrico

2016-08-01

The increasing liberalization of European electricity markets, the growing proportion of intermittent renewable energy being fed into the energy grids, and also new challenges in the patterns of energy consumption (such as electric mobility) require flexible and intelligent power grids capable of providing efficient, reliable, economical, and sustainable energy production and distribution. From the supplier side, particularly, the integration of renewable energy sources (e.g., wind and solar) into the grid imposes an engineering and economic challenge because of the limited ability to control and dispatch these energy sources due to their intermittent characteristics. Time-series prediction of wind speed for wind power production is a particularly important and challenging task, wherein prediction intervals (PIs) are preferable results of the prediction, rather than point estimates, because they provide information on the confidence in the prediction. In this paper, two different machine learning approaches to assess PIs of time-series predictions are considered and compared: 1) multilayer perceptron neural networks trained with a multiobjective genetic algorithm and 2) extreme learning machines combined with the nearest neighbors approach. The proposed approaches are applied for short-term wind speed prediction from a real data set of hourly wind speed measurements for the region of Regina in Saskatchewan, Canada. Both approaches demonstrate good prediction precision and provide complementary advantages with respect to different evaluation criteria.

First and second order Markov chain models for synthetic generation of wind speed time series

International Nuclear Information System (INIS)

Shamshad, A.; Bawadi, M.A.; Wan Hussin, W.M.A.; Majid, T.A.; Sanusi, S.A.M.

2005-01-01

Hourly wind speed time series data of two meteorological stations in Malaysia have been used for stochastic generation of wind speed data using the transition matrix approach of the Markov chain process. The transition probability matrices have been formed using two different approaches: the first approach involves the use of the first order transition probability matrix of a Markov chain, and the second involves the use of a second order transition probability matrix that uses the current and preceding values to describe the next wind speed value. The algorithm to generate the wind speed time series from the transition probability matrices is described. Uniform random number generators have been used for transition between successive time states and within state wind speed values. The ability of each approach to retain the statistical properties of the generated speed is compared with the observed ones. The main statistical properties used for this purpose are mean, standard deviation, median, percentiles, Weibull distribution parameters, autocorrelations and spectral density of wind speed values. The comparison of the observed wind speed and the synthetically generated ones shows that the statistical characteristics are satisfactorily preserved

Aerodynamic analysis of S series wind turbine airfoils by using X foil technique

International Nuclear Information System (INIS)

Zaheer, M.A.; Munir, M.A.; Zahid, I.; Rizwan, M.

2015-01-01

In order to attain supreme energy from wind turbine economically, blade profile enactment must be acquired. For extracting extreme power from wind, it is necessary to develop rotor models of wind turbine which have high rotation rates and power coefficients. Maximum power can also be haul out by using suitable airfoils at root and tip sections of wind turbine blades. In this research four different S-series airfoils have been selected to study their behavior for maximum power extraction from wind. The wind conditions during the research were scertained from the wind speeds over Kallar Kahar Pakistan. In order to study the wind turbine operation, the extremely important parameters are lift and drag forces. Therefore an endeavor to study lift force and drag force at various sections of wind turbine blade is shown in current research. In order to acquire the utmost power from wind turbine, highest value of sliding ratio is prerequisite. At various wind speeds, performance of several blade profiles was analyzed and for every wind speed, the appropriate blade profile is ascertained grounded on the utmost sliding ratio. For every airfoil, prime angle of attack is resolute at numerous wind speeds. (author)

A General Probabilistic Forecasting Framework for Offshore Wind Power Fluctuations

Directory of Open Access Journals (Sweden)

Henrik Madsen

2012-03-01

Full Text Available Accurate wind power forecasts highly contribute to the integration of wind power into power systems. The focus of the present study is on large-scale offshore wind farms and the complexity of generating accurate probabilistic forecasts of wind power fluctuations at time-scales of a few minutes. Such complexity is addressed from three perspectives: (i the modeling of a nonlinear and non-stationary stochastic process; (ii the practical implementation of the model we proposed; (iii the gap between working on synthetic data and real world observations. At time-scales of a few minutes, offshore fluctuations are characterized by highly volatile dynamics which are difficult to capture and predict. Due to the lack of adequate on-site meteorological observations to relate these dynamics to meteorological phenomena, we propose a general model formulation based on a statistical approach and historical wind power measurements only. We introduce an advanced Markov Chain Monte Carlo (MCMC estimation method to account for the different features observed in an empirical time series of wind power: autocorrelation, heteroscedasticity and regime-switching. The model we propose is an extension of Markov-Switching Autoregressive (MSAR models with Generalized AutoRegressive Conditional Heteroscedastic (GARCH errors in each regime to cope with the heteroscedasticity. Then, we analyze the predictive power of our model on a one-step ahead exercise of time series sampled over 10 min intervals. Its performances are compared to state-of-the-art models and highlight the interest of including a GARCH specification for density forecasts.

Measurements of Coastal Winds and Temperature. Sensor Evaluation, Data Quality, and Wind Structures

Energy Technology Data Exchange (ETDEWEB)

Heggem, Tore

1997-12-31

The long Norwegian coastline has excellent sites for wind power production. This thesis contains a documentation of a measurement station for maritime meteorological data at the coast of Mid-Norway, and analysis of temperature and wind data. It discusses experience with different types of wind speed and wind direction sensors. Accurate air temperature measurements are essential to obtain information about the stability of the atmosphere, and a sensor based on separately calibrated thermistors is described. The quality of the calibrations and the measurements is discussed. A database built up from measurements from 1982 to 1995 has been available. The data acquisition systems and the programs used to read the data are described, as well as data control and gap-filling methods. Then basic statistics from the data like mean values and distributions are given. Quality control of the measurements with emphasis on shade effects from the masts and direction alignment is discussed. The concept of atmospheric stability is discussed. The temperature profile tends to change from unstable to slightly stable as maritime winds passes land. Temperature spectra based on two-year time series are presented. Finally, there is a discussion of long-term turbulence spectra calculated from 14 years of measurements. The lack of a gap in the one-hour region of the spectra is explained from the overweight of unstable atmospheric conditions in the dominating maritime wind. Examples of time series with regular 40-minute cycles, and corresponding effect spectra are given. The validity of local lapse rate as a criterion of atmospheric stability is discussed. 34 refs., 86 figs., 11 tabs.

Measurements of Coastal Winds and Temperature. Sensor Evaluation, Data Quality, and Wind Structures

Energy Technology Data Exchange (ETDEWEB)

Heggem, Tore

1998-12-31

The long Norwegian coastline has excellent sites for wind power production. This thesis contains a documentation of a measurement station for maritime meteorological data at the coast of Mid-Norway, and analysis of temperature and wind data. It discusses experience with different types of wind speed and wind direction sensors. Accurate air temperature measurements are essential to obtain information about the stability of the atmosphere, and a sensor based on separately calibrated thermistors is described. The quality of the calibrations and the measurements is discussed. A database built up from measurements from 1982 to 1995 has been available. The data acquisition systems and the programs used to read the data are described, as well as data control and gap-filling methods. Then basic statistics from the data like mean values and distributions are given. Quality control of the measurements with emphasis on shade effects from the masts and direction alignment is discussed. The concept of atmospheric stability is discussed. The temperature profile tends to change from unstable to slightly stable as maritime winds passes land. Temperature spectra based on two-year time series are presented. Finally, there is a discussion of long-term turbulence spectra calculated from 14 years of measurements. The lack of a gap in the one-hour region of the spectra is explained from the overweight of unstable atmospheric conditions in the dominating maritime wind. Examples of time series with regular 40-minute cycles, and corresponding effect spectra are given. The validity of local lapse rate as a criterion of atmospheric stability is discussed. 34 refs., 86 figs., 11 tabs.

A General Probabilistic Forecasting Framework for Offshore Wind Power Fluctuations

DEFF Research Database (Denmark)

Trombe, Pierre-Julien; Pinson, Pierre; Madsen, Henrik

2012-01-01

Accurate wind power forecasts highly contribute to the integration of wind power into power systems. The focus of the present study is on large-scale offshore wind farms and the complexity of generating accurate probabilistic forecasts of wind power fluctuations at time-scales of a few minutes...... fluctuations are characterized by highly volatile dynamics which are difficult to capture and predict. Due to the lack of adequate on-site meteorological observations to relate these dynamics to meteorological phenomena, we propose a general model formulation based on a statistical approach and historical wind...... power measurements only. We introduce an advanced Markov Chain Monte Carlo (MCMC) estimation method to account for the different features observed in an empirical time series of wind power: autocorrelation, heteroscedasticity and regime-switching. The model we propose is an extension of Markov...

Taking minutes of meetings

CERN Document Server

Gutmann, Joanna

2016-01-01

aking Minutes of Meetings guides you through the entire process behind minute taking: arranging the meeting; writing the agenda; creating the optimum environment; structuring the meeting and writing notes up accurately. The minute-taker is one of the most important and powerful people in a meeting and you can use this opportunity to develop your knowledge, broaden your horizons and build credibility within the organization. Taking Minutes of Meetings is an easy to read 'dip-in, dip-out' guide which shows you how to confidently arrange meetings and produce minutes. It provides hands-on advice about the sections of a meeting as well as tips on how to create an agenda, personal preparation, best practice advice on taking notes and how to improve your accuracy. Brand new chapters of this 4th edition include guidance on using technology to maximize effectiveness and practical help with taking minutes for a variety of different types of meetings. The creating success series of books... With over one million copi...

Adaptive settings of distance relay for MOV-protected series compensated line with distributed capacitance considering wind power

Science.gov (United States)

Sivov, Oleg Viktorovich

Series compensated lines are protected from overvoltage by metal-oxide-varistors (MOVs) connected in parallel with the capacitor bank. The nonlinear characteristics of MOV devices add complexity to fault analysis and distance protection operation. During faults, the impedance of the line is modified by an equivalent impedance of the parallel MOV/capacitor circuit, which affects the distance protection. The intermittent wind generation introduces additional complexity to the system performance and distance protection. Wind variation affects the fault current level and equivalent MOV/capacitor impedance during a fault, and hence the distance relay operation. This thesis studies the impact of the intermittent wind power generation on the operation of MOV during faults. For the purpose of simulation, an equivalent wind farm model is proposed to generate a wind generation profile using wind farm generation from California independent system operator (ISO) as a guide for wind power variation to perform the study. The IEEE 12-bus test system is modified to include MOV-protected series capacitor and the equivalent wind farm model. The modified test system is simulated in the MATLAB/Simulink environment. The study has been achieved considering three phase and single line to ground (SLG) faults on the series compensated line to show the effect of wind variation on the MOV operation. This thesis proposes an adaptive setting method for the mho relay distance protection of series compensated line considering effects of wind power variation and MOV operation. The distributed parameters of a transmission line are taken into account to avoid overreaching and underreaching of distance relays. The study shows that variable wind power affects system power flow and fault current in the compensated line during a fault which affects the operation of MOVs for different fault conditions. The equivalent per-phase impedance of the MOV/capacitor circuit has an effect on the system operation

NOS CO-OPS Meteorological Data, Wind, 6-Minute

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset has Wind data from NOAA NOS Center for Operational Oceanographic Products and Services (CO-OPS). WARNING: These preliminary data have not been subjected...

Modeling long correlation times using additive binary Markov chains: Applications to wind generation time series

Science.gov (United States)

Weber, Juliane; Zachow, Christopher; Witthaut, Dirk

2018-03-01

Wind power generation exhibits a strong temporal variability, which is crucial for system integration in highly renewable power systems. Different methods exist to simulate wind power generation but they often cannot represent the crucial temporal fluctuations properly. We apply the concept of additive binary Markov chains to model a wind generation time series consisting of two states: periods of high and low wind generation. The only input parameter for this model is the empirical autocorrelation function. The two-state model is readily extended to stochastically reproduce the actual generation per period. To evaluate the additive binary Markov chain method, we introduce a coarse model of the electric power system to derive backup and storage needs. We find that the temporal correlations of wind power generation, the backup need as a function of the storage capacity, and the resting time distribution of high and low wind events for different shares of wind generation can be reconstructed.

Modeling long correlation times using additive binary Markov chains: Applications to wind generation time series.

Science.gov (United States)

Weber, Juliane; Zachow, Christopher; Witthaut, Dirk

2018-03-01

Wind power generation exhibits a strong temporal variability, which is crucial for system integration in highly renewable power systems. Different methods exist to simulate wind power generation but they often cannot represent the crucial temporal fluctuations properly. We apply the concept of additive binary Markov chains to model a wind generation time series consisting of two states: periods of high and low wind generation. The only input parameter for this model is the empirical autocorrelation function. The two-state model is readily extended to stochastically reproduce the actual generation per period. To evaluate the additive binary Markov chain method, we introduce a coarse model of the electric power system to derive backup and storage needs. We find that the temporal correlations of wind power generation, the backup need as a function of the storage capacity, and the resting time distribution of high and low wind events for different shares of wind generation can be reconstructed.

A new wind speed forecasting strategy based on the chaotic time series modelling technique and the Apriori algorithm

International Nuclear Information System (INIS)

Guo, Zhenhai; Chi, Dezhong; Wu, Jie; Zhang, Wenyu

2014-01-01

Highlights: • Impact of meteorological factors on wind speed forecasting is taken into account. • Forecasted wind speed results are corrected by the associated rules. • Forecasting accuracy is improved by the new wind speed forecasting strategy. • Robust of the proposed model is validated by data sampled from different sites. - Abstract: Wind energy has been the fastest growing renewable energy resource in recent years. Because of the intermittent nature of wind, wind power is a fluctuating source of electrical energy. Therefore, to minimize the impact of wind power on the electrical grid, accurate and reliable wind power forecasting is mandatory. In this paper, a new wind speed forecasting approach based on based on the chaotic time series modelling technique and the Apriori algorithm has been developed. The new approach consists of four procedures: (I) Clustering by using the k-means clustering approach; (II) Employing the Apriori algorithm to discover the association rules; (III) Forecasting the wind speed according to the chaotic time series forecasting model; and (IV) Correcting the forecasted wind speed data using the associated rules discovered previously. This procedure has been verified by 31-day-ahead daily average wind speed forecasting case studies, which employed the wind speed and other meteorological data collected from four meteorological stations located in the Hexi Corridor area of China. The results of these case studies reveal that the chaotic forecasting model can efficiently improve the accuracy of the wind speed forecasting, and the Apriori algorithm can effectively discover the association rules between the wind speed and other meteorological factors. In addition, the correction results demonstrate that the association rules discovered by the Apriori algorithm have powerful capacities in handling the forecasted wind speed values correction when the forecasted values do not match the classification discovered by the association rules

Guide to Using the WIND Toolkit Validation Code

Energy Technology Data Exchange (ETDEWEB)

Lieberman-Cribbin, W.; Draxl, C.; Clifton, A.

2014-12-01

In response to the U.S. Department of Energy's goal of using 20% wind energy by 2030, the Wind Integration National Dataset (WIND) Toolkit was created to provide information on wind speed, wind direction, temperature, surface air pressure, and air density on more than 126,000 locations across the United States from 2007 to 2013. The numerical weather prediction model output, gridded at 2-km and at a 5-minute resolution, was further converted to detail the wind power production time series of existing and potential wind facility sites. For users of the dataset it is important that the information presented in the WIND Toolkit is accurate and that errors are known, as then corrective steps can be taken. Therefore, we provide validation code written in R that will be made public to provide users with tools to validate data of their own locations. Validation is based on statistical analyses of wind speed, using error metrics such as bias, root-mean-square error, centered root-mean-square error, mean absolute error, and percent error. Plots of diurnal cycles, annual cycles, wind roses, histograms of wind speed, and quantile-quantile plots are created to visualize how well observational data compares to model data. Ideally, validation will confirm beneficial locations to utilize wind energy and encourage regional wind integration studies using the WIND Toolkit.

Different methods for analysing and imputation missing values in wind speed series; La problematica de la calidad de la informacion en series de velocidad del viento-metodologias de analisis y imputacion de datos faltantes

Energy Technology Data Exchange (ETDEWEB)

Ferreira, A. M.

2004-07-01

This study concerns about different methods for analysing and imputation missing values in wind speed series. The algorithm EM and a methodology derivated from the sequential hot deck have been utilized. Series with missing values imputed are compared with original and complete series, using several criteria, such the wind potential; and appears to exist a significant goodness of fit between the estimates and real values. (Author)

The use of Markov chains in forecasting wind speed: Matlab source code and applied case study

Directory of Open Access Journals (Sweden)

Ionuţ Alexandru Petre

2017-01-01

Full Text Available The ability to predict the wind speed has an important role for renewable energy industry which relies on wind speed forecasts in order to calculate the power a wind farm can produce in an area. There are several well-known methods to predict wind speed, but in this paper we focus on short-term wind forecasting using Markov chains. Often gaps can be found in the time series of the wind speed measurements and repeating the measurements is usually not a valid option. In this study it is shown that using Markov chains these gaps from the time series can be filled (they can be generated in an efficient way, but only when the missing data is for a short period of time. Also, the developed Matlab programms that are used in the case study, are included in the paper beeing presented and commented by the authors. In the case study data from a wind farm in Italy is used. The available data are as average wind speed at an interval of 10 minutes in the time period 11/23/2005 - 4/27/2006.

A new long instrumental serie for the Etesian winds since 1877

Science.gov (United States)

Gómez-Delgado, F. de Paula; Vega, Inmaculada; Gallego, David; Peña-Ortiz, Cristina; Ribera, Pedro; García-Herrera, Ricardo

2016-04-01

The meteorological observations found in old ships' logbooks have been recognized as a useful source of climatic information in periods and areas not covered by other sources. In the last five years several studies have employed the wind direction observations contained in logbooks to generate climatic indices of instrumental character related to large scale patterns such as the atmospheric westerly circulation in North Atlantic, the strength of the West African Monsoon or the start date of the Indian Summer Monsoon (ISM). This study is focused on the winds in the eastern Mediterranean (EM) and its relation to the subtropical climate at decadal scale. Previous studies have shown a significant link between the frequency and strength of the prevalent summer northerly winds (Etesian winds) of the EM and the strength of the ISM. This relationship had only been studied in detail for the second half of the 20th century due to the absence of long and continuous series of wind observations in the EM for previous periods. In this work, we use historical wind data contained in ship's logbooks to generate a new climatic index, the "Etesian Wind Index", which can be defined as the percentage of days with prevalent northerly wind (between 315° and 45°) in a fixed region [10°W-20°W, 32°N-36°N]. We have been able to produce an index of the Etesian winds starting in 1877 suitable to analyze its long term variability and its relation with the ISM in unprecedented detail. Our first results show that the frequency of the northerly winds in the EM was significantly larger in the first half of the studied period, mainly due to an intensification of the zonal component in the second half of the studied period. Interestingly, the comparison with analogous Etesian wind indices computed from reanalysis products (NCEP/NCAR 20th Century (V2c) and ERA20C), shows strong discrepancies among them and with our instrumental reconstruction, which could indicate a misrepresentation of the

Development and testing of an innovative short-term large wind ramp forecasting system

Energy Technology Data Exchange (ETDEWEB)

Zack, J.W. [AWS Truepower LLC, Troy, NY (United States)

2010-07-01

This PowerPoint presentation discussed a ramp forecasting tool designed for use in a region of Texas with a high wind-generating capacity. Large system-wide ramps frequently occur in the region, and curtailments are common due to transmission constraints. The average hourly load of the power system is 32,101 MW. Wind power capacity in the region is 9382 MW. However, actual production rarely exceeds 6500 MW due to the curtailments. The short-term ramp forecasting tool was designed to aid in grid management decisions for the 0-6 hour ahead period as well as to address issues related to wind farm time series data and the lack of situational awareness information. The tool provided rapid updates for grid point wind analysis with feature detection and tracking algorithms and a rapid update cycle model. The tool also featured a suite of web-based applications that included deterministic ramp even forecasts, power production time series forecasts, and situational awareness products that are updated every 15 minutes. A performance evaluation study of the tool was provided. tabs., figs.

Sizing of the Series Dynamic Breaking Resistor in a Doubly Fed Induction Generator Wind Turbine

DEFF Research Database (Denmark)

Soliman, Hammam; Wang, Huai; Zhou, Dao

2014-01-01

This paper investigates the effect of Series Dynamic Breaking Resistor (SDBR) sizing on a Doubly Fed Induction Generator (DFIG) based wind power conversion system. The boundary of the SDBR value is firstly derived by taking into account the controllability of the rotor side converter and the maxi......This paper investigates the effect of Series Dynamic Breaking Resistor (SDBR) sizing on a Doubly Fed Induction Generator (DFIG) based wind power conversion system. The boundary of the SDBR value is firstly derived by taking into account the controllability of the rotor side converter...... and the maximum allowable voltage of the stator. Then the impact of the SDBR value on the rotor current, stator voltage, DC-link voltage, reactive power capability and introduced power loss during voltage sag operation is evaluated by simulation. The presented study enables a trade-off sizing of the SDBR among...

Adaptive modelling and forecasting of offshore wind power fluctuations with Markov-switching autoregressive models

DEFF Research Database (Denmark)

Pinson, Pierre; Madsen, Henrik

2012-01-01

optimized is based on penalized maximum likelihood, with exponential forgetting of past observations. MSAR models are then employed for one-step-ahead point forecasting of 10 min resolution time series of wind power at two large offshore wind farms. They are favourably compared against persistence......Wind power production data at temporal resolutions of a few minutes exhibit successive periods with fluctuations of various dynamic nature and magnitude, which cannot be explained (so far) by the evolution of some explanatory variable. Our proposal is to capture this regime-switching behaviour...... and autoregressive models. It is finally shown that the main interest of MSAR models lies in their ability to generate interval/density forecasts of significantly higher skill....

Comparison of Artificial Neural Networks and ARIMA statistical models in simulations of target wind time series

Science.gov (United States)

Kolokythas, Kostantinos; Vasileios, Salamalikis; Athanassios, Argiriou; Kazantzidis, Andreas

2015-04-01

The wind is a result of complex interactions of numerous mechanisms taking place in small or large scales, so, the better knowledge of its behavior is essential in a variety of applications, especially in the field of power production coming from wind turbines. In the literature there is a considerable number of models, either physical or statistical ones, dealing with the problem of simulation and prediction of wind speed. Among others, Artificial Neural Networks (ANNs) are widely used for the purpose of wind forecasting and, in the great majority of cases, outperform other conventional statistical models. In this study, a number of ANNs with different architectures, which have been created and applied in a dataset of wind time series, are compared to Auto Regressive Integrated Moving Average (ARIMA) statistical models. The data consist of mean hourly wind speeds coming from a wind farm on a hilly Greek region and cover a period of one year (2013). The main goal is to evaluate the models ability to simulate successfully the wind speed at a significant point (target). Goodness-of-fit statistics are performed for the comparison of the different methods. In general, the ANN showed the best performance in the estimation of wind speed prevailing over the ARIMA models.

Comparisons between two wavelet functions in extracting coherent structures from solar wind time series

International Nuclear Information System (INIS)

Bolzani, M.J.A.; Guarnieri, F.L.; Vieira, Paulo Cesar

2009-01-01

Nowadays, wavelet analysis of turbulent flows have become increasingly popular. However, the study of geometric characteristics from wavelet functions is still poorly explored. In this work we compare the performance of two wavelet functions in extracting the coherent structures from solar wind velocity time series. The data series are from years 1996 to 2002 (except 1998 and 1999). The wavelet algorithm decomposes the annual time-series in two components: the coherent part and non-coherent one, using the daubechies-4 and haar wavelet function. The threshold assumed is based on a percentage of maximum variance found in each dyadic scale. After the extracting procedure, we applied the power spectral density on the original time series and coherent time series to obtain spectral indices. The results from spectral indices show higher values for the coherent part obtained by daubechies-4 than those obtained by the haar wavelet function. Using the kurtosis statistical parameter, on coherent and non-coherent time series, it was possible to conjecture that the differences found between two wavelet functions may be associated with their geometric forms. (author)

NODC Standard Format Ocean Wind Time Series from Buoys (F101) Data (1975-1985) (NODC Accession 0014194)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This file type contains time series measurements of wind and other surface meteorological parameters taken at fixed locations. The instrument arrays may be deployed...

Uncertainties of the 50-year wind from short time series using generalized extreme value distribution and generalized Pareto distribution

DEFF Research Database (Denmark)

Larsén, Xiaoli Guo; Mann, Jakob; Rathmann, Ole

2015-01-01

This study examines the various sources to the uncertainties in the application of two widely used extreme value distribution functions, the generalized extreme value distribution (GEVD) and the generalized Pareto distribution (GPD). The study is done through the analysis of measurements from...... as a guideline for applying GEVD and GPD to wind time series of limited length. The data analysis shows that, with reasonable choice of relevant parameters, GEVD and GPD give consistent estimates of the return winds. For GEVD, the base period should be chosen in accordance with the occurrence of the extreme wind...

Configuration study of large wind parks

Energy Technology Data Exchange (ETDEWEB)

Lundberg, Stefan

2003-07-01

In this thesis, layouts of various large-scale wind parks, using both AC as well as DC, are investigated. Loss modelling of the wind park components as well as calculations of the energy capture of the turbines using various electrical systems are performed, and the energy production cost of the various park configurations is determined. The most interesting candidate for a DC transmission based wind park was investigated more in detail, the series DC wind park. Finally, the power quality impact in the PCC (point of common coupling) was studied. It was found that from an energy capture point of view, the difference in energy production between various wind turbine systems is very small. Of all the investigated wind park configurations, the wind park with the series connected DC wind turbines seems to have the best potential to give the lowest energy production cost, if the transmission distance is longer then 10-20 km. Regarding the series DC wind park it was found that it is the most difficult one to control. However, a control algorithm for the series park and its turbines was derived and successfully tested. Still, several more details regarding the control of the series wind park has to be dealt with.

Wind-wave, and turbidity time-series data from Little Holland Tract (station HWC), Sacramento-San Joaquin Delta, California

Data.gov (United States)

Department of the Interior — Time series data of water surface elevation, wave height, and turbidity were collected in Little Holland Tract (LHT) beginning in December 2015 as part of “Wind-wave...

A comparison of various forecasting techniques applied to mean hourly wind speed time series

Energy Technology Data Exchange (ETDEWEB)

Sfetsos, A. [7 Pirsou Street, Athens (Greece)

2000-09-01

This paper presents a comparison of various forecasting approaches, using time series analysis, on mean hourly wind speed data. In addition to the traditional linear (ARMA) models and the commonly used feed forward and recurrent neural networks, other approaches are also examined including the Adaptive Neuro-Fuzzy Inference Systems (ANFIS) and Neural Logic Networks. The developed models are evaluated for their ability to produce accurate and fast forecasts. (Author)

Wind Climate Parameters for Wind Turbine Fatigue Load Assessment

DEFF Research Database (Denmark)

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

2016-01-01

Site-specific assessment of wind turbine design requires verification that the individual wind turbine components can survive the site-specific wind climate. The wind turbine design standard, IEC 61400-1 (third edition), describes how this should be done using a simplified, equivalent wind climate...... 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...

Series resonant converter with auxiliary winding turns: analysis, design and implementation

Science.gov (United States)

Lin, Bor-Ren

2018-05-01

Conventional series resonant converters have researched and applied for high-efficiency power units due to the benefit of its low switching losses. The main problems of series resonant converters are wide frequency variation and high circulating current. Thus, resonant converter is limited at narrow input voltage range and large input capacitor is normally adopted in commercial power units to provide the minimum hold-up time requirement when AC power is off. To overcome these problems, the resonant converter with auxiliary secondary windings are presented in this paper to achieve high voltage gain at low input voltage case such as hold-up time duration when utility power is off. Since the high voltage gain is used at low input voltage cased, the frequency variation of the proposed converter compared to the conventional resonant converter is reduced. Compared to conventional resonant converter, the hold-up time in the proposed converter is more than 40ms. The larger magnetising inductance of transformer is used to reduce the circulating current losses. Finally, a laboratory prototype is constructed and experiments are provided to verify the converter performance.

Satellite winds as a tool for offshore wind resource assessment: The Great Lakes Wind Atlas

DEFF Research Database (Denmark)

Doubrawa, Paula; Barthelmie, Rebecca Jane; Pryor, Sara C.

2015-01-01

and combine all scenes into one wind speed map. QuikSCAT winds undergo a seasonal correction due to lack of data during the cold season that is based on its ratio relative to buoy time series. All processing steps reduce the biases of the individual maps relative to the buoy observed wind climates. The remote...

Wind Integration National Dataset (WIND) Toolkit; NREL (National Renewable Energy Laboratory)

Energy Technology Data Exchange (ETDEWEB)

Draxl, Caroline; Hodge, Bri-Mathias

2015-07-14

A webinar about the Wind Integration National Dataset (WIND) Toolkit was presented by Bri-Mathias Hodge and Caroline Draxl on July 14, 2015. It was hosted by the Southern Alliance for Clean Energy. The toolkit is a grid integration data set that contains meteorological and power data at a 5-minute resolution across the continental United States for 7 years and hourly power forecasts.

An assessment on seasonal analysis of wind energy characteristics and wind turbine characteristics

International Nuclear Information System (INIS)

Akpinar, E. Kavak; Akpinar, S.

2005-01-01

This paper presents seasonal variations of the wind characteristics and wind turbine characteristics in the regions around Elazig, namely Maden, Agin and Keban. Mean wind speed data in measured hourly time series format is statistically analyzed for the six year period 1998-2003. The probability density distributions are derived from the time series data and their distributional parameters are identified. Two probability density functions are fitted to the measured probability distributions on a seasonal basis. The wind energy characteristics of all the regions is studied based on the Weibull and Rayleigh distributions. Energy calculations and capacity factors for the wind turbine characteristics were determined for wind machines of different sizes between 300 and 2300 kW. It was found that Maden is the best region, among the regions analyzed, for wind characteristics and wind turbine characteristics

A multiple-fan active control wind tunnel for outdoor wind speed and direction simulation

Science.gov (United States)

Wang, Jia-Ying; Meng, Qing-Hao; Luo, Bing; Zeng, Ming

2018-03-01

This article presents a new type of active controlled multiple-fan wind tunnel. The wind tunnel consists of swivel plates and arrays of direct current fans, and the rotation speed of each fan and the shaft angle of each swivel plate can be controlled independently for simulating different kinds of outdoor wind fields. To measure the similarity between the simulated wind field and the outdoor wind field, wind speed and direction time series of two kinds of wind fields are recorded by nine two-dimensional ultrasonic anemometers, and then statistical properties of the wind signals in different time scales are analyzed based on the empirical mode decomposition. In addition, the complexity of wind speed and direction time series is also investigated using multiscale entropy and multivariate multiscale entropy. Results suggest that the simulated wind field in the multiple-fan wind tunnel has a high degree of similarity with the outdoor wind field.

Application of the nonlinear time series prediction method of genetic algorithm for forecasting surface wind of point station in the South China Sea with scatterometer observations

International Nuclear Information System (INIS)

Zhong Jian; Dong Gang; Sun Yimei; Zhang Zhaoyang; Wu Yuqin

2016-01-01

The present work reports the development of nonlinear time series prediction method of genetic algorithm (GA) with singular spectrum analysis (SSA) for forecasting the surface wind of a point station in the South China Sea (SCS) with scatterometer observations. Before the nonlinear technique GA is used for forecasting the time series of surface wind, the SSA is applied to reduce the noise. The surface wind speed and surface wind components from scatterometer observations at three locations in the SCS have been used to develop and test the technique. The predictions have been compared with persistence forecasts in terms of root mean square error. The predicted surface wind with GA and SSA made up to four days (longer for some point station) in advance have been found to be significantly superior to those made by persistence model. This method can serve as a cost-effective alternate prediction technique for forecasting surface wind of a point station in the SCS basin. (paper)

Extreme Response for Wind Turbines

DEFF Research Database (Denmark)

Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

2009-01-01

The characteristic load on wind turbines during operation are among others dependent on the mean wind speed, the turbulence intensity and type and settings of the control system. The characteristic load during operation is normally estimated by statistical extrapolation of a limited number...... of simulated 10min time series of the response according to the wind turbine standard IEC 61400-1. However, this method assumes that the individual 10min time series and the extracted peaks from the time series are independent. In the present paper is this assumption investigated based on field measurements...

Application of Portfolio Theory to Minimization of Generation Variability in a System with Wind plants

International Nuclear Information System (INIS)

Sabolic, D.

2016-01-01

This paper evaluates validity of modern portfolio theory (MPT) for planning of installation of new wind plants with the lowest possible generation variability for given expected yearly generation. Suppose a Planner had historic meteorological data on wind speeds at a finite number of locations over longer time periods, and that they were technically convertible to time series of forecasted generation powers per megawatt of installed capacity. Suppose further that she intended to upgrade existing system with certain fixed amount of new wind plant capacity. Then she would be able to allocate shares in that total capacity to the available locations in a way that suits her policy goals regarding relation between total expected annual generation and total variability of generation best. Minimization of variability is a legitimate policy goal because it increases total costs of energy supply, so that leaving generation to vary more than technically necessary is economically inefficient. This article focuses on applicability of portfolio theory to such a problem. In the presented research, measured 15-minute data of wind generation in existing Croatian wind plants were used.(author).

Improved Synthesis of Global Irradiance with One-Minute Resolution for PV System Simulations

Directory of Open Access Journals (Sweden)

Martin Hofmann

2014-01-01

Full Text Available High resolution global irradiance time series are needed for accurate simulations of photovoltaic (PV systems, since the typical volatile PV power output induced by fast irradiance changes cannot be simulated properly with commonly available hourly averages of global irradiance. We present a two-step algorithm that is capable of synthesizing one-minute global irradiance time series based on hourly averaged datasets. The algorithm is initialized by deriving characteristic transition probability matrices (TPM for different weather conditions (cloudless, broken clouds and overcast from a large number of high resolution measurements. Once initialized, the algorithm is location-independent and capable of synthesizing one-minute values based on hourly averaged global irradiance of any desired location. The one-minute time series are derived by discrete-time Markov chains based on a TPM that matches the weather condition of the input dataset. One-minute time series generated with the presented algorithm are compared with measured high resolution data and show a better agreement compared to two existing synthesizing algorithms in terms of temporal variability and characteristic frequency distributions of global irradiance and clearness index values. A comparison based on measurements performed in Lindenberg, Germany, and Carpentras, France, shows a reduction of the frequency distribution root mean square errors of more than 60% compared to the two existing synthesizing algorithms.

Extreme winds in Denmark

DEFF Research Database (Denmark)

Kristensen, L.; Rathmann, Ole; Hansen, S.O.

1999-01-01

Wind-speed data from four sites in Denmark have been analyzed in order to obtain estimates of the basic wind velocity which is defined as the 50-year wind speed under standard conditions, i.e. ten-minute averages at the height 10 m over a uniform terrainwith the roughness length 0.05 m. The sites...... by means of the geostrophic drag law for neutral stratification. The basic wind velocity in 30o sectors are obtainedthrough ranking of the largest values of the ¤friction velocity pressure¤ 1/2 ¤#rho#¤¤u¤"2_x taken both once every two months and once every year. The main conclusion is that the basic wind...

Turbulent wind at the equatorial segment of an operating Darrieus wind turbine blade

Science.gov (United States)

Connell, J. R.; Morris, V. R.

1989-09-01

Six turbulent wind time series, measured at equally spaced equator-height locations on a circle 3 m outside a 34-m Darrieus rotor, are analyzed to approximate the wind fluctuations experienced by the rotor. The flatwise lower root-bending stress of one blade was concurrently recorded. The wind data are analyzed in three ways: wind components that are radial and tangential to the rotation of a blade were rotationally sampled; induction and wake effects of the rotor were estimated from the six Eulerian time series; and turbulence spectra of both the measured wind and the modeled wind from the PNL theory of rotationally sampled turbulence. The wind and the rotor response are related by computing the spectral response function of the flatwise lower root-bending stress. Two bands of resonant response that surround the first and second flatwise modal frequencies shift with the rotor rotation rate.

Advancements in Wind Integration Study Data Modeling: The Wind Integration National Dataset (WIND) Toolkit; Preprint

Energy Technology Data Exchange (ETDEWEB)

Draxl, C.; Hodge, B. M.; Orwig, K.; Jones, W.; Searight, K.; Getman, D.; Harrold, S.; McCaa, J.; Cline, J.; Clark, C.

2013-10-01

Regional wind integration studies in the United States require detailed wind power output data at many locations to perform simulations of how the power system will operate under high-penetration scenarios. The wind data sets that serve as inputs into the study must realistically reflect the ramping characteristics, spatial and temporal correlations, and capacity factors of the simulated wind plants, as well as be time synchronized with available load profiles. The Wind Integration National Dataset (WIND) Toolkit described in this paper fulfills these requirements. A wind resource dataset, wind power production time series, and simulated forecasts from a numerical weather prediction model run on a nationwide 2-km grid at 5-min resolution will be made publicly available for more than 110,000 onshore and offshore wind power production sites.

Influence of local wind speed and direction on wind power dynamics – Application to offshore very short-term forecasting

DEFF Research Database (Denmark)

Gallego, Cristobal; Pinson, Pierre; Madsen, Henrik

2011-01-01

Wind power time series usually show complex dynamics mainly due to non-linearities related to the wind physics and the power transformation process in wind farms. This article provides an approach to the incorporation of observed local variables (wind speed and direction) to model some of these e......Wind power time series usually show complex dynamics mainly due to non-linearities related to the wind physics and the power transformation process in wind farms. This article provides an approach to the incorporation of observed local variables (wind speed and direction) to model some...... on one-step ahead forecasting and a time series resolution of 10 min. It has been found that the local wind direction contributes to model some features of the prevailing winds, such as the impact of the wind direction on the wind variability, whereas the non-linearities related to the power...... transformation process can be introduced by considering the local wind speed. In both cases, conditional parametric models showed a better performance than the one achieved by the regime-switching strategy. The results attained reinforce the idea that each explanatory variable allows the modelling of different...

Wind Turbine Converter Control Interaction with Complex Wind Farm Systems

DEFF Research Database (Denmark)

Kocewiak, Lukasz Hubert; Hjerrild, Jesper; Bak, Claus Leth

2013-01-01

. The same wind turbine converter control strategy is evaluated in two different wind farms. It is emphasised that the grid-side converter controller should be characterised by sufficient harmonic/noise rejection and adjusted depending on wind farms to which it is connected. Various stability indices......This study presents wind turbine converter stability analysis of wind farms in frequency domain. The interaction between the wind turbine control system and the wind farm structure in wind farms is deeply investigated. Two wind farms (i.e. Horns Rev II and Karnice) are taken into consideration...... in this study. It is shown that wind farm components, such as long high-voltage alternating current cables and park transformers, can introduce significant low-frequency series resonances seen from the wind turbine terminals that can affect wind turbine control system operation and overall wind farm stability...

Wind resource analysis. Annual report

Energy Technology Data Exchange (ETDEWEB)

Hardy, D. M.

1978-12-01

FY78 results of the Wind Resource Analyses task of the ERAB are described. Initial steps were taken to acquire modern atmosphere models of near-surface wind flow and primary data sets used in previous studies of national and regional wind resources. Because numerous assumptions are necessary to interpret available data in terms of wind energy potential, conclusions of previous studies differ considerably. These data analyses may be improved by future SERI research. State-of-the-art atmosphere models are a necessary component of the SERI wind resource analyses capacity. However, these methods also need to be tested and verified in diverse applications. The primary data sets and principal features of the models are discussed.

Wind Forces on Container Ships

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....

ARIMA-Based Time Series Model of Stochastic Wind Power Generation

DEFF Research Database (Denmark)

Chen, Peiyuan; Pedersen, Troels; Bak-Jensen, Birgitte

2010-01-01

This paper proposes a stochastic wind power model based on an autoregressive integrated moving average (ARIMA) process. The model takes into account the nonstationarity and physical limits of stochastic wind power generation. The model is constructed based on wind power measurement of one year from...... the Nysted offshore wind farm in Denmark. The proposed limited-ARIMA (LARIMA) model introduces a limiter and characterizes the stochastic wind power generation by mean level, temporal correlation and driving noise. The model is validated against the measurement in terms of temporal correlation...... and probability distribution. The LARIMA model outperforms a first-order transition matrix based discrete Markov model in terms of temporal correlation, probability distribution and model parameter number. The proposed LARIMA model is further extended to include the monthly variation of the stochastic wind power...

Database on wind characteristics

Energy Technology Data Exchange (ETDEWEB)

Hansen, K.S. [The Technical Univ. of Denmark (Denmark); Courtney, M.S. [Risoe National Lab., (Denmark)

1999-08-01

The organisations that participated in the project consists of five research organisations: MIUU (Sweden), ECN (The Netherlands), CRES (Greece), DTU (Denmark), Risoe (Denmark) and one wind turbine manufacturer: Vestas Wind System A/S (Denmark). The overall goal was to build a database consisting of a large number of wind speed time series and create tools for efficiently searching through the data to select interesting data. The project resulted in a database located at DTU, Denmark with online access through the Internet. The database contains more than 50.000 hours of measured wind speed measurements. A wide range of wind climates and terrain types are represented with significant amounts of time series. Data have been chosen selectively with a deliberate over-representation of high wind and complex terrain cases. This makes the database ideal for wind turbine design needs but completely unsuitable for resource studies. Diversity has also been an important aim and this is realised with data from a large range of terrain types; everything from offshore to mountain, from Norway to Greece. (EHS)

Wind resource and plant output data sets for wind integration studies

Energy Technology Data Exchange (ETDEWEB)

Frank, Jaclyn D.; Manobianco, John; Alonge, Charles J.; Brower, Michael C. [AWS Truepower, Albany, NY (United States)

2010-07-01

One of the first step towards understanding the impact of increasing penetrations of wind is developing data sets of wind power output over large regions. To facilitate the development of these data sets, AWS Truepower (AWST) generated wind speeds over multiple years (2-3) using the Mesoscale Atmospheric Simulation System (MASS). These simulations were performed with high spatial resolution (1-2 km) to capture the wind flows over each area of interest. Output was saved in 10-minute interval to capture variations in wind speed so that plant output could be analyzed against utility load and system operations. This paper will describe the methodology of mesoscale modeling, site selection, conversion to power, and downscaling to high frequency output. Additionally, the generation of synthetic forecasts will be discussed. The validation results from recent studies in the eastern United States and Hawaii will be highlighted. (orig.)

Wind power development field test project at Ashibe-cho. Detailed wind characteristics survey; Ashibecho ni okeru furyoku kaihatsu field test jigyo (fukyo seisa) hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-11-01

A detailed wind characteristics survey was conducted at Ashibe-cho, Iki-gun, Nagasaki Prefecture, on the assumption that a wind power generation system would be constructed. The survey was a 1-year project from October 1998 through September 1999, and wind characteristics such as the average wind speed, average wind direction, standard deviation of wind velocity, and the maximum instantaneous wind speed were observed. The observation point was fixed at 20m above ground, the minimum time unit for observation was 10 minutes, and the 10-minute average value was defined as the measured value. For the maximum instantaneous wind speed, the minimum time unit for observation was set to be 2 seconds. The yearly average wind speed was 5.8m/s and the maximum wind speed in the period was 35m/s. Winds came from the prevailing direction of NE (21.3%), and then from NNE (14.7%) and ENE (7.9%). The wind axis was in the NE-SW direction, and the total wind direction occurrence rate from the 6 directions was 60.2%. Turbulence intensity was 0.19 at wind speed 2.0m/s or more and 0.17 at wind speed 4.0m/s or more. Estimated wind turbine yearly operating factors of 66-84% were obtained using rated values of a 150kW, 300kW, and 750kW-class wind turbines. (NEDO)

Three Dimensional Dynamic Model Based Wind Field Reconstruction from Lidar Data

International Nuclear Information System (INIS)

Raach, Steffen; Schlipf, David; Haizmann, Florian; Cheng, Po Wen

2014-01-01

Using the inflowing horizontal and vertical wind shears for individual pitch controller is a promising method if blade bending measurements are not available. Due to the limited information provided by a lidar system the reconstruction of shears in real-time is a challenging task especially for the horizontal shear in the presence of changing wind direction. The internal model principle has shown to be a promising approach to estimate the shears and directions in 10 minutes averages with real measurement data. The static model based wind vector field reconstruction is extended in this work taking into account a dynamic reconstruction model based on Taylor's Frozen Turbulence Hypothesis. The presented method provides time series over several seconds of the wind speed, shears and direction, which can be directly used in advanced optimal preview control. Therefore, this work is an important step towards the application of preview individual blade pitch control under realistic wind conditions. The method is tested using a turbulent wind field and a detailed lidar simulator. For the simulation, the turbulent wind field structure is flowing towards the lidar system and is continuously misaligned with respect to the horizontal axis of the wind turbine. Taylor's Frozen Turbulence Hypothesis is taken into account to model the wind evolution. For the reconstruction, the structure is discretized into several stages where each stage is reduced to an effective wind speed, superposed with a linear horizontal and vertical wind shear. Previous lidar measurements are shifted using again Taylor's Hypothesis. The wind field reconstruction problem is then formulated as a nonlinear optimization problem, which minimizes the residual between the assumed wind model and the lidar measurements to obtain the misalignment angle and the effective wind speed and the wind shears for each stage. This method shows good results in reconstructing the wind characteristics of a three

Periodic fluctuations in correlation-based connectivity density time series: Application to wind speed-monitoring network in Switzerland

Science.gov (United States)

Laib, Mohamed; Telesca, Luciano; Kanevski, Mikhail

2018-02-01

In this paper, we study the periodic fluctuations of connectivity density time series of a wind speed-monitoring network in Switzerland. By using the correlogram-based robust periodogram annual periodic oscillations were found in the correlation-based network. The intensity of such annual periodic oscillations is larger for lower correlation thresholds and smaller for higher. The annual periodicity in the connectivity density seems reasonably consistent with the seasonal meteo-climatic cycle.

Wind power development field test project at Hirashima, Sakito-cho. Detailed wind characteristics survey; Sakitocho Hirashima ni okeru furyoku kaihatsu field test jigyo (fukyo seisa) hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-11-01

A detailed wind characteristics survey was conducted at Hirashima, Sakito-cho, Nishisonogi-gun, Nagasaki Prefecture, on the assumption that a wind power generation system would be constructed. The survey was a 1-year project from October 1998 through September 1999, and wind characteristics such as the average wind speed, average wind direction, standard deviation of wind velocity, and the maximum instantaneous wind speed were observed. The observation point was fixed at 20m above ground, the minimum time unit for observation was 10 minutes, and the 10-minute average value was defined as the measured value. For the maximum instantaneous wind speed, the minimum time unit for observation was set to be 2 seconds. The yearly average wind speed was 7.1m/s and the maximum wind speed in the period was 37m/s. Winds came prevalently from N (13.9%), and then from NNE (13.3%), NW (12.2%), and NE (10.7%). The total wind direction occurrence rate involving the 4 directions was 50.1%. Turbulence intensity was 0.14 at wind speed 2.0m/s or more and 0.12 at wind speed 4.0m/s or more. Estimated wind turbine yearly operating factors of 77-87% were obtained using rated values of a 150kW, 300kW, and 750kW-class wind turbines. (NEDO)

Wind power development field test project at Maruyama-machi. Close survey on wind conditions; Maruyamamachi ni okeru furyoku kaihatsu field test jigyo (fukyo seisa) hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-11-01

A survey was made on wind conditions in Maruyama-machi, Awa-gun, Chiba prefecture, on the assumption that a wind power generation system was installed therein. The survey period was one year from Oct., 1998 to Sept., 1999. The observations were carried out on the average wind velocity, average wind direction, standard deviation of velocity, and the maximum instantaneous wind velocity. With a fixed point observation at 20 m above ground, and with the minimum observation time unit of 10 minutes, an average value during the 10 minutes was determined as the measurement of each category. However, the maximum instantaneous wind velocity was determined on the measurement with the minimum observation time unit of 2 seconds. The average annual wind velocity was 3.5 m/s, the maximum wind velocity during the period was 27 m/s, and the wind axis was WSW-ENE, with the total occurrence rate of the wind direction 44.1%. The intensity of turbulence was 0.23 at a wind velocity of 2.0 m/s or above and was 0.22 at 4.0 m/s or above. An estimated annual operation rate of a windmill was 40-60% using the rated value of a 150 kW, 300 kW and 750 kW class windmills. (NEDO)

Resistance exercise-induced microinjuries do not depend on 1or 3 minutes rest time interval between series. (Las microlesiones inducidas por el entrenamiento con cargas no dependen de los intervalos de descanso entre series de 1 o 3 minutos.

Directory of Open Access Journals (Sweden)

Rafael Pereira

2008-10-01

Full Text Available AbstractIn order to examine the effects of different rest intervals between sets on the muscle fiber integrity, 14 male subjects volunteered to participate in randomized crossover design methodology. All subjects completed 2 experimental training sessions. Both sessions consisted of 3 sets of 10 repetitions with 10 repetition maximum resistance bench press, cable pulldowns, military press, biceps curl, triceps curl, leg press, leg extension, and lying leg curls. The 2 experimental sessions differed only in the length of the rest period between sets and exercises: 1 session with a 1-minute and the other with a 3-minute rest period. the mechanical stress caused by the proposed training session cause similar damage in the muscle fibers do not depend of the 1 or 3 minutes of rest interval between series. ResumenEl propósito de ese estudio fue comparar los efectos de 2 diferentes períodos de descanso durante una sesión de entrenamiento con cargas en la integridad de la fibra muscular. Participaron de forma voluntaria 14 hombres en un estudio con diseño cruzado aleatorio. Todos los sujetos realizaron 2 sesiones de entrenamiento con cargas. Durante cada sesión, los sujetos completaban 3 series de 10 repeticiones máximas de press de banca, jalón en polea alta para dorsal, press militar, curl de bíceps con barra, extensión de tríceps trasnuca con mancuerna, prensa de piernas en máquina, extensión de rodillas en máquina, y flexión de rodillas en máquina. Las 2 sesiones experimentales diferían sólo en la longitud del período de descanso entre las series y los ejercicios: una sesión con 1 minuto y la otra con 3 minutos en los períodos de descanso. La tensión mecánica causada por las sesiones puede causar daños similares en las fibras musculares y no dependen de hacer 1 o 3 minutos de intervalo de descanso entre las series.

Wind, Wave, and Tidal Energy Without Power Conditioning

Science.gov (United States)

Jones, Jack A.

2013-01-01

Most present wind, wave, and tidal energy systems require expensive power conditioning systems that reduce overall efficiency. This new design eliminates power conditioning all, or nearly all, of the time. Wind, wave, and tidal energy systems can transmit their energy to pumps that send high-pressure fluid to a central power production area. The central power production area can consist of a series of hydraulic generators. The hydraulic generators can be variable displacement generators such that the RPM, and thus the voltage, remains constant, eliminating the need for further power conditioning. A series of wind blades is attached to a series of radial piston pumps, which pump fluid to a series of axial piston motors attached to generators. As the wind is reduced, the amount of energy is reduced, and the number of active hydraulic generators can be reduced to maintain a nearly constant RPM. If the axial piston motors have variable displacement, an exact RPM can be maintained for all, or nearly all, wind speeds. Analyses have been performed that show over 20% performance improvements with this technique over conventional wind turbines

On the Predictability of Hub Height Winds

DEFF Research Database (Denmark)

Draxl, Caroline

Wind energy is a major source of power in over 70 countries across the world, and the worldwide share of wind energy in electricity consumption is growing. The introduction of signicant amounts of wind energy into power systems makes accurate wind forecasting a crucial element of modern electrical...... grids. These systems require forecasts with temporal scales of tens of minutes to a few days in advance at wind farm locations. Traditionally these forecasts predict the wind at turbine hub heights; this information is then converted by transmission system operators and energy companies into predictions...... of power output at wind farms. Since the power available in the wind is proportional to the wind speed cubed, even small wind forecast errors result in large power prediction errors. Accurate wind forecasts are worth billions of dollars annually; forecast improvements will result in reduced costs...

Wind power development field test project at Okkobe-cho. Close survey on wind conditions; Okkobecho ni okeru furyoku kaihatsu field test jigyo (fukyo seisa) hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-11-01

A survey was made on regional wind conditions on the assumption that a wind power generator was installed around Okkobe Rakuno-no-oka, Okkobe-cho, Monbetsu-gun, Hokkaido. The survey period was one year from Oct., 1998 to Sept., 1999. The observations were carried out on the average wind velocity, average wind direction, standard deviation of velocity, and the maximum instantaneous wind velocity. With a fixed point observation at 20 m above ground, and with the minimum observation time unit of 10 minutes, an average value during the 10 minutes was determined as the measurement of each category. However, the maximum instantaneous wind velocity was determined on the measurement with the minimum observation time unit of 2 seconds. The average wind velocity was 4.8 m/s, the maximum wind velocity during the period was 29.9 m/s, the prevailing wind direction was WSW (17.1%), the wind axis was WSW-ENE, and the total occurrence rate of wind direction was 51.1%. The intensity of turbulence was 0.19 at a wind velocity of 2.0 m/s or above and was 0.16 at 4.0 m/s or above. An estimated annual operation rate of a windmill was 59-77% using the rated value of a 150 kW, 300 kW and 750 kW class windmills. (NEDO)

A Diagnostic and Predictive Framework for Wind Turbine Drive Train Monitoring

DEFF Research Database (Denmark)

Bach-Andersen, Martin

Vast amount of data are collected minute by minute from wind turbines around the world. This thesis represents a focused research effort into discovering new ways of processing these data streams in order to gain insights which can be used to lower the maintenance costs of wind turbines and increase......, early fault identification based on analysis of complex vibration patterns which is a domain previously reserved for human experts, is shown to be solved with high accuracy using deep learning architecture strained in a fully supervised sense from the data collected in a large scale wind turbine...... monitoring platform. The research shows a way towards a fully automatized data-driven wind turbine diagnostic processing system that is highly scalable and requires little or no feature engineering and system modeling....

Modelling of wind power plant controller, wind speed time series, aggregation and sample results

DEFF Research Database (Denmark)

Hansen, Anca Daniela; Altin, Müfit; Cutululis, Nicolaos Antonio

This report describes the modelling of a wind power plant (WPP) including its controller. Several ancillary services like inertial response (IR), power oscillation damping (POD) and synchronising power (SP) are implemented. The focus in this document is on the performance of the WPP output...... and not the impact of the WPP on the power system. By means of simulation tests, the capability of the implemented wind power plant model to deliver ancillary services is investigated....

Scaling forecast models for wind turbulence and wind turbine power intermittency

Science.gov (United States)

Duran Medina, Olmo; Schmitt, Francois G.; Calif, Rudy

2017-04-01

The intermittency of the wind turbine power remains an important issue for the massive development of this renewable energy. The energy peaks injected in the electric grid produce difficulties in the energy distribution management. Hence, a correct forecast of the wind power in the short and middle term is needed due to the high unpredictability of the intermittency phenomenon. We consider a statistical approach through the analysis and characterization of stochastic fluctuations. The theoretical framework is the multifractal modelisation of wind velocity fluctuations. Here, we consider three wind turbine data where two possess a direct drive technology. Those turbines are producing energy in real exploitation conditions and allow to test our forecast models of power production at a different time horizons. Two forecast models were developed based on two physical principles observed in the wind and the power time series: the scaling properties on the one hand and the intermittency in the wind power increments on the other. The first tool is related to the intermittency through a multifractal lognormal fit of the power fluctuations. The second tool is based on an analogy of the power scaling properties with a fractional brownian motion. Indeed, an inner long-term memory is found in both time series. Both models show encouraging results since a correct tendency of the signal is respected over different time scales. Those tools are first steps to a search of efficient forecasting approaches for grid adaptation facing the wind energy fluctuations.

Absence of robust ischemic preconditioning by five 1-minute total umbilical cord occlusions in fetal sheep.

NARCIS (Netherlands)

Lotgering, F.K.; Bishai, J.M.; Struijk, P.C.; Blood, A.B.; Hunter, C.J.; Oberg, K.C.; Power, G.G.; Longo, L.D.

2004-01-01

OBJECTIVE: To determine to what extent a series of five 1-minute total umbilical cord occlusions, intended to induce ischemic preconditioning (IP), affects the physiologic responses to a 10-minute total umbilical cord occlusion (damaging insult [DI]) 1 hour later and provides cardio- and

Wind power development field test project at Aoyama Heights, Aoyama-cho. Detailed wind characteristics survey; Aoyamacho Aoyama Kogen ni okeru furyoku kaihatsu field test jigyo (fukyo seisa) hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-11-01

A detailed wind characteristics survey was conducted at Aoyama Heights, Aoyama-cho, Naga-gun, Mie Prefecture, on the assumption that a wind power generation system would be constructed. The survey was a 1-year project from October 1998 through September 1999, and wind characteristics such as the average wind speed, average wind direction, standard deviation of wind velocity, and the maximum instantaneous wind speed were observed. The observation point was fixed at 20m above ground, the minimum time unit for observation was 10 minutes, and the 10-minute average value was defined as the measured value. For the maximum instantaneous wind speed, the minimum time unit for observation was set to be 2 seconds. The yearly average wind speed was 5.3m/s and the maximum wind speed in the period was 32m/s. Winds came prevalently from WNW (31.6%), and then from NW (16.8%), ESE (20.9%), and E (9.9%). The wind axis was in the direction of WNW-ESE, and the total wind direction occurrence rate was 89.0%. Turbulence intensity was 0.25 at wind speed 2.0m/s or more and 0.23 at wind speed 4.0m/s or more. Estimated wind turbine yearly operating factors of 70-84% were obtained using rated values of a 150kW, 300kW, and 750kW-class wind turbines. (NEDO)

Wind power development field test project at Kodomari-mura 'Marinetopia'. Close survey on wind conditions; Kodomarimura Marinetopia ni okeru furyoku kaihatsu field test jigyo (fukyo seisa) hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-11-01

A survey was made on wind conditions in Imabetsu-machi, Higashi Tsugaru-gun, Aomori prefecture, on the assumption that a wind power generation system was installed therein. The survey period was one year from Oct., 1998 to Sept., 1999. The observations were carried out on the average wind velocity, average wind direction, standard deviation of velocity, and the maximum instantaneous wind velocity. With a fixed point observation at 20 m above ground, and with the minimum observation time unit of 10 minutes, an average value during the 10 minutes was determined as the measurement of each category. However, the maximum instantaneous wind velocity was determined on the measurement with the minimum observation time unit of 2 seconds. The annual average wind velocity was 4.8 m/s, the maximum wind velocity during the period was 35 m/s, the prevailing wind direction was NW-WNW and ESE-SEW, and the occurrence rate of wind direction at the wind axis of NW-SE was 88.1%. The intensity of turbulence was 0.24 at a wind velocity of 2.0 m/s or above and was 0.20 at 4.0 m/s or above. An estimated annual operation rate of a windmill was 46-64% using the rated value of a 150 kW, 300 kW and 750 kW class windmills. (NEDO)

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...

Empirical investigation on using wind speed volatility to estimate the operation probability and power output of wind turbines

International Nuclear Information System (INIS)

Liu, Heping; Shi, Jing; Qu, Xiuli

2013-01-01

Highlights: ► Ten-minute wind speed and power generation data of an offshore wind turbine are used. ► An ARMA–GARCH-M model is built to simultaneously forecast wind speed mean and volatility. ► The operation probability and expected power output of the wind turbine are predicted. ► The integrated approach produces more accurate wind power forecasting than other conventional methods. - Abstract: In this paper, we introduce a quantitative methodology that performs the interval estimation of wind speed, calculates the operation probability of wind turbine, and forecasts the wind power output. The technological advantage of this methodology stems from the empowered capability of mean and volatility forecasting of wind speed. Based on the real wind speed and corresponding wind power output data from an offshore wind turbine, this methodology is applied to build an ARMA–GARCH-M model for wind speed forecasting, and then to compute the operation probability and the expected power output of the wind turbine. The results show that the developed methodology is effective, the obtained interval estimation of wind speed is reliable, and the forecasted operation probability and expected wind power output of the wind turbine are accurate

Comparison of NACA 6-series and 4-digit airfoils for Darrieus wind turbines

Science.gov (United States)

Migliore, P. G.

1983-08-01

The aerodynamic efficiency of Darrieus wind turbines as effected by blade airfoil geometry was investigated. Analysis was limited to curved-bladed machines having rotor solidities of 7-21 percent and operating at a Reynolds number of 3 x 10 to the 6th. Ten different airfoils, having thickness-to-chord ratios of 12, 15, and 18 percent, were studied. Performance estimates were made using a blade element/momentum theory approach. Results indicated that NACA 6-series airfoils yield peak power coefficients as great as NACA 4-digit airfoils and have broader and flatter power coefficient-tip speed ratio curves. Sample calculations for an NACA 63(2)-015 airfoil showed an annual energy output increase of 17-27 percent, depending on rotor solidity, compared to an NACA 0015 airfoil.

Effect of wind turbine generator model and siting on wind power changes out of large WECS arrays

Science.gov (United States)

Schleuter, R. A.; Park, G. L.; Lotfalian, M.; Dorsey, J.; Shayanfar, H.

1981-01-01

Methods of reducing the WECS generation change through selection of the wind turbine model for each site, selection of an appropriate siting configuration, and wind array controls are discussed. An analysis of wind generation change from an echelon and a farm for passage of a thunderstorm is presented. Reduction of the wind generation change over ten minutes is shown to reduce the increase in spinning reserve, unloadable generation and load following requirements on unit commitment when significant WECS generation is present and the farm penetration constraint is satisfied. Controls on the blade pitch angle of all wind turbines in an array or a battery control are shown to reduce both the wind generation change out of an array and the effective farm penetration in anticipation of a storm so that the farm penetration constraint may be satisfied.

Wind power development field test project at Rokkasho-mura, Aomori prefecture. Close survey on wind conditions; Aomoriken Rokkashomura ni okeru furyoku kaihatsu field test jigyo (fukyo seisa) hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-11-01

A survey was made on wind conditions in Rokkasho-mura, Kamikita-gun, Aomori prefecture, on the assumption that a wind power generation system was installed therein. The survey period was one year from Oct., 1998 to Sept., 1999. The observations were carried out on the average wind velocity, average wind direction, standard deviation of velocity, and the maximum instantaneous wind velocity. With a fixed point observation at 20 m above ground, and with the minimum observation time unit of 10 minutes, an average value during the 10 minutes was determined as the measurement of each category. However, the maximum instantaneous wind velocity was determined on the measurement with the minimum observation time unit of 2 seconds. The annual average wind velocity was 4.6 m/s, the maximum wind velocity during the period was 26.0 m/s, the prevailing wind direction was NW (20.8%), WNW (18.0%), and SE (13.5%), and the total occurrence rate of wind direction at the wind axis of NW-SE was 75.7%. The intensity of turbulence was 0.25 at a wind velocity of 2.0 m/s or above and was 0.21 at 4.0 m/s or above. An estimated annual operation rate of a windmill was 59-72% using the rated value of a 150 kW, 300 kW and 750 kW class windmills. (NEDO)

Database on wind characteristics. Users manual

Energy Technology Data Exchange (ETDEWEB)

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

2001-11-01

The main objective of IEA R and D Wind Annex XVII - Database on Wind Characteristics - is to provide wind energy planners and designers, as well as the international wind engineering community in general, with easy access to quality controlled measured wind field time series observed in a wide range of environments. The project partners are Sweden, Norway, U.S.A., The Netherlands, Japan and Denmark, with Denmark as the Operating Agent. The reporting of IEA R and D Annex XVII falls in three separate parts. Part one deals with the overall structure and philosophy behind the database (including the applied data quality control procedures), part two accounts in details for the available data in the established database bank and part three is the Users Manual describing the various ways to access and analyse the data. The present report constitutes part three of the Annex XVII reporting and contains a trough description of the available online facilities for identifying, selecting, downloading and handling measured wind field time series and resource data from 'Database on Wind Characteristics'. (au)

Wind Farm Power Forecasting for Less Than an Hour Using Multi Dimensional Models

DEFF Research Database (Denmark)

Knudsen, Torben; Bak, Thomas; Jensen, Tom Nørgaard

2018-01-01

The paper focus on prediction of wind farm power for horizons of 0-10 minutes and not more than one hour using statistical methods. These short term predictions are relevant for both transmission system operators, wind farm operators and traders. Previous research indicates that for short time ho...... the prediction error variance estimate compared to the persistence method. We also present convincing examples showing that the predictions follow the wind farm power over a window of an hour.......The paper focus on prediction of wind farm power for horizons of 0-10 minutes and not more than one hour using statistical methods. These short term predictions are relevant for both transmission system operators, wind farm operators and traders. Previous research indicates that for short time...... horizons the persistence method performs as well as more complex methods. However, these results are based on accumulated power for an entire wind farm. The contribution in this paper is to develop multi-dimensional linear methods based on measurements of power or wind speed from individual wind turbine...

Creating a Positive Classroom Culture: Minute by Minute

Science.gov (United States)

Wright, Ali

2014-01-01

This article offers a peek into high school math teacher Ali Wright's typical school day, which includes time-tested strategies that she uses to build a positive culture in her classroom. Scheduled timeframes and activities include before school starts, five minutes before class, during announcements, during class, last five minutes of class,…

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....

Enteroclysis and small bowel series: Comparison of radiation dose and examination time

International Nuclear Information System (INIS)

Thoeni, R.F.; Gould, R.G.

1991-01-01

Respective radiation doses and total examination and fluoroscopy times were compared for 50 patients; 25 underwent enteroclysis and 25 underwent small bowel series with (n = 17) and without (n = 8) an examination of the upper gastrointestinal (GI) tract. For enteroclysis, the mean skin entry radiation dose (12.3 rad [123 mGy]) and mean fluoroscopy time (18.4 minutes) were almost 1 1/2 times greater than those for the small bowel series with examination of the upper GI tract (8.4 rad [84 mGy]; 11.4 minutes) and almost three times greater than those for the small bowel series without upper GI examination (4.6 rad [46 mGy]; 6.3 minutes). However, the mean total examination completion time for enteroclysis (31.2 minutes) was almost half that of the small bowel series without upper GI examination (57.5 minutes) and almost four times shorter than that of the small bowel series with upper GI examination (114 minutes). The higher radiation dose of enteroclysis should be considered along with the short examination time, the age and clinical condition of the patient, and the reported higher accuracy when deciding on the appropriate radiographic examination of the small bowel

Modelling of hydro and wind power in the regulation market

International Nuclear Information System (INIS)

Kiviluoma, J.; Holttinen, H.; Meibom, P.

2006-01-01

The amount of required regulation capacity in the power system is affected by the wind power prediction errors. A model has been developed which can evaluate the monetary effects of prediction errors. The model can be used to evaluate (1) the regulation costs of wind power, (2) regulation market prices including effects related to the participation of power producers in the regulating power market, (3) value of accurate wind forecasts and (4) the effect of decreasing the length of the spot market clearance. This article discusses the problems related to developing a realistic model of the regulating power market including the interaction between the spot market and the regulating power market. There are several issues that make things complicated. (1) How to calculate the minimum amount of needed secondary (minute) reserves. Traditionally the Nordic TSOs have used an N-1 criteria in each country to determine the required amounts of positive secondary reserve, but as installed wind power capacity grows, it will become relevant to include the wind power prediction errors in the estimation of secondary reserves. (2) Consumption forecast errors and plant outages also contribute to activation of regulating power and should have stochastic input series besides wind power. (3) Risk premiums and transaction costs in the regulating power market are difficult to estimate as well as the effects of the possible use of market power. This is especially true in the Nordic system with the high share of hydro power, since the water value and hydrological limitations make things more complex than in a thermal system. (4) The available regulation capacity is not necessarily equal to the truly available capacity. All producers don't participate in the regulation market although in principle they could. (orig.)

Integration of wind power in the Danish generation system. EC wind power penetration study, phase 2

Energy Technology Data Exchange (ETDEWEB)

NONE

1989-06-01

The Commission of the European Communities has asked utilities in the member countries to carry out a coordinated study of the wind energy potential. The main objective is to show the consequences for the future electricity system when integrating wind power production covering 5, 10 or 15% of total demand. In addition to the best estimate scenario believed to be operational, some additional calculations have been carried out: wind power production as a negative load only (not operational for the total system); different levels of investment in wind farms. The methodology is based on the following steps: define a reference scenario for year 2000; define an alternative scenario with a certain amount of wind power production; calculate time-series for electrical load and district heating from combined heat/power production; calculate time-series for wind power production; make economic evaluation and sensitivity analysis; show environmental differences. Incorporation of wind power into the ELSAM power system, with the wind energy meeting, about 5% of demand will give rise to additional control capacity, or call for new contracts with neighbouring countries. The study includes estimated network investments. The simulations have been made with the SIM and SLUMP computer programmes. The economic analyses and the sensitivity analyses have been carried out using spreadsheets. The conclusion concerning profitability - based on the best estimate assumptions - is that the studied wind power scenarios are unprofitable. (EG)

Wind energy systems information user study

Energy Technology Data Exchange (ETDEWEB)

Belew, W.W.; Wood, B.L.; Marle, T.L.; Reinhardt, C.L.

1981-01-01

This report describes the results of a series of telephone interviews with potential users of information on wind energy conversion. These interviews, part of a larger study covering nine different solar technologies, attempted to identify: the type of information each distinctive group of information users needed, and the best way of getting information to that group. Groups studied include: wind energy conversion system researchers; wind energy conversion system manufacturer representatives; wind energy conversion system distributors; wind turbine engineers; utility representatives; educators; county agents and extension service agents; and wind turbine owners.

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.

Forecasting and simulating wind speed in Corsica by using an autoregressive model

International Nuclear Information System (INIS)

Poggi, P.; Muselli, M.; Notton, G.; Cristofari, C.; Louche, A.

2003-01-01

Alternative approaches for generating wind speed time series are discussed. The method utilized involves the use of an autoregressive process model. The model has been applied to three Mediterranean sites in Corsica and has been used to generate 3-hourly synthetic time series for these considered sites. The synthetic time series have been examined to determine their ability to preserve the statistical properties of the Corsican wind speed time series. In this context, using the main statistical characteristics of the wind speed (mean, variance, probability distribution, autocorrelation function), the data simulated are compared to experimental ones in order to check whether the wind speed behavior was correctly reproduced over the studied periods. The purpose is to create a data generator in order to construct a reference year for wind systems simulation in Corsica

Non-Extensive Statistical Analysis of Solar Wind Electric, Magnetic Fields and Solar Energetic Particle time series.

Science.gov (United States)

Pavlos, G. P.; Malandraki, O.; Khabarova, O.; Livadiotis, G.; Pavlos, E.; Karakatsanis, L. P.; Iliopoulos, A. C.; Parisis, K.

2017-12-01

In this work we study the non-extensivity of Solar Wind space plasma by using electric-magnetic field data obtained by in situ spacecraft observations at different dynamical states of solar wind system especially in interplanetary coronal mass ejections (ICMEs), Interplanetary shocks, magnetic islands, or near the Earth Bow shock. Especially, we study the energetic particle non extensive fractional acceleration mechanism producing kappa distributions as well as the intermittent turbulence mechanism producing multifractal structures related with the Tsallis q-entropy principle. We present some new and significant results concerning the dynamics of ICMEs observed in the near Earth at L1 solar wind environment, as well as its effect in Earth's magnetosphere as well as magnetic islands. In-situ measurements of energetic particles at L1 are analyzed, in response to major solar eruptive events at the Sun (intense flares, fast CMEs). The statistical characteristics are obtained and compared for the Solar Energetic Particles (SEPs) originating at the Sun, the energetic particle enhancements associated with local acceleration during the CME-driven shock passage over the spacecraft (Energetic Particle Enhancements, ESPs) as well as the energetic particle signatures observed during the passage of the ICME. The results are referred to Tsallis non-extensive statistics and in particular to the estimation of Tsallis q-triplet, (qstat, qsen, qrel) of electric-magnetic field and the kappa distributions of solar energetic particles time series of the ICME, magnetic islands, resulting from the solar eruptive activity or the internal Solar Wind dynamics. Our results reveal significant differences in statistical and dynamical features, indicating important variations of the magnetic field dynamics both in time and space domains during the shock event, in terms of rate of entropy production, relaxation dynamics and non-equilibrium meta-stable stationary states.

Profiling the regional wind power fluctuation in China

International Nuclear Information System (INIS)

Yu Dayang; Liang Jun; Han Xueshan; Zhao Jianguo

2011-01-01

As China starts to build 6 10-GW wind zones in 5 provinces by 2020, accommodating the wind electricity generated from these large wind zones will be a great challenge for the regional grids. Inadequate wind observing data hinders profiling the wind power fluctuations at the regional grid level. This paper proposed a method to assess the seasonal and diurnal wind power patterns based on the wind speed data from the NASA GEOS-5 DAS system, which provides data to the study of climate processes including the long-term estimates of meteorological quantities. The wind power fluctuations for the 6 largest wind zones in China are presented with both the capacity factor and the megawatt wind power output. The measured hourly wind output in a regional grid is compared to the calculating result to test the analyzing model. To investigate the offsetting effect of dispersed wind farms over large regions, the regional correlations of hourly wind power fluctuations are calculated. The result illustrates the different offsetting effects of minute and hourly fluctuations.

Fluctuations and predictability of wind and hydropower. Deliverable 2.1

DEFF Research Database (Denmark)

Giebel, Gregor; Holttinen, H.; Söder, L.

2004-01-01

The report forms the deliverable D2.1 of the EU supported project Wind Power Integration in a Liberalised Electricity Market (WILMAR). The handling and generation of the necessary wind and hydro time series for the project’s power system planningsimulation model is described. The wind power...... and the hydro power time series on hourly basis are generated on basis of real data for all the geographical regions included in the analysis in order to realistically represent the various correlations intime and displacement. Models have been developed to generate various realistic future time series based...

Integrating wind output with bulk power operations and wholesale electricity markets

International Nuclear Information System (INIS)

Hirst, E.

2002-01-01

Wind farms have three characteristics that complicate their widespread application as an electricity resource: limited control, unpredictability and variability. Therefore the integration of wind output into bulk power electric systems is qualitatively different from that of other types of generators. The electric system operator must move other generators up or down to offset the time-varying wind fluctuations. Such movements raise the costs of fuel and maintenance for these other generators. Not only is wind power different, it is new. The operators of bulk power systems have limited experience in integrating wind output into the larger system. As a consequence, market rules that treat wind fairly - neither subsidizing nor penalizing its operation - have not yet been developed. The lack of data and analytical methods encourages wind advocates and sceptics to rely primarily on their biases and beliefs in suggesting how wind should be integrated into bulk power systems. This project helps fill this data and analysis gap. Specifically, it develops and applies a quantitative method for the integration of a wind resource into a large electric system. The method permits wind to bid its output into a short-term forward market (specifically, an hour-ahead energy market) or to appear in real time and accept only intrahour and hourly imbalance payments for the unscheduled energy it delivers to the system. Finally, the method analyses the short-term (minute-to-minute) variation in wind output to determine the regulation requirement the wind resource imposes on the electrical system. (author)

Modeling of the dynamics of wind to power conversion including high wind speed behavior

DEFF Research Database (Denmark)

Litong-Palima, Marisciel; Bjerge, Martin Huus; Cutululis, Nicolaos Antonio

2016-01-01

This paper proposes and validates an efficient, generic and computationally simple dynamic model for the conversion of the wind speed at hub height into the electrical power by a wind turbine. This proposed wind turbine model was developed as a first step to simulate wind power time series...... for power system studies. This paper focuses on describing and validating the single wind turbine model, and is therefore neither describing wind speed modeling nor aggregation of contributions from a whole wind farm or a power system area. The state-of-the-art is to use static power curves for the purpose...... of power system studies, but the idea of the proposed wind turbine model is to include the main dynamic effects in order to have a better representation of the fluctuations in the output power and of the fast power ramping especially because of high wind speed shutdowns of the wind turbine. The high wind...

WIND SPEED AND ENERGY POTENTIAL ANALYSES

Directory of Open Access Journals (Sweden)

A. TOKGÖZLÜ

2013-01-01

Full Text Available This paper provides a case study on application of wavelet techniques to analyze wind speed and energy (renewable and environmental friendly energy. Solar and wind are main sources of energy that allows farmers to have the potential for transferring kinetic energy captured by the wind mill for pumping water, drying crops, heating systems of green houses, rural electrification's or cooking. Larger wind turbines (over 1 MW can pump enough water for small-scale irrigation. This study tried to initiate data gathering process for wavelet analyses, different scale effects and their role on wind speed and direction variations. The wind data gathering system is mounted at latitudes: 37° 50" N; longitude 30° 33" E and height: 1200 m above mean sea level at a hill near Süleyman Demirel University campus. 10 minutes average values of two levels wind speed and direction (10m and 30m above ground level have been recorded by a data logger between July 2001 and February 2002. Wind speed values changed between the range of 0 m/s and 54 m/s. Annual mean speed value is 4.5 m/s at 10 m ground level. Prevalent wind

Wind Turbine Power Curves Incorporating Turbulence Intensity

DEFF Research Database (Denmark)

Sørensen, Emil Hedevang Lohse

2014-01-01

. The model and method are parsimonious in the sense that only a single function (the zero-turbulence power curve) and a single auxiliary parameter (the equivalent turbulence factor) are needed to predict the mean power at any desired turbulence intensity. The method requires only ten minute statistics......The performance of a wind turbine in terms of power production (the power curve) is important to the wind energy industry. The current IEC-61400-12-1 standard for power curve evaluation recognizes only the mean wind speed at hub height and the air density as relevant to the power production...

A Comparison of Wind Speed Data from Mechanical and Ultrasonic Anemometers

Science.gov (United States)

Short, D.; Wells, L.; Merceret, F.; Roeder, W. P.

2006-01-01

This study compared the performance of mechanical and ultrasonic anemometers at the Eastern Range (ER; Kennedy Space Center and Cape Canaveral Air Force Station on Florida's Atlantic coast) and the Western Range (WR; Vandenberg Air Force Base on California's Pacific coast). Launch Weather Officers, forecasters, and Range Safety analysts need to understand the performance of wind sensors at the ER and WR for weather warnings, watches, advisories, special ground processing operations, launch pad exposure forecasts, user Launch Commit Criteria (LCC) forecasts and evaluations, and toxic dispersion support. The current ER and WR weather tower wind instruments are being changed from the current propeller-and-vane (ER) and cup-and-vane (WR) sensors to ultrasonic sensors through the Range Standardization and Automation (RSA) program. The differences between mechanical and ultrasonic techniques have been found to cause differences in the statistics of peak wind speed in previous studies. The 45th Weather Squadron (45 WS) and the 30th Weather Squadron (30 WS) requested the Applied Meteorology Unit (AMU) to compare data between RSA and current sensors to determine if there are significant differences. Approximately 3 weeks of Legacy and RSA wind data from each range were used in the study, archived during May and June 2005. The ER data spanned the full diurnal cycle, while the WR data was confined to 1000-1600 local time. The sample of 1-minute data from numerous levels on 5 different towers on each range totaled more than 500,000 minutes of data (482,979 minutes of data after quality control). The 10 towers were instrumented at several levels, ranging from 12 ft to 492 ft above ground level. The RSA sensors were collocated at the same vertical levels as the present sensors and typically within 15 ft horizontally of each another. Data from a total of 53 RSA ultrasonic sensors, collocated with present sensors were compared. The 1-minute average wind speed/direction and the 1

A combined modeling approach for wind power feed-in and electricity spot prices

International Nuclear Information System (INIS)

Keles, Dogan; Genoese, Massimo; Möst, Dominik; Ortlieb, Sebastian; Fichtner, Wolf

2013-01-01

Wind power generation and its impacts on electricity prices has strongly increased in the EU. Therefore, appropriate mark-to-market evaluation of new investments in wind power and energy storage plants should consider the fluctuant generation of wind power and uncertain electricity prices, which are affected by wind power feed-in (WPF). To gain the input data for WPF and electricity prices, simulation models, such as econometric models, can serve as a data basis. This paper describes a combined modeling approach for the simulation of WPF series and electricity prices considering the impacts of WPF on prices based on an autoregressive approach. Thereby WPF series are firstly simulated for each hour of the year and integrated in the electricity price model to generate an hourly resolved price series for a year. The model results demonstrate that the WPF model delivers satisfying WPF series and that the extended electricity price model considering WPF leads to a significant improvement of the electricity price simulation compared to a model version without WPF effects. As the simulated series of WPF and electricity prices also contain the correlation between both series, market evaluation of wind power technologies can be accurately done based on these series. - Highlights: • Wind power feed-in can be directly simulated with stochastic processes. • Non-linear relationship between wind power feed-in and electricity prices. • Price reduction effect of wind power feed-in depends on the actual load. • Considering wind power feed-in effects improves the electricity price simulation. • Combined modeling of both parameters delivers a data basis for evaluation tools

Opportunities for ice storage to provide ancillary services to power grids incorporating wind turbine generation

Science.gov (United States)

Finley, Christopher

Power generation using wind turbines increases the electrical system balancing, regulation and ramp rate requirements due to the minute to minute variability in wind speed and the difficulty in accurately forecasting wind speeds. The addition of thermal energy storage, such as ice storage, to a building's space cooling equipment increases the operational flexibility of the equipment by allowing the owner to choose when the chiller is run. The ability of the building owner to increase the power demand from the chiller (e.g. make ice) or to decrease the power demand (e.g. melt ice) to provide electrical system ancillary services was evaluated.

Synthetic atmospheric turbulence and wind shear in large eddy simulations of wind turbine wakes

DEFF Research Database (Denmark)

Keck, Rolf-Erik; Mikkelsen, Robert Flemming; Troldborg, Niels

2014-01-01

, superimposed on top of a mean deterministic shear layer consistent with that used in the IEC standard for wind turbine load calculations. First, the method is evaluated by running a series of large-eddy simulations in an empty domain, where the imposed turbulence and wind shear is allowed to reach a fully...

Seasonal trend analysis and ARIMA modeling of relative humidity and wind speed time series around Yamula Dam

Science.gov (United States)

Eymen, Abdurrahman; Köylü, Ümran

2018-02-01

Local climate change is determined by analysis of long-term recorded meteorological data. In the statistical analysis of the meteorological data, the Mann-Kendall rank test, which is one of the non-parametrical tests, has been used; on the other hand, for determining the power of the trend, Theil-Sen method has been used on the data obtained from 16 meteorological stations. The stations cover the provinces of Kayseri, Sivas, Yozgat, and Nevşehir in the Central Anatolia region of Turkey. Changes in land-use affect local climate. Dams are structures that cause major changes on the land. Yamula Dam is located 25 km northwest of Kayseri. The dam has huge water body which is approximately 85 km2. The mentioned tests have been used for detecting the presence of any positive or negative trend in meteorological data. The meteorological data in relation to the seasonal average, maximum, and minimum values of the relative humidity and seasonal average wind speed have been organized as time series and the tests have been conducted accordingly. As a result of these tests, the following have been identified: increase was observed in minimum relative humidity values in the spring, summer, and autumn seasons. As for the seasonal average wind speed, decrease was detected for nine stations in all seasons, whereas increase was observed in four stations. After the trend analysis, pre-dam mean relative humidity time series were modeled with Autoregressive Integrated Moving Averages (ARIMA) model which is statistical modeling tool. Post-dam relative humidity values were predicted by ARIMA models.

Model of a synthetic wind speed time series generator

DEFF Research Database (Denmark)

Negra, N.B.; Holmstrøm, O.; Bak-Jensen, B.

2008-01-01

is described and some statistical issues (seasonal characteristics, autocorrelation functions, average values and distribution functions) are used for verification. The output of the model has been designed as input for sequential Monte Carlo simulation; however, it is expected that it can be used for other...... of the main elements to consider for this purpose is the model of the wind speed that is usually required as input. Wind speed measurements may represent a solution for this problem, but, for techniques such as sequential Monte Carlo simulation, they have to be long enough in order to describe a wide range...

MCMC for Wind Power Simulation

NARCIS (Netherlands)

Papaefthymiou, G.; Klöckl, B.

2008-01-01

This paper contributes a Markov chain Monte Carlo (MCMC) method for the direct generation of synthetic time series of wind power output. It is shown that obtaining a stochastic model directly in the wind power domain leads to reduced number of states and to lower order of the Markov chain at equal

Regional tendencies of extreme wind characteristics in Hungary

Science.gov (United States)

Radics, Dr.; Bartholy, Dr.; Péliné

2009-09-01

Human activities have substantial effects on climate system. It has already accepted that change in the long-term climatic mean state will have significant consequences in the global economy and society, but the most important effects of climate change may come from changes in the intensity and frequency of climatic extremes. It is therefore of great interest to document the extremes of surface wind that could assist in estimating the regional effects of climate change. The research presented is based on 34-year-long (1975-2008) wind (speed, direction, and wind gust) data sets of 36 Hungarian synoptic meteorological stations. After processing (including digitalisation of old instrumental records, quality control and homogenisation of wind time series) the measured wind data sets, time series and complex wind climate analysis were carried out. Spatial and temporal distributions of mean and extreme wind climate characteristics were estimated, wind extremes and trends were interpolated and mapped over the country. Finally, measured and reanalysed (ERA40) wind data were compared over Hungary, in order to verify not only the validity of ERA40 reanalysed data sets, but the adaptability of climate simulation results in estimation of regional climate change effects.

Analysis of series resonant converter with series-parallel connection

Science.gov (United States)

Lin, Bor-Ren; Huang, Chien-Lan

2011-02-01

In this study, a parallel inductor-inductor-capacitor (LLC) resonant converter series-connected on the primary side and parallel-connected on the secondary side is presented for server power supply systems. Based on series resonant behaviour, the power metal-oxide-semiconductor field-effect transistors are turned on at zero voltage switching and the rectifier diodes are turned off at zero current switching. Thus, the switching losses on the power semiconductors are reduced. In the proposed converter, the primary windings of the two LLC converters are connected in series. Thus, the two converters have the same primary currents to ensure that they can supply the balance load current. On the output side, two LLC converters are connected in parallel to share the load current and to reduce the current stress on the secondary windings and the rectifier diodes. In this article, the principle of operation, steady-state analysis and design considerations of the proposed converter are provided and discussed. Experiments with a laboratory prototype with a 24 V/21 A output for server power supply were performed to verify the effectiveness of the proposed converter.

Calorimetry measurements in less than 20 minutes

International Nuclear Information System (INIS)

Perry, R.B.; Cremers, T.

1991-01-01

Argonne National Laboratory has developed a new series of 10 watt Bulk Plutonium Assay Calorimeters (BPAC10). The calorimeter measures bulk samples of plutonium bearing material in containers up to 5in. in diameter and 7in. high. The average measurement time is 19.7 minutes compared to 2--9 hours for the same sample measured in a water bath calorimeter. Measurement precision in the range of 1--10 watts is 1% to 0.1% and it is 0.010 watt for sample power less than 1 watt. BPAC10 series calorimeters are in use in two plutonium facilities at the EG ampersand G Rocky Flats Plant and at the Los Alamos National Laboratory TA55 Plutonium Facility. The paper presents a description of the calorimeter, discusses operating experience at Los Alamos, and presents a comparison of data on typical samples measured with both types of calorimeters. 5 refs., 5 figs., 1 tab

WEP. A wind energy planning system

International Nuclear Information System (INIS)

Larsen, H.V.

1991-11-01

The report describes the Wind Energy Planning system (WEP). It is intended as a decision support system to be used in the economic evaluation of wind energy projects. Such projects could be minor projects with only a single wind turbine or large wind farm projects consisting of several wind turbine plants. In the WEP system, a wind turbine is described by data on initial investment, possible later reinvestments, O and M costs, expected yearly production, life time, and capacity factor. The raising of loans are modelled, too. Depending on which output report is created, the value of the wind generated electricity is calculated in two different ways: either the electricity is assumed to be sold at a price (time series) given by the user, or the alternative conventional power production is modelled by its specific investment, O and M costs, life time, effectivity, fuel mix, and time series for fuel prices. Using these data, capacity credit and saved fuel and O and M costs are calculated. Due to the flexible data structure of the model, the user can easily create a scenario that models a large scale introduction of wind power. In such a scenario the gradual build up through several years of the wind power capacity can be modelled. The report describes in detail the menu structure, the input facilities, the output reports, and the organization of data. Also included is an example with full input documentation and output reports. (au)

Vientos extremos en la provincia de Neuquén Extreme winds in the province of Neuquén

Directory of Open Access Journals (Sweden)

Jorge L. Lassig

2011-12-01

Full Text Available El objetivo de este trabajo es calcular los valores extremos de la velocidad del viento con distintos modelos propuestos en normas internacionales que son utilizadas tanto en el diseño de parques eólicos como en el de obras civiles. Se describen los modelos empleados y se realizan los cálculos en 5 lugares de la Provincia de Neuquén, utilizando datos de vientos medidos cuyas series tienen entre 8 meses y 5 años de longitud. Los valores extremos se obtienen con una recurrencia media de 50 años, y corresponden a la velocidad del viento media en intervalos de 10 minutos y de 3 segundos. Los valores encontrados se analizan y se los compara entre sí, con mediciones y con valores propuestos en la norma argentina de seguridad de obras civiles. Los valores extremos estimados según la European Wind Turbine Standards II no subestiman las mediciones disponibles, y comparados con los obtenidos por los otros modelos, se observa que las menores diferencias corresponden a las estaciones con series de mayor longitud. El parámetro de forma de Weibull y la longitud de los registros serían los factores más importantes en las estimaciones de los valores extremos de la velocidad del viento.The objective of this work is to calculate the extreme values of wind speed with different models proposed in international standards that are utilized so much in the design of wind farms as in civil structures. The employed models are described and the calculations are carried out in 5 places of the Neuquén Province, utilizing data of winds measured whose series have between 8 months and 5 years of length. The extreme values are obtained with a return period of 50 years and they correspond to the extreme of the 10-minute and 3-second average wind speed. The found values are analysed and it are compared among them, with measurements and with values proposed in the standard of security of civil structures of Argentina. The extremes values that were estimated according

An Analysis of Peak Wind Speed Data from Collocated Mechanical and Ultrasonic Anemometers

Science.gov (United States)

Short, David A.; Wells, Leonard; Merceret, Francis J.; Roeder, William P.

2007-01-01

This study compared peak wind speeds reported by mechanical and ultrasonic anemometers at Cape Canaveral Air Force Station and Kennedy Space Center (CCAFS/KSC) on the east central coast of Florida and Vandenberg Air Force Base (VAFB) on the central coast of California. Launch Weather Officers, forecasters, and Range Safety analysts need to understand the performance of wind sensors at CCAFS/KSC and VAFB for weather warnings, watches, advisories, special ground processing operations, launch pad exposure forecasts, user Launch Commit Criteria (LCC) forecasts and evaluations, and toxic dispersion support. The legacy CCAFS/KSC and VAFB weather tower wind instruments are being changed from propeller-and-vane (CCAFS/KSC) and cup-and-vane (VAFB) sensors to ultrasonic sensors under the Range Standardization and Automation (RSA) program. Mechanical and ultrasonic wind measuring techniques are known to cause differences in the statistics of peak wind speed as shown in previous studies. The 45th Weather Squadron (45 WS) and the 30th Weather Squadron (30 WS) requested the Applied Meteorology Unit (AMU) to compare data between the RSA ultrasonic and legacy mechanical sensors to determine if there are significant differences. Note that the instruments were sited outdoors under naturally varying conditions and that this comparison was not designed to verify either technology. Approximately 3 weeks of mechanical and ultrasonic wind data from each range from May and June 2005 were used in this study. The CCAFS/KSC data spanned the full diurnal cycle, while the VAFB data were confined to 1000-1600 local time. The sample of 1-minute data from numerous levels on five different towers on each range totaled more than 500,000 minutes of data (482,979 minutes of data after quality control). The ten towers were instrumented at several levels, ranging from 12 ft to 492 ft above ground level. The ultrasonic sensors were collocated at the same vertical levels as the mechanical sensors and

Wind Profiling Radar

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Clutter present in radar return signals as used for wind profiling is substantially removed by carrying out a Daubechies wavelet transformation on a time series of...

The atmospheric transfer of pollution for a site with rapidly variable winds (low winds)

International Nuclear Information System (INIS)

Maigne, J.P.

1980-01-01

This paper firstly describes the ICAIR 2 computer model which takes into account the variability in space and time of wind speed and direction in estimating the dispersion of a pollutant in the atmosphere. This is done by breaking down each release into a series of separate puffs which continuously respond to the meteorological conditions applying at the point in time to the positions in which they are located. The law governing the change in each of the puffs is tri-Gaussian and the standard deviations used are a function of the transfer time and the wind speed for transfer times of less than 2000 seconds and of the transfer time alone beyond this period. Finally, the concentration patterns at various points calculated using ICAIR 2 are compared with those obtained during a series of experiments in situ using tracers at low wind speeds (< 1 m/s)

The aerodynamics of wind turbines

DEFF Research Database (Denmark)

Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming; Troldborg, Niels

2013-01-01

In the paper we present state-of-the-art of research in wind turbine aerodynamics. We start be giving a brief historical review and a survey over aerodynamic research in wind energy. Next, we focus on some recent research results obtained by our wind energy group at Department of Mechanical...... Engineering at DTU. In particular, we show some new results on the classical problem of the ideal rotor and present a series of new results from an on-going research project dealing with the modelling and simulation of turbulent flow structures in the wake behind wind turbines....

Wind power development field test project at Ebetsu plant of Oji Paper Co., Ltd. Close survey on wind conditions; Oji seishi Ebetsu kojo ni okeru furyoku kaihatsu field test jigyo (fukyo seisa) hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-11-01

A survey was made on wind conditions at the Ebetsu plant of Oji Paper Co., Ltd., on the assumption that a demonstrative equipment of a wind power generation system was installed in the plant. The survey period was one year from Oct., 1998 to Sept., 1999. The observations were carried out on the average wind velocity, average wind direction, standard deviation of velocity, and the maximum instantaneous wind velocity. With a fixed point observation at 20 m above ground, and with the minimum observation time unit of 10 minutes, an average value during the 10 minutes was determined as the measurement of each category. However, the maximum instantaneous wind velocity was determined on the measurement with the minimum observation time unit of 2 seconds. The average wind velocity was 3.2 m/s, the maximum wind velocity during the period was 34 m/s, and the prevailing wind direction was SSE (25.6%), while the total occurrence probability on the wind axis with NW-SE as the main axis was 62.9%. The intensity of turbulence was 0.28 at a wind velocity of 2.0 m/s or above and was 0.25 at 4.0 m/s or above. An estimated annual operation rate of a windmill was 37-59% using the rated value of a 150 kW, 300 kW and 750 kW class windmills. (NEDO)

Database on wind characteristics. Contents of database bank

DEFF Research Database (Denmark)

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

2001-01-01

for the available data in the established database bank and part three is the Users Manual describing the various ways to access and analyse the data. The present report constitutes the second part of the Annex XVII reporting. Basically, the database bank contains three categories of data, i.e. i) high sampled wind...... field time series; ii) high sampled wind turbine structural response time series; andiii) wind resource data. The main emphasis, however, is on category i). The available data, within each of the three categories, are described in details. The description embraces site characteristics, terrain type...

Methodology for obtaining wind gusts using Doppler lidar

DEFF Research Database (Denmark)

Suomi, Irene; Gryning, Sven-Erik; O'Connor, Ewan J.

2017-01-01

reduced the bias in the Doppler lidar gust factors from 0.07 to 0.03 and can be improved further to reduce the bias by using a realistic estimate of turbulence. Wind gust measurements are often prone to outliers in the time series, because they represent the maximum of a (moving-averaged) horizontal wind...... detection also outperformed the traditional Doppler lidar quality assurance method based on carrier-to-noise ratio, by removing additional unrealistic outliers present in the time series.......A new methodology is proposed for scaling Doppler lidar observations of wind gusts to make them comparable with those observed at a meteorological mast. Doppler lidars can then be used to measure wind gusts in regions and heights where traditional meteorological mast measurements are not available...

WindPACT Reference Wind Turbines

Energy Technology Data Exchange (ETDEWEB)

Dykes, Katherine L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rinker, Jennifer [Former National Renewable Energy Laboratory (NREL) employee

2018-04-02

To fully understand how loads and turbine cost scale with turbine size, it is necessary to have identical turbine models that have been scaled to different rated powers. The report presents the WindPACT baseline models, which are a series of four baseline models that were designed to facilitate investigations into the scalings of loads and turbine cost with size. The models have four different rated powers (750 kW, 1.5 MW, 3.0 MW, and 5.0 MW), and each model was designed to its specified rated power using the same design methodology. The models were originally implemented in FAST_AD, the predecessor to NREL's open-source wind turbine simulator FAST, but have yet to be implemented in FAST. This report contains the specifications for all four WindPACT baseline models - including structural, aerodynamic, and control specifications - along with the inherent assumptions and equations that were used to calculate the model parameters. It is hoped that these baseline models will serve as extremely useful resources for investigations into the scalings of costs, loads, or optimization routines.

TRNSYS HYBRID wind diesel PV simulator

Energy Technology Data Exchange (ETDEWEB)

Quinlan, P.J.A.; Mitchell, J.W.; Klein, S.A.; Beckman, W.A.; Blair, N.J. [Univ. of Wisconsin, Madison, WI (United States)

1996-12-31

The Solar Energy Laboratory (SEL) has developed a wind diesel PV hybrid systems simulator, UW-HYBRID 1.0, an application of the TRNSYS 14.2 time-series simulation environment. An AC/DC bus links up to five diesels and wind turbine models, along with PV modules, a battery bank, and an AC/DC converter. Multiple units can be selected. PV system simulations include solar angle and peak power tracking options. Weather data are Typical Meteorological Year data, parametrically generated synthesized data, or external data files. PV performance simulations rely on long-standing SEL-developed algorithms. Loads data are read as scalable time series. Diesel simulations include estimated fuel-use and waste heat output, and are dispatched using a least-cost of fuel strategy. Wind system simulations include varying air density, wind shear and wake effects. Time step duration is user-selectable. UW-HYBRID 1.0 runs in Windows{reg_sign}, with TRNSED providing a customizable user interface. 12 refs., 6 figs.

The Wind Energy Potential of Kurdistan, Iran

Science.gov (United States)

Arefi, Farzad; Moshtagh, Jamal; Moradi, Mohammad

2014-01-01

In the current work by using statistical methods and available software, the wind energy assessment of prone regions for installation of wind turbines in, Qorveh, has been investigated. Information was obtained from weather stations of Baneh, Bijar, Zarina, Saqez, Sanandaj, Qorveh, and Marivan. The monthly average and maximum of wind speed were investigated between the years 2000–2010 and the related curves were drawn. The Golobad curve (direction and percentage of dominant wind and calm wind as monthly rate) between the years 1997–2000 was analyzed and drawn with plot software. The ten-minute speed (at 10, 30, and 60 m height) and direction (at 37.5 and 10 m height) wind data were collected from weather stations of Iranian new energy organization. The wind speed distribution during one year was evaluated by using Weibull probability density function (two-parametrical), and the Weibull curve histograms were drawn by MATLAB software. According to the average wind speed of stations and technical specifications of the types of turbines, the suitable wind turbine for the station was selected. Finally, the Divandareh and Qorveh sites with favorable potential were considered for installation of wind turbines and construction of wind farms. PMID:27355042

Current Status and Challenges in Wind Energy Assessment

DEFF Research Database (Denmark)

Gryning, Sven-Erik; Badger, Jake; Hahmann, Andrea N.

2014-01-01

Here we discuss the status and challenges in the development of atlases for the assessment of the regional and global wind resources. The text more specifically describes a methodology that is under development at DTU Wind Energy in Denmark. As the wind assessment is based on mesoscale modelling,......, some of the specific challenges in mesoscale modelling for wind energy purposes are discussed such as wind profiles and long-term statistics of the wind speed time series. Solutions to these challenges will help secure an economic and effective deployment of wind energy....

Minutes

International Nuclear Information System (INIS)

1998-01-01

In the minutes of II Uruguayan Geological Congress have been included the following topics: structural geology, tectonic, sedimentology, stratigraphy, mineralogy, petrology, geochemistry, paleontology, mineral prospecting, economic, regional and applied geology. (author)

Observing Equatorial Thermospheric Winds and Temperatures with a New Mapping Technique

Science.gov (United States)

Faivre, M. W.; Meriwether, J. W.; Sherwood, P.; Veliz, O.

2005-12-01

Application of the Fabry-Perot interferometer (FPI) at Arequipa, Peru (16.4S, 71.4 W) to measure the Doppler shifts and Doppler broadenings in the equatorial O(1D) 630-nm nightglow has resulted in numerous detections of a large-scale thermospheric phenomenon called the Midnight Temperature Maximum (MTM). A recent detector upgrade with a CCD camera has improved the accuracy of these measurements by a factor of 5. Temperature increases of 50 to 150K have been measured during nights in April and July, 2005, with error bars less than 10K after averaging in all directions. Moreover, the meridional wind measurements show evidence for a flow reversal from equatorward to poleward near local midnight for such events. A new observing strategy based upon the pioneering work of Burnside et al.[1981] maps the equatorial wind and temperature fields by observing in eight equally-spaced azimuth directions, each with a zenith angle of 60 degrees. Analysis of the data obtained with this technique gives the mean wind velocities in the meridional and zonal directions as well as the horizontal gradients of the wind field for these directions. Significant horizontal wind gradients are found for the meridional direction but not for the zonal direction. The zonal wind blows eastward throughout the night with a maximum speed of ~150 m/s near the middle of the night and then decreases towards zero just before dawn. In general, the fastest poleward meridional wind is observed near mid-evening. By the end of the night, the meridional flow tends to be more equatorward at speeds of about 50 m/s. Using the assumption that local time and longitude are equivalent over a period of 30 minutes, a map of the horizontal wind field vector field is constructed over a range of 12 degrees latitude centered at 16.5 S. Comparison between MTM nights and quiet nights (no MTM) revealed significant differences in the horizontal wind fields. Using the method of Fourier decomposition of the line-of-sight winds

Novel STATCOM Controller for Mitigating SSR and Damping Power System Oscillations in a Series Compensated Wind Parks

DEFF Research Database (Denmark)

Bak-Jensen, Birgitte; El-Moursi, M. S.; Abdel-Rahman, Mansour Hassan

2010-01-01

This paper addresses implementation issues associated with a novel damping control algorithm for a STATCOM in a series compensated wind park for mitigating SSR (subsynchronous resonance) and damping power system oscillations. The IEEE first benchmark model on subsynchronous resonance is adopted...... the SSR, damping the power system oscillation and enhancing the transient stability margin in response to different SCRs....... in the STATCOM control structure. The performances of the controllers are tested in steady state operation and in response to system contingencies, taking into account the impact of short circuit ratios (SCRs). Simulation results are presented to demonstrate the capability of the controllers for mitigating...

Evaluation of Dynamical Downscaling Resolution Effect on Wind Energy Forecast Value for a Wind Farm in Central Sweden

DEFF Research Database (Denmark)

Rosgaard, Martin Haubjerg; Hahmann, Andrea N.; Nielsen, Torben Skov

accuracy metric evaluated for wind speed data consistently translates to an improvement for wind power. For two time series describing the temporal development of the same variable, though by different means, it is assumed that phase errors account for most of the departure from perfect correlation between...... the two time series. Results on limited-area NWP model performance, with focus on the 12th to 48th forecast hour horizon relevant for Elspot auction bidding on the Nord Pool Spot market [2], are presented....

Wind tunnel tests of a free yawing downwind wind turbine

DEFF Research Database (Denmark)

Verelst, David Robert; Larsen, Torben J.; van Wingerden, Jan-Willem

2014-01-01

. The discussed test cases show that the turbine is stable while operating in free yawing conditions. Further, the effect of the tower shadow passage on the blade flapwise strain measurement is evaluated. Finally, data from the experiment is compared with preliminary simulations using DTU Wind Energy......This research paper presents preliminary results on a behavioural study of a free yawing downwind wind turbine. A series of wind tunnel tests was performed at the TU Delft Open Jet Facility with a three bladed downwind wind turbine and a rotor radius of 0.8 meters. The setup includes an off...... the shelf three bladed hub, nacelle and generator on which relatively flexible blades are mounted. The tower support structure has free yawing capabilities provided at the base. A short overview on the technical details of the experiment is given as well as a brief summary of the design process...

Ionospheric cusp flows pulsed by solar wind Alfvén waves

Directory of Open Access Journals (Sweden)

P. Prikryl

2002-02-01

Full Text Available Pulsed ionospheric flows (PIFs in the cusp foot-print have been observed by the SuperDARN radars with periods between a few minutes and several tens of minutes. PIFs are believed to be a consequence of the interplanetary magnetic field (IMF reconnection with the magnetospheric magnetic field on the dayside magnetopause, ionospheric signatures of flux transfer events (FTEs. The quasiperiodic PIFs are correlated with Alfvénic fluctuations observed in the upstream solar wind. It is concluded that on these occasions, the FTEs were driven by Alfvén waves coupling to the day-side magnetosphere. Case studies are presented in which the dawn-dusk component of the Alfvén wave electric field modulates the reconnection rate as evidenced by the radar observations of the ionospheric cusp flows. The arrival of the IMF southward turning at the magnetopause is determined from multipoint solar wind magnetic field and/or plasma measurements, assuming plane phase fronts in solar wind. The cross-correlation lag between the solar wind data and ground magnetograms that were obtained near the cusp footprint exceeded the estimated spacecraft-to-magnetopause propagation time by up to several minutes. The difference can account for and/or exceeds the Alfvén propagation time between the magnetopause and ionosphere. For the case of short period ( < 13 min PIFs, the onset times of the flow transients appear to be further delayed by at most a few more minutes after the IMF southward turning arrived at the magnetopause. For the case of long period (30 – 40 min PIFs, the observed additional delays were 10–20 min. We interpret the excess delay in terms of an intrinsic time scale for reconnection (Russell et al., 1997 which can be explained by the surface-wave induced magnetic reconnection mechanism (Uberoi et al., 1999. Here, surface waves with wavelengths larger than the thickness of the neutral layer induce a tearing-mode instability whose rise time explains the

Limitations of wind power availability over Europe: a conceptual study

Directory of Open Access Journals (Sweden)

P. Kiss

2008-11-01

Full Text Available Wind field statistics are evaluated from the ERA-40 data bank covering a period of 44 years with a temporal resolution of 6 h. Instantaneous wind speed values are provided in geographic cells of size 1°×1° (lat/long for surface (10 m and 1000 hPa pressure heights. Potential wind power generation is estimated in two steps. Firstly, the wind speed at hub height is approximated from surface data based on the statistical analysis of the wind and geopotential records for 1000 hPa pressure level. Secondly, the wind speed values are transformed by an idealised power curve fitted for measured data. The model time series are fed into various hypothetical electric networks. The main quantity of interest is the aggregated output from the networks. A reference power time series is determined for a static network connecting each continental site and an envelope of 1° around the shorelines (representing off-shore locations over Europe. This time series exhibits a low average value and a marked annual periodicity. Wind power integration over limited areas results in higher average outputs at the expense of stronger fluctuations. The long-range spatial correlations of the wind field limit the level of fluctuations strongly which can not be eliminated either by an increase of the area of integration or by dynamic control. This study is fully conceptual, however it demonstrates the limitations of wind power integration over Europe.

Current projects of the National Wind Coordinating Committee

Energy Technology Data Exchange (ETDEWEB)

Rhoads, H. [National Wind Coordinating Committee, Washington, DC (United States)

1997-12-31

This paper summarizes the activities of the National Wind Coordinating Committee (NWCC), a multi-stakeholder collaborative formed in 1994 to support the responsible use of wind power in the USA. The NWCC`s vision is a self-sustaining commercial market for wind power - environmentally, economically, and politically sustainable. Current NWCC activities include: outreach initiatives, disseminating information about wind energy to regulators and legislators through the Wind Energy Issue Paper Series, researching distributed wind energy models, producing a wind facility permitting handbook, improving avian research, addressing transmission and resource assessment issues, and exploring sustainable development and marketing approaches.

Fluctuations of offshore wind generation: Statistical modelling

DEFF Research Database (Denmark)

Pinson, Pierre; Christensen, Lasse E.A.; Madsen, Henrik

2007-01-01

The magnitude of power fluctuations at large offshore wind farms has a significant impact on the control and management strategies of their power output. If focusing on the minute scale, one observes successive periods with smaller and larger power fluctuations. It seems that different regimes yi...

Quantifying wind blown landscapes using time-series airborne LiDAR at White Sands Dune Field, New Mexico

Science.gov (United States)

Ewing, R. C.

2011-12-01

Wind blown landscapes are a default geomorphic and sedimentary environment in our solar system. Wind sand dunes are ubiquitous features on the surfaces of Earth, Mars and Titan and prevalent within the aeolian rock records of Earth and Mars. Dunes are sensitive to environmental and climatic changes and a complete understanding of this system promises a unique, robust and quantitative record of paleoclimate extending to the early histories of these worlds. However, our understanding of how aeolian dune landscapes evolve and how the details of the wind are recorded in cross-strata is limited by our lack of understanding of three-dimensional dune morphodynamics related to changing boundary conditions such as wind direction and magnitude and sediment source area. We use airborne LiDAR datasets over 40 km2 of White Sands Dune Field collected from June 2007, June 2008, January 2009, September 2009 and June 2010 to quantify 1) three-dimensional dune geometries, 2) annual and seasonal patterns of erosion and deposition across dune topography, 3) spatial changes in sediment flux related to position within the field, 4) spatial changes in sediment flux across sinuous crestlines and 5) morphologic changes through dune-dune interactions. In addition to measurements, we use the LiDAR data along with wind data from two near-by weather stations to develop a simple model that predicts depositional and stratigraphic patterns on dune lee slopes. Several challenges emerged using time series LiDAR data sets at White Sands Dune Field. The topography upon which the dunes sit is variable and rises by 16 meters over the length of the dune field. In order to compare individual dune geometries across the field and between data sets a base surface was interpolated from local minima and subtracted from the dune topography. Co-registration and error calculation between datasets was done manually using permanent vegetated features within the active dune field and structures built by the

A short-term ensemble wind speed forecasting system for wind power applications

Science.gov (United States)

Baidya Roy, S.; Traiteur, J. J.; Callicutt, D.; Smith, M.

2011-12-01

This study develops an adaptive, blended forecasting system to provide accurate wind speed forecasts 1 hour ahead of time for wind power applications. The system consists of an ensemble of 21 forecasts with different configurations of the Weather Research and Forecasting Single Column Model (WRFSCM) and a persistence model. The ensemble is calibrated against observations for a 2 month period (June-July, 2008) at a potential wind farm site in Illinois using the Bayesian Model Averaging (BMA) technique. The forecasting system is evaluated against observations for August 2008 at the same site. The calibrated ensemble forecasts significantly outperform the forecasts from the uncalibrated ensemble while significantly reducing forecast uncertainty under all environmental stability conditions. The system also generates significantly better forecasts than persistence, autoregressive (AR) and autoregressive moving average (ARMA) models during the morning transition and the diurnal convective regimes. This forecasting system is computationally more efficient than traditional numerical weather prediction models and can generate a calibrated forecast, including model runs and calibration, in approximately 1 minute. Currently, hour-ahead wind speed forecasts are almost exclusively produced using statistical models. However, numerical models have several distinct advantages over statistical models including the potential to provide turbulence forecasts. Hence, there is an urgent need to explore the role of numerical models in short-term wind speed forecasting. This work is a step in that direction and is likely to trigger a debate within the wind speed forecasting community.

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...

Reliability of offshore wind power production under extreme wind conditions. Deliverable D 9.5. Work Package 9: Electrical grid

DEFF Research Database (Denmark)

Cutululis, Nicolaos Antonio; Zeni, Lorenzo

years, with each year simulated with five random seeds, leading to a total of 25 annual wind power time series for six large offshore wind farms, summing up to a little over 330 wind turbines. Two storm control strategies were used. The analysis involved several aspects inspired from reliability studies....... The aspects investigated are storm events occurrences and durations, storm control strategy impact on the capacity factor (lost production), the loss of production (power produced from wind drops below a certain threshold due to high wind speeds and storm controller) and finally, the wind power production......Reliability of offshore wind production under extreme wind conditions was investigated in this report. The wind power variability from existing and future large offshore wind farms in Western Denmark were simulated using the Correlated Wind model developed at Risø. The analysis was done for five...

Golf in the Wind: Exploring the Effect of Wind on the Accuracy of Golf Shots

Science.gov (United States)

Yaghoobian, Neda; Mittal, Rajat

2015-11-01

Golf play is highly dependent on the weather conditions with wind being the most significant factor in the unpredictability of the ball landing position. The direction and strength of the wind alters the aerodynamic forces on a ball in flight, and consequently its speed, distance and direction of travel. The fact that local wind conditions on any particular hole change over times-scales ranging all the way from a few seconds to minutes, hours and days introduces an element of variability in the ball trajectory that is not understood. Any such analysis is complicated by the effect of the local terrestrial and vegetation topology, as well as the inherent complexity of golf-ball aerodynamics. In the current study, we use computational modeling to examine the unpredictability of the shots under different wind conditions over Hole-12 at the Augusta National Golf Club, where the Masters Golf Tournament takes place every year. Despite this being the shortest hole on the course, the presence of complex vegetation canopy around this hole introduces a spatial and temporal variability in wind conditions that evokes uncertainty and even fear among professional golfers. We use our model to examine the effect of wind direction and wind-speed on the accuracy of the golf shots at this hole and use the simulations to determine the key aerodynamic factors that affect the accuracy of the shot.

Wind Power Prediction Considering Nonlinear Atmospheric Disturbances

Directory of Open Access Journals (Sweden)

Yagang Zhang

2015-01-01

Full Text Available This paper considers the effect of nonlinear atmospheric disturbances on wind power prediction. A Lorenz system is introduced as an atmospheric disturbance model. Three new improved wind forecasting models combined with a Lorenz comprehensive disturbance are put forward in this study. Firstly, we define the form of the Lorenz disturbance variable and the wind speed perturbation formula. Then, different artificial neural network models are used to verify the new idea and obtain better wind speed predictions. Finally we separately use the original and improved wind speed series to predict the related wind power. This proves that the corrected wind speed provides higher precision wind power predictions. This research presents a totally new direction in the wind prediction field and has profound theoretical research value and practical guiding significance.

Wind turbine wake measurement in complex terrain

DEFF Research Database (Denmark)

Hansen, Kurt Schaldemose; Larsen, Gunner Chr.; Menke, Robert

2016-01-01

SCADA data from a wind farm and high frequency time series measurements obtained with remote scanning systems have been analysed with focus on identification of wind turbine wake properties in complex terrain. The analysis indicates that within the flow regime characterized by medium to large dow...

Probabilistic forecasting of wind power generation using extreme learning machine

DEFF Research Database (Denmark)

Wan, Can; Xu, Zhao; Pinson, Pierre

2014-01-01

an extreme learning machine (ELM)-based probabilistic forecasting method for wind power generation. To account for the uncertainties in the forecasting results, several bootstrapmethods have been compared for modeling the regression uncertainty, based on which the pairs bootstrap method is identified......Accurate and reliable forecast of wind power is essential to power system operation and control. However, due to the nonstationarity of wind power series, traditional point forecasting can hardly be accurate, leading to increased uncertainties and risks for system operation. This paper proposes...... with the best performance. Consequently, a new method for prediction intervals formulation based on theELMand the pairs bootstrap is developed.Wind power forecasting has been conducted in different seasons using the proposed approach with the historical wind power time series as the inputs alone. The results...

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)

Shortlist masterplan wind. Ship-based monitoring of seabirds and cetaceans

Energy Technology Data Exchange (ETDEWEB)

Van Bemmelen, R.; Geelhoed, S.; Leopold, M. [Institute for Marine Resources and Ecosystem Studies IMARES, Wageningen UR, IJmuiden (Netherlands)

2011-02-15

During April 2010 - February 2011, monthly surveys of seabirds and marine mammals were conducted aboard ships engaged in plankton surveys. After many years of little or no effort in far offshore areas of the DCS (Dutch Continental Shelf), this series of surveys provided the first recent ship-based data on seabirds, covering a large area (the entire DCS, including some Belgian and British waters) almost year round. Due to changes in the design of the survey grid, the use of several ships, spells of bad weather conditions and seasonal differences in the number of daylight hours, the resulting coverage is not evenly spread in space and time. Still, both in terms of areas covered and detailed data gathered, this series of surveys complement the aerial surveys carried out under the same programme Shortlist Masterplan Wind. By surveying beyond the designated areas for round II offshore wind farms on the DCS, areas that might be targeted for round III, such as the shallow Dogger Bank area, got a first boost in T-zero survey effort. From April 2010 till February 2011 11 surveys, totalling to 48 at-sea days, 4610 5-minute counts were conducted over a distance of 9021 km. At a counting strip width of mostly 300 m (200 m over a very small percentage of the counts), this amounts to a total surveyed area of 2706 km{sup 2}. The surveys have provided rough data on seabird distribution in far offshore areas. In total, 54,593 individuals of 90 bird species were recorded, from which 15,003 individuals of 36 species were recorded within the counting strip. Marine mammals were represented by 616 individuals of seven species, of which 389 individuals of six species were seen within the counting strip. Flying heights were noted for 5044 clusters of individuals, covering 75 species. Behaviour was noted for 1790 (clusters of) individuals. Apart from birds and marine mammals, 352 balloons were counted (of which 164 were within the counting strip) and proved omnipresent in periods of

Intelligent control on wind farm

DEFF Research Database (Denmark)

Wei, Mu; Chen, Zhe

2010-01-01

with the wind farm makes the grid more vulnerable. The communication technologies have been considered as a solution to solve the problems according to the IEC 61400-25 series protocols. This paper presents the significance of communication technologies in wind farm system by the simulations on some practical......Since the renewable energy is popularly applied in power industry, especially the smart grid is fast developing all over the world during these years, the reliable connection between a wind farm and the main grid has been focused on. Due to the difficult control on the wind energy, the connection...... scenarios. By delivering the signals among WTs (wind turbines) and control centers, they both are able to recognize another side’s operation situation and to adjust its own state to realize the optimization. A scenario is designed in this paper, in which a fault occurs in wind farm; then the protection...

Time series analysis of continuous-wave coherent Doppler Lidar wind measurements

International Nuclear Information System (INIS)

Sjoeholm, M; Mikkelsen, T; Mann, J; Enevoldsen, K; Courtney, M

2008-01-01

The influence of spatial volume averaging of a focused 1.55 μm continuous-wave coherent Doppler Lidar on observed wind turbulence measured in the atmospheric surface layer over homogeneous terrain is described and analysed. Comparison of Lidar-measured turbulent spectra with spectra simultaneously obtained from a mast-mounted sonic anemometer at 78 meters height at the test station for large wind turbines at Hoevsoere in Western Jutland, Denmark is presented for the first time

Managing Critical Weather Conditions in a Large-Scale Wind Based European Power System - The TWENTIES Project

DEFF Research Database (Denmark)

Detlefsen, N.; Sørensen, Poul Ejnar; Eriksen, P.

2011-01-01

the cut-off wind speed (typically 25 m/s). Experience has shown that a large offshore wind farm in this way can be shut down from full power to zero power in less than 5 minutes. Thus, in the planned offshore development in the North Sea, several GW of wind power could be shut down within less than one...

A new wind power prediction method based on chaotic theory and Bernstein Neural Network

International Nuclear Information System (INIS)

Wang, Cong; Zhang, Hongli; Fan, Wenhui; Fan, Xiaochao

2016-01-01

The accuracy of wind power prediction is important for assessing the security and economy of the system operation when wind power connects to the grids. However, multiple factors cause a long delay and large errors in wind power prediction. Hence, efficient wind power forecasting approaches are still required for practical applications. In this paper, a new wind power forecasting method based on Chaos Theory and Bernstein Neural Network (BNN) is proposed. Firstly, the largest Lyapunov exponent as a judgment for wind power system's chaotic behavior is made. Secondly, Phase Space Reconstruction (PSR) is used to reconstruct the wind power series' phase space. Thirdly, the prediction model is constructed using the Bernstein polynomial and neural network. Finally, the weights and thresholds of the model are optimized by Primal Dual State Transition Algorithm (PDSTA). The practical hourly data of wind power generation in Xinjiang is used to test this forecaster. The proposed forecaster is compared with several current prominent research findings. Analytical results indicate that the forecasting error of PDSTA + BNN is 3.893% for 24 look-ahead hours, and has lower errors obtained compared with the other forecast methods discussed in this paper. The results of all cases studying confirm the validity of the new forecast method. - Highlights: • Lyapunov exponent is used to verify chaotic behavior of wind power series. • Phase Space Reconstruction is used to reconstruct chaotic wind power series. • A new Bernstein Neural Network to predict wind power series is proposed. • Primal dual state transition algorithm is chosen as the training strategy of BNN.

Estimating annoyance to calculated wind turbine shadow flicker is improved when variables associated with wind turbine noise exposure are considered.

Science.gov (United States)

Voicescu, Sonia A; Michaud, David S; Feder, Katya; Marro, Leonora; Than, John; Guay, Mireille; Denning, Allison; Bower, Tara; van den Berg, Frits; Broner, Norm; Lavigne, Eric

2016-03-01

The Community Noise and Health Study conducted by Health Canada included randomly selected participants aged 18-79 yrs (606 males, 632 females, response rate 78.9%), living between 0.25 and 11.22 km from operational wind turbines. Annoyance to wind turbine noise (WTN) and other features, including shadow flicker (SF) was assessed. The current analysis reports on the degree to which estimating high annoyance to wind turbine shadow flicker (HAWTSF) was improved when variables known to be related to WTN exposure were also considered. As SF exposure increased [calculated as maximum minutes per day (SFm)], HAWTSF increased from 3.8% at 0 ≤ SFm wind turbine-related features, concern for physical safety, and noise sensitivity. Reported dizziness was also retained in the final model at p = 0.0581. Study findings add to the growing science base in this area and may be helpful in identifying factors associated with community reactions to SF exposure from wind turbines.

Quality Control Algorithms for the Kennedy Space Center 50-Megahertz Doppler Radar Wind Profiler Winds Database

Science.gov (United States)

Barbre, Robert E., Jr.

2012-01-01

This paper presents the process used by the Marshall Space Flight Center Natural Environments Branch (EV44) to quality control (QC) data from the Kennedy Space Center's 50-MHz Doppler Radar Wind Profiler for use in vehicle wind loads and steering commands. The database has been built to mitigate limitations of using the currently archived databases from weather balloons. The DRWP database contains wind measurements from approximately 2.7-18.6 km altitude at roughly five minute intervals for the August 1997 to December 2009 period of record, and the extensive QC process was designed to remove spurious data from various forms of atmospheric and non-atmospheric artifacts. The QC process is largely based on DRWP literature, but two new algorithms have been developed to remove data contaminated by convection and excessive first guess propagations from the Median Filter First Guess Algorithm. In addition to describing the automated and manual QC process in detail, this paper describes the extent of the data retained. Roughly 58% of all possible wind observations exist in the database, with approximately 100 times as many complete profile sets existing relative to the EV44 balloon databases. This increased sample of near-continuous wind profile measurements may help increase launch availability by reducing the uncertainty of wind changes during launch countdown

Neural Network Classifiers for Local Wind Prediction.

Science.gov (United States)

Kretzschmar, Ralf; Eckert, Pierre; Cattani, Daniel; Eggimann, Fritz

2004-05-01

This paper evaluates the quality of neural network classifiers for wind speed and wind gust prediction with prediction lead times between +1 and +24 h. The predictions were realized based on local time series and model data. The selection of appropriate input features was initiated by time series analysis and completed by empirical comparison of neural network classifiers trained on several choices of input features. The selected input features involved day time, yearday, features from a single wind observation device at the site of interest, and features derived from model data. The quality of the resulting classifiers was benchmarked against persistence for two different sites in Switzerland. The neural network classifiers exhibited superior quality when compared with persistence judged on a specific performance measure, hit and false-alarm rates.

Time-dependent theoretical model of the polar wind: Preliminary results

International Nuclear Information System (INIS)

Gombosi, T.I.; Cravens, T.E.; Nagy, A.F.

1985-01-01

The coupled time dependent continuity, momentum and energy equations of a two ion (O + and H + ) quasineutral plasma were solved in order to extend our understanding of polar wind behavior. This numerical code allows studies of the time dependent behavior of polar wind-type flows into and out of the ionosphere. Initial studies indicate that the typical time constants for electron and ion temperature changes are of the order of minutes and tens of minutes, respectively. The response time of the minor high altitude ion O + is less than an hour, whereas that of the major ion, H + , is many hours. The initial test runs also demonstrate the fact that temporary supersonic flows of both O + and H + are possible, especially in the presence of significant ion heating

Artificial intelligence to predict short-term wind speed

Energy Technology Data Exchange (ETDEWEB)

Pinto, Tiago; Soares, Joao; Ramos, Sergio; Vale, Zita [Polytechnic of Porto (Portugal). GECAD - ISEP

2012-07-01

The use of renewable energy is increasing exponentially in many countries due to the introduction of new energy and environmental policies. Thus, the focus on energy and on the environment makes the efficient integration of renewable energy into the electric power system extremely important. Several European countries have been seeing a high penetration of wind power, representing, gradually, a significant penetration on electricity generation. The introduction of wind power in the network power system causes new challenges for the power system operator due to the variability and uncertainty in weather conditions and, consequently, in the wind power generation. As result, the scheduling dispatch has a significantly portion of uncertainty. In order to deal with the uncertainty in wind power and, with that, introduce improvements in the power system operator efficiency, the wind power forecasting may reveal as a useful tool. This paper proposes a data-mining-based methodology to forecast wind speed. This method is based on the use of data mining techniques applied to a real database of historical wind data. The paper includes a case study based on a real database regarding the last three years to predict wind speed at 5 minute intervals. (orig.)

Application of Taylor-Series Integration to Reentry Problems with Wind

NARCIS (Netherlands)

Bergsma, Michiel; Mooij, E.

2016-01-01

Taylor-series integration is a numerical integration technique that computes the Taylor series of state variables using recurrence relations and uses this series to propagate the state in time. A Taylor-series integration reentry integrator is developed and compared with the fifth-order

Wind power forecasting-a review of the state of the art

DEFF Research Database (Denmark)

Giebel, Gregor; Kariniotakis, George

2017-01-01

This chapter gives an overview over past and present attempts to predict wind power for single turbines, wind, farms or for whole regions, for a few minutes up to a few days ahead. It is based on a survey and report (Giebel et al., 2011) initiated in the frame of the European project ANEMOS, whic...... integration of the forecasts in the work flow of end users....

Offshore wind resources at Danish measurement sites

Energy Technology Data Exchange (ETDEWEB)

Barthelmie, R J; Courtney, M S; Lange, B; Nielsen, M; Sempreviva, A M [Risoe National Lab., Dept. of Wind Energy and Atmospheric Physics, Roskilde (Denmark); Svenson, J; Olsen, F [SEAS, Haslev (Denmark); Christensen, T [Elsamprojekt, Fredericia (Denmark)

1999-03-01

In order to characterise wind and turbulence characteristics at prospective offshore wind energy sites, meteorological observations from a number of purpose-built offshore monitoring sites have been analyzed and compared with long wind speed time series. New analyses have been conducted on the data sets focussing on meteorology, turbulence, extreme winds and wind and wave interactions. Relationships between wind speed, turbulence and fetch are highly complex. Minimum turbulence intensity offshore is associated with wind speeds of about 12 m/s. At lower wind speeds, stability effects are important while at higher winds speeds wind and wave interactions appear to dominate. On average, turbulence intensity offshore at 48 m height is approximately 0.08 if no coastal effects are present. However, the effect of the coastal discontinuity persists in wind speed and turbulence characteristics for considerable distances offshore. The majority of the adjustment of appears to occur within 20 km of the coast. (au)

The new European wind atlas

DEFF Research Database (Denmark)

Lundtang Petersen, Erik; Troen, Ib; Ejsing Jørgensen, Hans

2014-01-01

, from insufficient input data to deficient physics and resolution in any of the models, model linking issues, insufficient resolution or errors in surface topographical data such as terrain heights, land cover data etc. Therefore it has been decided on a European Union level to launch a project “The New...... European Wind Atlas” aiming at reducing overall uncertainties in determining wind conditions; standing on three legs: A data bank from a series of intensive measuring campaigns; a thorough examination and redesign of the model chain from global, mesoscale to microscale models and creation of the wind atlas...

Short-Term Wind Speed Prediction Using EEMD-LSSVM Model

Directory of Open Access Journals (Sweden)

Aiqing Kang

2017-01-01

Full Text Available Hybrid Ensemble Empirical Mode Decomposition (EEMD and Least Square Support Vector Machine (LSSVM is proposed to improve short-term wind speed forecasting precision. The EEMD is firstly utilized to decompose the original wind speed time series into a set of subseries. Then the LSSVM models are established to forecast these subseries. Partial autocorrelation function is adopted to analyze the inner relationships between the historical wind speed series in order to determine input variables of LSSVM models for prediction of every subseries. Finally, the superposition principle is employed to sum the predicted values of every subseries as the final wind speed prediction. The performance of hybrid model is evaluated based on six metrics. Compared with LSSVM, Back Propagation Neural Networks (BP, Auto-Regressive Integrated Moving Average (ARIMA, combination of Empirical Mode Decomposition (EMD with LSSVM, and hybrid EEMD with ARIMA models, the wind speed forecasting results show that the proposed hybrid model outperforms these models in terms of six metrics. Furthermore, the scatter diagrams of predicted versus actual wind speed and histograms of prediction errors are presented to verify the superiority of the hybrid model in short-term wind speed prediction.

A preliminary impact assessment of typhoon wind risk of residential buildings in Japan under future climate change

DEFF Research Database (Denmark)

Nishijima, Kazuyoshi; Maruyama, Takashi; Graf, Mathias

2012-01-01

are that in the future (2075–2099) at most locations of Japan: (1) extreme wind events (10-minute sustained wind speed exceeding 30 m/s) are more likely to occur; (2) the median of the annual maximum wind speed decreases; (3) the expected number of damaged residential buildings decreases, assuming that the profile...

Effects of Yaw Error on Wind Turbine Running Characteristics Based on the Equivalent Wind Speed Model

Directory of Open Access Journals (Sweden)

Shuting Wan

2015-06-01

Full Text Available Natural wind is stochastic, being characterized by its speed and direction which change randomly and frequently. Because of the certain lag in control systems and the yaw body itself, wind turbines cannot be accurately aligned toward the wind direction when the wind speed and wind direction change frequently. Thus, wind turbines often suffer from a series of engineering issues during operation, including frequent yaw, vibration overruns and downtime. This paper aims to study the effects of yaw error on wind turbine running characteristics at different wind speeds and control stages by establishing a wind turbine model, yaw error model and the equivalent wind speed model that includes the wind shear and tower shadow effects. Formulas for the relevant effect coefficients Tc, Sc and Pc were derived. The simulation results indicate that the effects of the aerodynamic torque, rotor speed and power output due to yaw error at different running stages are different and that the effect rules for each coefficient are not identical when the yaw error varies. These results may provide theoretical support for optimizing the yaw control strategies for each stage to increase the running stability of wind turbines and the utilization rate of wind energy.

Baseline avian use and behavior at the CARES wind plant site, Klickitat County, Washington

Energy Technology Data Exchange (ETDEWEB)

Erickson, W.P.; Johnson, G.D.; Strickland, M.D.; Kronner, K.; Becker, P.S.; Orloff, S.

2000-01-03

This report presents a literature review on avian-wind turbine interactions and the results of a one-year avian baseline study conducted in 1998 at the proposed Conservation and Renewable Energy System (CARES) wind development site in Klickitat County, Washington. Avian use of the site ranged from 1.11/survey in the winter to 5.69/survey in the spring. Average use by passerines in the study plots ranged from 1.15 minutes/survey in the winter to 40.98 minutes/survey in the spring. Raptors spent much less time within plots than other groups, ranging from 0.05 minutes/survey in the winter to 0.77 minutes/survey during the fall. Thirteen percent of all flying birds were within the rotor-swept height (25 to 75 m); 41.6% of all raptors were flying at this height. Raptors with the greatest potential turbine exposure are red-tailed hawks and golden eagles. Passerines with the highest turbine exposure are common ravens, American robins, and horned larks. Spatial use data for the site indicate that avian use tends to be concentrated near the rim, indicating that placing turbines away from the rim may reduce risk. Avian use data at the CARES site indicate that if a wind plant is constructed in the future, avian mortality would likely be relatively low.

Baseline avian use and behavior at the CARES wind plant site, Klickitat County, Washington

International Nuclear Information System (INIS)

Erickson, W.P.; Johnson, G.D.; Strickland, M.D.; Kronner, K.; Becker, P.S.; Orloff, S.

2000-01-01

This report presents a literature review on avian-wind turbine interactions and the results of a one-year avian baseline study conducted in 1998 at the proposed Conservation and Renewable Energy System (CARES) wind development site in Klickitat County, Washington. Avian use of the site ranged from 1.11/survey in the winter to 5.69/survey in the spring. Average use by passerines in the study plots ranged from 1.15 minutes/survey in the winter to 40.98 minutes/survey in the spring. Raptors spent much less time within plots than other groups, ranging from 0.05 minutes/survey in the winter to 0.77 minutes/survey during the fall. Thirteen percent of all flying birds were within the rotor-swept height (25 to 75 m); 41.6% of all raptors were flying at this height. Raptors with the greatest potential turbine exposure are red-tailed hawks and golden eagles. Passerines with the highest turbine exposure are common ravens, American robins, and horned larks. Spatial use data for the site indicate that avian use tends to be concentrated near the rim, indicating that placing turbines away from the rim may reduce risk. Avian use data at the CARES site indicate that if a wind plant is constructed in the future, avian mortality would likely be relatively low

Wind tunnel tests of a free yawing downwind wind turbine

DEFF Research Database (Denmark)

Verelst, David Robert; Larsen, Torben J.; van Wingerden, J.W.

2012-01-01

During February and April 2012 a series of wind tunnel tests were performed at the TU Delft Open Jet Facility (OJF) with a three bladed downwind wind turbine and a rotor radius of 0.8 meters. The setup includes an off the shelf three bladed hub, nacelle and generator on which relatively flexible ...... in free yawing conditions. Further, the effect of the tower shadow passage on the blade flapwise strain measurement is evaluated. Finally, data from the experiment is compared with preliminary simulations using DTU Wind Energy's aeroelastic simulation program HAWC2....... blades are mounted. The tower support structure has free yawing capabilities provided at the tower base. A short overview on the technical details of the experiment is provided as well as a brief summary of the design process. The discussed test cases show that the turbine is stable while operating...

Wind-induced response analysis of a wind turbine tower including the blade-tower coupling effect

Institute of Scientific and Technical Information of China (English)

Xiao-bo CHEN; Jing LI; Jian-yun CHEN

2009-01-01

To analyze wind-induced response characteristics of a wind turbine tower more accurately, the blade-tower coupling effect was investigated. The mean wind velocity of the rotating blades and tower was simulated according to wind shear effects,and the fluctuating wind velocity time series of the wind turbine were simulated by a harmony superposition method. A dynamic finite element method (FEM) was used to calculate the wind-induced response of the blades and tower. Wind-induced responses of the tower were calculated in two cases (one included the blade-tower coupling effect, and the other only added the mass of blades and the hub at the top of the tower), and then the maximal displacements at the top of the tower of the tow cases were compared with each other. As a result of the influence of the blade-tower coupling effect and the total base shear of the blades, the maximal displacement of the first case increased nearly by 300% compared to the second case. To obtain more precise analysis, the blade-tower coupling effect and the total base shear of the blades should be considered simultaneously in the design of wind turbine towers.

A hybrid wind power forecasting model based on data mining and wavelets analysis

International Nuclear Information System (INIS)

Azimi, R.; Ghofrani, M.; Ghayekhloo, M.

2016-01-01

Highlights: • An improved version of K-means algorithm is proposed for clustering wind data. • A persistence based method is applied to select the best cluster for NN training. • A combination of DWT and HANTS methods is used to provide a deep learning for NN. • A hybrid of T.S.B K-means, DWT and HANTS and NN is developed for wind forecasting. - Abstract: Accurate forecasting of wind power plays a key role in energy balancing and wind power integration into the grid. This paper proposes a novel time-series based K-means clustering method, named T.S.B K-means, and a cluster selection algorithm to better extract features of wind time-series data. A hybrid of T.S.B K-means, discrete wavelet transform (DWT) and harmonic analysis time series (HANTS) methods, and a multilayer perceptron neural network (MLPNN) is developed for wind power forecasting. The proposed T.S.B K-means classifies data into separate groups and leads to more appropriate learning for neural networks by identifying anomalies and irregular patterns. This improves the accuracy of the forecast results. A cluster selection method is developed to determine the cluster that provides the best training for the MLPNN. This significantly accelerates the forecast process as the most appropriate portion of the data rather than the whole data is used for the NN training. The wind power data is decomposed by the Daubechies D4 wavelet transform, filtered by the HANTS, and pre-processed to provide the most appropriate inputs for the MLPNN. Time-series analysis is used to pre-process the historical wind-power generation data and structure it into input-output series. Wind power datasets with diverse characteristics, from different wind farms located in the United States, are used to evaluate the accuracy of the hybrid forecasting method through various performance measures and different experiments. A comparative analysis with well-established forecasting models shows the superior performance of the proposed

Study on transient stability of asynchronous wind turbine based on series dynamic braking resistor%基于串联动态制动电阻的异步风电机组暂态稳定性研究

Institute of Scientific and Technical Information of China (English)

肖兰; 赵斌; 李建; 范镇南

2011-01-01

以并网笼型异步风电机组为例,分析了利用串联动态制动电阻提高并网异步风电机组在电网故障下暂态稳定性的作用机理以及效果.建立了并网异步风电机组的数学模型,基于Matlab/Simulink仿真平台,对比分析了采用串联动态制动电阻、并联动态制动电阻以及无功补偿装置的作用效果.仿真结果表明,采用串联动态制动电阻可以有效改善并网异步风力发电机组的暂态稳定性；同时,采用串联动态制动电阻和无功补偿装置,可显著提高机组的暂态稳定性,减少对无功补偿的需求,降低风电场的运行成本.%Take the squirrel-cage type asynchronous wind turbine as example, the mechanism and efficiency of the improvement on the transient stability of wind turbine with grid-connected used by series dynamic braking resistor under the power grid fault is analyzed, the mathematical model of asynchronous wind turbine.with grid-connected is established, the transient behaviors of the wind turbine generator system using series dynamic breaking resistor, parallel dynamic breaking resistor and reactive compensation device are analyzed and compared based on Matlab/Simulink,. The simulation results have shown that the series dynamic breaking resistor can effectively improve the transient stability of asynchronous wind turbine system. Using series dynamic breaking resistor and reactive compensation device simultaneously can improve the transient stability of wind turbine generator system significantly , which reducing the reactive compensation requirement and cost of wind farm.

An investigation of the utility scale wind energy for north‐eastern ...

African Journals Online (AJOL)

In the present study, the wind energy potential for Garissa (0°28S, 39°38'E) and Marsabit (2° 19N, 37° 58'E), both rural towns in north-eastern Kenya have been statistically analyzed on a 6-year measured hourly time series wind speed data. The probability distribution parameters are derived the time series data and the ...

How 60 Minutes ticked off Illinois Power

International Nuclear Information System (INIS)

Anon.

1980-01-01

A November 60 Minutes broadcast on CBS television asserting that costs are out of control at the Illinois Power Co's(IP) Clinton nuclear power project because of management incompetence triggered a series of rebuttals and counter-rebuttals. A review of the events and correspondence during the planning stage and after the broadcast explores the question of construction cost overruns and the economic impact the broadcast had on IP's investors, employees, and customers. A parallel filming by IP was aired to show how the CBS edited the interview with IP officials. IP personnel feel betrayed by what they consider misconceptions and errors in the broadcast and are unhappy that an employee morale problem was worsened. Counter-arguments by both parties indicate a disagreement on both facts and interpretations

Field investigation of a wake structure downwind of a VANT (Vertical-Axis Wind Turbine) in a wind farm array

Science.gov (United States)

Liu, H. T.; Buck, J. W.; Germain, A. C.; Hinchee, M. E.; Solt, T. S.; Leroy, G. M.; Srnsky, R. A.

1988-09-01

The effects of upwind turbine wakes on the performance of a FloWind 17-m vertical-axis wind turbine (VAWT) were investigated through a series of field experiments conducted at the FloWind wind farm on Cameron Ridge, Tehachapi, California. From the field measurements, we derived the velocity and power/energy deficits under various turbine on/off configurations. Much information was provided to characterize the structure of VAWT wakes and to assess their effects on the performance of downwind turbines. A method to estimate the energy deficit was developed based on the measured power deficit and the wind speed distributions. This method may be adopted for other turbine types and sites. Recommendations are made for optimizing wind farm design and operations, as well as for wind energy management.

Time series analysis of continuous-wave coherent Doppler Lidar wind measurements

DEFF Research Database (Denmark)

Sjöholm, Mikael; Mikkelsen, Torben; Mann, Jakob

2008-01-01

The influence of spatial volume averaging of a focused 1.55 mu m continuous-wave coherent Doppler Lidar on observed wind turbulence measured in the atmospheric surface layer over homogeneous terrain is described and analysed. Comparison of Lidar-measured turbulent spectra with spectra simultaneou......The influence of spatial volume averaging of a focused 1.55 mu m continuous-wave coherent Doppler Lidar on observed wind turbulence measured in the atmospheric surface layer over homogeneous terrain is described and analysed. Comparison of Lidar-measured turbulent spectra with spectra...

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

Theoretical derivation of wind power probability distribution function and applications

International Nuclear Information System (INIS)

Altunkaynak, Abdüsselam; Erdik, Tarkan; Dabanlı, İsmail; Şen, Zekai

2012-01-01

Highlights: ► Derivation of wind power stochastic characteristics are standard deviation and the dimensionless skewness. ► The perturbation is expressions for the wind power statistics from Weibull probability distribution function (PDF). ► Comparisons with the corresponding characteristics of wind speed PDF abides by the Weibull PDF. ► The wind power abides with the Weibull-PDF. -- Abstract: The instantaneous wind power contained in the air current is directly proportional with the cube of the wind speed. In practice, there is a record of wind speeds in the form of a time series. It is, therefore, necessary to develop a formulation that takes into consideration the statistical parameters of such a time series. The purpose of this paper is to derive the general wind power formulation in terms of the statistical parameters by using the perturbation theory, which leads to a general formulation of the wind power expectation and other statistical parameter expressions such as the standard deviation and the coefficient of variation. The formulation is very general and can be applied specifically for any wind speed probability distribution function. Its application to two-parameter Weibull probability distribution of wind speeds is presented in full detail. It is concluded that provided wind speed is distributed according to a Weibull distribution, the wind power could be derived based on wind speed data. It is possible to determine wind power at any desired risk level, however, in practical studies most often 5% or 10% risk levels are preferred and the necessary simple procedure is presented for this purpose in this paper.

Electronically commutated serial-parallel switching for motor windings

Science.gov (United States)

Hsu, John S [Oak Ridge, TN

2012-03-27

A method and a circuit for controlling an ac machine comprises controlling a full bridge network of commutation switches which are connected between a multiphase voltage source and the phase windings to switch the phase windings between a parallel connection and a series connection while providing commutation discharge paths for electrical current resulting from inductance in the phase windings. This provides extra torque for starting a vehicle from lower battery current.

Performance comparison of wind park configurations

Energy Technology Data Exchange (ETDEWEB)

Lundberg, Stefan

2003-07-01

In this report, layouts of various large-scale wind parks, both AC as well as DC, are investigated. Loss modelling of the wind park components as well as calculations of the energy capture of the turbines using various electrical systems are performed, and the energy production cost of the various park configurations is determined. It was found that from an energy capture point of view, the difference in energy production between various wind turbine systems is very small. In addition, a study of the suitability of various DC/DC-converters is made. Three DC/DC-converters, Boost, Full Bridge and Full Bridge Isolated Boost, are found to be interesting candidates as the 'transformer' component in potential DC-based wind parks. Of all the investigated wind park configurations, the wind park with the series connected DC wind turbines seems to have the best potential to give the lowest energy production cost, if the transmission distance is longer then 10-20 km.

Short-term Wind Forecasting to Support Virtual Power Player Operation

OpenAIRE

Ramos, Sérgio; Soares, João; Pinto, Tiago; Vale, Zita

2013-01-01

This paper proposes a wind speed forecasting model that contributes to the development and implementation of adequate methodologies for Energy Resource Man-agement in a distribution power network, with intensive use of wind based power generation. The proposed fore-casting methodology aims to support the operation in the scope of the intraday resources scheduling model, name-ly with a time horizon of 10 minutes. A case study using a real database from the meteoro-logical station installed ...

Atmospheric air density analysis with Meteo-40S wind monitoring system

Directory of Open Access Journals (Sweden)

Zahariea Dănuţ

2017-01-01

Full Text Available In order to estimate the wind potential of wind turbine sites, the wind resource maps can be used for mean annual wind speed, wind speed frequency distribution and mean annual wind power density determination. The general evaluation of the wind resource and the wind turbine ratings are based on the standard air density measured at sea level and at 15°C, ρs=1.225 kg/m3. Based on the experimental data obtained for a continental climate specific location, this study will present the relative error between the standard air density and the density of the dry and the moist air. Considering a cold day, for example on Friday 10th February 2017, on 1-second measurement rate and 10-minute measuring interval starting at 16:20, the mean relative errors obtained are 10.4145% for dry air, and 10.3634% for moist air. Based on these results, a correction for temperature, atmospheric air pressure and relative humidity should be always considered for wind resource assessment, as well as for the predicting the wind turbines performance.

Early warnings of extreme winds using the ECMWF Extreme Forecast Index

OpenAIRE

Petroliagis, Thomas I.; Pinson, Pierre

2014-01-01

The European FP7 SafeWind Project aims at developing research towards a European vision of wind power forecasting, which requires advanced meteorological support concerning extreme wind events. This study is focused mainly on early warnings of extreme winds in the early medium-range. Three synoptic stations (airports) of North Germany (Bremen, Hamburg and Hannover) were considered for the construction of time series of daily maximum wind speeds. All daily wind extremes were found to be linked...

The Skipheia Wind Measurement Station. Instrumentation, Wind Speed Profiles and Turbulence Spectra

Energy Technology Data Exchange (ETDEWEB)

Aasen, S E

1995-10-01

This thesis describes the design of a measurement station for turbulent wind and presents results from an analysis of the collected data. The station is located at Skipheia near the south-west end of Froeya, an island off the coast of Mid-Norway. The station is unique for studies of turbulent winds because of the large numbers of sensors, which are located at various heights above ground up to 100 m, a sampling rate of 0.85 Hz and storage of the complete time series. The frequency of lightning and atmospheric discharges to the masts are quite high and much effort has gone into minimizing the damage caused by lightning activity. A major part of the thesis deals with data analysis and modelling. There are detailed discussions on the various types of wind sensors and their calibration, the data acquisition system and operating experiences with it, the database, data quality control, the wind speed profile and turbulence. 40 refs., 78 figs., 17 tabs.

Quality-Controlled Wind Data from the Kennedy Space Center 915 Megahertz Doppler Radar Wind Profiler Network

Science.gov (United States)

Dryden, Rachel L.

2011-01-01

The National Aeronautics and Space Administration s (NASA) Kennedy Space Center (KSC) has installed a five-instrument 915-Megahertz (MHz) Doppler Radar Wind Profiler (DRWP) system that records atmospheric wind profile properties. The purpose of these profilers is to fill data gaps between the top of the KSC wind tower network and the lowest measurement altitude of the KSC 50-MHz DRWP. The 915-MHz DRWP system has the capability to generate three-dimensional wind data outputs from approximately 150 meters (m) to 6,000 m at roughly 15-minute (min) intervals. NASA s long-term objective is to combine the 915-MHz and 50-MHz DRWP systems to create complete vertical wind profiles up to 18,300 m to be used in trajectory and loads analyses of space vehicles and by forecasters on day-of-launch (DOL). This analysis utilizes automated and manual quality control (QC) processes to remove erroneous and unrealistic wind data returned by the 915-MHz DRWP system. The percentage of data affected by each individual QC check in the period of record (POR) (i.e., January to April 2006) was computed, demonstrating the variability in the amount of data affected by the QC processes. The number of complete wind profiles available at given altitude thresholds for each profiler in the POR was calculated and outputted graphically, followed by an assessment of the number of complete wind profiles available for any profiler in the POR. A case study is also provided to demonstrate the QC process on a day of a known weather event.

Studies of Sub-Synchronous Oscillations in Large-Scale Wind Farm Integrated System

Science.gov (United States)

Yue, Liu; Hang, Mend

2018-01-01

With the rapid development and construction of large-scale wind farms and grid-connected operation, the series compensation wind power AC transmission is gradually becoming the main way of power usage and improvement of wind power availability and grid stability, but the integration of wind farm will change the SSO (Sub-Synchronous oscillation) damping characteristics of synchronous generator system. Regarding the above SSO problem caused by integration of large-scale wind farms, this paper focusing on doubly fed induction generator (DFIG) based wind farms, aim to summarize the SSO mechanism in large-scale wind power integrated system with series compensation, which can be classified as three types: sub-synchronous control interaction (SSCI), sub-synchronous torsional interaction (SSTI), sub-synchronous resonance (SSR). Then, SSO modelling and analysis methods are categorized and compared by its applicable areas. Furthermore, this paper summarizes the suppression measures of actual SSO projects based on different control objectives. Finally, the research prospect on this field is explored.

OW CCMP Ocean Surface Wind

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Cross-Calibrated Multi-Platform (CCMP) Ocean Surface Wind Vector Analyses (Atlas et al., 2011) provide a consistent, gap-free long-term time-series of monthly...

A multi-state model for wind farms considering operational outage probability

DEFF Research Database (Denmark)

Cheng, Lin; Liu, Manjun; Sun, Yuanzhang

2013-01-01

As one of the most important renewable energy resources, wind power has drawn much attention in recent years. The stochastic characteristics of wind speed lead to generation output uncertainties of wind energy conversion system (WECS) and affect power system reliability, especially at high wind...... as well as solving a series of reliability-centered decision-making problems of power system scheduling and maintenance arrangements....

Statistics of wind direction and its increments

International Nuclear Information System (INIS)

Doorn, Eric van; Dhruva, Brindesh; Sreenivasan, Katepalli R.; Cassella, Victor

2000-01-01

We study some elementary statistics of wind direction fluctuations in the atmosphere for a wide range of time scales (10 -4 sec to 1 h), and in both vertical and horizontal planes. In the plane parallel to the ground surface, the direction time series consists of two parts: a constant drift due to large weather systems moving with the mean wind speed, and fluctuations about this drift. The statistics of the direction fluctuations show a rough similarity to Brownian motion but depend, in detail, on the wind speed. This dependence manifests itself quite clearly in the statistics of wind-direction increments over various intervals of time. These increments are intermittent during periods of low wind speeds but Gaussian-like during periods of high wind speeds. (c) 2000 American Institute of Physics

Off-Shore wind potential estimation along the coast of Chile by using scatterometer and Reanalysis data

Directory of Open Access Journals (Sweden)

C. Mattar

2014-06-01

Full Text Available This work presents the first offshore wind potential estimation over the coast of Chile using long term data series from “QuikSCAT (V04 wind vectors” and ERA-interim’s wind product between 1999-2009 and 1979-2012, respectively. Weibull and Rayleigh’s distribution were used to adjust the data series from the study period to find the probability density function, mean wind speed, maximum and minimum from each data series adjusted per pixel. Power generation and a capacity factor were estimated for the whole scene using three wind turbine models corresponding to 3.6, 5.0 and 8.0 MW. The images obtained from the data processing were grouped into three different wind power zones named (A located up north, (B in the center and (C down south-center. The mean capacity factors are higher than 20%, moreover B and C areas have an average of 36%. This work shows the high wind power potential to generate electricity by using wind off-shore technologies along the coast of Chile.

Wind energy technology developments

DEFF Research Database (Denmark)

Madsen, Peter Hauge; Hansen, Morten Hartvig; Pedersen, Niels Leergaard

2014-01-01

turbine blades and towers are very large series-produced components, which costs and quality are strongly dependent on the manufacturing methods. The industrial wind energy sector is well developed in Denmark, and the competitive advantage of the Danish sector and the potential for job creation...

Active Power Controls from Wind Power: Bridging the Gaps

Energy Technology Data Exchange (ETDEWEB)

Ela, E. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gevorgian, V. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Fleming, P. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Zhang, Y. C. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Singh, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Muljadi, E. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Scholbrook, A. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Aho, J. [Univ. of Colorado, Boulder, CO (United States); Buckspan, A. [Univ. of Colorado, Boulder, CO (United States); Pao, L. [Univ. of Colorado, Boulder, CO (United States); Singhvi, V. [Electric Power Research Inst. (EPRI), Palo Alto, CA (United States); Tuohy, A. [Electric Power Research Inst. (EPRI), Palo Alto, CA (United States); Pourbeik, P. [Electric Power Research Inst. (EPRI), Palo Alto, CA (United States); Brooks, D. [Electric Power Research Inst. (EPRI), Palo Alto, CA (United States); Bhatt, N. [Electric Power Research Inst. (EPRI), Palo Alto, CA (United States)

2014-01-01

This paper details a comprehensive study undertaken by the National Renewable Energy Laboratory, Electric Power Research Institute, and the University of Colorado to understand how the contribution of wind power providing active power control (APC) can benefit the total power system economics, increase revenue streams, improve the reliability and security of the power system, and provide superior and efficient response while reducing any structural and loading impacts that may reduce the life of the wind turbine or its components. The study includes power system simulations, control simulations, and actual field tests using turbines at NREL's National Wind Technology Center (NWTC). The study focuses on synthetic inertial control, primary frequency control, and automatic generation control, and analyzes timeframes ranging from milliseconds to minutes to the lifetime of wind turbines, locational scope ranging from components of turbines to large wind plants to entire synchronous interconnections, and additional topics ranging from economics to power system engineering to control design.

Numerical simulations of flow fields through conventionally controlled wind turbines and wind farms

International Nuclear Information System (INIS)

Yilmaz, Ali Emre; Meyers, Johan

2014-01-01

In the current study, an Actuator-Line Model (ALM) is implemented in our in-house pseudo-spectral LES solver SP-WIND, including a turbine controller. Below rated wind speed, turbines are controlled by a standard-torque-controller aiming at maximum power extraction from the wind. Above rated wind speed, the extracted power is limited by a blade pitch controller which is based on a proportional-integral type control algorithm. This model is used to perform a series of single turbine and wind farm simulations using the NREL 5MW turbine. First of all, we focus on below-rated wind speed, and investigate the effect of the farm layout on the controller calibration curves. These calibration curves are expressed in terms of nondimensional torque and rotational speed, using the mean turbine-disk velocity as reference. We show that this normalization leads to calibration curves that are independent of wind speed, but the calibration curves do depend on the farm layout, in particular for tightly spaced farms. Compared to turbines in a lone-standing set-up, turbines in a farm experience a different wind distribution over the rotor due to the farm boundary-layer interaction. We demonstrate this for fully developed wind-farm boundary layers with aligned turbine arrangements at different spacings (5D, 7D, 9D). Further we also compare calibration curves obtained from full farm simulations with calibration curves that can be obtained at a much lower cost using a minimal flow unit

Wind Speed Prediction Using a Univariate ARIMA Model and a Multivariate NARX Model

Directory of Open Access Journals (Sweden)

Erasmo Cadenas

2016-02-01

Full Text Available Two on step ahead wind speed forecasting models were compared. A univariate model was developed using a linear autoregressive integrated moving average (ARIMA. This method’s performance is well studied for a large number of prediction problems. The other is a multivariate model developed using a nonlinear autoregressive exogenous artificial neural network (NARX. This uses the variables: barometric pressure, air temperature, wind direction and solar radiation or relative humidity, as well as delayed wind speed. Both models were developed from two databases from two sites: an hourly average measurements database from La Mata, Oaxaca, Mexico, and a ten minute average measurements database from Metepec, Hidalgo, Mexico. The main objective was to compare the impact of the various meteorological variables on the performance of the multivariate model of wind speed prediction with respect to the high performance univariate linear model. The NARX model gave better results with improvements on the ARIMA model of between 5.5% and 10. 6% for the hourly database and of between 2.3% and 12.8% for the ten minute database for mean absolute error and mean squared error, respectively.

Wind and load variability in the Nordic countries

DEFF Research Database (Denmark)

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

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......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...... of wind power production than Denmark, and Finland and Norway only 50% of the wind power production in Denmark. Wind power production in Denmark and Sweden is somewhat correlated (coefficient 0.7) but less correlation is found between the other countries. The variations from one hour to the next are only...

RSA/Legacy Wind Sensor Comparison. Part 2; Eastern Range

Science.gov (United States)

Short, David A.; Wheeler, Mark M.

2006-01-01

This report describes a comparison of data from ultrasonic and propeller-and-vane anemometers on 5 wind towers at Kennedy Space Center and Cape Canaveral Air Force Station. The ultrasonic sensors are scheduled to replace the Legacy propeller-and-vane sensors under the Range Standardization and Automation (RSA) program. Because previous studies have noted differences between peak wind speeds reported by mechanical and ultrasonic wind sensors, the latter having no moving parts, the 30th and 45th Weather Squadrons wanted to understand possible differences between the two sensor types. The period-of-record was 13-30 May 2005, A total of 357,626 readings of 1-minute average and peak wind speed/direction from each sensor type were used. Statistics of differences in speed and direction were used to identify 15 out of 19 RSA sensors having the most consistent performance, with respect to the Legacy sensors. RSA average wind speed data from these 15 showed a small positive bias of 0.38 kts. A slightly larger positive bias of 0.94 kts was found in the RSA peak wind speed.

Distributed Wind Market Applications

Energy Technology Data Exchange (ETDEWEB)

Forsyth, T.; Baring-Gould, I.

2007-11-01

Distributed wind energy systems provide clean, renewable power for on-site use and help relieve pressure on the power grid while providing jobs and contributing to energy security for homes, farms, schools, factories, private and public facilities, distribution utilities, and remote locations. America pioneered small wind technology in the 1920s, and it is the only renewable energy industry segment that the United States still dominates in technology, manufacturing, and world market share. The series of analyses covered by this report were conducted to assess some of the most likely ways that advanced wind turbines could be utilized apart from large, central station power systems. Each chapter represents a final report on specific market segments written by leading experts in this field. As such, this document does not speak with one voice but rather a compendium of different perspectives, which are documented from a variety of people in the U.S. distributed wind field.

European wind power integration study. Periodic report 1

Energy Technology Data Exchange (ETDEWEB)

NONE

1992-12-31

This periodic report no. 1 describes the work done in the Danish part of the European Wind Power Integration Study in the period until 1.4.1991. The R and D project was initiated January 1, 1989 upon prior establishment of registration equipment at 7 wind farms and at the Tjaereborg turbine. ELSAM and the meteorological service centre in Karup (VTC-Karup) have supplied data for the task. Wind Predictability, Potential and Benefits, Wind Farm - Grid Interface, Distribution System Strength, Wind Farm Cost and Operation, and Co-generation Wind Turbines/Other renewables were measured and modelled. The statistical distribution of the wind speed variations (changes in wind speed from one period of time to another) has been established with great certainty in the report. The wind speed variations follow a Weibull distribution, irrespective of the time intervals with which the data are considered. Duration curves and power distributions for the 7 wind farms have been estimated. Registration equipment for one-minute measurements was chosen in order to clarify the short-term variations in the wind power production. The possibility of working out production forecasts, to be applied in the daily load dispatching, were to be assessed for the total amount of wind power production in Jutland and Funen. The report has examined whether it would be possible to have only one wind measurement and then let it be `guiding` for the total wind farm production. Some simulations are to be carried out in the attempt to set up guidelines for the connection between the strength of distribution systems and the requirements which must be made to the wind farms which are to be places in the system. (EG)

Real time wave forecasting using wind time history and numerical model

Science.gov (United States)

Jain, Pooja; Deo, M. C.; Latha, G.; Rajendran, V.

Operational activities in the ocean like planning for structural repairs or fishing expeditions require real time prediction of waves over typical time duration of say a few hours. Such predictions can be made by using a numerical model or a time series model employing continuously recorded waves. This paper presents another option to do so and it is based on a different time series approach in which the input is in the form of preceding wind speed and wind direction observations. This would be useful for those stations where the costly wave buoys are not deployed and instead only meteorological buoys measuring wind are moored. The technique employs alternative artificial intelligence approaches of an artificial neural network (ANN), genetic programming (GP) and model tree (MT) to carry out the time series modeling of wind to obtain waves. Wind observations at four offshore sites along the east coast of India were used. For calibration purpose the wave data was generated using a numerical model. The predicted waves obtained using the proposed time series models when compared with the numerically generated waves showed good resemblance in terms of the selected error criteria. Large differences across the chosen techniques of ANN, GP, MT were not noticed. Wave hindcasting at the same time step and the predictions over shorter lead times were better than the predictions over longer lead times. The proposed method is a cost effective and convenient option when a site-specific information is desired.

Synthetic wind speed scenarios generation for probabilistic analysis of hybrid energy systems

International Nuclear Information System (INIS)

Chen, Jun; Rabiti, Cristian

2017-01-01

Hybrid energy systems consisting of multiple energy inputs and multiple energy outputs have been proposed to be an effective element to enable ever increasing penetration of clean energy. In order to better understand the dynamic and probabilistic behavior of hybrid energy systems, this paper proposes a model combining Fourier series and autoregressive moving average (ARMA) to characterize historical weather measurements and to generate synthetic weather (e.g., wind speed) data. In particular, Fourier series is used to characterize the seasonal trend in historical data, while ARMA is applied to capture the autocorrelation in residue time series (e.g., measurements with seasonal trends subtracted). The generated synthetic wind speed data is then utilized to perform probabilistic analysis of a particular hybrid energy system configuration, which consists of nuclear power plant, wind farm, battery storage, natural gas boiler, and chemical plant. Requirements on component ramping rate, economic and environmental impacts of hybrid energy systems, and the effects of deploying different sizes of batteries in smoothing renewable variability, are all investigated. - Highlights: • Computational model to synthesize artificial wind speed data with consistent characteristics with database. • Fourier series to capture seasonal trends in the database. • Monte Carlo simulation and probabilistic analysis of hybrid energy systems. • Investigation of the effect of battery in smoothing variability of wind power generation.

Wind Power Plants Fundamentals, Design, Construction and Operation

CERN Document Server

Twele, Jochen

2012-01-01

Wind power plants teaches the physical foundations of usage of Wind Power. It includes the areas like Construction of Wind Power Plants, Design, Development of Production Series, Control, and discusses the dynamic forces acting on the systems as well as the power conversion and its connection to the distribution system. The book is written for graduate students, practitioners and inquisitive readers of any kind. It is based on lectures held at several universities. Its German version it already is the standard text book for courses on Wind Energy Engineering but serves also as reference for practising engineers.

Contribution of Strong Discontinuities to the Power Spectrum of the Solar Wind

International Nuclear Information System (INIS)

Borovsky, Joseph E.

2010-01-01

Eight and a half years of magnetic field measurements (2 22 samples) from the ACE spacecraft in the solar wind at 1 A.U. are analyzed. Strong (large-rotation-angle) discontinuities in the solar wind are collected and measured. An artificial time series is created that preserves the timing and amplitudes of the discontinuities. The power spectral density of the discontinuity series is calculated and compared with the power spectral density of the solar-wind magnetic field. The strong discontinuities produce a power-law spectrum in the ''inertial subrange'' with a spectral index near the Kolmogorov -5/3 index. The discontinuity spectrum contains about half of the power of the full solar-wind magnetic field over this ''inertial subrange.'' Warnings are issued about the significant contribution of discontinuities to the spectrum of the solar wind, complicating interpretation of spectral power and spectral indices.

A variance analysis of the capacity displaced by wind energy in Europe

DEFF Research Database (Denmark)

Giebel, Gregor

2007-01-01

into a longer-term context. The results are that wind energy can contribute more than 20% of the European demand without significant changes in the system and can replace conventional capacity worth about 10% of the installed wind power capacity. The long-term reference shows that the analysed year is the worst...... simulating the scheduling of the European power plants to cover the demand at every hour of the year. The wind power generation was modelled using wind speed measurements from 60 meteorological stations, for 1 year. The distributed wind power also displaces fossil-fuelled capacity. However, every assessment...... of the displaced capacity (or a capacity credit) by means of a chronological model is highly sensitive to single events. Therefore the wind time series was shifted by integer days against the load time series, and the different results were aggregated. The some set of results is shown for two other options, one...

Error analysis of short term wind power prediction models

International Nuclear Information System (INIS)

De Giorgi, Maria Grazia; Ficarella, Antonio; Tarantino, Marco

2011-01-01

The integration of wind farms in power networks has become an important problem. This is because the electricity produced cannot be preserved because of the high cost of storage and electricity production must follow market demand. Short-long-range wind forecasting over different lengths/periods of time is becoming an important process for the management of wind farms. Time series modelling of wind speeds is based upon the valid assumption that all the causative factors are implicitly accounted for in the sequence of occurrence of the process itself. Hence time series modelling is equivalent to physical modelling. Auto Regressive Moving Average (ARMA) models, which perform a linear mapping between inputs and outputs, and Artificial Neural Networks (ANNs) and Adaptive Neuro-Fuzzy Inference Systems (ANFIS), which perform a non-linear mapping, provide a robust approach to wind power prediction. In this work, these models are developed in order to forecast power production of a wind farm with three wind turbines, using real load data and comparing different time prediction periods. This comparative analysis takes in the first time, various forecasting methods, time horizons and a deep performance analysis focused upon the normalised mean error and the statistical distribution hereof in order to evaluate error distribution within a narrower curve and therefore forecasting methods whereby it is more improbable to make errors in prediction. (author)

Error analysis of short term wind power prediction models

Energy Technology Data Exchange (ETDEWEB)

De Giorgi, Maria Grazia; Ficarella, Antonio; Tarantino, Marco [Dipartimento di Ingegneria dell' Innovazione, Universita del Salento, Via per Monteroni, 73100 Lecce (Italy)

2011-04-15

The integration of wind farms in power networks has become an important problem. This is because the electricity produced cannot be preserved because of the high cost of storage and electricity production must follow market demand. Short-long-range wind forecasting over different lengths/periods of time is becoming an important process for the management of wind farms. Time series modelling of wind speeds is based upon the valid assumption that all the causative factors are implicitly accounted for in the sequence of occurrence of the process itself. Hence time series modelling is equivalent to physical modelling. Auto Regressive Moving Average (ARMA) models, which perform a linear mapping between inputs and outputs, and Artificial Neural Networks (ANNs) and Adaptive Neuro-Fuzzy Inference Systems (ANFIS), which perform a non-linear mapping, provide a robust approach to wind power prediction. In this work, these models are developed in order to forecast power production of a wind farm with three wind turbines, using real load data and comparing different time prediction periods. This comparative analysis takes in the first time, various forecasting methods, time horizons and a deep performance analysis focused upon the normalised mean error and the statistical distribution hereof in order to evaluate error distribution within a narrower curve and therefore forecasting methods whereby it is more improbable to make errors in prediction. (author)

Dynamic responses of a wind turbine drivetrain under turbulent wind and voltage disturbance conditions

Directory of Open Access Journals (Sweden)

Chengwu Li

2016-05-01

Full Text Available Wind energy is known as one of the most efficient clean renewable energy sources and has attracted extensive research interests in both academic and industry fields. In this study, the effects of turbulent wind and voltage disturbance on a wind turbine drivetrain are analyzed, and a wind turbine drivetrain dynamic model combined with the electric model of a doubly fed induction generator is established. The proposed model is able to account for the dynamic interaction between turbulent wind, voltage disturbance, and mechanical system. Also, the effects of time-varying meshing stiffness, transmission error, and bearing stiffness are included in the mechanical part of the coupled dynamic model. From the resultant model, system modes are computed. In addition, by considering the actual control strategies in the simulation process, the effects of turbulent wind and voltage disturbance on the geared rotor system are analyzed. The computational results show that the turbulent wind and voltage disturbance can cause adverse effects on the wind turbine drivetrain, especially the gearbox. A series of parametric studies are also performed to understand the influences of generator and gearbox parameters on the drivetrain system dynamics. Finally, the appropriate generator parameters having a positive effect on the gearbox in alleviating the extreme loads and the modeling approach for investigating the transient performance of generator are discussed.

Complex terrain experiments in the New European Wind Atlas

DEFF Research Database (Denmark)

Mann, Jakob; Angelou, Nikolas; Arnqvist, Johan

2017-01-01

The New European Wind Atlas project will create a freely accessible wind atlas covering Europe and Turkey, develop the model chain to create the atlas and perform a series of experiments on flow in many different kinds of complex terrain to validate the models. This paper describes the experiment...

Preliminary modelling study of ice accretion on wind turbines

DEFF Research Database (Denmark)

Pedersen, Marie Cecilie; Yin, Chungen

2014-01-01

One of the main challenges associated with cold-climate wind energy is icing on wind turbines and a series of icing-induced problems such as production loss, blade fatigue and safety issues. Because of the difficulties with on-site measurements, simulations are often used to understand and predic...

Wind speed power spectrum analysis for Bushland, Texas

Energy Technology Data Exchange (ETDEWEB)

Eggleston, E.D. [USDA-Agricultural Research Service, Bushland, TX (United States)

1996-12-31

Numerous papers and publications on wind turbulence have referenced the wind speed spectrum presented by Isaac Van der Hoven in his article entitled Power Spectrum of Horizontal Wind Speed Spectrum in the Frequency Range from 0.0007 to 900 Cycles per Hour. Van der Hoven used data measured at different heights between 91 and 125 meters above the ground, and represented the high frequency end of the spectrum with data from the peak hour of hurricane Connie. These facts suggest we should question the use of his power spectrum in the wind industry. During the USDA - Agricultural Research Service`s investigation of wind/diesel system power storage, using the appropriate wind speed power spectrum became a significant issue. We developed a power spectrum from 13 years of hourly average data, 1 year of 5 minute average data, and 2 particularly gusty day`s 1 second average data all collected at a height of 10 meters. While the general shape is similar to the Van der Hoven spectrum, few of his peaks were found in the Bushland spectrum. While higher average wind speeds tend to suggest higher amplitudes in the high frequency end of the spectrum, this is not always true. Also, the high frequency end of the spectrum is not accurately described by simple wind statistics such as standard deviation and turbulence intensity. 2 refs., 5 figs., 1 tab.

Wind Statistics Offshore based on Satellite Images

DEFF Research Database (Denmark)

Hasager, Charlotte Bay; Mouche, Alexis; Badger, Merete

2009-01-01

-based observations become available. At present preliminary results are obtained using the routine methods. The first step in the process is to retrieve raw SAR data, calibrate the images and use a priori wind direction as input to the geophysical model function. From this process the wind speed maps are produced....... The wind maps are geo-referenced. The second process is the analysis of a series of geo-referenced SAR-based wind maps. Previous research has shown that a relatively large number of images are needed for achieving certain accuracies on mean wind speed, Weibull A and k (scale and shape parameters......Ocean wind maps from satellites are routinely processed both at Risø DTU and CLS based on the European Space Agency Envisat ASAR data. At Risø the a priori wind direction is taken from the atmospheric model NOGAPS (Navel Operational Global Atmospheric Prediction System) provided by the U.S. Navy...

Time Series Analysis and Forecasting for Wind Speeds Using Support Vector Regression Coupled with Artificial Intelligent Algorithms

Directory of Open Access Journals (Sweden)

Ping Jiang

2015-01-01

Full Text Available Wind speed/power has received increasing attention around the earth due to its renewable nature as well as environmental friendliness. With the global installed wind power capacity rapidly increasing, wind industry is growing into a large-scale business. Reliable short-term wind speed forecasts play a practical and crucial role in wind energy conversion systems, such as the dynamic control of wind turbines and power system scheduling. In this paper, an intelligent hybrid model for short-term wind speed prediction is examined; the model is based on cross correlation (CC analysis and a support vector regression (SVR model that is coupled with brainstorm optimization (BSO and cuckoo search (CS algorithms, which are successfully utilized for parameter determination. The proposed hybrid models were used to forecast short-term wind speeds collected from four wind turbines located on a wind farm in China. The forecasting results demonstrate that the intelligent hybrid models outperform single models for short-term wind speed forecasting, which mainly results from the superiority of BSO and CS for parameter optimization.

Multi-component wind measurements of wind turbine wakes performed with three LiDARs

Science.gov (United States)

Iungo, G. V.; Wu, Y.-T.; Porté-Agel, F.

2012-04-01

Field measurements of the wake flow produced from the interaction between atmospheric boundary layer and a wind turbine are performed with three wind LiDARs. The tested wind turbine is a 2 MW Enercon E-70 located in Collonges, Switzerland. First, accuracy of mean values and frequency resolution of the wind measurements are surveyed as a function of the number of laser rays emitted for each measurement. Indeed, measurements performed with one single ray allow maximizing sampling frequency, thus characterizing wake turbulence. On the other hand, if the number of emitted rays is increased accuracy of mean wind is increased due to the longer sampling period. Subsequently, two-dimensional measurements with a single LiDAR are carried out over vertical sections of the wind turbine wake and mean wake flow is obtained by averaging 2D measurements consecutively performed. The high spatial resolution of the used LiDAR allows characterizing in details velocity defect present in the central part of the wake and its downstream recovery. Single LiDAR measurements are also performed by staring the laser beam at fixed directions for a sampling period of about ten minutes and maximizing the sampling frequency in order to characterize wake turbulence. From these tests wind fluctuation peaks are detected in the wind turbine wake at blade top-tip height for different downstream locations. The magnitude of these turbulence peaks is generally reduced by moving downstream. This increased turbulence level at blade top-tip height observed for a real wind turbine has been already detected from previous wind tunnel tests and Large Eddy simulations, thus confirming the presence of a source of dangerous fatigue loads for following wind turbines within a wind farm. Furthermore, the proper characterization of wind fluctuations through LiDAR measurements is proved by the detection of the inertial subrange from spectral analysis of these velocity signals. Finally, simultaneous measurements with two

Technology Roadmaps: China Wind Energy Development Roadmap 2050

Energy Technology Data Exchange (ETDEWEB)

NONE

2011-07-01

The report shows how China, already the world's largest wind market, could reach 1 000 GW of wind power by the middle of the century, an achievement that would reduce carbon dioxide emissions by 1.5 gigatonnes per year, or roughly equivalent to the combined CO2 emissions of Germany, France and Italy in 2009. The China Wind Energy Roadmap is the first national roadmap that has been developed by a country with IEA support, drawing from its global roadmap series.

Open access wind tunnel measurements of a downwind free yawing wind turbine

DEFF Research Database (Denmark)

Verelst, David Robert; Larsen, Torben J.; van Wingerden, Jan-Willem

2016-01-01

A series of free yawing wind tunnel experiments was held in the Open Jet Facility (OJF) of the TU Delft. The ≈ 300 W turbine has three blades in a downwind configuration and is optionally free to yaw. Different 1.6m diameter rotor configurations are tested such as blade flexibility and sweep...

Wind resources at turbine height from Envisat and Sentinel-1 SAR

DEFF Research Database (Denmark)

Badger, Merete; Hasager, Charlotte Bay; Pena Diaz, Alfredo

for the standard output level of 10 m above the sea surface. This presentation demonstrates the effects of two recent improvements related to satellite-based wind resource mapping: 1) The number of satellite samples has increased dramatically since the launch of Sentinel-1A/B 2) A new method looks promising...... National Ice Center. Once the instantaneous wind maps are stored in our database, they can be organized as time series in order to calculate wind resources for any point location or area. Since the time series comprises data from both Envisat and Sentinel-1, a check of the data calibration against one....... To extrapolate the 10-m wind resource maps from SAR to higher levels within the atmospheric boundary layer, we estimate a wind profile for each grid cell in the maps. Simulations from the Weather Research and Forecasting (WRF) model are used to correct this profile for long-term atmospheric stability effects...

Non-Gaussian probability distributions of solar wind fluctuations

Directory of Open Access Journals (Sweden)

E. Marsch

Full Text Available The probability distributions of field differences ∆x(τ=x(t+τ-x(t, where the variable x(t may denote any solar wind scalar field or vector field component at time t, have been calculated from time series of Helios data obtained in 1976 at heliocentric distances near 0.3 AU. It is found that for comparatively long time lag τ, ranging from a few hours to 1 day, the differences are normally distributed according to a Gaussian. For shorter time lags, of less than ten minutes, significant changes in shape are observed. The distributions are often spikier and narrower than the equivalent Gaussian distribution with the same standard deviation, and they are enhanced for large, reduced for intermediate and enhanced for very small values of ∆x. This result is in accordance with fluid observations and numerical simulations. Hence statistical properties are dominated at small scale τ by large fluctuation amplitudes that are sparsely distributed, which is direct evidence for spatial intermittency of the fluctuations. This is in agreement with results from earlier analyses of the structure functions of ∆x. The non-Gaussian features are differently developed for the various types of fluctuations. The relevance of these observations to the interpretation and understanding of the nature of solar wind magnetohydrodynamic (MHD turbulence is pointed out, and contact is made with existing theoretical concepts of intermittency in fluid turbulence.

Wind speed forecasting using FEEMD echo state networks with RELM in Hebei, China

International Nuclear Information System (INIS)

Sun, Wei; Liu, Mohan

2016-01-01

Highlights: • FEEMD–RELM is proposed for wind speed forecasting. • Short-term and mid-term wind speed are forecasted by the proposed model. • PACF is introduced to select the input of RELM. • Three cases in Hebei province are applied in this paper. - Abstract: Reducing the dependence on fossil-fuel-based resources is becoming significant due to the detrimental effects on environment and global energy-dependent. Thus, increased attention has been paid to wind power, a type of clean and renewable energy. However, owing to the stochastic nature of wind speed, it is essential to build a wind speed forecasting model with high-precision for wind power utilization. Therefore, this paper proposes a hybrid model which combines fast ensemble empirical model decomposition (FEEMD) with regularized extreme learning machine (RELM). The original wind speed series are first decomposed into a limited number of intrinsic mode functions (IMFs) and one residual series. Then RELM is built to forecast the sub-series. Partial auto correlation function (PACF) is applied to analyze the intrinsic relationships between the historical speeds so as to select the inputs of RELM. To verify the developed models, short-term wind speed data in July 2010 and monthly data from January 2000 to May 2010 in Hong songwa wind farm, Chengde city are used for model construction and testing. Two additional forecasting cases in Hebei province are also applied to prove the model’s validity. The simulation test results show that the built model is effective, efficient and practicable.

Design analysis of vertical wind turbine with airfoil variation

Science.gov (United States)

Maulana, Muhammad Ilham; Qaedy, T. Masykur Al; Nawawi, Muhammad

2016-03-01

With an ever increasing electrical energy crisis occurring in the Banda Aceh City, it will be important to investigate alternative methods of generating power in ways different than fossil fuels. In fact, one of the biggest sources of energy in Aceh is wind energy. It can be harnessed not only by big corporations but also by individuals using Vertical Axis Wind Turbines (VAWT). This paper presents a three-dimensional CFD analysis of the influence of airfoil design on performance of a Darrieus-type vertical-axis wind turbine (VAWT). The main objective of this paper is to develop an airfoil design for NACA 63-series vertical axis wind turbine, for average wind velocity 2,5 m/s. To utilize both lift and drag force, some of designs of airfoil are analyzed using a commercial computational fluid dynamics solver such us Fluent. Simulation is performed for this airfoil at different angles of attach rearranging from -12°, -8°, -4°, 0°, 4°, 8°, and 12°. The analysis showed that the significant enhancement in value of lift coefficient for airfoil NACA 63-series is occurred for NACA 63-412.

Transient stability enhancement of wind farms using power electronics and facts controllers

Science.gov (United States)

Mohammadpour, Hossein Ali

Nowadays, it is well-understood that the burning of fossil fuels in electric power station has a significant influence on the global climate due to greenhouse gases. In many countries, the use of cost-effective and reliable low-carbon electricity energy sources is becoming an important energy policy. Among different kinds of clean energy resources- such as solar power, hydro-power, ocean wave power and so on, wind power is the fastest-growing form of renewable energy at the present time. Moreover, adjustable speed generator wind turbines (ASGWT) has key advantages over the fixed-speed generator wind turbines (FSGWT) in terms of less mechanical stress, improved power quality, high system efficiency, and reduced acoustic noise. One important class of ASGWT is the doubly-fed induction generator (DFIG), which has gained a significant attention of the electric power industry due to their advantages over the other class of ASGWT, i.e. fully rated converter-based wind turbines. Because of increased integration of DFIG-based wind farms into electric power grids, it is necessary to transmit the generated power from wind farms to the existing grids via transmission networks without congestion. Series capacitive compensation of DFIG-based wind farm is an economical way to increase the power transfer capability of the transmission line connecting wind farm to the grid. For example, a study performed by ABB reveals that increasing the power transfer capability of an existing transmission line from 1300 MW to 2000 MW using series compensation is 90% less than the cost of building a new transmission line. However, a factor hindering the extensive use of series capacitive compensation is the potential risk of sub- synchronous resonance (SSR). The SSR is a condition where the wind farm exchanges energy with the electric network, to which it is connected, at one or more natural frequencies of the electric or mechanical part of the combined system, comprising the wind farm and the

Results from a three-month intercomparison of boundary-layer wind profiler and sodar wind measurements at Lindenberg, Germany

Energy Technology Data Exchange (ETDEWEB)

Beyrich, F.; Goersdorf, U.; Neisser, J.; Steinhagen, H.; Weisensee, U. [Deutscher Wetterdienst, Lindenberg (Germany). Meteorologisches Observatorium

1998-10-01

Intercomparison experiments with a wind profiler and a Doppler sodar have been performed at the meteorological observatory Lindenberg of the German weather service in summer, 1994, and in autumn, 1995, over a total period of about three months. The paper presents selected results of the wind measurements performed with the two systems. Sodar and wind profiler are shown to complement each other quite well. Therefore, a combination of both is a promising tool for continuous, high-resolution measurements of the wind profile. A problem to be solved is the construction of composite wind profiles when the measurements with the two systems disagree in the height range of overlapping. Measurements of the vertical velocity are difficult to assess due to their small absolute values. Long-term averages of the vertical velocity show slightly negative values, especially for the wind profiler. However, similar signatures have been found in the vertical velocity time series during frontal passages or during well-developed convection. (orig.) 7 refs.

De-trending of wind speed variance based on first-order and second-order statistical moments only

DEFF Research Database (Denmark)

Larsen, Gunner Chr.; Hansen, Kurt Schaldemose

2014-01-01

The lack of efficient methods for de-trending of wind speed resource data may lead to erroneous wind turbine fatigue and ultimate load predictions. The present paper presents two models, which quantify the effect of an assumed linear trend on wind speed standard deviations as based on available...... statistical data only. The first model is a pure time series analysis approach, which quantifies the effect of non-stationary characteristics of ensemble mean wind speeds on the estimated wind speed standard deviations as based on mean wind speed statistics only. This model is applicable to statistics...... of arbitrary types of time series. The second model uses the full set of information and includes thus additionally observed wind speed standard deviations to estimate the effect of ensemble mean non-stationarities on wind speed standard deviations. This model takes advantage of a simple physical relationship...

Short-Term Wind Speed Forecasting for Power System Operations

KAUST Repository

Zhu, Xinxin

2012-04-01

The emphasis on renewable energy and concerns about the environment have led to large-scale wind energy penetration worldwide. However, there are also significant challenges associated with the use of wind energy due to the intermittent and unstable nature of wind. High-quality short-term wind speed forecasting is critical to reliable and secure power system operations. This article begins with an overview of the current status of worldwide wind power developments and future trends. It then reviews some statistical short-term wind speed forecasting models, including traditional time series approaches and more advanced space-time statistical models. It also discusses the evaluation of forecast accuracy, in particular, the need for realistic loss functions. New challenges in wind speed forecasting regarding ramp events and offshore wind farms are also presented. © 2012 The Authors. International Statistical Review © 2012 International Statistical Institute.

A reward semi-Markov process with memory for wind speed modeling

Science.gov (United States)

Petroni, F.; D'Amico, G.; Prattico, F.

2012-04-01

-order Markov chain with different number of states, and Weibull distribution. All this model use Markov chains to generate synthetic wind speed time series but the search for a better model is still open. Approaching this issue, we applied new models which are generalization of Markov models. More precisely we applied semi-Markov models to generate synthetic wind speed time series. The primary goal of this analysis is the study of the time history of the wind in order to assess its reliability as a source of power and to determine the associated storage levels required. In order to assess this issue we use a probabilistic model based on indexed semi-Markov process [4] to which a reward structure is attached. Our model is used to calculate the expected energy produced by a given turbine and its variability expressed by the variance of the process. Our results can be used to compare different wind farms based on their reward and also on the risk of missed production due to the intrinsic variability of the wind speed process. The model is used to generate synthetic time series for wind speed by means of Monte Carlo simulations and backtesting procedure is used to compare results on first and second oder moments of rewards between real and synthetic data. [1] A. Shamshad, M.A. Bawadi, W.M.W. Wan Hussin, T.A. Majid, S.A.M. Sanusi, First and second order Markov chain models for synthetic gen- eration of wind speed time series, Energy 30 (2005) 693-708. [2] H. Nfaoui, H. Essiarab, A.A.M. Sayigh, A stochastic Markov chain model for simulating wind speed time series at Tangiers, Morocco, Re- newable Energy 29 (2004) 1407-1418. [3] F. Youcef Ettoumi, H. Sauvageot, A.-E.-H. Adane, Statistical bivariate modeling of wind using first-order Markov chain and Weibull distribu- tion, Renewable Energy 28 (2003) 1787-1802. [4]F. Petroni, G. D'Amico, F. Prattico, Indexed semi-Markov process for wind speed modeling. To be submitted.

Along-wind response of a wind turbine tower with blade coupling subjected to rotationally sampled wind loading

Energy Technology Data Exchange (ETDEWEB)

Murtagh, P J; Basu, B; Broderick, B M [Department of Civil, Structural and Environmental Engineering, Trinity College, Dublin (Ireland)

2005-07-15

This paper proposes an approach to investigate the along-wind forced vibration response of a wind turbine tower and rotating blades assembly subjected to rotationally sampled stationary wind loading. The wind turbine assembly consists of three rotating rotor blades connected to the top of a flexible annular tower, constituting a multi-body dynamic entity. The tower and rotating blades are each modelled as discretized multi-degree-of-freedom (MDOF) entities, allowing the free vibration characteristics of each to be obtained using a discrete parameter approach. The free vibration properties of the tower include the effect of a rigid mass at the top, representing the nacelle, and those of the blade include the effects of centrifugal stiffening due to rotation and blade gravity loadings. The blades are excited by drag force time-histories derived from discrete Fourier transform (DFT) representations of rotationally sampled wind turbulence spectra. Blade response time-histories are obtained using the mode acceleration method, which allows for the quantification of base shear forces due to flapping for the three blades to be obtained. This resultant base shear is imparted into the top of the tower. Wind drag loading on the tower is also considered, with a series of spatially correlated nodal force time-histories being derived using DFTs of wind force spectra. The tower/nacelle is then coupled with the rotating blades by combining their equations of motion and solving for the displacement at the top of the tower under compatibility conditions in the frequency domain. An inverse Fourier transform of the frequency domain response yields the response time-history of the coupled system. The response of an equivalent system that does not consider the blade/tower interaction is also investigated, and the results are compared. (Author)

Test and evaluation of the Argonne BPAC10 Series air chamber calorimeter designed for 20 minute measurements

International Nuclear Information System (INIS)

Perry, R.B.; Fiarman, S.; Jung, E.A.; Cremers, T.

1990-10-01

This paper is the final report on DOE-OSS Task ANLE88002 ''Fast Air Chamber Calorimetry.'' The task objective was to design, construct, and test an isothermal air chamber calorimeter for plutonium assay of bulk samples that would meet the following requirements for sample power measurement: average sample measurement time less than 20 minutes. Measurement of samples with power output up to 10 W. Precision of better than 1% RSD for sample power greater than 1 W. Precision better than 0.010 watt SD, for sample power less than 1 W. This report gives a description of the calorimeter hardware and software and discusses the test results. The instrument operating procedure, included as an appendix, gives examples of typical input/output and explains the menu driven software. Sample measurement time of less than 20 minutes was attained by pre-equilibration of the samples in low cost precision preheaters and by prediction of equilibrium measurements. Tests at the TA55 Plutonium Facility at Los Alamos National Laboratory, on typical samples, indicates that the instrument meets all the measurement requirements

A Time Series Regime Classification Approach for Short-Term Forecasting; Identificacion de Mecanismos en Series Temporales para la Prediccion a Corto Plazo

Energy Technology Data Exchange (ETDEWEB)

Gallego, C. J.

2010-03-08

Abstract: This technical report is focused on the analysis of stochastic processes that switch between different dynamics (also called regimes or mechanisms) over time. The so-called Switching-regime models consider several underlying functions instead of one. In this case, a classification problem arises as the current regime has to be assessed at each time-step. The identification of the regimes allows the performance of regime-switching models for short-term forecasting purposes. Within this framework, identifying different regimes showed by time-series is the aim of this work. The proposed approach is based on a statistical tool called Gamma-test. One of the main advantages of this methodology is the absence of a mathematical definition for the different underlying functions. Applications with both simulated and real wind power data have been considered. Results on simulated time series show that regimes can be successfully identified under certain hypothesis. Nevertheless, this work highlights that further research has to be done when considering real wind power time-series, which usually show different behaviours (e.g. fluctuations or ramps, followed by low variance periods). A better understanding of these events eventually will improve wind power forecasting. (Author) 15 refs.

Comparison of prediction quality of wind speed in hourly wind using different ARMA models; Comparacion de la calidad de las predicciones a corto plazo de velocidades de viento horarias. Realizadas con modelos armas obtenidos con series temporales de diferente longitud

Energy Technology Data Exchange (ETDEWEB)

Izco, E.; Prieto, E.; Garcia, A.; Torres, J. L.

2004-07-01

In this communication we have used different ARMA (Autoregressive Moving Average Process) models to predict the hourly average wind speed. It has been compared the results in predictions made in hourly average wind speed up to 10 hours in advance, when it is used as basis for establishment of prediction model the data of previous year and the other model is made with an historical series of several years of duration. The study expands to five locations with different topographic characteristics , in mountains surroundings and others in smoother relief area. It has been proven that the RMSE and MBE obtained in the adjustment between the predictions and the future observations with both models are bigger in the model make with data of previous year. (Author)

Blyth Harbour wind farm - operational aspects

Energy Technology Data Exchange (ETDEWEB)

NONE

2004-07-01

This report is the last in a series of seven on various aspects of the monitoring and evaluation of the Blyth Northumberland off-shore wind farm project. The wind farm was the first to be built in the UK: it consists of two 2MW wind turbines about 1 km from the coast in water of depth 5-6 m. The subject of this report is the actual performance of the wind turbine relative to predicted performance. The study showed up the problems of operating a wind farm at sea and the need for comprehensive testing before installation. The problems encountered were numerous but in no case major. A lightning strike destroyed a turbine blade (for which no replacement was readily available) and there was a cable fault caused by installation deficiencies. Better planning could have avoided lengthy shutdowns. The report covers the availability of the turbines and performance of ancillary equipment.

A statistical investigation of wind characteristics and wind energy potential based on the Weibull and Rayleigh models in Rwanda

Energy Technology Data Exchange (ETDEWEB)

Safari, Bonfils; Gasore, Jimmy [Department of Physics, National University of Rwanda, P.O. Box 117, Huye, South Province (Rwanda)

2010-12-15

A wind energy system converts the kinetic energy of the wind into mechanical or electrical energy that can be harnessed for practical uses and transform the economy of rural areas where access to water and electricity is very restricted and industry is almost nonexistent in most of the developing countries like Rwanda. Assessing wind power potential for a location is an imperative requirement before making a decision for the installation of windmills or a wind electric generator and evaluating plans for relating projects. The aim of the present study was to evaluate the potential of wind resource in Rwanda and to constitute a database for the users of the wind power. A time series of hourly daily measured wind speed and wind direction for the period between 1974 and 1993 on five main Rwandan meteorological stations was provided by the National Meteorology Department. Statistical methods applying Weibull and Rayleigh distribution were presented to evaluate the wind speed characteristics and the wind power potential at a height of 10 m above ground level using hourly monthly average data. Those characteristics were extrapolated for higher levels in altitude. The results give a global picture of the distribution of the wind potential in different locations of Rwanda. (author)

Fundamentals for remote structural health monitoring of wind turbine blades - a preproject. Annex E. Full-scale test of wind turbine blade, using sensors and NDT

DEFF Research Database (Denmark)

Kristensen, O.J.D.; McGugan, Malcolm; Sendrup, P.

2002-01-01

A 19.1 metre wind turbine blade was subjected to static tests. The purpose of the test series was to verify the abilities of different types of sensors to detect damage in wind turbine blades. Prior to each of the static test-series an artificial damagewas made on the blade. The damage made...... for each test-series was surveyed during each series by acoustic emission, fiber optic micro bend displacement transducers and strain gauges. The propagation of the damage was determined by use of ultra sonic andX-ray surveillance during stops in the test-series. By use of acoustic emission it was possible...... to measure damage propagation before the propagation was of visible size. By use of fiber optic micro bend displacement transducers and strain gauges it waspossible to measure minor damage propagation. By use of both ultra sonic, and X-ray NDT-equipment it were possible to determine the size of propagated...

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

Wake effects in a wind farm (WF) include the wind velocity deficit and added turbulence. The wind velocity deficit may bring significant loss of the wind power and the added turbulence may cause extra fatigue load on the wind turbines (WTs). Inclusion of the wake effects in the wind farm control...... 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....

1-3-7 minute intravenous urography

International Nuclear Information System (INIS)

Bahk, Yong Whee; Yoon, Sei Chul; Lee, Myung Hee

1980-01-01

Intravenous urography (IVU) as it is used widely today was probably started in early 1950's after the introduction of triiodobenzoic acid compounds as contrast media. This long cherished traditional method consists of taking radiograms at 5, 15 and 25 minutes after the injection of contrast medium. There are a few modifications of this standard urographic examination such as five minute IVU (Woodruff, 1959), minute-sequence pyelogram (Maxwell et al., 1964), drip infusion pyelography (Schencker, 1964) and nephrotomography (Evans et al., 1955). The present study has been undertaken to test if the conventional standard IVU can be more rapidly performed without losing essential informational contents of urograms. In this new clinical trial, urograms were taken at the end of 1, 3 and 7 minutes instead of 5, 15 and 25 minutes after the intravenous injection of contrast medium. We injected 40 ml of meglumine diatrizoate solution within 30 seconds using an 18G iv needle. (The amount of injected contrast medium has been reduced recently to ordinary single dose of 20 ml for subjects weighing less than 8 kg). Upon viewing the 7 minute film in front of an automatic processor, the examination was terminated after obtaining an upright view unless any further radiogram was indicated. As shown in Tables and Figures, our new 1-3-7 minute method has been proven to provide us with as much essential and useful information as conventional 5-15-25 minute urography. Thus, we were able to finish one examination within 10 minutes without losing any necessary diagnostic information. In some of patients with obstructive uropathy such as stone the examination was extended as long as it was desired. Side reactions were occasional nausea, flushing and rare mild vomiting which never prevented the examination

2009 Wind Technologies Market Report

Energy Technology Data Exchange (ETDEWEB)

Wiser, R.; Bolinger, M.

2010-08-01

The U.S. wind power industry experienced yet another record year in 2009, once again surpassing even optimistic growth projections from years past. At the same time, 2009 was a year of upheaval, with the global financial crisis impacting the wind power industry and with federal policy changes enacted to push the industry toward continued aggressive expansion. The year 2010, meanwhile, is anticipated to be one of some retrenchment, with expectations for fewer wind power capacity additions than seen in 2009. The rapid pace of development and change within the industry has made it difficult to keep up with trends in the marketplace, yet the need for timely, objective information on the industry and its progress has never been greater. This report - the fourth in an ongoing annual series - attempts to meet this need by providing a detailed overview of developments and trends in the United States wind power market, with a particular focus on 2009.

LIDAR Wind Speed Measurement Analysis and Feed-Forward Blade Pitch Control for Load Mitigation in Wind Turbines: January 2010--January 2011

Energy Technology Data Exchange (ETDEWEB)

Dunne, F.; Simley, E.; Pao, L.Y.

2011-10-01

This report examines the accuracy of measurements that rely on Doppler LIDAR systems to determine their applicability to wind turbine feed-forward control systems and discusses feed-forward control system designs that use preview wind measurements. Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feed-forward control systems designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. The first half of this report examines the accuracy of different measurement scenarios that rely on coherent continuous-wave or pulsed Doppler LIDAR systems to determine their applicability to feed-forward control. In particular, the impacts of measurement range and angular offset from the wind direction are studied for various wind conditions. A realistic case involving a scanning LIDAR unit mounted in the spinner of a wind turbine is studied in depth with emphasis on choices for scan radius and preview distance. The effects of turbulence parameters on measurement accuracy are studied as well. Continuous-wave and pulsed LIDAR models based on typical commercially available units were used in the studies present in this report. The second half of this report discusses feed-forward control system designs that use preview wind measurements. Combined feedback/feed-forward blade pitch control is compared to industry standard feedback control when simulated in realistic turbulent above-rated winds. The feed-forward controllers are designed to reduce fatigue loads, increasing turbine lifetime and therefore reducing the cost of energy. Three feed-forward designs are studied: non-causal series expansion, Preview Control, and optimized FIR filter. The input to the feed-forward controller is a measurement of

Wind distribution and capacity factor estimation for wind turbines in the coastal region of South Africa

International Nuclear Information System (INIS)

Ayodele, T.R.; Jimoh, A.A.; Munda, J.L.; Agee, J.T.

2012-01-01

Highlights: ► We evaluate capacity factor of some commercially available wind turbines. ► Wind speed in the sites studied can best be modelled using Weibull distribution. ► Site WM05 has the highest wind power potential while site WM02 has the lowest. ► More wind power can be harnessed during the day period compared to the night. ► Turbine K seems to be the best turbine for the coastal region of South Africa. - Abstract: The operating curve parameters of a wind turbine should match the local wind regime optimally to ensure maximum exploitation of available energy in a mass of moving air. This paper provides estimates of the capacity factor of 20 commercially available wind turbines, based on the local wind characteristics of ten different sites located in the Western Cape region of South Africa. Ten-min average time series wind-speed data for a period of 1 year are used for the study. First, the wind distribution that best models the local wind regime of the sites is determined. This is based on root mean square error (RMSE) and coefficient of determination (R 2 ) which are used to test goodness of fit. First, annual, seasonal, diurnal and peak period-capacity factor are estimated analytically. Then, the influence of turbine power curve parameters on the capacity factor is investigated. Some of the key results show that the wind distribution of the entire site can best be modelled statistically using the Weibull distribution. Site WM05 (Napier) presents the highest capacity factor for all the turbines. This indicates that this site has the highest wind power potential of all the available sites. Site WM02 (Calvinia) has the lowest capacity factor i.e. lowest wind power potential. This paper can assist in the planning and development of large-scale wind power-generating sites in South Africa.

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

OpenAIRE

Xavier Ortiz; David Rival; David Wood

2015-01-01

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 × 10 4 to 2 × 10 5 . Measurements were made for angles of attack between 0°...

Generation of statistical scenarios of short-term wind power production

DEFF Research Database (Denmark)

Pinson, Pierre; Papaefthymiou, George; Klockl, Bernd

2007-01-01

Short-term (up to 2-3 days ahead) probabilistic forecasts of wind power provide forecast users with a paramount information on the uncertainty of expected wind generation. Whatever the type of these probabilistic forecasts, they are produced on a per horizon basis, and hence do not inform...... on the development of the forecast uncertainty through forecast series. This issue is addressed here by describing a method that permits to generate statistical scenarios of wind generation that accounts for the interdependence structure of prediction errors, in plus of respecting predictive distributions of wind...

Wind Profiles and Wave Spectra for Potential Wind Farms in South China Sea. Part II: Wave Spectrum Model

Directory of Open Access Journals (Sweden)

Yichao Liu

2017-01-01

Full Text Available Along with the commercialization of offshore wind energy in China, the South China Sea has been identified as ideal for constructing offshore wind farms, especially for farms consisting of floating wind turbines over deep waters. Since the wind profiles and wave spectra are somewhat primitive for the design of an offshore wind turbine, engineering models describing the wind and wave characteristics in the South China Sea area are necessary for the offshore wind energy exploitation given the meteorological, hydrological, and geographical differences between the South China Sea and the North/Norwegian Sea, where the commonly used wind profile and wave spectrum models were designated. In the present study; a series of numerical simulations were conducted to reveal the wave characteristics in the South China Sea under both typhoon and non-typhoon conditions. By analyzing the simulation results; the applicability of the Joint North Sea Wave Project (JONSWAP spectrum model; in terms of characterizing the wind-induced wave fields in the South China Sea; was discussed. In detail; the key parameters of the JONSWAP spectrum model; such as the Phillips constant; spectral width parameter; peak-enhancement factor, and high frequency tail decay; were investigated in the context of finding suitable values.

Homogenization of Tianjin monthly near-surface wind speed using RHtestsV4 for 1951-2014

Science.gov (United States)

Si, Peng; Luo, Chuanjun; Liang, Dongpo

2018-05-01

Historical Chinese surface meteorological records provided by the special fund for basic meteorological data from the National Meteorological Information Center (NMIC) were processed to produce accurate wind speed data. Monthly 2-min near-surface wind speeds from 13 observation stations in Tianjin covering 1951-2014 were homogenized using RHtestV4 combined with their metadata. Results indicate that 10 stations had significant breakpoints—77% of the Tianjin stations—suggesting that inhomogeneity was common in the Tianjin wind speed series. Instrument change accounted for most changes, based on the metadata, including changes in type and height, especially for the instrument type. Average positive quantile matching (QM) adjustments were more than negative adjustments at 10 stations; positive biases with a probability density of 0.2 or more were mainly concentrates in the range 0.2 m s-1 to 1.2 m s-1, while the corresponding negative biases were mainly in the range -0.1 to -1.2 m s-1. Here, changes in variances and trends in the monthly mean surface wind speed series at 10 stations before and after adjustment were compared. Climate characteristics of wind speed in Tianjin were more reasonably reflected by the adjusted data; inhomogeneity in wind speed series was largely corrected. Moreover, error analysis reveals that there was a high consistency between the two datasets here and that from the NMIC, with the latter as the reference. The adjusted monthly near-surface wind speed series shows a certain reliability for the period 1951-2014 in Tianjin.

Incorporation of a Wind Generator Model into a Dynamic Power Flow Analysis

Directory of Open Access Journals (Sweden)

Angeles-Camacho C.

2011-07-01

Full Text Available Wind energy is nowadays one of the most cost-effective and practical options for electric generation from renewable resources. However, increased penetration of wind generation causes the power networks to be more depend on, and vulnerable to, the varying wind speed. Modeling is a tool which can provide valuable information about the interaction between wind farms and the power network to which they are connected. This paper develops a realistic characterization of a wind generator. The wind generator model is incorporated into an algorithm to investigate its contribution to the stability of the power network in the time domain. The tool obtained is termed dynamic power flow. The wind generator model takes on account the wind speed and the reactive power consumption by induction generators. Dynamic power flow analysis is carried-out using real wind data at 10-minute time intervals collected for one meteorological station. The generation injected at one point into the network provides active power locally and is found to reduce global power losses. However, the power supplied is time-varying and causes fluctuations in voltage magnitude and power fl ows in transmission lines.

Measuring tropospheric wind with microwave sounders

Science.gov (United States)

Lambrigtsen, B.; Su, H.; Turk, J.; Hristova-Veleva, S. M.; Dang, V. T.

2017-12-01

In its 2007 "Decadal Survey" of earth science missions for NASA the U.S. National Research Council recommended that a Doppler wind lidar be developed for a three-dimensional tropospheric winds mission ("3D-Winds"). The technology required for such a mission has not yet been developed, and it is expected that the next Decadal Survey, planned to be released by the end of 2017, will put additional emphasis on the still pressing need for wind measurements from space. The first Decadal Survey also called for a geostationary microwave sounder (GMS) on a Precipitation and All-weather Temperature and Humidity (PATH) mission, which could be used to measure wind from space. Such a sounder, the Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR), has been developed at the Jet Propulsion Laboratory (JPL). The PATH mission has not yet been funded by NASA, but a low-cost subset of PATH, GeoStorm has been proposed as a hosted payload on a commercial communications satellite. Both PATH and GeoStorm would obtain frequent (every 15 minutes of better) measurements of tropospheric water vapor profiles, and they can be used to derive atmospheric motion vector (AMV) wind profiles, even in the presence of clouds. Measurement of wind is particularly important in the tropics, where the atmosphere is largely not in thermal balance and wind estimates cannot generally be derived from temperature and pressure fields. We report on simulation studies of AMV wind vectors derived from a GMS and from a cluster of low-earth-orbiting (LEO) small satellites (e.g., CubeSats). The results of two separate simulation studies are very encouraging and show that a ±2 m/s wind speed precision is attainable, which would satisfy WMO requirements. A GMS observing system in particular, which can be implemented now, would enable significant progress in the study of atmospheric dynamics. Copyright 2017 California Institute of Technology. Government sponsorship acknowledged

The first installation of the WindWall in the Netherlands; Eerste WindWall in Nederland geplaatst

Energy Technology Data Exchange (ETDEWEB)

Ten Bolscher, G.H.; Vander Heide, H. [DWA Installatie- en energieadvies, Bodegraven (Netherlands)

2004-02-01

This article is the first in a series of four on the experiment with the WindWall, a wind turbine on the roof of a school building in Zwolle, Netherlands. The experiment started September 5, 2003. [Dutch] Door diverse marktpartijen worden momenteel kleinere, voor de gebouwde omgeving geschikte windturbines ontwikkeld, die de negatieve eigenschappen van grote windturbines (waarschijnlijk) niet hebben. Hierbij gaat het om eigenschappen als geluidsbelasting, beschaduwing, zichtbare aanwezigheid en visuele vervuiling van het vrije landschap. Op 11 juli 2003 is de eerste WindWall, een 'liggende' windturbine, geplaatst op het dak van het Deltion college in Zwolle in het kader van een praktijkexperiment, dat gesubsidieerd wordt door de Provincie Overijssel. Op 5 september 2003 is het systeern officieel in gebruik genomen.

Multi-decadal Variability of the Wind Power Output

Science.gov (United States)

Kirchner Bossi, Nicolas; García-Herrera, Ricardo; Prieto, Luis; Trigo, Ricardo M.

2014-05-01

The knowledge of the long-term wind power variability is essential to provide a realistic outlook on the power output during the lifetime of a planned wind power project. In this work, the Power Output (Po) of a market wind turbine is simulated with a daily resolution for the period 1871-2009 at two different locations in Spain, one at the Central Iberian Plateau and another at the Gibraltar Strait Area. This is attained through a statistical downscaling of the daily wind conditions. It implements a Greedy Algorithm as classificator of a geostrophic-based wind predictor, which is derived by considering the SLP daily field from the 56 ensemble members of the longest homogeneous reanalysis available (20CR, 1871-2009). For calibration and validation purposes we use 10 years of wind observations (the predictand) at both sites. As a result, a series of 139 annual wind speed Probability Density Functions (PDF) are obtained, with a good performance in terms of wind speed uncertainty reduction (average daily wind speed MAE=1.48 m/s). The obtained centennial series allow to investigate the multi-decadal variability of wind power from different points of view. Significant periodicities around the 25-yr frequency band, as well as long-term linear trends are detected at both locations. In addition, a negative correlation is found between annual Po at both locations, evidencing the differences in the dynamical mechanisms ruling them (and possible complementary behavior). Furthermore, the impact that the three leading large-scale circulation patterns over Iberia (NAO, EA and SCAND) exert over wind power output is evaluated. Results show distinct (and non-stationary) couplings to these forcings depending on the geographical position and season or month. Moreover, significant non-stationary correlations are observed with the slow varying Atlantic Multidecadal Oscillation (AMO) index for both case studies. Finally, an empirical relationship is explored between the annual Po and the

Fundamentals for remote structural health monitoring of wind turbine blades - a pre-project. Annex D - Full-scale test of wind turbine blade, using sensors and NDT

Energy Technology Data Exchange (ETDEWEB)

Kristensen, O.J.D.; McGugan, M.; Sendrup, P.; Rheinlaender, J.; Rusborg, J.; Hansen, A.M.; Debel, C.P.; Soerensen, B.F.

2002-05-01

A 19.1 metre wind turbine blade was subjected to static tests. The purpose of the test series was to verify the abilities of different types of sensors to detect damage in wind turbine blades. Prior to each of the static test-series an artificial damage was made on the blade. The damage made for each test-series was surveyed during each series by acoustic emission, fiber optic micro bend displacement transducers and strain gauges. The propagation of the damage was determined by use of ultra sonic and X-ray surveillance during stops in the test series. By use of acoustic emission it was possible to measure damage propagation before the propagation was of visible size. By use of fiber optic micro bend displacement transducers and strain gauges it was possible to measure minor damage propagation. By use of both ultra sonic, and X-ray NDT-equipment it were possible to determine the size of propagated damage. (au)

Comparison of five-minute radon-daughter measurements with long-term radon and radon-daughter concentrations

International Nuclear Information System (INIS)

Young, J.A.; Jackson, P.O.; Thomas, V.W.

1983-01-01

Five-minute air filter radon daughter measurements were made in 84 buildings in Edgemont, South Dakota, in which annual average radon daughter concentrations have been determined from six 100-hour Radon Progeny Integrating Sampling Unit (RPISU) measurements. Averaging radon concentrations were also determined in 50 of these buildings using Terradex Track Etch detectors. The standard deviation of the difference between the (natural) logarithms of the RPISU annual averages and the logarithms of the air filter measurements (SD-ln) was found to be 0.52. This SD-ln is considerably smaller than the SD-ln of 0.71 between the RPISU annual averages and the air filter measurements reported by ALARA at Grand Junction, Colorado; presumably because a considerable number of air filter measurements in Edgemont were disregarded because of short turnover times or high wind speeds. Using the SD-ln of 0.52 it can be calculated that there would only be a 5% probability in Edgemont that the RPISU annual average would be greater than 0.015 WL if the five-minute measurement were equal to 0.010 WL. This indicates that the procedure used in Edgemont of clearing buildings from remedial action if the five-minute measurement were less than 0.010 WL was reasonable. There was about a 28% probability that the RPISU annual average would be less than 0.015 WL if the five-minute measurement were 0.033 WL, indicating that the procedure of performing an engineering assessment if the average of two five-minute measurements was greater than 0.033 WL was also reasonable. Comparison indicates that the average of two RPISU measurements taken six months apart would provide a dependable estimate of the annual average

Correlation and multifractality in climatological time series

International Nuclear Information System (INIS)

Pedron, I T

2010-01-01

Climate can be described by statistical analysis of mean values of atmospheric variables over a period. It is possible to detect correlations in climatological time series and to classify its behavior. In this work the Hurst exponent, which can characterize correlation and persistence in time series, is obtained by using the Detrended Fluctuation Analysis (DFA) method. Data series of temperature, precipitation, humidity, solar radiation, wind speed, maximum squall, atmospheric pressure and randomic series are studied. Furthermore, the multifractality of such series is analyzed applying the Multifractal Detrended Fluctuation Analysis (MF-DFA) method. The results indicate presence of correlation (persistent character) in all climatological series and multifractality as well. A larger set of data, and longer, could provide better results indicating the universality of the exponents.

Correlation of mesoscale wind speeds over the sea

DEFF Research Database (Denmark)

Mehrens, Anna R.; Hahmann, Andrea N.; Hahmann, Andrea N.

2016-01-01

A large offshore observational data set from stations across the North and Baltic Sea is used to investigate the planetary boundary layer wind characteristics and their coherence, correlation and power spectra. The data of thirteen sites, with pairs of sites at a horizontal distance of 4 to 848 km...... on measurements and the WRF-derived time series. By normalising the frequency axes with the distance and mean wind speed it can be demonstrated that even for data with a wide range of distances, the coherence is a function of the frequency, mean wind and distance, which is consistent with earlier studies....... The correlation coefficient as a function of the distance calculated from WRF is however higher than observed in the measurements. For the power spectra, wind speed and wind speed step changes distribution the results for all sites are quite similar. The land masses strongly influence the individual wind...

Scaling properties of Polish rain series

Science.gov (United States)

Licznar, P.

2009-04-01

Scaling properties as well as multifractal nature of precipitation time series have not been studied for local Polish conditions until recently due to lack of long series of high-resolution data. The first Polish study of precipitation time series scaling phenomena was made on the base of pluviograph data from the Wroclaw University of Environmental and Life Sciences meteorological station located at the south-western part of the country. The 38 annual rainfall records from years 1962-2004 were converted into digital format and transformed into a standard format of 5-minute time series. The scaling properties and multifractal character of this material were studied by means of several different techniques: power spectral density analysis, functional box-counting, probability distribution/multiple scaling and trace moment methods. The result proved the general scaling character of time series at the range of time scales ranging form 5 minutes up to at least 24 hours. At the same time some characteristic breaks at scaling behavior were recognized. It is believed that the breaks were artificial and arising from the pluviograph rain gauge measuring precision limitations. Especially strong limitations at the precision of low-intensity precipitations recording by pluviograph rain gauge were found to be the main reason for artificial break at energy spectra, as was reported by other authors before. The analysis of co-dimension and moments scaling functions showed the signs of the first-order multifractal phase transition. Such behavior is typical for dressed multifractal processes that are observed by spatial or temporal averaging on scales larger than the inner-scale of those processes. The fractal dimension of rainfall process support derived from codimension and moments scaling functions geometry analysis was found to be 0.45. The same fractal dimension estimated by means of the functional box-counting method was equal to 0.58. At the final part of the study

ANALYSIS OF FACTORS AFFECTING WIND-ENERGY POTENTIAL IN LOW BUILT-UP URBAN ENVIRONMENTS

Directory of Open Access Journals (Sweden)

LÁZÁR I.

2014-03-01

Full Text Available his study is concerned with the examination of roughness factor affecting wind potential in low built-up urban areas (e.g. subdivision, light industrial area. The test interval is the transition between summer and winter, as a secondary wind maximum period. The ten-minute data-pairs empirical distribution was approached by several theoretical distributions where a fitting test research was also performed. Extrapolation to higher levels is possible by defining the Hellmann exponent. The wind speed in respective height and the specific wind power are derived from it. Knowing the daily progress of the Hellmann exponent value, more accurate estimation can be given of the wind potential calculated to different heights according to the measuring point. The results were compared to the surface cover of the surrounding area as well as to the literary alpha values.

Wind-wave modelling aspects within complicate topography

Directory of Open Access Journals (Sweden)

S. Christopoulos

Full Text Available Wave forecasting aspects for basins with complicate geomorphology, such as the Aegean Sea, are investigated through an intercomparison study. The efficiency of the available wind models (ECMWF, UKMO to reproduce wind patterns over special basins, as well as three wave models incorporating different physics and characteristics (WAM, AUT, WACCAS, are tested for selected storm cases representing the typical wind situations over the basin. From the wave results, discussed in terms of time-series and statistical parameters, the crucial role is pointed out of the wind resolution and the reliability of the different wave models to estimate the wave climate in such a basin. The necessary grid resolution is also tested, while for a specific test case (December 1991 ERS-1 satellite data are compared with those of the model.

Reduction of wind power induced reserve requirements by advanced shortest-term forecasts and prediction intervals

Energy Technology Data Exchange (ETDEWEB)

Dobschinski, Jan; Wessel, Arne; Lange, Bernhard; Bremen, Lueder von [Fraunhofer Institut fuer Windenergie und Energiesystemtechnik (IWES), Kassel (Germany)

2009-07-01

In electricity systems with large penetration of wind power, the limited predictability of the wind power generation leads to an increase in reserve and balancing requirements. At first the present study concentrates on the capability of dynamic day-ahead prediction intervals to reduce the wind power induced reserve and balancing requirements. Alternatively the reduction of large forecast errors of the German wind power generation by using advanced shortest-term predictions has been evaluated in a second approach. With focus on the allocation of minute reserve power the aim is to estimate the maximal remaining uncertainty after trading activities on the intraday market. Finally both approaches were used in a case study concerning the reserve requirements induced by the total German wind power expansion in 2007. (orig.)

Mapping wind erosion hazard in Australia using MODIS-derived ground cover, soil moisture and climate data

International Nuclear Information System (INIS)

Yang, X; Leys, J

2014-01-01

This paper describes spatial modeling methods to identify wind erosion hazard (WEH) areas across Australia using the recently available time-series products of satellite-derived ground cover, soil moisture and wind speed. We implemented the approach and data sets in a geographic information system to produce WEH maps for Australia at 500 m ground resolution on a monthly basis for the recent thirteen year period (2000–2012). These maps reveal the significant wind erosion hazard areas and their dynamic tendencies at paddock and regional scales. Dust measurements from the DustWatch network were used to validate the model and interpret the dust source areas. The modeled hazard areas and changes were compared with results from a rule-set approach and the Computational Environmental Management System (CEMSYS) model. The study demonstrates that the time series products of ground cover, soil moisture and wind speed can be jointly used to identify landscape erodibility and to map seasonal changes of wind erosion hazard across Australia. The time series wind erosion hazard maps provide detailed and useful information to assist in better targeting areas for investments and continuous monitoring, evaluation and reporting that will lead to reduced wind erosion and improved soil condition

RSA/Legacy Wind Sensor Comparison. Part 1; Western Range

Science.gov (United States)

Short, David A.; Wheeler, Mark M.

2006-01-01

This report describes a comparison of data from ultrasonic and cup-and-vane anemometers on 5 wind towers at Vandenberg AFB. The ultrasonic sensors are scheduled to replace the Legacy cup-and-vane sensors under the Range Standardization and Automation (RSA) program. Because previous studies have noted differences between peak wind speeds reported by mechanical and ultrasonic wind sensors, the latter having no moving parts, the 30th and 45th Weather Squadrons wanted to understand possible differences between the two sensor types. The period-of-record was 13-30 May 2005. A total of 153,961 readings of I-minute average and peak wind speed/direction from each sensor type were used. Statistics of differences in speed and direction were used to identify 18 out of 34 RSA sensors having the most consistent performance, with respect to the Legacy sensors. Data from these 18 were used to form a composite comparison. A small positive bias in the composite RSA average wind speed increased from +0.5 kts at 15 kts, to +1 kt at 25 kts. A slightly larger positive bias in the RSA peak wind speed increased from +1 kt at 15 kts, to +2 kts at 30 kts.

German offshore wind turbine farms - status and prospective

International Nuclear Information System (INIS)

2004-08-01

As a consequence of Germany's forthcoming phase-out of nuclear power the German government has initiated a number of activities in order to further development of renewable energy in the future. Offshore wind power has been chosen to play a central part. Although the first wind turbine has yet to be erected in German waters there is no doubt that it is a matter of time before the growing German market will gather speed. The objective of this report is to provide Danish business enterprises with interests in wind power with an insight into the German offshore wind power market and the export possibilities of the present and in the near future. As introduction the report lists the general outlines for construction and operation of wind turbine farms in Germany, furthermore, a number of additional conditions that Danish business enterprises should be aware of are listed. The introduction is followed by an up-to-the -minute status account of all ongoing projects. This part of the report has been made on the basis of a questionnaire send out by the Danish Embassy to project leaders in the business enterprises behind the project planning. Finally, the report provides an overview of all partners behind the planned wind farms. The overview contains contact information as well as information about the composition of project companies and consortiums. (BA)

Taylor Law in Wind Energy Data

Directory of Open Access Journals (Sweden)

Rudy Calif

2015-10-01

Full Text Available The Taylor power law (or temporal fluctuation scaling, is a scaling relationship of the form σ ~  (Pλ where !! is the standard deviation and hPi the mean value of a sample of a time series has been observed for power output data sampled at 5 min and 1 s and from five wind farms and a single wind turbine, located at different places. Furthermore, an analogy with the turbulence field is performed, consequently allowing the establishment of a scaling relationship between the turbulent production IP and the mean value (P.

French enterprises build on wind power

International Nuclear Information System (INIS)

Rap, C.

2013-01-01

Being confronted by the economic crisis French enterprises look for diversification towards sectors which appear to bear promise of growth. The wind industry is one of them despite the slowing demand for land-based installations. A wind turbine is made of 11 components which represents a total of 3000 parts. A series of French enterprises benefit from this market by specialising in narrow market niches like bearings, toothed wheels,... This document gathers short information notes on the following enterprises: SKF, Mersen, les Forges de Trie-Chateau, Guerton, Rollix, and NTN-SNR. (A.C.)

High power, medium voltage, series resonant converter for DC wind turbines

DEFF Research Database (Denmark)

Dincan, Catalin Gabriel; Kjær, Philip Carne; Chen, Yu-Hsing

2018-01-01

, and the resulting compact and efficient transformer, and soft-commutated inverter, present particular advantages in high-power, high-voltage applications, like DC offshore wind turbines. With transformer excitation frequency in hundreds of Hz range, line-frequency diodes can be employed in the high...

Statistical Modeling of Large Wind Plant System's Generation - A Case Study

International Nuclear Information System (INIS)

Sabolic, D.

2014-01-01

This paper presents simplistic, yet very accurate, descriptive statistical models of various static and dynamic parameters of energy output from a large system of wind plants operated by Bonneville Power Administration (BPA), USA. The system's size at the end of 2013 was 4515 MW of installed capacity. The 5-minute readings from the beginning of 2007 to the end of 2013, recorded and published by BPA, were used to derive a number of experimental distributions, which were then used to devise theoretic statistical models with merely one or two parameters. In spite of the simplicity, they reproduced experimental data with great accuracy, which was checked by rigorous tests of goodness-of-fit. Statistical distribution functions were obtained for the following wind generation-related quantities: total generation as percentage of total installed capacity; change in total generation power in 5, 10, 15, 20, 25, 30, 45, and 60 minutes as percentage of total installed capacity; duration of intervals with total generated power, expressed as percentage of total installed capacity, lower than certain pre-specified level. Limitation of total installed wind plant capacity, when it is determined by regulation demand from wind plants, is discussed, too. The models presented here can be utilized in analyses related to power system economics/policy, which is also briefly discussed in the paper. (author).

Improved Wind Speed Prediction Using Empirical Mode Decomposition

Directory of Open Access Journals (Sweden)

ZHANG, Y.

2018-05-01

Full Text Available Wind power industry plays an important role in promoting the development of low-carbon economic and energy transformation in the world. However, the randomness and volatility of wind speed series restrict the healthy development of the wind power industry. Accurate wind speed prediction is the key to realize the stability of wind power integration and to guarantee the safe operation of the power system. In this paper, combined with the Empirical Mode Decomposition (EMD, the Radial Basis Function Neural Network (RBF and the Least Square Support Vector Machine (SVM, an improved wind speed prediction model based on Empirical Mode Decomposition (EMD-RBF-LS-SVM is proposed. The prediction result indicates that compared with the traditional prediction model (RBF, LS-SVM, the EMD-RBF-LS-SVM model can weaken the random fluctuation to a certain extent and improve the short-term accuracy of wind speed prediction significantly. In a word, this research will significantly reduce the impact of wind power instability on the power grid, ensure the power grid supply and demand balance, reduce the operating costs in the grid-connected systems, and enhance the market competitiveness of the wind power.

Wind Alliance for the Sustainable Development

Energy Technology Data Exchange (ETDEWEB)

Camacho, Damarys Gonzalez [Puerto Rico Energy Affairs Administration, San Juan (Puerto Rico). Executive Office of the Commonwealth of Puerto Rico

2012-09-30

The Puerto Rico Energy Affairs Administration (PREAA) is actively engaged in the implementation of existing public policy for the conservation of energy and promotion of renewable energy to reduce consumer’s costs and reduce environmental impact. Puerto Rico is an island in where no own reserves of gas, oil or coal exists. This severe dependence in on foreign oil is reflected in the higher cost of electricity in Puerto Rico, which is significantly higher than most of the United States. Therefore, public energy policy of Puerto Rico places emphasis on diversification of energy sources and the use of renewable energy technologies. The Wind energy Alliance for the Sustainable Development project focused on the formation of a wind energy working group to educate and promote wind energy technologies; at the same time the evaluating the viability of wind energy in Puerto Rico. The educational outreach was performed through a series of wind energy workshops where interested parties such as, installers, sellers, engineers, general public even opposing groups participate from the activities.

Development of Self-Powered Wireless Structural Health Monitoring (SHM) for Wind Turbine Blades

Science.gov (United States)

Lim, Dong-Won

Wind turbine blade failure can lead to unexpected power interruptions. Monitoring wind turbine blades is important to ensure seamless electricity delivery from power generation to consumers. Structural health monitoring (SHM) enables early recognition of structural problems so that the safety and reliability of operation can be enhanced. This dissertation focuses on the development of a wireless SHM system for wind turbine blades. The sensor is comprised of a piezoelectric energy harvester (EH) and a telemetry unit. The sensor node is mounted on the blade surface. As the blade rotates, the blade flexes, and the energy harvester captures the strain energy on the blade surface. Once sufficient electricity is captured, a pulse is sent from the sensing node to a gateway. Then, a central monitoring algorithm processes a series of pulses received from all three blades. This wireless SHM, which uses commercially available components, can be retrofitted to existing turbines. The harvested energy for sensing can be estimated in terms of two factors: the available strain energy and conversion efficiency. The available strain energy was evaluated using the FAST (Fatigue, Aerodynamics, Structures, and Turbulence) simulator. The conversion efficiency was studied analytically and experimentally. An experimental set-up was designed to mimic the expected strain frequency and amplitude for rotor blades. From a series of experiments, the efficiency of a piezoelectric EH at a typical rotor speed (0.2 Hz) was approximately 0.5%. The power requirement for sending one measurement (280 muJ) can be achieved in 10 minutes. Designing a detection algorithm is challenging due to this low sampling rate. A new sensing approach-the timing of pulses from the transmitter-was introduced. This pulse timing, which is tied to the charging time, is indicative of the structural health. The SHM system exploits the inherent triple redundancy of the three blades. The timing data of the three blades are

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

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 of the mea......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...... of the measurements over a week is taken as input to stochastic load extrapolation whereby the one year extrapolated design extreme is obtained, which are then compared with the maximum extremes obtained from direct measurements over a six month period to validate the magnification in the load levels for the blade...... 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...

On the Response of Interleaved Transformer Windings to Surge Voltages

DEFF Research Database (Denmark)

Pedersen, A.

1963-01-01

The high series capacitance theory for the response of interleaved transformer windings to surge voltages is criticized from the point of view that an increased series capacitance as a result of interleaving is incompatible with the concept of a pure capacitive initial voltage distribution. A new...

Assessment of the National Wind Coordinating Collaborative: Addressing Environmental and Siting Issues Associated with Wind Energy Development

Energy Technology Data Exchange (ETDEWEB)

Van Cleve, Frances B.; States, Jennifer C.

2010-11-09

The National Wind Coordinating Collaborative (NWCC) is a consensus-based stakeholder group comprised of representatives from the utility, wind industry, environmental, consumer, regulatory, power marketer, agricultural, tribal, economic development, and state and federal government sectors. The purpose of the NWCC is to support the development of an environmentally, economically, and politically sustainable commercial market for wind power (NWCC 2010). The NWCC has been funded by the U.S. Department of Energy (DOE) since its inception in 1994. In order to evaluate the impact of the work of the NWCC and how this work aligns with DOE’s strategic priorities, DOE tasked Pacific Northwest National Laboratory (PNNL) to conduct a series of informal interviews with a small sample of those involved with NWCC.

Developing a Local Neurofuzzy Model for Short-Term Wind Power Forecasting

Directory of Open Access Journals (Sweden)

E. Faghihnia

2014-01-01

Full Text Available Large scale integration of wind generation capacity into power systems introduces operational challenges due to wind power uncertainty and variability. Therefore, accurate wind power forecast is important for reliable and economic operation of the power systems. Complexities and nonlinearities exhibited by wind power time series necessitate use of elaborative and sophisticated approaches for wind power forecasting. In this paper, a local neurofuzzy (LNF approach, trained by the polynomial model tree (POLYMOT learning algorithm, is proposed for short-term wind power forecasting. The LNF approach is constructed based on the contribution of local polynomial models which can efficiently model wind power generation. Data from Sotavento wind farm in Spain was used to validate the proposed LNF approach. Comparison between performance of the proposed approach and several recently published approaches illustrates capability of the LNF model for accurate wind power forecasting.

Database on wind characteristics - Structure and philosophy

Energy Technology Data Exchange (ETDEWEB)

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

2001-11-01

The main objective of IEA R and D Wind Annex XVII - Database on Wind Characteristics - is to provide wind energy planners and designers, as well as the international wind engineering community in general, with easy access to quality controlled measured wind field time series observed in a wide range of environments. The project partners are Sweden, Norway, U.S.A., The Netherlands, Japan and Denmark, with Denmark as the Operating Agent. The reporting of IEA R and D Annex XVII falls in three separate parts. Part one deals with the overall structure and philosophy behind the database, part two accounts in details for the available data in the established database bank and part three is the Users Manual describing the various ways to access and analyse the data. The present report constitutes the first part of the Annex XVII reporting, and it contains a detailed description of the database structure, the data quality control procedures, the selected indexing of the data and the hardware system. (au)

Who should own the nearshore wind turbines?

DEFF Research Database (Denmark)

Jensen, Louise Krog; Sperling, Karl

This report examines the possibility for non-profit organisations to participate in tenders for nearshore wind turbines in Denmark under the current frame-work conditions in the area. The point of departure is a case study of the non-profit organisation Wind People’s attempt to participate...... with a popular project in the Danish tender for 350 MW nearshore wind turbines. A series of in-depth interviews have been carried out with Wind People’s staff in order to make an in-depth analysis of their actions and experiences of entering into the market for nearshore wind turbines. The report concludes...... the way for non-profit organisations to be able to enter the market, however, as the study shows that the established actors in the market also have a large influence on who is allowed to enter the market. The results of the report are a number of recommendations to the Danish politicians and the Danish...

Lake Michigan Wind Assessment Analysis, 2012 and 2013

Directory of Open Access Journals (Sweden)

Charles R Standridge

2017-03-01

Full Text Available A study was conducted to address the wind energy potential over Lake Michigan to support a commercial wind farm.  Lake Michigan is an inland sea in the upper mid-western United States.  A laser wind sensor mounted on a floating platform was located at the mid-lake plateau in 2012 and about 10.5 kilometers from the eastern shoreline near Muskegon Michigan in 2013.  Range gate heights for the laser wind sensor were centered at 75, 90, 105, 125, 150, and 175 meters.  Wind speed and direction were measured once each second and aggregated into 10 minute averages.  The two sample t-test and the paired-t method were used to perform the analysis.  Average wind speed stopped increasing between 105 m and 150 m depending on location.  Thus, the collected data is inconsistent with the idea that average wind speed increases with height. This result implies that measuring wind speed at wind turbine hub height is essential as opposed to using the wind energy power law to project the wind speed from lower heights.  Average speed at the mid-lake plateau is no more that 10% greater than at the location near Muskegon.  Thus, it may be possible to harvest much of the available wind energy at a lower height and closer to the shoreline than previously thought.  At both locations, the predominate wind direction is from the south-southwest.  The ability of the laser wind sensor to measure wind speed appears to be affected by a lack of particulate matter at greater heights.   Keywords: wind assessment, Lake Michigan, LIDAR wind sensor, statistical analysis. Article History: Received June 15th 2016; Received in revised form January 16th 2017; Accepted February 2nd 2017 Available online How to Cite This Article: Standridge, C., Zeitler, D., Clark, A., Spoelma, T., Nordman, E., Boezaart, T.A., Edmonson, J.,  Howe, G., Meadows, G., Cotel, A. and Marsik, F. (2017 Lake Michigan Wind Assessment Analysis, 2012 and 2013. Int. Journal of Renewable Energy Development

Safety standards for wind turbines; Sicherheitsnormen fuer Windenergieanlagen

Energy Technology Data Exchange (ETDEWEB)

Boyce, K. [Underwriters Laboratories Inc., Northbrook, IL (United States)

2012-08-15

As the global wind infrastructure sustains rapid growth, compliance with relevant standards provide validation of design principles and establish due diligence in addressing critical attributes such as safety. The IEC 61400 series of standards provides important information for addressing safety and performance of wind turbine systems. Efforts to address unique issues within the United States market has led to development of two safety standards, UL 6141 for large wind turbines and UL 6142 for small wind turbines. These standards, which are being published as American National Standards, contain key safety requirements for the electrical system, electrical safety and controls system, grid connection, and related safety issues. In the future, collaborative efforts will lead to continued exchange of best practices and opportunities for broader harmonization. Development of these standards, and their use by the manufacturing community in design and development of wind turbine products, supports maximal safety and performance of the burgeoning wind infrastructure. (orig.)

Winding design of series AC inductor for dual active bridge converters

DEFF Research Database (Denmark)

Shen, Zhan; Wang, Huai; Shen, Yanfeng

2018-01-01

The ac resistance and parasitic capacitance of the inductor are the primary considerations in the winding design for the dual-active bridge converter (DAB). They are dependent of up to four independent structure variables. The interactive restrictions between those variables makes the design diff...

A methodology to generate statistically dependent wind speed scenarios

Energy Technology Data Exchange (ETDEWEB)

Morales, J.M.; Conejo, A.J. [Department of Electrical Engineering, Univ. Castilla - La Mancha, Campus Universitario s/n, 13071 Ciudad Real (Spain); Minguez, R. [Environmental Hydraulics Institute ' ' IH Cantabria' ' , Univ. Cantabria, Avenida de los Castros s/n, 39005 Santander (Spain)

2010-03-15

Wind power - a renewable energy source increasingly attractive from an economic viewpoint - constitutes an electricity production alternative of growing relevance in current electric energy systems. However, wind power is an intermittent source that cannot be dispatched at the will of the producer. Modeling wind power production requires characterizing wind speed at the sites where the wind farms are located. The wind speed at a particular location can be described through a stochastic process that is spatially correlated with the stochastic processes describing wind speeds at other locations. This paper provides a methodology to characterize the stochastic processes pertaining to wind speed at different geographical locations via scenarios. Each one of these scenarios embodies time dependencies and is spatially dependent of the scenarios describing other wind stochastic processes. The scenarios generated by the proposed methodology are intended to be used within stochastic programming decision models to make informed decisions pertaining to wind power production. The methodology proposed is accurate in reproducing wind speed historical series as well as computationally efficient. A comprehensive case study is used to illustrate the capabilities of the proposed methodology. Appropriate conclusions are finally drawn. (author)

A methodology to generate statistically dependent wind speed scenarios

International Nuclear Information System (INIS)

Morales, J.M.; Minguez, R.; Conejo, A.J.

2010-01-01

Wind power - a renewable energy source increasingly attractive from an economic viewpoint - constitutes an electricity production alternative of growing relevance in current electric energy systems. However, wind power is an intermittent source that cannot be dispatched at the will of the producer. Modeling wind power production requires characterizing wind speed at the sites where the wind farms are located. The wind speed at a particular location can be described through a stochastic process that is spatially correlated with the stochastic processes describing wind speeds at other locations. This paper provides a methodology to characterize the stochastic processes pertaining to wind speed at different geographical locations via scenarios. Each one of these scenarios embodies time dependencies and is spatially dependent of the scenarios describing other wind stochastic processes. The scenarios generated by the proposed methodology are intended to be used within stochastic programming decision models to make informed decisions pertaining to wind power production. The methodology proposed is accurate in reproducing wind speed historical series as well as computationally efficient. A comprehensive case study is used to illustrate the capabilities of the proposed methodology. Appropriate conclusions are finally drawn.

Deterministic prediction of surface wind speed variations

Directory of Open Access Journals (Sweden)

G. V. Drisya

2014-11-01

Full Text Available Accurate prediction of wind speed is an important aspect of various tasks related to wind energy management such as wind turbine predictive control and wind power scheduling. The most typical characteristic of wind speed data is its persistent temporal variations. Most of the techniques reported in the literature for prediction of wind speed and power are based on statistical methods or probabilistic distribution of wind speed data. In this paper we demonstrate that deterministic forecasting methods can make accurate short-term predictions of wind speed using past data, at locations where the wind dynamics exhibit chaotic behaviour. The predictions are remarkably accurate up to 1 h with a normalised RMSE (root mean square error of less than 0.02 and reasonably accurate up to 3 h with an error of less than 0.06. Repeated application of these methods at 234 different geographical locations for predicting wind speeds at 30-day intervals for 3 years reveals that the accuracy of prediction is more or less the same across all locations and time periods. Comparison of the results with f-ARIMA model predictions shows that the deterministic models with suitable parameters are capable of returning improved prediction accuracy and capturing the dynamical variations of the actual time series more faithfully. These methods are simple and computationally efficient and require only records of past data for making short-term wind speed forecasts within practically tolerable margin of errors.

On practical challenges of decomposition-based hybrid forecasting algorithms for wind speed and solar irradiation

International Nuclear Information System (INIS)

Wang, Yamin; Wu, Lei

2016-01-01

This paper presents a comprehensive analysis on practical challenges of empirical mode decomposition (EMD) based algorithms on wind speed and solar irradiation forecasts that have been largely neglected in literature, and proposes an alternative approach to mitigate such challenges. Specifically, the challenges are: (1) Decomposed sub-series are very sensitive to the original time series data. That is, sub-series of the new time series, consisting of the original one plus a limit number of new data samples, may significantly differ from those used in training forecasting models. In turn, forecasting models established by original sub-series may not be suitable for newly decomposed sub-series and have to be trained more frequently; and (2) Key environmental factors usually play a critical role in non-decomposition based methods for forecasting wind speed and solar irradiation. However, it is difficult to incorporate such critical environmental factors into forecasting models of individual decomposed sub-series, because the correlation between the original data and environmental factors is lost after decomposition. Numerical case studies on wind speed and solar irradiation forecasting show that the performance of existing EMD-based forecasting methods could be worse than the non-decomposition based forecasting model, and are not effective in practical cases. Finally, the approximated forecasting model based on EMD is proposed to mitigate the challenges and achieve better forecasting results than existing EMD-based forecasting algorithms and the non-decomposition based forecasting models on practical wind speed and solar irradiation forecasting cases. - Highlights: • Two challenges of existing EMD-based forecasting methods are discussed. • Significant changes of sub-series in each step of the rolling forecast procedure. • Difficulties in incorporating environmental factors into sub-series forecasting models. • The approximated forecasting method is proposed to

Planning your first wind power project. A primer for utilities: Everything you need to know to bring your first wind power plant on-line

International Nuclear Information System (INIS)

Conover, K.; Davis, E.

1994-12-01

This primer has been prepared to help utility personnel become familiar with some or the details relative to wind power technology and project development. It is written as a series of relatively independent chapters to address specific topics or phases of wind power evaluation and development as they might occur within a utility. The topics include: wind prospecting and the first pass analysis, resource validation, project feasibility, resource planning and evaluation, resource acquisition, project development, equipment selection, project design and construction, and plant operation and maintenance

100-kW hingeless metal wind turbine blade design, analysis and fabrication

Science.gov (United States)

Donham, R. E.; Schmidt, J.; Linscott, B. S.

1975-01-01

The design, fabrication and analysis of aluminum wind turbine rotor blades is discussed. The blades are designed to meet criteria established for a 100-kilowatt wind turbine generator operating between 8 and 60-mile-per-hour speeds at 40 revolutions per minute. The design wind speed is 18 miles per hour. Two rotor blades are used on a new facility which includes a hingeless hub and its shaft, gearbox, generator and tower. Experience shows that, for stopped rotors, safe wind speeds are strongly dependent on blade torsional and bending rigidities which the basic D spar structural blade design provides. The 0.25-inch-thick nose skin is brake/bump formed to provide the basic 'D' spar structure for the tapered, twisted blades. Adequate margins for flutter and divergence are predicted from the use of existing, correlated stopped rotor and helicopter rotor analysis programs.

2 minute Southcentral Alaska Elevation Grid

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The 2-minute Southcentral Alaska Elevation Grid provides bathymetric data in ASCII raster format of 2-minute resolution in geographic coordinates. This grid is...

Locations and attributes of wind turbines in Colorado, 2011

Science.gov (United States)

Carr, Natasha B.; Diffendorfer, James E.; Fancher, Tammy; Hawkins, Sarah J.; Latysh, Natalie; Leib, Kenneth J.; Matherne, Anne Marie

2013-01-01

This dataset represents an update to U.S. Geological Survey Data Series 597. Locations and attributes of wind turbines in Colorado, 2009 (available at http://pubs.usgs.gov/ds/597/). This updated Colorado wind turbine Data Series provides geospatial data for all 1,204 wind turbines established within the State of Colorado as of September 2011, an increase of 297 wind turbines from 2009. Attributes specific to each turbine include: turbine location, manufacturer and model, rotor diameter, hub height, rotor height, potential megawatt output, land ownership, county, and development status of the wind turbine. Wind energy facility data for each turbine include: facility name, facility power capacity, number of turbines associated with each facility to date, facility developer, facility ownership, and year the facility went online. The locations of turbines are derived from 1-meter true-color aerial photographs produced by the National Agriculture Imagery Program (NAIP); the photographs have a positional accuracy of about ±5 meters. Locations of turbines constructed during or prior to August 2009 are based on August 2009 NAIP imagery and turbine locations constructed after August 2009 were based on September 2011 NAIP imagery. The location of turbines under construction during September 2011 likely will be less accurate than the location of existing turbines. This data series contributes to an Online Interactive Energy Atlas developed by the U.S. Geological Survey (http://my.usgs.gov/eerma/). The Energy Atlas synthesizes data on existing and potential energy development in Colorado and New Mexico and includes additional natural resource data layers. This information may be used by decisionmakers to evaluate and compare the potential benefits and tradeoffs associated with different energy development strategies or scenarios. Interactive maps, downloadable data layers, comprehensive metadata, and decision-support tools also are included in the Energy Atlas. The format of

Wind energy statistics 2011; Vindkraftsstatistik 2011

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-11-01

Wind energy statistics 2011 is the fifth publication in the annual series. The report's focus is on regional distribution, i e the number of plants and installed capacity allocated to counties and municipalities. The publication also reports a division between sea- and land-based plants and the size of wind farms in Sweden in terms of installed capacity. The publication is published in spring in report form and since 2010 statistics on number of plants, installed capacity, and regional distribution semi-annually are also presented on the Swedish Energy Agency's website. The statistics relating to installed capacity, number of wind farms and location in this publication is taken from the electricity certificate system, introduced in May 2003. Thanks to the electricity certificate system there is in principle comprehensive statistics of wind energy which in this publication is presented in different intersections. Statistics related to electricity production is taken from the Swedish Kraftnaets [Swedish national grid's] registry Cesar.

Automatic Classification of Offshore Wind Regimes With Weather Radar Observations

DEFF Research Database (Denmark)

Trombe, Pierre-Julien; Pinson, Pierre; Madsen, Henrik

2014-01-01

Weather radar observations are called to play an important role in offshore wind energy. In particular, they can enable the monitoring of weather conditions in the vicinity of large-scale offshore wind farms and thereby notify the arrival of precipitation systems associated with severe wind...... and amplitude) using reflectivity observations from a single weather radar system. A categorical sequence of most likely wind regimes is estimated from a wind speed time series by combining a Markov-Switching model and a global decoding technique, the Viterbi algorithm. In parallel, attributes of precipitation...... systems are extracted from weather radar images. These attributes describe the global intensity, spatial continuity and motion of precipitation echoes on the images. Finally, a CART classification tree is used to find the broad relationships between precipitation attributes and wind regimes...

Short-Term Wind Speed Forecasting Using Decomposition-Based Neural Networks Combining Abnormal Detection Method

Directory of Open Access Journals (Sweden)

Xuejun Chen

2014-01-01

Full Text Available As one of the most promising renewable resources in electricity generation, wind energy is acknowledged for its significant environmental contributions and economic competitiveness. Because wind fluctuates with strong variation, it is quite difficult to describe the characteristics of wind or to estimate the power output that will be injected into the grid. In particular, short-term wind speed forecasting, an essential support for the regulatory actions and short-term load dispatching planning during the operation of wind farms, is currently regarded as one of the most difficult problems to be solved. This paper contributes to short-term wind speed forecasting by developing two three-stage hybrid approaches; both are combinations of the five-three-Hanning (53H weighted average smoothing method, ensemble empirical mode decomposition (EEMD algorithm, and nonlinear autoregressive (NAR neural networks. The chosen datasets are ten-minute wind speed observations, including twelve samples, and our simulation indicates that the proposed methods perform much better than the traditional ones when addressing short-term wind speed forecasting problems.

Hourly Wind Speed Interval Prediction in Arid Regions

Science.gov (United States)

Chaouch, M.; Ouarda, T.

2013-12-01

The long and extended warm and dry summers, the low rate of rain and humidity are the main factors that explain the increase of electricity consumption in hot arid regions. In such regions, the ventilating and air-conditioning installations, that are typically the most energy-intensive among energy consumption activities, are essential for securing healthy, safe and suitable indoor thermal conditions for building occupants and stored materials. The use of renewable energy resources such as solar and wind represents one of the most relevant solutions to overcome the increase of the electricity demand challenge. In the recent years, wind energy is gaining more importance among the researchers worldwide. Wind energy is intermittent in nature and hence the power system scheduling and dynamic control of wind turbine requires an estimate of wind energy. Accurate forecast of wind speed is a challenging task for the wind energy research field. In fact, due to the large variability of wind speed caused by the unpredictable and dynamic nature of the earth's atmosphere, there are many fluctuations in wind power production. This inherent variability of wind speed is the main cause of the uncertainty observed in wind power generation. Furthermore, producing wind power forecasts might be obtained indirectly by modeling the wind speed series and then transforming the forecasts through a power curve. Wind speed forecasting techniques have received substantial attention recently and several models have been developed. Basically two main approaches have been proposed in the literature: (1) physical models such as Numerical Weather Forecast and (2) statistical models such as Autoregressive integrated moving average (ARIMA) models, Neural Networks. While the initial focus in the literature has been on point forecasts, the need to quantify forecast uncertainty and communicate the risk of extreme ramp events has led to an interest in producing probabilistic forecasts. In short term

Optimization of electrical parameters of windings used in axial flux electrical machines

International Nuclear Information System (INIS)

Uhrik, M.

2012-01-01

This paper deals with shape optimization of windings used in electrical machines with disc type construction. These machines have short axial length what makes them suitable for use in small wind-power turbines or in-wheel traction drives. Disc type construction of stator offers more possibilities for winding arrangements than are available in classical machines with cylindrical construction. To find out the best winding arrangement for the novel disc type machine construction a series of analytical calculations, simulations and experimental measurements were performed. (Authors)

The collection of the main issues for wind farm optimisation in complex terrain

DEFF Research Database (Denmark)

Xu, Chang; Chen, Dandan; Han, Xingxing

2016-01-01

The paper aims at establishing the collection of the main issues for wind farm optimisation in complex terrain. To make wind farm cost effective, this paper briefly analyses the main factors influencing wind farm design in complex terrain and sets up a series of mathematical model that includes...... micro-siting, collector circuits, access roads design for optimization problems. The paper relies on the existing one year wind data in the wind farm area and uses genetic algorithm to optimize the micro-siting problem. After optimization of the turbine layout, single-source shortest path algorithm...

Employing unmanned aerial vehicle to monitor the health condition of wind turbines

Science.gov (United States)

Huang, Yishuo; Chiang, Chih-Hung; Hsu, Keng-Tsang; Cheng, Chia-Chi

2018-04-01

Unmanned aerial vehicle (UAV) can gather the spatial information of huge structures, such as wind turbines, that can be difficult to obtain with traditional approaches. In this paper, the UAV used in the experiments is equipped with high resolution camera and thermal infrared camera. The high resolution camera can provide a series of images with resolution up to 10 Megapixels. Those images can be used to form the 3D model using the digital photogrammetry technique. By comparing the 3D scenes of the same wind turbine at different times, possible displacement of the supporting tower of the wind turbine, caused by ground movement or foundation deterioration may be determined. The recorded thermal images are analyzed by applying the image segmentation methods to the surface temperature distribution. A series of sub-regions are separated by the differences of the surface temperature. The high-resolution optical image and the segmented thermal image are fused such that the surface anomalies are more easily identified for wind turbines.

Database on wind characteristics

Energy Technology Data Exchange (ETDEWEB)

Hoejstrup, J. [Risoe National Lab., Roskilde (Denmark). Dept. of Meterology and Wind Energy; Hansen, K.S. [DTU, Lyngby (Denmark). Fluid Mechanics Section

1996-12-31

Wind data with high temporal resolution exist from a variety of sites, and have been in demand by windturbine designers and wind engineers. Unfortunately it has always been a problem to gain access to a suitable amount of this data, because they are available from many different sources in different formats and with very different levels of documentation and quality control. We are in the process of gaining access to a large amount of this data, checking the quality of the data and putting the data at the disposition of the windturbine designer community through easy Internet access. Online search will use summary statistics calculated for each series to help in the selection of data. The selected data can then be downloaded directly to the user. (Author)

Wind Effects on Retention Time in Highway Ponds

DEFF Research Database (Denmark)

Bentzen, Thomas Ruby; Larsen, Torben; Rasmussen, Michael R.

2007-01-01

is to evaluate the quality of long term simulations based on historical rain series of the pollutant discharges from roads and highways. The idea of this paper is to evaluate the effects of wind on the retention time and compare the retention time for the situation of a spatial uniform wind shear stress...... with the situation of a "real" spatial non-uniform shear stress distribution on the surface of the pond. The result of this paper shows that wind plays a dominant role for the retention time and flow pattern. Furthermore, the results shows that the differences in retention time between the use of uniform and non...

Wind Effects on Retention Time in Highway Ponds

DEFF Research Database (Denmark)

Bentzen, Thomas Ruby; Larsen, Torben; Rasmussen, Michael R.

2008-01-01

is to evaluate the quality of long term simulations based on historical rain series of the pollutant discharges from roads and highways. The idea of this paper is to evaluate the effects of wind on the retention time and compare the retention time for the situation of a spatial uniform wind shear stress...... with the situation of a "real" spatial non-uniform shear stress distribution on the surface of the pond. The result of this paper shows that wind plays a dominant role for the retention time and flow pattern. Furthermore, the results shows that the differences in retention time between the use of uniform and non...

Enhancing Study Motivation and Efficacy among First-year Students Using Minute Papers in the Interdisciplinary Subject of Yakugaku Nyumon.

Science.gov (United States)

Yamaki, Kouya; Ikeda, Koji; Ueda, Kumiko; Habu, Yasushi; Nakayama, Yoshiaki; Takeda, Norihiko; Moriwaki, Kensuke; Wada, Akimori; Koyama, Junko; Kodama, Noriko; Kitagawa, Shuji

2017-01-01

Active learning in higher education is important for learning efficacy and motivation. Accordingly, lectures that integrate strategies toward active learning, such as minute papers, debates, and collaborative learning, have become widely adopted. Minute papers facilitate communication among both teachers and students, and can be used as a tool for reviewing lectures. In the present study, we examined the effect of using minute papers on learning efficacy and motivation. To enhance the curriculum of the interdisciplinary course Yakugaku Nyumon, which consists of an omnibus lecture series and problem-based learning, minute papers with exercises were provided to applicants. In a follow-up questionnaire, students who used minute papers (S-USE) responded that they had a better understanding of the relationships, ranging from basic to clinical subject matter, than students who did not use such papers (S-NON). Using the Attention, Relevance, Confidence, and Satisfaction (ARCS) model questionnaire to measure study motivation, S-USE scored higher for some questionnaires than S-NON. This finding indicates that minute papers promoted learning motivation among students taking the Yakugaku Nyumon course. In regular examinations, the average score of S-USE was also statistically higher than that of S-NON. These results demonstrate that minute papers possibly encouraged students to actively review the lectures, thereby increasing both learning efficacy and motivation. This study shows that through promoting active, self-learning, minute papers are suitable for improving curricular strategies in subjects that rely on passive learning methods.

Optimized Swinging Door Algorithm for Wind Power Ramp Event Detection: Preprint

Energy Technology Data Exchange (ETDEWEB)

Cui, Mingjian; Zhang, Jie; Florita, Anthony R.; Hodge, Bri-Mathias; Ke, Deping; Sun, Yuanzhang

2015-08-06

Significant wind power ramp events (WPREs) are those that influence the integration of wind power, and they are a concern to the continued reliable operation of the power grid. As wind power penetration has increased in recent years, so has the importance of wind power ramps. In this paper, an optimized swinging door algorithm (SDA) is developed to improve ramp detection performance. Wind power time series data are segmented by the original SDA, and then all significant ramps are detected and merged through a dynamic programming algorithm. An application of the optimized SDA is provided to ascertain the optimal parameter of the original SDA. Measured wind power data from the Electric Reliability Council of Texas (ERCOT) are used to evaluate the proposed optimized SDA.

Wind Speed Forecasting Based on FEEMD and LSSVM Optimized by the Bat Algorithm

Directory of Open Access Journals (Sweden)

Wei Sun

2015-06-01

Full Text Available Affected by various environmental factors, wind speed presents high fluctuation, nonlinear and non-stationary characteristics. To evaluate wind energy properly and efficiently, this paper proposes a modified fast ensemble empirical model decomposition (FEEMD-bat algorithm (BA-least support vector machines (LSSVM (FEEMD-BA-LSSVM model combined with input selected by deep quantitative analysis. The original wind speed series are first decomposed into a limited number of intrinsic mode functions (IMFs with one residual series. Then a LSSVM is built to forecast these sub-series. In order to select input from environment variables, Cointegration and Granger causality tests are proposed to check the influence of temperature with different leading lengths. Partial correlation is applied to analyze the inner relationships between the historical speeds thus to select the LSSVM input. The parameters in LSSVM are fine-tuned by BA to ensure the generalization of LSSVM. The forecasting results suggest the hybrid approach outperforms the compared models.

Simulating European wind power generation applying statistical downscaling to reanalysis data

International Nuclear Information System (INIS)

González-Aparicio, I.; Monforti, F.; Volker, P.; Zucker, A.; Careri, F.; Huld, T.; Badger, J.

2017-01-01

Highlights: •Wind speed spatial resolution highly influences calculated wind power peaks and ramps. •Reduction of wind power generation uncertainties using statistical downscaling. •Publicly available dataset of wind power generation hourly time series at NUTS2. -- Abstract: The growing share of electricity production from solar and mainly wind resources constantly increases the stochastic nature of the power system. Modelling the high share of renewable energy sources – and in particular wind power – crucially depends on the adequate representation of the intermittency and characteristics of the wind resource which is related to the accuracy of the approach in converting wind speed data into power values. One of the main factors contributing to the uncertainty in these conversion methods is the selection of the spatial resolution. Although numerical weather prediction models can simulate wind speeds at higher spatial resolution (up to 1 × 1 km) than a reanalysis (generally, ranging from about 25 km to 70 km), they require high computational resources and massive storage systems: therefore, the most common alternative is to use the reanalysis data. However, local wind features could not be captured by the use of a reanalysis technique and could be translated into misinterpretations of the wind power peaks, ramping capacities, the behaviour of power prices, as well as bidding strategies for the electricity market. This study contributes to the understanding what is captured by different wind speeds spatial resolution datasets, the importance of using high resolution data for the conversion into power and the implications in power system analyses. It is proposed a methodology to increase the spatial resolution from a reanalysis. This study presents an open access renewable generation time series dataset for the EU-28 and neighbouring countries at hourly intervals and at different geographical aggregation levels (country, bidding zone and administrative

A continuous winding scheme for superconducting tokamak coils with cable-in-conduit conductor

International Nuclear Information System (INIS)

Kim, Sang-ho; Chung, Kie-hyung; Lee, Deok Kyo

2001-01-01

Superconducting magnet coils are essential for steady-state or long-pulse operation of tokamaks. In an advanced tokamak, the central solenoid (CS) coils are usually divided into several pairs of modules to provide for an extra plasma shaping capability in addition to those available from the shaping (poloidal field) coils. In the conventional pancake winding scheme of superconducting coils, each coil consists of separate superconducting 'double-pancake' coils connected together in series; however, such joints are not superconducting, which is one of the major disadvantages, especially in pulsed operations. A new type of winding was adopted for the ITER CS coil, which consists of cylindrical shell 'layers' joined in series. A disadvantage of this layer winding is its inability to yield modular coils that can provide certain degree of plasma shaping. Joints can be removed in a coil winding pack with the conventional pancake winding scheme, if the conductor is sufficiently long and the winding machine is properly equipped. The compactness, however, cannot be preserved with this scheme. The winding compactness is important since the radial build of the CS coils is one of the major parameters that determine the machine size. In this paper, we present a continuous winding scheme that requires no joints, allows coil fabrication at minimum dimension, and meets the flux swing requirement and other practical aspects

Intercomparison of state-of-the-art models for wind energy resources with mesoscale models:

Science.gov (United States)

Olsen, Bjarke Tobias; Hahmann, Andrea N.; Sempreviva, Anna Maria; Badger, Jake; Joergensen, Hans E.

2016-04-01

1. Introduction Mesoscale models are increasingly being used to estimate wind conditions to identify perspective areas and sites where to develop wind farm projects. Mesoscale models are functional for giving information over extensive areas with various terrain complexities where measurements are scarce and measurement campaigns costly. Several mesoscale models and families of models are being used, and each often contains thousands of setup options. Since long-term integrations are expensive and tedious to carry out, only limited comparisons exist. To remedy this problem and for evaluating the capabilities of mesoscale models to estimate site wind conditions, a tailored benchmarking study has been co-organized by the European Wind Energy Association (EWEA) and the European Energy Research Alliance Joint Programme Wind Energy (EERA JP WIND). EWEA hosted results and ensured that participants were anonymous. The blind evaluation was performed at the Wind Energy Department of the Technical University of Denmark (DTU) with the following objectives: (1) To highlight common issues on mesoscale modelling of wind conditions on sites with different characteristics, and (2) To identify gaps and strengths of models and understand the root conditions for further evaluating uncertainties. 2. Approach Three experimental sites were selected: FINO 3 (offshore, GE), Høvsore (coastal, DK), and Cabauw (land-based, NL), and three other sites without observations based on . The three mast sites were chosen because the availability of concurrent suitable time series of vertical profiles of winds speed and other surface parameters. The participants were asked to provide hourly time series of wind speed, wind direction, temperature, etc., at various vertical heights for a complete year. The methodology used to derive the time series was left to the choice of the participants, but they were asked for a brief description of their model and many other parameters (e.g., horizontal and

Technology Roadmaps: How2Guide for Wind Energy Roadmap

Energy Technology Data Exchange (ETDEWEB)

NONE

2014-03-01

Whether in OECD, emerging or developing country economies, governments are increasingly looking to diversify their energy mix beyond simply fossil fuels. While wind energy is developing towards a mainstream, competitive and reliable technology, a range of barriers can delay progress, such as financing, grid integration, social acceptance and aspects of planning processes. National and regional technology roadmaps can play a key role in supporting wind energy development and implementation, helping countries to identify priorities and pathways tailored to local resources and markets. Recognising this, the IEA has started the How2Guides - a new series co-ordinated by the International Low-Carbon Energy Technology Platform to address the need for more focused guidance in the development of national roadmaps, or strategies, for specific low-carbon technologies. This builds on the success of the IEA global technology roadmap series and responds to a growing number of requests for IEA guidance to adapt the findings of the IEA global technology roadmaps to national circumstances. A successful roadmap contains a clear statement of the desired outcome, followed by a specific pathway for reaching it. The How2Guide for Wind Energy builds on the IEA well established methodology for roadmap development and shares wind specific recommendations on how to address the four phases to developing and implementing a wind energy roadmap: Planning; Visioning; Development; and Implementation. The manual also offers menus of recommendations on policy and technical options for deployment of utility-scale wind energy installations. A matrix of barriers-versus-realistic solutions options is cross-listed with considerations such as planning, development, electricity market and system, infrastructure, and finance and economics. Drawing on several case studies from around the globe, as well as on the IEA Technology Roadmap for Wind Energy, the How2Guide for Wind Energy it is intended as a

"Take ten minutes": a dedicated ten minute medication review reduces polypharmacy in the elderly.

LENUS (Irish Health Repository)

Walsh, E K

2012-02-01

Multiple and inappropriate medications are often the cause for poor health status in the elderly. Medication reviews can improve prescribing. This study aimed to determine if a ten minute medication review by a general practitioner could reduce polypharmacy and inappropriate prescribing in elderly patients. A prospective, randomised study was conducted. Patients over the age of 65 (n = 50) underwent a 10-minute medication review. Inappropriate medications, dosage errors, and discrepancies between prescribed versus actual medication being consumed were recorded. A questionnaire to assess satisfaction was completed following review. The mean number of medications taken by patients was reduced (p < 0.001). A medication was stopped in 35 (70%) patients. Inappropriate medications were detected in 27 (54%) patients and reduced (p < 0.001). Dose errors were detected in 16 (32%). A high level of patient satisfaction was reported. A ten minute medication review reduces polypharmacy, improves prescribing and is associated with high levels of patient satisfaction.

"Take ten minutes": a dedicated ten minute medication review reduces polypharmacy in the elderly.

LENUS (Irish Health Repository)

Walsh, E K

2010-09-01

Multiple and inappropriate medications are often the cause for poor health status in the elderly. Medication reviews can improve prescribing. This study aimed to determine if a ten minute medication review by a general practitioner could reduce polypharmacy and inappropriate prescribing in elderly patients. A prospective, randomised study was conducted. Patients over the age of 65 (n = 50) underwent a 10-minute medication review. Inappropriate medications, dosage errors, and discrepancies between prescribed versus actual medication being consumed were recorded. A questionnaire to assess satisfaction was completed following review. The mean number of medications taken by patients was reduced (p < 0.001). A medication was stopped in 35 (70%) patients. Inappropriate medications were detected in 27 (54%) patients and reduced (p < 0.001). Dose errors were detected in 16 (32%). A high level of patient satisfaction was reported. A ten minute medication review reduces polypharmacy, improves prescribing and is associated with high levels of patient satisfaction.

Series pid pitch controller of large wind turbines generator

Directory of Open Access Journals (Sweden)

Micić Aleksandar D.

2015-01-01

Full Text Available For this stable process with oscillatory dynamics, characterized with small damping ratio and dominant transport delay, design of the series PID pitch controller is based on the model obtained from the open-loop process step response, filtered with the second-order Butterworth filter Fbw. Performance of the series PID pitch controller, with the filter Fbw, is analyzed by simulations of the set-point and input/output disturbance responses, including simulations with a colored noise added to the control variable. Excellent performance/robustness tradeoff is obtained, compared to the recently proposed PI pitch controllers and to the modified internal model pitch controller, developed here, which has a natural mechanism to compensate effect of dominant transport delay. [Projekat Ministarstva nauke Republike Srbije, br. III 47016

Cooperative field test program for wind systems

Energy Technology Data Exchange (ETDEWEB)

Bollmeier, W.S. II; Dodge, D.M.

1992-03-01

The objectives of the Federal Wind Energy Program, managed by the US Department of Energy (DOE), are (1) to assist industry and utilities in achieving a multi-regional US market penetration of wind systems, and (2) to establish the United States as the world leader in the development of advanced wind turbine technology. In 1984, the program conducted a series of planning workshops with representatives from the wind energy industry to obtain input on the Five-Year Research Plan then being prepared by DOE. One specific suggestion that came out of these meetings was that the federal program should conduct cooperative research tests with industry to enhance the technology transfer process. It was also felt that the active involvement of industry in DOE-funded research would improve the state of the art of wind turbine technology. DOE established the Cooperative Field Test Program (CFTP) in response to that suggestion. This program was one of the first in DOE to feature joint industry-government research test teams working toward common objectives.

Market to facilitate wind and solar energy integration in the bulk power supply

Energy Technology Data Exchange (ETDEWEB)

Milligan, Michael [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Soeder, Lennart [Royal Inst. of Tech., Stockholm (Sweden); Holttinen, Hannele [VTT Energy, Espoo (Finland); Clark, Charlton [U.S. Department of Energy Washington, DC (United States); Pineda, Ivan [European Wind Energy Association, Brussels (Belgium); Collaboration: IEA Task 25 collaboration

2012-07-01

Wind and solar power will give rise to challenges in electricity markets regarding flexibility, capacity adequacy, and the participation of wind and solar generators to markets. Large amounts of wind power will have impacts on bulk power system markets and electricity prices. If the markets respond to increased wind power by increasing investments in low-capital-cost/high-marginal-cost power, the average price may remain in the same range. However, the experiences so far from Denmark, Germany, Spain, and Ireland are that the average market prices decreased because of wind power. This reduction in price may result in additional revenue insufficiency, which may be corrected with a capacity market; however, capacity markets are difficult to design. Further, the flexibility attributes of the capacity need to be considered. Markets facilitating wind and solar integration will include possibilities for trading close to delivery (either by shorter gate closure times or intraday markets). Time steps chosen for markets can enable more flexibility to be assessed. Experience from 5- and 10-minute markets has been encouraging. (orig.)

One minute paper

African Journals Online (AJOL)

Arun Kumar Agnihotri

One-Minute Paper: A thinking centered assessment tool. Ashakiran ... achievement of objectives and learning ability of the students, to analyze the questioning pattern of ... factual information, rote memory and critical thinking. The aim of every teacher while teaching ... question prompts another higher order cognitive skill ...

A new generation of wind turbines; Une nouvelle generation d'eoliennes

Energy Technology Data Exchange (ETDEWEB)

Nica, H. [Tesnic, Laval, PQ (Canada)

2008-06-15

Although homeowners have expressed a desire to use wind energy to supply their electricity needs, many technical barriers have stood in the way of installing wind turbines in urban settings. This was due in part to three-bladed vertical axis turbines, high technical costs, limited performances in urban settings and questionable aesthetics. Tesnic has considered these issues and proposed a completely different turbine that uses a different method for extracting energy from the wind. The first approved 3.6 kW model should appear by the end of 2009. This new turbine is based on the same principal of the steam turbine patented in 1913 by Nikola Tesla. Instead of having blades, the Tesla turbine used closely spaced parallel disks and was recognized as being very robust with a high efficiency rating. Tesnic's new wind powered turbine is a vertical axis turbine with a series of valves that directs the wind on a rotor assembly of disk space. A series of blades on its circumference redirects the wind through the assembly of discs and accelerates the rotation of the rotor. The turbine extracts the wind energy in several ways, including conventional drag and lift, adherence and the vortex effect. This gives a 50 per cent added value of efficiency compared to other wind powered turbines. The global market for small wind powered energy is in full expansion. It has been projected that small turbines with 1 kW capacity will be abundant by 2020. It was noted that for household wind powered energy, the market must consider issues of cost, low maintenance, noise pollution, visual aesthetics, durability and safety. Wind energy can also be used in several industries, including plastics, composites, light metals, textiles and electronics. 2 figs.

Impacts from new 50 MW wind power plant - Bogdnaci on the price of electrical energy in Macedonia

International Nuclear Information System (INIS)

Minovski, D.; Sarac, V.; Causevski, A.

2012-01-01

The paper presents the impact from the new planned wind power plant Bogdnaci on the price for the end users of electrical energy in Republic of Macedonia. In the next years, 50 MW wind power will be installed in the Macedonian electric power system. Production of electricity from wind power plants is unpredictable and of stochastic nature i.e. depends on the weather or the wind speed at the appropriate locations. Output of wind power plants is changing every minute, thus changing in the hourly level can be from 0 - 100%, even several times depending on the occurrence of winds. Changes in output of wind power plants, leads to increased demand for operational reserve in a power system. Preferential price of electrical energy from the wind power plants and increased operational reserve in the electric power system will have big impact on the final price of electrical energy in Republic of Macedonia. (Authors)

Sizing wind/photovoltaic hybrids for households in inner Mongolia

Energy Technology Data Exchange (ETDEWEB)

Barley, C.D.; Lew, D.J.; Flowers, L.T. [National Renewable Energy Lab., Golden, CO (United States)

1997-12-31

Approximately 140,000 wind turbines currently provide electricity to about one-third of the non-grid-connected households in Inner Mongolia. However, these households often suffer from a lack of power during the low-wind summer months. This report describes an analysis of hybrid wind/photovoltaic (PV) systems for such households. The sizing of the major components is based on a subjective trade-off between the cost of the system and the percent unmet load, as determined by the Hybrid2 software in conjunction with a simplified time-series model. Actual resource data (wind speed and solar radiation) from the region are processed so as to best represent the scenarios of interest. Small wind turbines of both Chinese and U.S. manufacture are considered in the designs. The results indicate that combinations of wind and PV are more cost-effective than either one alone, and that the relative amount of PV in the design increases as the acceptable unmet load decreases and as the average wind speed decreases.

Small scale wind power harnessing in Colombian oil industry facilities: Wind resource and technology issues

Energy Technology Data Exchange (ETDEWEB)

Giraldo, Mauricio; Nieto, Cesar; Escudero, Ana C.; Cobos, Juan C.; Delgado, Fernando

2010-07-01

Full text: Looking to improve its national and international standing, Colombia's national oil company, Ecopetrol, has set its goal on becoming involved on the production of energy from multiple sources, most importantly, on having an important percentage of its installed capacity from renewable sources. Part of this effort entices the evaluation of wind power potential on its facilities, including production, transportation and administrative, as well as identifying those technologies most suitable for the specific conditions of an equatorial country such as Colombia. Due to the lack of adequate site information, the first step consisted in superimposing national data to the facilities map of the company; this allowed for the selection of the first set of potential sites. From this set, the terminal at Covenas-Sucre was selected taking into account not only wind resource, but ease of access and power needs, as well as having a more or less representative wind potential in comparison to the rest of the country. A weather station was then installed to monitor wind variables. Measurements taken showed high variations in wind direction, and relatively low velocity profiles, making most commercially available wind turbines difficult to implement. In light of the above, a series of iterative steps were taken, first considering a range of individual Vertical Axis Wind Turbines (VAWT), given their capacity to adapt to changing wind directions. However, wind speed variations proved to be a challenge for individual VAWT's, i.e. Darriues turbines do not work well with low wind speeds, and Savonius turbines are not efficient of high wind speeds. As a result, a combined Darrieus- Savonius VAWT was selected given the capacity to adapt to both wind regimes, while at the same time modifying the size and shape of the blades in order to adapt to the lower average wind speeds present at the site. The resulting prototype is currently under construction and is scheduled to

Recursive wind speed forecasting based on Hammerstein Auto-Regressive model

International Nuclear Information System (INIS)

Ait Maatallah, Othman; Achuthan, Ajit; Janoyan, Kerop; Marzocca, Pier

2015-01-01

Highlights: • Developed a new recursive WSF model for 1–24 h horizon based on Hammerstein model. • Nonlinear HAR model successfully captured chaotic dynamics of wind speed time series. • Recursive WSF intrinsic error accumulation corrected by applying rotation. • Model verified for real wind speed data from two sites with different characteristics. • HAR model outperformed both ARIMA and ANN models in terms of accuracy of prediction. - Abstract: A new Wind Speed Forecasting (WSF) model, suitable for a short term 1–24 h forecast horizon, is developed by adapting Hammerstein model to an Autoregressive approach. The model is applied to real data collected for a period of three years (2004–2006) from two different sites. The performance of HAR model is evaluated by comparing its prediction with the classical Autoregressive Integrated Moving Average (ARIMA) model and a multi-layer perceptron Artificial Neural Network (ANN). Results show that the HAR model outperforms both the ARIMA model and ANN model in terms of root mean square error (RMSE), mean absolute error (MAE), and Mean Absolute Percentage Error (MAPE). When compared to the conventional models, the new HAR model can better capture various wind speed characteristics, including asymmetric (non-gaussian) wind speed distribution, non-stationary time series profile, and the chaotic dynamics. The new model is beneficial for various applications in the renewable energy area, particularly for power scheduling

Locations and attributes of wind turbines in New Mexico, 2011

Science.gov (United States)

Carr, Natasha B.; Diffendorfer, James B.; Fancher, Tammy; Hawkins, Sarah J.; Latysh, Natalie; Leib, Kenneth J.; Matherne, Anne Marie

2013-01-01

This dataset represents an update to U.S. Geological Survey Data Series 596. Locations and attributes of wind turbines in New Mexico, 2009 (available at http://pubs.usgs.gov/ds/596/).This updated New Mexico wind turbine Data Series provides geospatial data for all 562 wind turbines established within the State of New Mexico as of June 2011, an increase of 155 wind turbines from 2009. Attributes specific to each turbine include: turbine location, manufacturer and model, rotor diameter, hub height, rotor height, potential megawatt output, land ownership, county, and development status of wind turbine. Wind energy facility data for each turbine include: facility name, facility power capacity, number of turbines associated with each facility to date, facility developer, facility ownership, and year the facility went online. The locations of turbines are derived from 1-meter true-color aerial photographs produced by the National Agriculture Imagery Program (NAIP); the photographs have a positional accuracy of about ±5 meters. The locations of turbines constructed during or prior to August 2009 are based on August 2009 NAIP imagery and turbine locations constructed after August 2009 were based June 2011 NAIP imagery. The location of turbines under construction during June 2011 likely will be less accurate than the location of existing turbines. This data series contributes to an Online Interactive Energy Atlas developed by the U.S. Geological Survey (http://my.usgs.gov/eerma/). The Energy Atlas synthesizes data on existing and potential energy development in Colorado and New Mexico and includes additional natural resource data layers. This information may be used by decisionmakers to evaluate and compare the potential benefits and tradeoffs associated with different energy development strategies or scenarios. Interactive maps, downloadable data layers, comprehensive metadata, and decision-support tools also are included in the Energy Atlas. The format of the Energy

EU 2004 Declaration. EU policy workshop development of offshore wind energy. Background document

International Nuclear Information System (INIS)

De Bruijne, R.

2004-09-01

Participants of the Dutch EU Presidency's 'EU Policy Workshop on the development of offshore wind energy' published this Declaration that called for action at the EU Transport, Energy and Telecom Council on November 29, 2004. The Declaration lists a series of action points on three main issues relating to the development of offshore wind energy in Europe: market development; environment; and grid integration of large scale offshore wind

Robust Model Predictive Control of a Wind Turbine

DEFF Research Database (Denmark)

Mirzaei, Mahmood; Poulsen, Niels Kjølstad; Niemann, Hans Henrik

2012-01-01

In this work the problem of robust model predictive control (robust MPC) of a wind turbine in the full load region is considered. A minimax robust MPC approach is used to tackle the problem. Nonlinear dynamics of the wind turbine are derived by combining blade element momentum (BEM) theory...... of the uncertain system is employed and a norm-bounded uncertainty model is used to formulate a minimax model predictive control. The resulting optimization problem is simplified by semidefinite relaxation and the controller obtained is applied on a full complexity, high fidelity wind turbine model. Finally...... and first principle modeling of the turbine flexible structure. Thereafter the nonlinear model is linearized using Taylor series expansion around system operating points. Operating points are determined by effective wind speed and an extended Kalman filter (EKF) is employed to estimate this. In addition...

Database on wind characteristics

Energy Technology Data Exchange (ETDEWEB)

Hojstrup, J. [Riso National Lab., Roskilde (Denmark); Hansen, K.S. [Fluid Mechanics Section, Lyngby (Denmark)

1996-12-31

Wind data with high temporal resolution exist from a variety of sites, and is in demand by windturbine designers and wind engineers. Unfortunately it has always been a problem to gain access to a suitable amount of this data, because they are available from many different sources in different formats and with very different levels of documentation and quality control. We are now in the process of gaining access to a large amount of this type of data, checking the quality of the data and putting the data at the disposition of the windturbine designer community through easy Internet access. Online search will use summary statistics calculated for each series to help in the selection of data. The selected data can then be downloaded directly to the user. 3 figs.

An Assessment of Wind Plant Complex Flows Using Advanced Doppler Radar Measurements

Science.gov (United States)

Gunter, W. S.; Schroeder, J.; Hirth, B.; Duncan, J.; Guynes, J.

2015-12-01

As installed wind energy capacity continues to steadily increase, the need for comprehensive measurements of wind plant complex flows to further reduce the cost of wind energy has been well advertised by the industry as a whole. Such measurements serve diverse perspectives including resource assessment, turbine inflow and power curve validation, wake and wind plant layout model verification, operations and maintenance, and the development of future advanced wind plant control schemes. While various measurement devices have been matured for wind energy applications (e.g. meteorological towers, LIDAR, SODAR), this presentation will focus on the use of advanced Doppler radar systems to observe the complex wind flows within and surrounding wind plants. Advanced Doppler radars can provide the combined advantage of a large analysis footprint (tens of square kilometers) with rapid data analysis updates (a few seconds to one minute) using both single- and dual-Doppler data collection methods. This presentation demonstrates the utility of measurements collected by the Texas Tech University Ka-band (TTUKa) radars to identify complex wind flows occurring within and nearby operational wind plants, and provide reliable forecasts of wind speeds and directions at given locations (i.e. turbine or instrumented tower sites) 45+ seconds in advance. Radar-derived wind maps reveal commonly observed features such as turbine wakes and turbine-to-turbine interaction, high momentum wind speed channels between turbine wakes, turbine array edge effects, transient boundary layer flow structures (such as wind streaks, frontal boundaries, etc.), and the impact of local terrain. Operational turbine or instrumented tower data are merged with the radar analysis to link the observed complex flow features to turbine and wind plant performance.

Short-Term Wind Speed Forecasting Using Support Vector Regression Optimized by Cuckoo Optimization Algorithm

Directory of Open Access Journals (Sweden)

Jianzhou Wang

2015-01-01

Full Text Available This paper develops an effectively intelligent model to forecast short-term wind speed series. A hybrid forecasting technique is proposed based on recurrence plot (RP and optimized support vector regression (SVR. Wind caused by the interaction of meteorological systems makes itself extremely unsteady and difficult to forecast. To understand the wind system, the wind speed series is analyzed using RP. Then, the SVR model is employed to forecast wind speed, in which the input variables are selected by RP, and two crucial parameters, including the penalties factor and gamma of the kernel function RBF, are optimized by various optimization algorithms. Those optimized algorithms are genetic algorithm (GA, particle swarm optimization algorithm (PSO, and cuckoo optimization algorithm (COA. Finally, the optimized SVR models, including COA-SVR, PSO-SVR, and GA-SVR, are evaluated based on some criteria and a hypothesis test. The experimental results show that (1 analysis of RP reveals that wind speed has short-term predictability on a short-term time scale, (2 the performance of the COA-SVR model is superior to that of the PSO-SVR and GA-SVR methods, especially for the jumping samplings, and (3 the COA-SVR method is statistically robust in multi-step-ahead prediction and can be applied to practical wind farm applications.

Are wind farms set to become the next dotcom bubble?

International Nuclear Information System (INIS)

Desbarres, A.

2008-01-01

In the current context of soaring turbine prices, supply bottlenecks and record wind farm valuations, carefully crafted entry strategies are key to growing profitable and competitive wind portfolios. The wind energy industry is growing rapidly on the back of technological advancements, political will and government subsidies. Utility companies, independent power providers, institutional investors and oil companies are all seeking to capitalise on lucrative support mechanisms to unlock greater commercial and competitive advantages, meet their renewables targets and boost their green credentials. Strong growth therefore continues on the back of record sustainable energy investments, yet record wind-farm development costs and valuations are now driving 'dotcom' comparisons as the economics of wind farming projects come under increasing pressure. However, a new series of reports by market analyst Datamonitor reveals that wind farm projects can still be profitable and competitive under very specific financial, technical, regulatory and legislative conditions [nl

Assimilating high-resolution winds from a Doppler lidar using an ensemble Kalman filter with lateral boundary adjustment

Directory of Open Access Journals (Sweden)

Masahiro Sawada

2015-03-01

Full Text Available Monitoring severe weather, including wind shear and clear air turbulence, is important for aviation safety. To provide accurate information for nowcasts and very short-range forecasts up to an hour, a rapid-update prediction system has been developed, with a particular focus on lateral boundary adjustment (LBA using the local ensemble transform Kalman filter (LETKF. Due to the small forecast domain, limited-area forecasts are dominated by the lateral boundary conditions from coarse-resolution global forecasts. To effectively extend the forecast lead time for the small domain, a new LBA scheme using the LETKF has been developed and assessed with three sea-breeze front cases. Observing system simulation experiments for high-resolution winds from a simulated Doppler lidar were performed with the Japan Meteorological Agency Nonhydrostatic Mesoscale Model at a horizontal resolution of 400 m and 15-minute update cycle. The results indicate that the LBA improved the forecast significantly. In particular, the 1-hour wind-speed forecast with the LBA is as accurate as the 15-minute forecast without the LBA. The assimilation of Doppler lidar high-resolution wind data with the LBA is a promising approach for very short-range forecasts up to an hour with a small domain, such as for aviation weather.

Peak Wind Tool for General Forecasting

Science.gov (United States)

Barrett, Joe H., III

2010-01-01

The expected peak wind speed of the day is an important forecast element in the 45th Weather Squadron's (45 WS) daily 24-Hour and Weekly Planning Forecasts. The forecasts are used for ground and space launch operations at the Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS). The 45 WS also issues wind advisories for KSC/CCAFS when they expect wind gusts to meet or exceed 25 kt, 35 kt and 50 kt thresholds at any level from the surface to 300 ft. The 45 WS forecasters have indicated peak wind speeds are challenging to forecast, particularly in the cool season months of October - April. In Phase I of this task, the Applied Meteorology Unit (AMU) developed a tool to help the 45 WS forecast non-convective winds at KSC/CCAFS for the 24-hour period of 0800 to 0800 local time. The tool was delivered as a Microsoft Excel graphical user interface (GUI). The GUI displayed the forecast of peak wind speed, 5-minute average wind speed at the time of the peak wind, timing of the peak wind and probability the peak speed would meet or exceed 25 kt, 35 kt and 50 kt. For the current task (Phase II ), the 45 WS requested additional observations be used for the creation of the forecast equations by expanding the period of record (POR). Additional parameters were evaluated as predictors, including wind speeds between 500 ft and 3000 ft, static stability classification, Bulk Richardson Number, mixing depth, vertical wind shear, temperature inversion strength and depth and wind direction. Using a verification data set, the AMU compared the performance of the Phase I and II prediction methods. Just as in Phase I, the tool was delivered as a Microsoft Excel GUI. The 45 WS requested the tool also be available in the Meteorological Interactive Data Display System (MIDDS). The AMU first expanded the POR by two years by adding tower observations, surface observations and CCAFS (XMR) soundings for the cool season months of March 2007 to April 2009. The POR was expanded

Hydrogen storage for wind parks: A real options evaluation for an optimal investment in more flexibility

International Nuclear Information System (INIS)

Kroniger, Daniel; Madlener, Reinhard

2014-01-01

Highlights: • Economic analysis of investing in H 2 storage for excess wind power production. • Use of real options analysis to account for uncertainty and managerial flexibility. • Hourly profits are simulated for profit-maximizing operation of the storage device. • Revenues by load factor increase, offering minute reserve, temporal arbitrage, H 2 sale. • Power-to-power is unprofitable under current techno-political conditions in Germany. - Abstract: In this paper, we investigate the economic viability of hydrogen storage for excess electricity produced in wind power plants. For the analysis, we define two scenarios (50 MW system with and without re-electrification unit) and apply Monte Carlo simulation and real options analysis (ROA) to compute hourly profits under uncertainty regarding wind speed, spot market electricity prices, and call of minute reserve capacity. Hydrogen as a storage medium helps to either (1) increase capacity utilization of the wind park in case of grid disconnection; (2) to offer minute reserve; or (3) to exploit temporal price arbitrage at the electricity spot market; additionally, hydrogen can also be directly sold as a commodity. We find that power-to-power operation is highly uneconomical under current framework conditions in Germany, irrespective of potential energy efficiency gains. Interestingly, due to counterbalancing effects, offshore wind parks are found to have only a modest economic advantage compared to onshore ones. The power-to-fuel plant can be operated profitably (at hydrogen prices of more than 0.36 € m −3 and a 100% utilization of the electrolyzer) if hydrogen is directly marketed instead of used to store and re-generate electrical energy. The ROA recommends investment in a storage device without re-electrification unit beyond an expected project value that is about twice the investment cost of the storage device, a figure which is reduced markedly as conversion efficiency rises, assuming technical change

Temporal and spatial patterns in wind stress and wind stress curl over the central Southern California Bight

Science.gov (United States)

Noble, Marlene A.; Rosenberger, Kurt J.; Rosenfeld, Leslie K.; Robertson, George L.

2012-01-01

In 2001, the U.S. Geological Survey, together with several other federal and municipal agencies, began a series of field programs to determine along and cross-shelf transport patterns over the continental shelves in the central Southern California Bight. As a part of these programs, moorings that monitor winds were deployed off the Palos Verdes peninsula and within San Pedro Bay for six 3–4 month summer and winter periods between 2001 and 2008. In addition, nearly continuous records of winds for this 7-year period were obtained from a terrestrial site at the coast and from a basin site offshore of the long-term coastal site. The mean annual winds are downcoast at all sites. The alongshelf components of wind stress, which are the largest part of the low-frequency wind stress fields, are well correlated between basin, shelf and coastal sites. On average, the amplitude of alongshelf fluctuations in wind stress are 3–4 times larger over the offshore basin, compared to the coastal site, irrespective of whether the fluctuations represent the total, or just the correlated portion of the wind stress field. The curl in the large-scale wind stress tends to be positive, especially in the winter season when the mean wind stress is downcoast and larger at the offshore basin site than at the beach. However, since the fluctuation in wind stress amplitudes are usually larger than the mean, periods of weak negative curl do occur, especially in the summer season when the largest normalized differences in the amplitude of wind stress fluctuations are found in the nearshore region of the coastal ocean. Even though the low-frequency wind stress field is well-correlated over the continental shelf and offshore basins, out to distances of 35 km or more from the coast, winds even 10 km inshore of the beach do not represent the coastal wind field, at least in the summer months. The seasonal changes in the spatial structures in wind stress amplitudes suggest that an assessment of the

WIND SPEED Monitoring in Northern Eurasia

Science.gov (United States)

Bulygina, O.; Korshunova, N. N.; Razuvaev, V. N.; Groisman, P. Y.

2016-12-01

The wind regime of Russia varies a great deal due to the large size of the country's territory and variety of climate and terrain conditions. Changes in the regime of surface wind are of great practical importance. They can affect heat and water balance. Strong wind is one of the most hazardous meteorological event for various sectors of economy and for infrastructure. The main objective of this research is to monitoring wind speed change in Northern Eurasia At meteorological stations wind speed and wind direction are measured at the height of 10-12 meters over the land surface with the help of wind meters or wind wanes. Calculations were made on the basis of data for the period of 1980-2015. It allowed the massive scale disruption of homogeneity to be eliminated and sufficient period needed to obtain sustainable statistic characteristics to be retained. Data on average and maximum wind speed measured at 1457 stations of Russia were used. The analysis of changes in wind characteristics was made on the basis of point data and series of average characteristics obtained for 18 quasi-homogeneous climatic regions. Statistical characteristics (average and maximum values of wind speed, prevailing wind direction, values of the boundary of the 90%, 95% and 99%-confidence interval in the distribution of maximum wind speed) were obtained for all seasons and for the year as a whole. Values of boundaries of the 95% and 99%-confidence interval in the distribution of maximum wind speed were considered as indicators of extremeness of the wind regime. The trend of changes in average and maximum wind speed was assessed with a linear trend coefficient. A special attention was paid to wind changes in the Arctic where dramatic changes in surface air temperature and sea ice extent and density have been observed during the past decade. The analysis of the results allowed seasonal and regional features of changes in the wind regime on the territory of the northern part of Eurasia to be

Variability of interconnected wind plants: correlation length and its dependence on variability time scale

Science.gov (United States)

St. Martin, Clara M.; Lundquist, Julie K.; Handschy, Mark A.

2015-04-01

The variability in wind-generated electricity complicates the integration of this electricity into the electrical grid. This challenge steepens as the percentage of renewably-generated electricity on the grid grows, but variability can be reduced by exploiting geographic diversity: correlations between wind farms decrease as the separation between wind farms increases. But how far is far enough to reduce variability? Grid management requires balancing production on various timescales, and so consideration of correlations reflective of those timescales can guide the appropriate spatial scales of geographic diversity grid integration. To answer ‘how far is far enough,’ we investigate the universal behavior of geographic diversity by exploring wind-speed correlations using three extensive datasets spanning continents, durations and time resolution. First, one year of five-minute wind power generation data from 29 wind farms span 1270 km across Southeastern Australia (Australian Energy Market Operator). Second, 45 years of hourly 10 m wind-speeds from 117 stations span 5000 km across Canada (National Climate Data Archive of Environment Canada). Finally, four years of five-minute wind-speeds from 14 meteorological towers span 350 km of the Northwestern US (Bonneville Power Administration). After removing diurnal cycles and seasonal trends from all datasets, we investigate dependence of correlation length on time scale by digitally high-pass filtering the data on 0.25-2000 h timescales and calculating correlations between sites for each high-pass filter cut-off. Correlations fall to zero with increasing station separation distance, but the characteristic correlation length varies with the high-pass filter applied: the higher the cut-off frequency, the smaller the station separation required to achieve de-correlation. Remarkable similarities between these three datasets reveal behavior that, if universal, could be particularly useful for grid management. For high

LIDAR wind speed measurements from a rotating spinner (SpinnerEx 2009)

DEFF Research Database (Denmark)

Angelou, Nikolas; Mikkelsen, Torben; Hansen, Kasper Hjorth

spinner of a MW-sized wind turbine, and investigate the approaching wind fields from this vantage point. Time series of wind speed measurements from the lidar with 50 Hz sampling rate were successfully obtained for approximately 60 days, during the measurement campaign lasting from April to August 2009....... In this report, information is given regarding the experimental setup and the lidar’s operation parameters. The geometrical model used for the reconstruction of the scanning pattern of the lidar is described. This model takes into account the lidar’s pointing direction, the spinner axis’s vertical tilt...... and the wind turbine’s yaw relative to the mean wind speed direction. The data analysis processes are documented. A methodology for the calculation of the yaw misalignment of the wind turbine relative to the wind direction, as a function of various averaging times, is proposed, using the lidar’s instantaneous...

The Feasibility of Wind and Solar Energy Application for Oil and Gas Offshore Platform

International Nuclear Information System (INIS)

Tiong, Y K; Zahari, M A; Wong, S F; Dol, S S

2015-01-01

Renewable energy is an energy which is freely available in nature such as winds and solar energy. It plays a critical role in greening the energy sector as these sources of energy produce little or no pollution to environment. This paper will focus on capability of renewable energy (wind and solar) in generating power for offshore application. Data of wind speeds and solar irradiation that are available around SHELL Sabah Water Platform for every 10 minutes, 24 hours a day, for a period of one year are provided by SHELL Sarawak Sdn. Bhd. The suitable wind turbine and photovoltaic panel that are able to give a high output and higher reliability during operation period are selected by using the tabulated data. The highest power output generated using single wind energy application is equal to 492 kW while for solar energy application is equal to 20 kW. Using the calculated data, the feasibility of renewable energy is then determined based on the platform energy demand. (paper)

Analytical methods for wind persistence: Their application in assessing the best site for a wind farm in the State of Veracruz, Mexico

Energy Technology Data Exchange (ETDEWEB)

Cancino-Solorzano, Yoreley; Gutierrez-Trashorras, Antonio J.; Xiberta-Bernat, Jorge [Departamento de Energia, Escuela Tecnica Superior de Ingenieros de Minas, Universidad de Oviedo., c/ Independencia, 13, 2a Planta, 33004 Oviedo (Spain)

2010-12-15

The properties of wind persistence are an essential parameter in carrying out a complete analysis of possible sites for a wind farm. This parameter can be defined as a measure of the mean duration of wind speed within a given interval of values for a concrete site. In this study the persistence properties are evaluated from the methods based on the autocorrelation function, conditional probability and the curves of speed duration, used satisfactorily by other authors. The statistical analysis of the series of useful persistence is also carried out to validate the results obtained. These methods have been applied to hourly data of wind speed corresponding to five Weather Stations (WS) in the State of Veracruz, Mexico in the period 1995-2006. The results obtained indicate that the coastal areas have the best properties of wind speed persistence and are, therefore, the most indicated for the generation of electricity from this renewable energy source. (author)

Short-Term Wind Speed Forecasting for Power System Operations

KAUST Repository

Zhu, Xinxin; Genton, Marc G.

2012-01-01

some statistical short-term wind speed forecasting models, including traditional time series approaches and more advanced space-time statistical models. It also discusses the evaluation of forecast accuracy, in particular, the need for realistic loss

On multivariate imputation and forecasting of decadal wind speed missing data.

Science.gov (United States)

Wesonga, Ronald

2015-01-01

This paper demonstrates the application of multiple imputations by chained equations and time series forecasting of wind speed data. The study was motivated by the high prevalence of missing wind speed historic data. Findings based on the fully conditional specification under multiple imputations by chained equations, provided reliable wind speed missing data imputations. Further, the forecasting model shows, the smoothing parameter, alpha (0.014) close to zero, confirming that recent past observations are more suitable for use to forecast wind speeds. The maximum decadal wind speed for Entebbe International Airport was estimated to be 17.6 metres per second at a 0.05 level of significance with a bound on the error of estimation of 10.8 metres per second. The large bound on the error of estimations confirms the dynamic tendencies of wind speed at the airport under study.

Spatial-temporal analysis of coherent offshore wind field structures measured by scanning Doppler-lidar

Science.gov (United States)

Valldecabres, L.; Friedrichs, W.; von Bremen, L.; Kühn, M.

2016-09-01

An analysis of the spatial and temporal power fluctuations of a simplified wind farm model is conducted on four offshore wind fields data sets, two from lidar measurements and two from LES under unstable and neutral atmospheric conditions. The integral length scales of the horizontal wind speed computed in the streamwise and the cross-stream direction revealed the elongation of the structures in the direction of the mean flow. To analyse the effect of the structures on the power output of a wind turbine, the aggregated equivalent power of two wind turbines with different turbine spacing in the streamwise and cross-stream direction is analysed at different time scales under 10 minutes. The fact of considering the summation of the power of two wind turbines smooths out the fluctuations of the power output of a single wind turbine. This effect, which is stronger with increasing spacing between turbines, can be seen in the aggregation of the power of two wind turbines in the streamwise direction. Due to the anti-correlation of the coherent structures in the cross-stream direction, this smoothing effect is stronger when the aggregated power is computed with two wind turbines aligned orthogonally to the mean flow direction.

Simulation of transcontinental wind and solar PV generation time series

DEFF Research Database (Denmark)

Nuño Martinez, Edgar; Maule, Petr; Hahmann, Andrea N.

2018-01-01

to the technical characteristics of individual installations spread across large regions. The proposed methodology is validated using actual power data in Europe and can be applied to represent intermittent generation in network development plans, reliability and market studies, as well as operational guidelines.......The deployment of Renewable Energy Sources (RES) is driving modern power systems towards a fundamental green transition. In this regard, there is a need to develop models to accurately capture the variability of wind and solar photovoltaic (PV) power, at different geographical and temporal scales...

Wind rotor power station BONI-ShHV

International Nuclear Information System (INIS)

Bolotov, A.V.

1999-01-01

Wind rotor power station (WRPS) BONI-ShHV has following advantages : the increase of installation stability by rise of wind velocity and rotation speed of rotor due to gyroscopic effect; the absence noise and vibration; the safety for birds and animals; ability of compact installation and creation of series of wind power dams with higher capacity; the simplicity and fast assembling and putting into operation. The price of 1 k W of installing capacity is lower about 2.5-3 times compare to usual WRPS due to simple kinematic scheme. WRPS has high specific output of electrical energy due to use of low and long existing wind velocity and due to short storms, giving greater power. It has ability to be replayed when average annual wind velocity is above 5.5 m/s in comparison with propeller WRPS, which are never repaying. WRPS BONI-ShHV are made on the plants of Republic of Kazakhstan, and tested in wind velocity range up 45 m/s, have experience of 3 years of operation, showing their reliability and effectiveness. The repayment period of individual WRPS BONI-0.5/6 ShHV is from 10 month to 1 year depending on average annual velocity

Wind energy in electric power production. Preliminary study

Energy Technology Data Exchange (ETDEWEB)

Lento, R; Peltola, E

1984-01-15

The wind speed conditions in Finland have been studied with the aid of the existing statistics of the Finnish Meteorological Institute. With the aid of the statistics also estimates on the available wind energy were made. 800 wind power plants, 1.5 MW each, on the windiest west coast would produce about 2 TWh energy per year. Far more information on the temporal, geographical and vertical distribution of the wind speed than the present statistics include is needed when the available wind energy is estimated, when wind power plants are dimensioned optimally, and when suitable locations are chosen for them. The investment costs of a wind power plant increase when the height of the tower or the diameter of the rotor is increased, but the energy production increases, too. Thus, overdimensioning the wind power plant in view of energy needs or the wind conditions causes extra costs. The cost of energy produced by wind power can not yet compete with conventional energy, but the situation changes to the advantage of wind energy, if the real price of the plants decreases (among other things due to large series production and increasing experience), or if the real price of fuels rises. The inconvinience on the environment caused by the wind power plants is considered insignificant. The noise caused by the plant attenuates rapidly with distance. No harmful effects birds and other animals caused by the wind power plants have been observed in the studies made abroad. Parts of a plant getting loose during an accident, or ice forming on the blades are estimated to fly even from a large plant only a few hundred meters.

Taylor dispersion in wind-driven current

Science.gov (United States)

Li, Gang; Wang, Ping; Jiang, Wei-Quan; Zeng, Li; Li, Zhi; Chen, G. Q.

2017-12-01

Taylor dispersion associated with wind-driven currents in channels, shallow lakes and estuaries is essential to hydrological environmental management. For solute dispersion in a wind-driven current, presented in this paper is an analytical study of the evolution of concentration distribution. The concentration moments are intensively derived for an accurate presentation of the mean concentration distribution, up to the effect of kurtosis. The vertical divergence of concentration is then deduced by Gill's method of series expansion up to the fourth order. Based on the temporal evolution of the vertical concentration distribution, the dispersion process in the wind-driven current is concretely characterized. The uniform shear leads to a special symmetrical distribution of mean concentration free of skewness. The non-uniformity of vertical concentration is caused by convection and smeared out gradually by the effect of diffusion, but fails to disappear even at large times.

Design of High Performance Permanent-Magnet Synchronous Wind Generators

Directory of Open Access Journals (Sweden)

Chun-Yu Hsiao

2014-11-01

Full Text Available This paper is devoted to the analysis and design of high performance permanent-magnet synchronous wind generators (PSWGs. A systematic and sequential methodology for the design of PMSGs is proposed with a high performance wind generator as a design model. Aiming at high induced voltage, low harmonic distortion as well as high generator efficiency, optimal generator parameters such as pole-arc to pole-pitch ratio and stator-slot-shoes dimension, etc. are determined with the proposed technique using Maxwell 2-D, Matlab software and the Taguchi method. The proposed double three-phase and six-phase winding configurations, which consist of six windings in the stator, can provide evenly distributed current for versatile applications regarding the voltage and current demands for practical consideration. Specifically, windings are connected in series to increase the output voltage at low wind speed, and in parallel during high wind speed to generate electricity even when either one winding fails, thereby enhancing the reliability as well. A PMSG is designed and implemented based on the proposed method. When the simulation is performed with a 6 Ω load, the output power for the double three-phase winding and six-phase winding are correspondingly 10.64 and 11.13 kW. In addition, 24 Ω load experiments show that the efficiencies of double three-phase winding and six-phase winding are 96.56% and 98.54%, respectively, verifying the proposed high performance operation.

Exploiting sparsity of interconnections in spatio-temporal wind speed forecasting using Wavelet Transform

International Nuclear Information System (INIS)

Tascikaraoglu, Akin; Sanandaji, Borhan M.; Poolla, Kameshwar; Varaiya, Pravin

2016-01-01

Highlights: • We propose a spatio-temporal approach for wind speed forecasting. • The method is based on a combination of Wavelet decomposition and structured-sparse recovery. • Our analyses confirm that low-dimensional structures govern the interactions between stations. • Our method particularly shows improvements for profiles with high ramps. • We examine our approach on real data and illustrate its superiority over a set of benchmark models. - Abstract: Integration of renewable energy resources into the power grid is essential in achieving the envisioned sustainable energy future. Stochasticity and intermittency characteristics of renewable energies, however, present challenges for integrating these resources into the existing grid in a large scale. Reliable renewable energy integration is facilitated by accurate wind forecasts. In this paper, we propose a novel wind speed forecasting method which first utilizes Wavelet Transform (WT) for decomposition of the wind speed data into more stationary components and then uses a spatio-temporal model on each sub-series for incorporating both temporal and spatial information. The proposed spatio-temporal forecasting approach on each sub-series is based on the assumption that there usually exists an intrinsic low-dimensional structure between time series data in a collection of meteorological stations. Our approach is inspired by Compressive Sensing (CS) and structured-sparse recovery algorithms. Based on detailed case studies, we show that the proposed approach based on exploiting the sparsity of correlations between a large set of meteorological stations and decomposing time series for higher-accuracy forecasts considerably improve the short-term forecasts compared to the temporal and spatio-temporal benchmark methods.

Variability of Wind Speeds and Power over Europe

Science.gov (United States)

Tambke, J.; von Bremen, L.; de Decker, J.; Schmidt, M.; Steinfeld, G.; Wolff, J.-O.

2010-09-01

of momentum through the air-sea interface is described by a common wave boundary layer with enhanced Charnock dynamics. 2.) Wind Field Variability Time series of wind speed and power from 400 potential offshore locations and 16,000 onshore sites in the 2020 and 2030 scenarios are part of the design basis of the EU-project www.OffshoreGrid.eu. This project investigates the grid integration of all planned offshore farms in Northern Europe and will serve as the basis for the "Blueprint for Offshore Grids" by the European Commission. The synchronous wind time series were calculated with the WRF-model. The simulation comprises four years and was validated with a number of wind measurements. We present detailed statistics of local, clustered and regional power production. The analysis quantifies spatial and temporal correlations, extreme events and ramps. Important results are the smoothing effects in a pan-European offshore grid. Key words: Offshore Wind Resource Assessment; Marine Meteorology; Wind Speed Profile; Marine Atmospheric Boundary Layer; Wind Variability, Spatio-temporal Correlation; Electricity Grid Integration

Auto-correlation analysis of ocean surface wind vectors

Indian Academy of Sciences (India)

M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22

time series data of surface winds measured in situ by a deep water buoy in the Indian Ocean has been carried out. ... A case study using the TRMM Microwave Imager (TMI) and ... parameter is essential when the values of the parameter ...

Noise from wind turbines. Final report of project JOU2-CT92-0124

International Nuclear Information System (INIS)

Van der Borg, N.; Andersen, B.; Mackinnon, A.; Klug, H.; Theofiloyannakos, D.

1995-04-01

Part of the planning procedure for the erection of a wind turbine or a wind farm is the prediction of the acoustic noise due to the wind turbine(s) at the nearest dwelling. The noise is normally predicted using the acoustic characteristics of the regarded wind turbine as measured on a wind turbine of equal make and model and using a general noise propagation model. Both inputs introduce uncertainties in the predicted noise level: (a) turbines of equal make and model may have different acoustic characteristics; (b) the acoustic characteristics of a turbine may change in time - from day to day (repeatability of the measurement), - during the years (ageing of the turbine); (c) the general propagation model does not take into account the effects of source elevation and wind. The project aimed at the quantification of these uncertainties and at the development of a wind turbine noise propagation model. Statistical information has been collected on the individual differences of the sound power and tonality of turbines of equal make and model by measuring 6 different types of wind turbines. Of each type 5 individual turbines have been measured (total 30 turbines). Additionally the sound power of a series of 4 wind turbines and of a series of 29 wind turbines (from earlier measurements) have been introduced into the project. Statistical information has been collected on the day to day variations of the sound power and tonality of wind turbines by measuring 3 different turbines 5 times (total 15 measurements). Statistical information has been collected on the effect of ageing on the sound power and tonality of wind turbines by the repeated measurement of 5 wind turbines that have been measured in an identical situation 3 to 7 years earlier. A method for the prediction of wind turbine noise propagation has been developed based on measurements of sound propagation from an elevated noise source and theoretical calculations. (Abstract Truncated)

The first installation of the WindWall in the Netherlands; Eerste WindWall in Nederland geplaatst

Energy Technology Data Exchange (ETDEWEB)

Ten Bolscher, G.H.; Vander Heide, H. [DWA Installatie- en energieadvies, Bodegraven (Netherlands)

2003-09-01

This article is the first in a series of four on the experiment with the WindWall, a wind turbine on the roof of a school building in Zwolle, Netherlands. The experiment started September 5, 2003. [Dutch] ledereen kent de grote windturbines die elektriciteit opwekken. Nadeel ervan is dat het draagvlak voor plaatsing op het land minder wordt, laat staan dat er mogelijkheden zijn voor toepassing in de gebouwde orngeving. Door diverse marktpartijen worden momenteel kleinere, voor de gebouwde omgeving geschikte windturbines ontwikkeld, die de negatieve eigenschappen van grote windturbines (waarschijnlijk) niet hebben. Hierbij gaat het om eigenschappen als geluidsbelasting, beschaduwing, zichtbare aanwezigheid en visuele vervuiling van het vrije landschap. Op 11 juli 2003 is de eerste WindWall, een 'liggende' windturbine, geplaatst op het dak van het Deltion college in Zwolle in het kader van een praktijkexperiment, dat gesubsidieerd wordt door de Provincie Overijssel. Op 5 september 2003 is het systeern officieel in gebruik genomen.

Optimum sizing of wind-battery systems incorporating resource uncertainty

International Nuclear Information System (INIS)

Roy, Anindita; Kedare, Shireesh B.; Bandyopadhyay, Santanu

2010-01-01

The inherent uncertainty of the wind is a major impediment for successful implementation of wind based power generation technology. A methodology has been proposed in this paper to incorporate wind speed uncertainty in sizing wind-battery system for isolated applications. The uncertainty associated with the wind speed is incorporated using chance constraint programming approach. For a pre-specified reliability requirement, a deterministic equivalent energy balance equation may be derived from the chance constraint that allows time series simulation of the entire system. This results in a generation of the entire set of feasible design options, satisfying different system level constraints, on a battery capacity vs. generator rating diagram, also known as the design space. The proposed methodology highlights the trade-offs between the wind turbine rating, rotor diameter and the battery size for a given reliability of power supply. The optimum configuration is chosen on the basis of the minimum cost of energy (US$/kWh). It is shown with the help of illustrative examples that the proposed methodology is generic and flexible to incorporate alternate sub-component models. (author)

Performance Enhancement and Load Reduction on Wind Turbines Using Inflow Measurements

DEFF Research Database (Denmark)

Kragh, Knud Abildgaard

. 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...... wind energy research is focused on decreasing the cost of the energy that can be produced from the wind. The cost of energy can for example be decreased by ensuring that wind turbines are operated in a way that ensures that the maximum amount of energy is extracted, and that the turbines are not loaded...... 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...

The impacts of wind technology advancement on future global energy

International Nuclear Information System (INIS)

Zhang, Xiaochun; Ma, Chun; Song, Xia; Zhou, Yuyu; Chen, Weiping

2016-01-01

Highlights: • Integrated assessment model perform a series of scenarios of technology advances. • Explore the potential roles of wind energy technology advance in global energy. • Technology advance impacts on energy consumption and global low carbon market. • Technology advance influences on global energy security and stability. - Abstract: To avoid additional global warming and environmental damage, energy systems need to rely on the use of low carbon technologies like wind energy. However, supply uncertainties, production costs, and energy security are the main factors considered by the global economies when reshaping their energy systems. Here, we explore the potential roles of wind energy technology advancement in future global electricity generations, costs, and energy security. We use an integrated assessment model performing a series of technology advancement scenarios. The results show that double of the capital cost reduction causes 40% of generation increase and 10% of cost ​decrease on average in the long-term global wind electricity market. Today’s technology advancement could bring us the benefit of increasing electricity production in the future 40–50 years, and decreasing electricity cost in the future 90–100 years. The technology advancement of wind energy can help to keep global energy security and stability. An aggressive development and deployment of wind energy could in the long-term avoid 1/3 of gas and 1/28 of coal burned, and keep 1/2 biomass and 1/20 nuclear fuel saved from the global electricity system. The key is that wind resources are free and carbon-free. The results of this study are useful in broad coverage ranges from innovative technologies and systems of renewable energy to the economic industrial and domestic use of energy with no or minor impact on the environment.

Scales of North Atlantic wind stress curl determined from the comprehensive ocean-atmosphere data set

Science.gov (United States)

Ehret, Laura L.; O'Brien, James J.

1989-01-01

Nineteen years of wind data over the North Atlantic are used to calculate a field of wind stress curl. An empirical orthogonal function (EOF) analysis is performed on this field, resulting in spatial patterns of wind stress curl and associated time series. A Monte Carlo technique is used to establish the statistical significance of each spatial pattern, and the associated time series are spectrally analyzed. The first four statistically significant EOF modes represent more than 50 percent of the curl variance, and the spatial patterns of curl associated with these modes exhibit the major elements of North Atlantic climatology. Most of the time series spectral variance is contained in annual and semiannual frequencies. The features observed include the individual annual variation of the subtropical high and the subpolar low, the annual oscillation of intensity between pressure centers, the influence of localized strong SST gradients and associated cyclogenesis regions, and the constant nature of the trades.

A Novel Empirical Mode Decomposition With Support Vector Regression for Wind Speed Forecasting.

Science.gov (United States)

Ren, Ye; Suganthan, Ponnuthurai Nagaratnam; Srikanth, Narasimalu

2016-08-01

Wind energy is a clean and an abundant renewable energy source. Accurate wind speed forecasting is essential for power dispatch planning, unit commitment decision, maintenance scheduling, and regulation. However, wind is intermittent and wind speed is difficult to predict. This brief proposes a novel wind speed forecasting method by integrating empirical mode decomposition (EMD) and support vector regression (SVR) methods. The EMD is used to decompose the wind speed time series into several intrinsic mode functions (IMFs) and a residue. Subsequently, a vector combining one historical data from each IMF and the residue is generated to train the SVR. The proposed EMD-SVR model is evaluated with a wind speed data set. The proposed EMD-SVR model outperforms several recently reported methods with respect to accuracy or computational complexity.

Evaluation of a small-scale wind power plant; Utvaerdering av smaaskaligt vindkraftverk

Energy Technology Data Exchange (ETDEWEB)

Arvidsson, Ulf; Hilding, Sten [Elforsk AB, Stockholm (Sweden)

2001-12-01

The aim of this work is to evaluate the electrical performance of the 20 kW Pitch Wind turbine. The work was originally intended to focus on evaluating the first machine in a series of three, which should be a machine ready for series production. However, the control system of the machine was not tested and verified so instead a large part of the work has been to check that the electrical system and the control system operates as intended and to adjust and suggest improvements. The design includes a self-regulating variable speed wind turbine coupled to a permanent magnet generator and a converter.

Analysis of a high power, resonant DC-DC converter for DC wind turbines

DEFF Research Database (Denmark)

Dincan, Catalin Gabriel; Kjær, Philip Carne; Chen, Yu-Hsing

2018-01-01

This paper is introducing a new method of operation for a series resonant converter, with intended application in megawatt high-voltage DC wind turbines. Compared to a frequency controlled series resonant converter operated in sub resonant mode, the method (entitled pulse removal technique) allows...

Empirical models of wind conditions on Upper Klamath Lake, Oregon

Science.gov (United States)

Buccola, Norman L.; Wood, Tamara M.

2010-01-01

Upper Klamath Lake is a large (230 square kilometers), shallow (mean depth 2.8 meters at full pool) lake in southern Oregon. Lake circulation patterns are driven largely by wind, and the resulting currents affect the water quality and ecology of the lake. To support hydrodynamic modeling of the lake and statistical investigations of the relation between wind and lake water-quality measurements, the U.S. Geological Survey has monitored wind conditions along the lakeshore and at floating raft sites in the middle of the lake since 2005. In order to make the existing wind archive more useful, this report summarizes the development of empirical wind models that serve two purposes: (1) to fill short (on the order of hours or days) wind data gaps at raft sites in the middle of the lake, and (2) to reconstruct, on a daily basis, over periods of months to years, historical wind conditions at U.S. Geological Survey sites prior to 2005. Empirical wind models based on Artificial Neural Network (ANN) and Multivariate-Adaptive Regressive Splines (MARS) algorithms were compared. ANNs were better suited to simulating the 10-minute wind data that are the dependent variables of the gap-filling models, but the simpler MARS algorithm may be adequate to accurately simulate the daily wind data that are the dependent variables of the historical wind models. To further test the accuracy of the gap-filling models, the resulting simulated winds were used to force the hydrodynamic model of the lake, and the resulting simulated currents were compared to measurements from an acoustic Doppler current profiler. The error statistics indicated that the simulation of currents was degraded as compared to when the model was forced with observed winds, but probably is adequate for short gaps in the data of a few days or less. Transport seems to be less affected by the use of the simulated winds in place of observed winds. The simulated tracer concentration was similar between model results when

Entropic Analysis of Electromyography Time Series

Science.gov (United States)

Kaufman, Miron; Sung, Paul

2005-03-01

We are in the process of assessing the effectiveness of fractal and entropic measures for the diagnostic of low back pain from surface electromyography (EMG) time series. Surface electromyography (EMG) is used to assess patients with low back pain. In a typical EMG measurement, the voltage is measured every millisecond. We observed back muscle fatiguing during one minute, which results in a time series with 60,000 entries. We characterize the complexity of time series by computing the Shannon entropy time dependence. The analysis of the time series from different relevant muscles from healthy and low back pain (LBP) individuals provides evidence that the level of variability of back muscle activities is much larger for healthy individuals than for individuals with LBP. In general the time dependence of the entropy shows a crossover from a diffusive regime to a regime characterized by long time correlations (self organization) at about 0.01s.

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.

Fault diagnostics in power transformer model winding for different alpha values

Directory of Open Access Journals (Sweden)

G.H. Kusumadevi

2015-09-01

Full Text Available Transient overvoltages appearing at line terminal of power transformer HV windings can cause failure of winding insulation. The failure can be from winding to ground or between turns or sections of winding. In most of the cases, failure from winding to ground can be detected by changes in the wave shape of surge voltage appearing at line terminal. However, detection of insulation failure between turns may be difficult due to intricacies involved in identifications of faults. In this paper, simulation investigations carried out on a power transformer model winding for identifying faults between turns of winding has been reported. The power transformer HV winding has been represented by 8 sections, 16 sections and 24 sections. Neutral current waveform has been analyzed for same model winding represented by different number of sections. The values of α (‘α’ value is the square root of total ground capacitance to total series capacitance of winding considered for windings are 5, 10 and 20. Standard lightning impulse voltage (1.2/50 μs wave shape have been considered for analysis. Computer simulations have been carried out using software PSPICE version 10.0. Neutral current and frequency response analysis methods have been used for identification of faults within sections of transformer model winding.

Evaluating anemometer drift: A statistical approach to correct biases in wind speed measurement

Science.gov (United States)

Azorin-Molina, Cesar; Asin, Jesus; McVicar, Tim R.; Minola, Lorenzo; Lopez-Moreno, Juan I.; Vicente-Serrano, Sergio M.; Chen, Deliang

2018-05-01

Recent studies on observed wind variability have revealed a decline (termed "stilling") of near-surface wind speed during the last 30-50 years over many mid-latitude terrestrial regions, particularly in the Northern Hemisphere. The well-known impact of cup anemometer drift (i.e., wear on the bearings) on the observed weakening of wind speed has been mentioned as a potential contributor to the declining trend. However, to date, no research has quantified its contribution to stilling based on measurements, which is most likely due to lack of quantification of the ageing effect. In this study, a 3-year field experiment (2014-2016) with 10-minute paired wind speed measurements from one new and one malfunctioned (i.e., old bearings) SEAC SV5 cup anemometer which has been used by the Spanish Meteorological Agency in automatic weather stations since mid-1980s, was developed for assessing for the first time the role of anemometer drift on wind speed measurement. The results showed a statistical significant impact of anemometer drift on wind speed measurements, with the old anemometer measuring lower wind speeds than the new one. Biases show a marked temporal pattern and clear dependency on wind speed, with both weak and strong winds causing significant biases. This pioneering quantification of biases has allowed us to define two regression models that correct up to 37% of the artificial bias in wind speed due to measurement with an old anemometer.

Observation of solar wind with radio-star scintillation

International Nuclear Information System (INIS)

Watanabe, Takashi

1974-01-01

Large solar flares occurred in groups in early August 1972, and many interesting phenomena were observed. The solar wind condition during this period, obtained by scintillation observation, is reviewed. The velocity of solar wind has been determined from the observation of interplanetary space scintillation at Toyokawa, Fujigamine and Sugadaira. Four to ten radio wave sources were observed for ten minutes at each southing every day. Strong earth magnetic storm and the Forbush decrease of cosmic ray were observed during the period from August 3rd to 7th. Pioneer 9 observed a solar wind having the maximum velocity as high as 1,100 km/sec, and HEOS-II observed a solar wind having the velocity close to 2,000 km/sec. On the other hand, according to the scintillation of 3C-48 and 3C-144, the velocity of solar wind passing in the interplanetary space on the westside of the earth was only 300 to 400 km/sec. Therefore it is considered that the condition of solar wind on the east side of the earth differs from that on the west side of the earth. Pioneer 9 observed the pass of a shock wave on August 9th. With all radio wave sources, high velocity solar wind was observed and Pioneer 6 positioned on the west side of the earth also observed it. The thickness of this shock wave is at least 0.3 AU. Discussion is made on the cause for the difference between the asymmetric shock wave in the direction of south-west and symmetrical shock wave. The former may be blast wave, and the latter may be piston driven shock wave and the like. (Iwakiri, K.)

Computer model for large-scale offshore wind-power systems

Energy Technology Data Exchange (ETDEWEB)

Dambolena, I G [Bucknell Univ., Lewisburg, PA; Rikkers, R F; Kaminsky, F C

1977-01-01

A computer-based planning model has been developed to evaluate the cost and simulate the performance of offshore wind-power systems. In these systems, the electricity produced by wind generators either satisfies directly demand or produces hydrogen by water electrolysis. The hydrogen is stored and later used to produce electricity in fuel cells. Using as inputs basic characteristics of the system and historical or computer-generated time series for wind speed and electricity demand, the model simulates system performance over time. A history of the energy produced and the discounted annual cost of the system are used to evaluate alternatives. The output also contains information which is useful in pointing towards more favorable design alternatives. Use of the model to analyze a specific wind-power system for New England indicates that electric energy could perhaps be generated at a competitive cost.

Tool for Forecasting Cool-Season Peak Winds Across Kennedy Space Center and Cape Canaveral Air Force Station (CCAFS)

Science.gov (United States)

Barrett, Joe H., III; Roeder, William P.

2010-01-01

Peak wind speed is important element in 24-Hour and Weekly Planning Forecasts issued by 45th Weather Squadron (45 WS). Forecasts issued for planning operations at KSC/CCAFS. 45 WS wind advisories issued for wind gusts greater than or equal to 25 kt. 35 kt and 50 kt from surface to 300 ft. AMU developed cool-season (Oct - Apr) tool to help 45 WS forecast: daily peak wind speed, 5-minute average speed at time of peak wind, and probability peak speed greater than or equal to 25 kt, 35 kt, 50 kt. AMU tool also forecasts daily average wind speed from 30 ft to 60 ft. Phase I and II tools delivered as a Microsoft Excel graphical user interface (GUI). Phase II tool also delivered as Meteorological Interactive Data Display System (MIDDS) GUI. Phase I and II forecast methods were compared to climatology, 45 WS wind advisories and North American Mesoscale model (MesoNAM) forecasts in a verification data set.

Multivariable Wind Modeling in State Space

DEFF Research Database (Denmark)

Sichani, Mahdi Teimouri; Pedersen, B. J.

2011-01-01

Turbulence of the incoming wind field is of paramount importance to the dynamic response of wind turbines. Hence reliable stochastic models of the turbulence should be available from which time series can be generated for dynamic response and structural safety analysis. In the paper an empirical...... for the vector turbulence process incorporating its phase spectrum in one stage, and its results are compared with a conventional ARMA modeling method....... the succeeding state space and ARMA modeling of the turbulence rely on the positive definiteness of the cross-spectral density matrix, the problem with the non-positive definiteness of such matrices is at first addressed and suitable treatments regarding it are proposed. From the adjusted positive definite cross...

A 1290 MHZ profiler with RASS for monitoring wind and temperature in the boundary layer

Energy Technology Data Exchange (ETDEWEB)

Engelbart, D. [Deutscher Wetterdienst, Lindenberg (Germany). Meteorol. Obs.; Steinhagen, H. [Deutscher Wetterdienst, Lindenberg (Germany). Meteorol. Obs.; Goersdorf, U. [Deutscher Wetterdienst, Lindenberg (Germany). Meteorol. Obs.; Lippmann, J. [Deutscher Wetterdienst, Lindenberg (Germany). Meteorol. Obs.; Neisser, J. [Deutscher Wetterdienst, Lindenberg (Germany). Meteorol. Obs.

1996-02-01

A boundary layer wind profiler with RASS is described operating at 1290 MHz in a quasi-operational mode at the Meteorological Observatory Lindenberg of the German Weather Service (DWD). It provides vertical profiles of wind and temperature from the lower atmosphere with a height resolution of 50 m to 400 m and a time resolution of about 1 to 60 minutes. For an estimation of the system reliability, the availability of the measurements for all different height levels is analyzed. With regard to the data quality, a comparison of wind profiler/RASS and rawinsonde data is presented based on 856 wind and 451 temperature profiles. It reveals reasonable conformity of both sounding systems. Finally, case studies are shown, demonstrating the system ability to analyze some characteristic phenomena in the lower troposphere, which are unresolved temporally and spatially by the routine rawinsonde network. (orig.)

Offshore Variability in Critical Weather Conditions in Large-Scale Wind Based Danish Power System

DEFF Research Database (Denmark)

Cutululis, Nicolaos Antonio; Litong-Palima, Marisciel; Sørensen, Poul Ejnar

2013-01-01

of the variability for the 2020 Danish power system, one can see that in the worst case, up to 1500 MW of power can be lost in 30 minutes. We present results showing how this issue is partially solved by the new High Wind Storm Controller presented by Siemens in the TWENTIES project.......Offshore wind power has a significant development potential, especially in North Europe. The geographical concentration of offshore wind power leads to increased variability and in the case of critical weather conditions it may lead to sudden and considerable loss of production. In this context......, the chances of losing several GW of wind power due to critical weather conditions in a very short time period could potentially jeopardize the whole system’s reliability and stability. Forecasting such events is not trivial and the results so far are not encouraging. When assessing the impact...

Impact of wind power uncertainty forecasting on the market integration of wind energy in Spain

International Nuclear Information System (INIS)

González-Aparicio, I.; Zucker, A.

2015-01-01

Highlights: • Reduction wind power forecasting uncertainty for day ahead and intraday markets. • Statistical relationship between total load and wind power generation. • Accurately forecast expected revenues from wind producer’s perspective. - Abstract: The growing share of electricity production from variable renewable energy sources increases the stochastic nature of the power system. This has repercussions on the markets for electricity. Deviations from forecasted production schedules require balancing of a generator’s position within a day. Short term products that are traded on power and/or reserve markets have been developed for this purpose, providing opportunities to actors who can offer flexibility in the short term. The value of flexibility is typically modelled using stochastic scenario extensions of dispatch models which requires, as a first step, understanding the nature of forecast uncertainties. This study provides a new approach for determining the forecast errors of wind power generation in the time period between the closure of the day ahead and the opening of the first intraday session using Spain as an example. The methodology has been developed using time series analysis for the years 2010–2013 to find the explanatory variables of the wind error variability by applying clustering techniques to reduce the range of uncertainty, and regressive techniques to forecast the probability density functions of the intra-day price. This methodology has been tested considering different system actions showing its suitability for developing intra-day bidding strategies and also for the generation of electricity generated from Renewable Energy Sources scenarios. This methodology could help a wind power producer to optimally bid into the intraday market based on more accurate scenarios, increasing their revenues and the system value of wind.

Gastroparesis in patients with inactive Crohn's disease: a case series

Directory of Open Access Journals (Sweden)

Oyen Wim JG

2007-03-01

Full Text Available Abstract Background Few studies have described patients with foregut dysmotility in inflammatory bowel disease. The aim of this case series was to evaluate clinical characteristics of 5 patients with inflammatory bowel disease and symptoms and signs of upper gut dysmotility. Case presentations We describe a series of four patients with Crohn's disease and one with indeterminate colitis who presented with severe symptoms and signs of gastroparesis. We reviewed medical records of all cases. Gastric emptying of a solid meal was assessed by scintigraphy. Small bowel enteroclysis, gastroduodenoscopy and colonoscopy with biopsies were performed to estimate the activity of the disease and to exclude organic obstruction. None of the patients had any signs of active inflammation or stricture. All of the patients had markedly delayed gastric emptying with a mean t 1/2 of 234 minutes (range 110–380 minutes; normal values 54–94 minutes. Conclusion Clinicians should consider impaired gastric emptying when evaluating patients with Crohn's disease and severe symptoms of upper gut dysmotility, which cannot be attributed to active inflammation or organic obstruction of the digestive tract. Symptoms in these patients are refractory to various therapeutic interventions including tube feeding and gastric surgery.

Harmonisation of wind turbine certification in Europe JOULE project EWTC

Energy Technology Data Exchange (ETDEWEB)

Nath, C [Germanischer Lloyd, Hamburg (Germany); Eriksson, C [Det Norske Veritas, Hellerup (Denmark); Hulle, F van [Frans van Hulle, Petten (Netherlands); Skamris, C [Risoe National Lab., Roskilde (Denmark); Stam, W [CIWI Holland, Arnheim (Netherlands); Vionis, P [CRES, Attki (Greece)

1999-03-01

Wind turbine certification requirements are currently fairly divers within Europe. Therefore the leading European certification bodies initiated a JOULE project to harmonise the certification procedure on the basis of the current set of IEC/EN 61400 series standards. The paper presents a review of the state of the art of wind turbine certification in European countries and an outline of the sturcture of the project. The main steps of the project are (a) the collection of differences in certification practices by round robin certification of three wind turbine types; (b) assessment of the different certification results and (c) the development of a harmonised certification procedure. (au) EU-JOULE-3. 19 refs.

Performance testing of a small vertical-axis wind turbine

Energy Technology Data Exchange (ETDEWEB)

Bravo, R.; Tullis, S.; Ziada, S. [McMaster Univ., Hamilton, ON (Canada). Dept. of Mechanical Engineering

2007-07-01

Full-scale wind tunnel testing of a prototype 3.5 kW vertical-axis wind turbine (VAWT) was conducted in a low speed wind tunnel in Ottawa. The tests were conducted to determine nominal power curves as well as the system's structural integrity, safety and operational characteristics. Dimensionless power curves were used to assess the relation between the wind turbine's rotary speed and the produced power for various wind speeds. Tests began at the lowest wind speed and revolutions per minute (RPM) and were gradually increased. A proximity sensor was used to determine the passing frequency of spaced bolts. The aerodynamic performance of the turbine was evaluated using a servo-controlled mechanical variable load with a disc brake calliper and electro-hydraulic servo-actuator. A load cell was used to measure torque produced by the turbine. An active closed loop speed control system was used to regulate the rotary speed of the turbine. The system used a high gain proportional control law to guarantee stability. Calculated power was based on the average rotary speed measurement. Results of the study suggested that the dimensional power performance of the turbine could be predicted from the curve for all rotary speeds and for wind speeds between 8 and 16 m/s. The maximum power coefficient of 0.3 occurred at a tip speed ratio of 1.6. Test results demonstrated that the turbine reached its rated power at 14 m/s. However, the range of tip speed ratios for power production were lower than the range for most other small VAWT. 2 refs., 3 figs.

75 FR 23263 - Alta Wind I, LLC; Alta Wind II, LLC; Alta Wind III, LLC; Alta Wind IV, LLC; Alta Wind V, LLC...

Science.gov (United States)

2010-05-03

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL10-62-000] Alta Wind I, LLC; Alta Wind II, LLC; Alta Wind III, LLC; Alta Wind IV, LLC; Alta Wind V, LLC; Alta Wind VI, LLC; Alta Wind VII, LLC; Alta Wind VIII, LLC; Alta Windpower Development, LLC; TGP Development Company, LLC...

77 FR 29633 - Alta Wind VII, LLC, Alta Wind IX, LLC, Alta Wind X, LLC, Alta Wind XI, LLC, Alta Wind XII, LLC...

Science.gov (United States)

2012-05-18

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL12-68-000] Alta Wind VII, LLC, Alta Wind IX, LLC, Alta Wind X, LLC, Alta Wind XI, LLC, Alta Wind XII, LLC, Alta Wind XIII, LLC, Alta Wind XIV, LLC, Alta Wind XV, LLC, Alta Windpower Development, LLC, TGP Development Company, LLC...

Lightning discharges produced by wind turbines

Science.gov (United States)

Montanyà, Joan; van der Velde, Oscar; Williams, Earle R.

2014-02-01

New observations with a 3-D Lightning Mapping Array and high-speed video are presented and discussed. The first set of observations shows that under certain thunderstorm conditions, wind turbine blades can produce electric discharges at regular intervals of 3 s in relation to its rotation, over periods of time that range from a few minutes up to hours. This periodic effect has not been observed in static towers indicating that the effect of rotation is playing a critical role. The repeated discharges can occur tens of kilometers away from electrically active thunderstorm areas and may or may not precede a fully developed upward lightning discharge from the turbine. Similar to rockets used for triggering lightning, the fast movement of the blade tip plays an important role on the initiation of the discharge. The movement of the rotor blades allows the tip to "runaway" from the generated corona charge. The second observation is an uncommon upward/downward flash triggered by a wind turbine. In that flash, a negative upward leader was initiated from a wind turbine without preceding lightning activity. The flash produced a negative cloud-to-ground stroke several kilometers from the initiation point. The third observation corresponds to a high-speed video record showing simultaneous upward positive leaders from a group of wind turbines triggered by a preceding intracloud flash. The fact that multiple leaders develop simultaneously indicates a poor shielding effect among them. All these observations provide some special features on the initiation of lightning by nonstatic and complex tall structures.

Electrical and non-electrical environment of wind turbine main components

DEFF Research Database (Denmark)

Holboell, J.; Henriksen, M.; Olsen, R.S.

of the electrical components or even lead to catastrophic component failure. In the present paper, results are presented from investigations on existing standards which give detailed descriptions of the environmental and operational conditions of wind turbine components. It is found that there is currently a lack...... of application standards for wind turbine electrical equipment. Component-level environmental requirements as given in equipment-specific standards are compared with the environment described in the IEC's 61400 series concerning wind turbines. Based on methods defined in IEC 60721, the non-electrical environment...... of wind turbine is described by means of specific classes. In the paper, new class combinations are suggested covering the different operating conditions the components are exposed to. The class combinations include factors of climatic, mechanical and chemical character. The factors occur in different...

Near Real Time MISR Wind Observations for Numerical Weather Prediction

Science.gov (United States)

Mueller, K. J.; Protack, S.; Rheingans, B. E.; Hansen, E. G.; Jovanovic, V. M.; Baker, N.; Liu, J.; Val, S.

2014-12-01

The Multi-angle Imaging SpectroRadiometer (MISR) project, in association with the NASA Langley Atmospheric Science Data Center (ASDC), has this year adapted its original production software to generate near-real time (NRT) cloud-motion winds as well as radiance imagery from all nine MISR cameras. These products are made publicly available at the ASDC with a latency of less than 3 hours. Launched aboard the sun-synchronous Terra platform in 1999, the MISR instrument continues to acquire near-global, 275 m resolution, multi-angle imagery. During a single 7 minute overpass of any given area, MISR retrieves the stereoscopic height and horizontal motion of clouds from the multi-angle data, yielding meso-scale near-instantaneous wind vectors. The ongoing 15-year record of MISR height-resolved winds at 17.6 km resolution has been validated against independent data sources. Low-level winds dominate the sampling, and agree to within ±3 ms-1 of collocated GOES and other observations. Low-level wind observations are of particular interest to weather forecasting, where there is a dearth of observations suitable for assimilation, in part due to reliability concerns associated with winds whose heights are assigned by the infrared brightness temperature technique. MISR cloud heights, on the other hand, are generated from stereophotogrammetric pattern matching of visible radiances. MISR winds also address data gaps in the latitude bands between geostationary satellite coverage and polar orbiting instruments that obtain winds from multiple overpasses (e.g. MODIS). Observational impact studies conducted by the Naval Research Laboratory (NRL) and by the German Weather Service (Deutscher Wetterdienst) have both demonstrated forecast improvements when assimilating MISR winds. An impact assessment using the GEOS-5 system is currently in progress. To benefit air quality forecasts, the MISR project is currently investigating the feasibility of generating near-real time aerosol products.

The suitability of the IEC 61400-2 wind model for small wind turbines operating in the built environment★

Directory of Open Access Journals (Sweden)

Evans Samuel P.

2017-01-01

Full Text Available This paper investigates the applicability of the assumed wind fields in International Electrotechnical Commission (IEC standard 61400 Part 2, the design standard for small wind turbines, for a turbine operating in the built environment, and the effects these wind fields have on the predicted performance of a 5 kW Aerogenesis turbine using detailed aeroelastic models developed in Fatigue Aerodynamics Structures and Turbulence (FAST. Detailed wind measurements were acquired at two built environment sites: from the rooftop of a Bunnings Ltd. warehouse at Port Kennedy (PK (Perth, Australia and from the small wind turbine site at the University of Newcastle at Callaghan (Newcastle, Australia. For both sites, IEC 61400-2 underestimates the turbulence intensity for the majority of the measured wind speeds. A detailed aeroelastic model was built in FAST using the assumed wind field from IEC 61400-2 and the measured wind fields from PK and Callaghan as an input to predict key turbine performance parameters. The results of this analysis show a modest increase in the predicted mean power for the higher turbulence regimes of PK and Callaghan as well as higher variation in output power. Predicted mean rotor thrust and blade flapwise loading showed a minor increase due to higher turbulence, with mean predicted torque almost identical but with increased variations due to higher turbulence. Damage equivalent loading for the blade flapwise moment was predicted to be 58% and 11% higher for a turbine operating at Callaghan and PK respectively, when compared with IEC 61400-2 wind field. Time series plots for blade flapwise moments and power spectral density plots in the frequency domain show consistently higher blade flapwise bending moments for the Callaghan site with both the sites showing a once-per-revolution response.

Development of analog watch with minute repeater

Science.gov (United States)

Okigami, Tomio; Aoyama, Shigeru; Osa, Takashi; Igarashi, Kiyotaka; Ikegami, Tomomi

A complementary metal oxide semiconductor with large scale integration was developed for an electronic minute repeater. It is equipped with the synthetic struck sound circuit to generate natural struck sound necessary for the minute repeater. This circuit consists of an envelope curve drawing circuit, frequency mixer, polyphonic mixer, and booster circuit made by using analog circuit technology. This large scale integration is a single chip microcomputer with motor drivers and input ports in addition to the synthetic struck sound circuit, and it is possible to make an electronic system of minute repeater at a very low cost in comparison with the conventional type.

Mapping 3D plasma structure in the solar wind with the L1 constellation: joint observations from Wind, ACE, DSCOVR, and SoHO

Science.gov (United States)

Stevens, M. L.; Kasper, J. C.; Case, A. W.; Korreck, K. E.; Szabo, A.; Biesecker, D. A.; Prchlik, J.

2017-12-01

At this moment in time, four observatories with similar instrumentation- Wind, ACE, DSCOVR, and SoHO- are stationed directly upstream of the Earth and making continuous observations. They are separated by drift-time baselines of seconds to minutes, timescales on which MHD instabilities in the solar wind are known to grow and evolve, and spatial baselines of tens to 200 earth radii, length scales relevant to the Earth's magnetosphere. By comparing measurements of matched solar wind structures from the four vantage points, the form of structures and associated dynamics on these scales is illuminated. Our targets include shocks and MHD discontinuities, stream fronts, locii of reconnection and exhaust flow boundary layers, plasmoids, and solitary structures born of nonlinear instability. We use the tetrahedral quality factors and other conventions adopted for Cluster to identify periods where the WADS constellation is suitably non-degenerate and arranged in such a way as to enable specific types of spatial, temporal, or spatiotemporal inferences. We present here an overview of the geometries accessible to the L1 constellation and timing-based and plasma-based observations of solar wind structures from 2016-17. We discuss the unique potential of the constellation approach for space physics and space weather forecasting at 1 AU.

Spatial and temporal patterns of global onshore wind speed distribution

International Nuclear Information System (INIS)

Zhou, Yuyu; Smith, Steven J

2013-01-01

Wind power, a renewable energy source, can play an important role in electrical energy generation. Information regarding wind energy potential is important both for energy related modeling and for decision-making in the policy community. While wind speed datasets with high spatial and temporal resolution are often ultimately used for detailed planning, simpler assumptions are often used in analysis work. An accurate representation of the wind speed frequency distribution is needed in order to properly characterize wind energy potential. Using a power density method, this study estimated global variation in wind parameters as fitted to a Weibull density function using NCEP/climate forecast system reanalysis (CFSR) data over land areas. The Weibull distribution performs well in fitting the time series wind speed data at most locations according to R 2 , root mean square error, and power density error. The wind speed frequency distribution, as represented by the Weibull k parameter, exhibits a large amount of spatial variation, a regionally varying amount of seasonal variation, and relatively low decadal variation. We also analyzed the potential error in wind power estimation when a commonly assumed Rayleigh distribution (Weibull k = 2) is used. We find that the assumption of the same Weibull parameter across large regions can result in non-negligible errors. While large-scale wind speed data are often presented in the form of mean wind speeds, these results highlight the need to also provide information on the wind speed frequency distribution. (letter)

Database on wind characteristics - contents of database bank

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)

Bidirectional Flyback Converter with Multiple Series Connected Outputs for High Voltage Capacitive Charge and Discharge Applications

DEFF Research Database (Denmark)

Thummala, Prasanth; Schneider, Henrik; Zhang, Zhe

2015-01-01

is limited by the parasitics of the high voltage active components, which also prevent full utilization of valley switching during discharge process. A second implementation is therefore proposed, where the secondary of flyback transformer winding is split into multiple windings which are connected in series...

Measured wind speed trends on the west coast of Canada

Science.gov (United States)

Tuller, Stanton E.

2004-09-01

Trends in measured wind speed are discussed for four stations on the west coast of Canada. Periods of record vary with the station. They begin in the late 1940s or the 1950s and run through to the early to mid 1990s. The most prominent feature of the time series was a decline in mean annual and winter wind speeds at Cape St James, Victoria International Airport, and Vancouver International Airport during the middle portion of the record. Declines in mean annual wind speed are matched by increases in the percentage of calms and decreases in high wind speed observations. The pressure gradient between Victoria, Vancouver and Comox, the Pacific North American index, the Pacific decadal oscillation index, and other climate elements in British Columbia and the northwestern USA show trends at roughly the same time, indicating a natural cause of the wind speed decrease. Comox Airport mean wind speeds increased, however, perhaps the result of reduced friction in the vicinity of the anemometer outweighing the decrease in the regional pressure gradient.

Reliability measures for indexed semi-Markov chains applied to wind energy production

International Nuclear Information System (INIS)

D'Amico, Guglielmo; Petroni, Filippo; Prattico, Flavio

2015-01-01

The computation of the dependability measures is a crucial point in many engineering problems as well as in the planning and development of a wind farm. In this paper we address the issue of energy production by wind turbines by using an indexed semi-Markov chain as a model of wind speed. We present the mathematical model, the data and technical characteristics of a commercial wind turbine (Aircon HAWT-10kW). We show how to compute some of the main dependability measures such as reliability, availability and maintainability functions. We compare the results of the model with real energy production obtained from data available in the Lastem station (Italy) and sampled every 10 min. - Highlights: • Semi-Markov models. • Time series generation of wind speed. • Computation of availability, reliability and maintainability.

Stochastic model of wind-fuel cell for a semi-dispatchable power generation

DEFF Research Database (Denmark)

Alvarez-Mendoza, Fernanda; Bacher, Peder; Madsen, Henrik

2017-01-01

electrolyte membrane fuel cell, which are embedded in one complete system with the wind power. This study uses historic wind speed data from Mexico; the forecasts are obtained using the recursive least square algorithm with a forgetting factor. The proposed approach provides probabilistic information......Hybrid systems are implemented to improve the efficiency of individual generation technologies by complementing each other. Intermittence is a challenge to overcome especially for renewable energy sources for electric generation, as in the case of wind power. This paper proposes a hybrid system...... for short-term wind power generation and electric generation as the outcome of the hybrid system. A method for a semi-dispatchable electric generation based on time series analysis is presented, and the implementation of wind power and polymer electrolyte membrane fuel cell models controlled by a model...

Wavelet decomposition and neuro-fuzzy hybrid system applied to short-term wind power

Energy Technology Data Exchange (ETDEWEB)

Fernandez-Jimenez, L.A.; Mendoza-Villena, M. [La Rioja Univ., Logrono (Spain). Dept. of Electrical Engineering; Ramirez-Rosado, I.J.; Abebe, B. [Zaragoza Univ., Zaragoza (Spain). Dept. of Electrical Engineering

2010-03-09

Wind energy has become increasingly popular as a renewable energy source. However, the integration of wind farms in the electrical power systems presents several problems, including the chaotic fluctuation of wind flow which results in highly varied power generation from a wind farm. An accurate forecast of wind power generation has important consequences in the economic operation of the integrated power system. This paper presented a new statistical short-term wind power forecasting model based on wavelet decomposition and neuro-fuzzy systems optimized with a genetic algorithm. The paper discussed wavelet decomposition; the proposed wind power forecasting model; and computer results. The original time series, the mean electric power generated in a wind farm, was decomposing into wavelet coefficients that were utilized as inputs for the forecasting model. The forecasting results obtained with the final models were compared to those obtained with traditional forecasting models showing a better performance for all the forecasting horizons. 13 refs., 1 tab., 4 figs.

Cooperative field test program for wind systems. Final report

Energy Technology Data Exchange (ETDEWEB)

Bollmeier, W.S. II; Dodge, D.M.

1992-03-01

The objectives of the Federal Wind Energy Program, managed by the US Department of Energy (DOE), are (1) to assist industry and utilities in achieving a multi-regional US market penetration of wind systems, and (2) to establish the United States as the world leader in the development of advanced wind turbine technology. In 1984, the program conducted a series of planning workshops with representatives from the wind energy industry to obtain input on the Five-Year Research Plan then being prepared by DOE. One specific suggestion that came out of these meetings was that the federal program should conduct cooperative research tests with industry to enhance the technology transfer process. It was also felt that the active involvement of industry in DOE-funded research would improve the state of the art of wind turbine technology. DOE established the Cooperative Field Test Program (CFTP) in response to that suggestion. This program was one of the first in DOE to feature joint industry-government research test teams working toward common objectives.

Overcoming barriers to wind project finance in Australia

International Nuclear Information System (INIS)

Kann, Shayle

2009-01-01

The wind power industry in Australia is expected to grow rapidly over the next decade, primarily due to a forthcoming expanded national renewable energy target (RET) which will mandate that renewable sources provide approximately 20% of Australia's electricity production by 2020. However, development of new wind generation in Australia has stalled as a result of several barriers to project finance, the mechanism through which most wind farms have been developed historically. This paper provides an overview of wind power financing in Australia in light of recent political and financial trends. Drawing upon existing literature and a series of stakeholder interviews, it identifies three primary barriers to project finance: regulatory risk surrounding legislation of the RET, semi-privatization of electricity retailers in New South Wales, and limited capital availability resulting from the recent global credit crisis. The paper concludes that the confluence of these barriers limits the availability of long-term contracts that provide revenue certainty for pre-construction wind projects, while simultaneously making these contracts a necessity in order to obtain project finance. In an attempt to mitigate these effects, this paper identifies four alternative development strategies that can be pursued.

Equivalent models of wind farms by using aggregated wind turbines and equivalent winds

International Nuclear Information System (INIS)

Fernandez, L.M.; Garcia, C.A.; Saenz, J.R.; Jurado, F.

2009-01-01

As a result of the increasing wind farms penetration on power systems, the wind farms begin to influence power system, and therefore the modeling of wind farms has become an interesting research topic. In this paper, new equivalent models of wind farms equipped with wind turbines based on squirrel-cage induction generators and doubly-fed induction generators are proposed to represent the collective behavior on large power systems simulations, instead of using a complete model of wind farms where all the wind turbines are modeled. The models proposed here are based on aggregating wind turbines into an equivalent wind turbine which receives an equivalent wind of the ones incident on the aggregated wind turbines. The equivalent wind turbine presents re-scaled power capacity and the same complete model as the individual wind turbines, which supposes the main feature of the present equivalent models. Two equivalent winds are evaluated in this work: (1) the average wind from the ones incident on the aggregated wind turbines with similar winds, and (2) an equivalent incoming wind derived from the power curve and the wind incident on each wind turbine. The effectiveness of the equivalent models to represent the collective response of the wind farm at the point of common coupling to grid is demonstrated by comparison with the wind farm response obtained from the detailed model during power system dynamic simulations, such as wind fluctuations and a grid disturbance. The present models can be used for grid integration studies of large power system with an important reduction of the model order and the computation time

78 FR 29364 - Exelon Corporation, Exelon Wind 1, LLC, Exelon Wind 2, LLC, Exelon Wind 3, LLC, Exelon Wind 4...

Science.gov (United States)

2013-05-20

...-005, QF07-55-005, QF07-56-005, QF07-257-004] Exelon Corporation, Exelon Wind 1, LLC, Exelon Wind 2, LLC, Exelon Wind 3, LLC, Exelon Wind 4, LLC, Exelon Wind 5, LLC, Exelon Wind 6, LLC, Exelon Wind 7, LLC, Exelon Wind 8, LLC, Exelon Wind 9, LLC, Exelon Wind 10, LLC, Exelon Wind 11, LLC, High Plains...

Theory of radiatively driven stellar winds. I. A physical interpretation

International Nuclear Information System (INIS)

Abbott, D.C.

1980-01-01

This series of papers extends the line-driven wind theory of Castor, Abbott, and Klein (CAK). The present paper develops a physical interpretation of line-driven flows using analytic methods. Numerical results will follow in two subsequent papers

Testing the effectiveness of monolayers under wind and wave conditions.

Science.gov (United States)

Palada, C; Schouten, P; Lemckert, C

2012-01-01

Monolayers are highly desirable for their evaporation reducing capabilities due to their relatively minimal cost and ease of application. Despite these positive attributes, monolayers have consistently failed to perform effectively due to the harsh wind and wave conditions prevalent across real-world water reserves. An exhaustive and consistent study testing the influence of wind and wave combinations on monolayer performance has yet to be presented in the literature. To remedy this, the effect of simultaneous wind and wave conditions on a benchmark high-performance monolayer (octadecanol suspension, CH(3)(CH(2))(16)CH(2)OH) has been analysed. Subjected only to waves, the monolayer remained intact due to its innate ability to compress and expand. However, the constant simultaneous application of wind and waves caused the monolayer to break up and gather down-wind where it volatilised over time. At wind speeds above 1.3 m s(-1) the monolayer was completely ineffective. For wind speeds below this threshold, the monolayer had an influence on the evaporation rate dependent on wind speed. From these results a series of application protocols can now be developed for the optimised deployment of monolayers in real-world water reserves. This will be of interest to private, commercial and government organisations involved in the storage and management of water resources.

Determination trends and abnormal seasonal wind speed in Iraq

Energy Technology Data Exchange (ETDEWEB)

Hassoon, Ahmed F. [Department of Atmospheric Sciences, College of Science, AL- Mustansiriyah University, Baghdad (Iraq)

2013-07-01

Monthly observed wind speed data at four weather stations (Baghdad, Mosul, Basra, Rutba) at 10m above surface were used to explore the temporal variations of the wind speed (1971-2000) in Iraq. There are different methods to analyze wind speed variation data, but the time series are one of the powerful analysis methods to diagnose the seasonal wind speed anomaly. The results show most high abnormal data is found in summer seasons in all the stations of study, where it concentrated at 1975, 1976, 1978,1996-1995, 2000. Rutba station is different where its high deviation about annual average at nearly all the seasons, in this station there are trends in seasonal wind towards decreases in all the seasons, for example in winter it reached to about 0.046m/s.a-1, while in other stations Mosul and Basra there increases in annual seasonal wind speed trends in seasons spring, summer, autumn where its reached higher value at summer in Basra about 0.0482m/s.a-1. The second method to determine abnormal annual seasonal wind speed is through comparison seasonal average wind speed, where the average wind speed at the seasons summer and spring in Baghdad and Basra station have very high averages at nearly all years, this cannot see in Mosul and Rutba, in Rutba the seasonal average is intersected with each other, summer and spring is not have greater seasonal average in this station.

CEPF Western Ghats Special Series: Avian collision threat assessment at Bhambarwadi Wind Farm Plateau in northern Western Ghats, India

Directory of Open Access Journals (Sweden)

S. Pande

2013-01-01

Full Text Available To address the shortage of power in India, wind energy is increasingly harnessed as an alternate and renewable energy source. There is a rapid increase in the number of wind farms at suitable sites all over the country. Some of the key sites with optimal wind velocities are the plateaus on the Western Ghats - a global hotspot of biological diversity. The rocky plateaus on the Western Ghats are terrestrial habitat islands facing extreme micro-environmental conditions; however, scanty information is available on the ecology of these plateaus. We undertook a two-year study to assess the impact of wind farms on birds. We also documented the avian diversity at Bhambarwadi Plateau, northern Western Ghats, India. To the best of our knowledge this is the first such study in India. We recorded 89 avian species on the plateau, 27 of which flew in the risk area swept by the rotor blades, and hence are potentially at risk of collision. The collision index (the number of bird collisions with wind turbines over a period of one year assuming that the birds do not take any avoidance measure for these species were estimated. We also identified species at risk from collision with transformers and wind-masts, and at risk from electrocution. Reduction in avian activity in the study area was evident with progress of wind farm erection. Despite the small footprint of an individual wind turbine, the associated infrastructure development causes wider habitat modification and destruction resulting in a displacement effect. Therefore, wind farm erections in strategic locations such as biodiversity hotspots should be subject to prior site based strategic environmental assessments (SEA as well as environmental impact assessment (EIA studies.

Fabry-Perot interferometer measurements of neutral winds and F2 layer variations at the magnetic equator

Directory of Open Access Journals (Sweden)

P. Vila

1998-06-01

Full Text Available This letter presents some night-time observations of neutral wind variations at F2 layer levels near the dip equator, measured by the Fabry-Perot interferometer set up in 1994 at Korhogo (Ivory Coast, geographic latitude 9.25°N, longitude 355°E, dip latitude –2.5°. Our instrument uses the 630 nm (O1D line to determine radial Doppler velocities of the oxygen atoms between 200 and 400 km altitude. First results for November 1994 to March 1995 reveal persistent eastward flows, and frequent intervals of southward winds of larger than 50 ms–1 velocity. Compared with the simultaneous ionospheric patterns deduced from the three West African equatorial ionosondes at Korhogo, Ouagadougou (Burkina-Faso, dip latitude +1.5° and Dakar (Sénégal, dip latitude +5°, they illustrate various impacts of the thermospheric winds on F2 layer density: (1 on the mesoscale evolution (a few 103 km and a few 100 minutes scales and (2 on local fluctuations (hundreds of km and tens of minutes characteristic times. We report on these fluctuations and discuss the opportunity to improve the time-resolution of the Fabry-Perot interferometer at Korhogo.Key words. Ionosphere (Equatorial ionosphere; Ionosphere-atmosphere interaction · Meteorology and Atmospheric Dynamics (General circulation

Solar wind monitor—a school geophysics project

Science.gov (United States)

Robinson, Ian

2018-05-01

Described is an established geophysics project to construct a solar wind monitor based on a nT resolution fluxgate magnetometer. Low-cost and appropriate from school to university level it incorporates elements of astrophysics, geophysics, electronics, programming, computer networking and signal processing. The system monitors the earth’s field in real-time uploading data and graphs to a website every few minutes. Modular design encourages construction and testing by teams of students as well as expansion and refinement. The system has been tested running unattended for months at a time. Both the hardware design and software is published as open-source [1, 10].

SAT-WIND project. Final report[Winds from satellites for offshore and coastal wind energy mapping and wind-indexing

Energy Technology Data Exchange (ETDEWEB)

Hasager, C.B.; Astrup, P.; Nielsen, M. (and others)

2007-04-15

The SAT-WIND project 'Winds from satellites for offshore and coastal wind energy mapping and wind-indexing' was a research project funded by STVF/DSF in the years 2003 to 2006 (Sagsnr. 2058-03-0006). The goal of the project was to verify the applicability of satellite wind maps derived from passive microwave, altimeter, scatterometer and imaging Synthetic Aperture Radar (SAR) technologies for wind energy tools for wind resources and wind-indexing. The study area was the Danish Seas including the North Sea, interior seas and the Baltic Sea. The report describes technical details on the satellite data sources including: 1) passive microwave (SSM/I, AMSR-E), 2) passive microwave polarimetric (WindSat), 3) scatterometer (ERS, QuikSCAT, Midori-2 and NSCAT), 4) altimeter (ERS, Topex, Poseidon, GFO-1, Jason-1), 5) SAR (ERS, Envisat). The SAR wind maps were treated in S-WAsP developed by Risoe National Laboratory in cooperation with GRAS A/S in the innovative project SAT-WIND-SMV (Sagsnr. 2104-05-0084) in the years 2005 and 2006 in parallel with SAT-WIND. The results from the SAT-WIND project are presented. These include ocean wind statistics, offshore wind resource estimates and comparison results for wind-indexing. (au)

SAT-WIND project. Final report[Winds from satellites for offshore and coastal wind energy mapping and wind-indexing

Energy Technology Data Exchange (ETDEWEB)

Hasager, C B; Astrup, P; Nielsen, M [and others

2007-04-15

The SAT-WIND project 'Winds from satellites for offshore and coastal wind energy mapping and wind-indexing' was a research project funded by STVF/DSF in the years 2003 to 2006 (Sagsnr. 2058-03-0006). The goal of the project was to verify the applicability of satellite wind maps derived from passive microwave, altimeter, scatterometer and imaging Synthetic Aperture Radar (SAR) technologies for wind energy tools for wind resources and wind-indexing. The study area was the Danish Seas including the North Sea, interior seas and the Baltic Sea. The report describes technical details on the satellite data sources including: 1) passive microwave (SSM/I, AMSR-E), 2) passive microwave polarimetric (WindSat), 3) scatterometer (ERS, QuikSCAT, Midori-2 and NSCAT), 4) altimeter (ERS, Topex, Poseidon, GFO-1, Jason-1), 5) SAR (ERS, Envisat). The SAR wind maps were treated in S-WAsP developed by Risoe National Laboratory in cooperation with GRAS A/S in the innovative project SAT-WIND-SMV (Sagsnr. 2104-05-0084) in the years 2005 and 2006 in parallel with SAT-WIND. The results from the SAT-WIND project are presented. These include ocean wind statistics, offshore wind resource estimates and comparison results for wind-indexing. (au)

Wind speed forecasting in the South Coast of Oaxaca, Mexico

Energy Technology Data Exchange (ETDEWEB)

Cadenas, Erasmo [Facultad de Ingenieria Mecanica, Universidad Michoacana de San Nicolas de Hidalgo, Santiago Tapia No. 403, Centro (Mexico); Rivera, Wilfrido [Centro de Investigacion en Energia of the Universidad Nacional Autonoma de Mexico (UNAM), Apartado Postal 34, Temixco 62580, Morelos (Mexico)

2007-10-15

Comparison of two techniques for wind speed forecasting in the South Coast of the state of Oaxaca, Mexico is presented in this paper. The Autoregressive Integrated Moving Average (ARIMA) and the Artificial Neural Networks (ANN) methods are applied to a time series conformed by 7 years of wind speed measurements. Six years were used in the formulation of the models and the last year was used to validate and compare the effectiveness of the generated prediction by the techniques mentioned above. Seasonal ARIMA models present a better sensitivity to the adjustment and prediction of the wind speed for this case in particular. Nevertheless, it was shown both developed models can be used to predict in a reasonable way, the monthly electricity production of the wind power stations in La Venta, Oaxaca, Mexico to support the operators of the Electric Utility Control Centre. (author)

Measured and modelled local wind field over a frozen lake in a mountainous area

Energy Technology Data Exchange (ETDEWEB)

Smedman, A.S.; Bergstroem, H.; Hoegstroem, U. [Uppsala Univ. (Sweden). Dept. of Meteorology

1996-03-01

The study is a follow-up of a previous paper and concentrates on two very characteristic flow regimes: forced channeling, where the driving geostrophic wind and the lake axis are roughly aligned, and pressure-driven channeling or gap winds, which are characterized by a geostrophic wind direction more or less perpendicular to the lake axis. Both situations produce winds along the main axis of the lake. In the forced channeling case the wind direction varies insignificantly with height and the wind speed increases monotonically with height. The gap wind flow, which can give supergeostrophic speed, is restricted to the lowest 500 m above the lake surface, drops in speed to near zero just above that layer, changing to an across-wind direction higher up. Gap winds are found to require slightly stable stratification for their existence; strong stability forces the flow to go round the mountains rather than over, and neutral conditions give a turbulent wake in the lee of the mountains. The gap wind starts at any occasion as a sudden warm front approaching from either of the two along-lake directions (115 or 295 degrees). It is argued that the relative warmth of the `gap wind air` is due to air originally flowing at mountain top height across the lake axis being gradually turned and accelerated along the synoptic pressure gradient while descending. The strongly sheared layer at the top of the gap wind region is dynamically highly unstable, giving rise to vertically coherent variations in wind speed and direction which appear to be triggered by gravity waves. When the driving geostrophic wind is high enough, the disturbed region reaches all the way down to the ground surface. Then periods with strong turbulence and low mean wind alternate with pronounced gap winds on typically a 10 minute scale. 11 refs, 18 figs

Impact of Short Interval SMS Digital Data on Wind Vector Determination for a Severe Local Storms Area

Science.gov (United States)

Peslen, C. A.

1979-01-01

The impact of 5 minute interval SMS-2 visible digital image data in analyzing severe local storms is examined using wind vectors derived from cloud tracking on time lapsed sequence of geosynchronous satellite images. The cloud tracking areas are located in the Central Plains, where on 6 May 1975, hail-producing thunderstorms occurred ahead of a well defined dry line. The results demonstrate that satellite-derived wind vectors and their associated divergence fields complement conventional meteorological analyses in describing the conditions preceding severe local storm development.

Modelling Wind for Wind Farm Layout Optimization Using Joint Distribution of Wind Speed and Wind Direction

OpenAIRE

Ju Feng; Wen Zhong Shen

2015-01-01

Reliable wind modelling is of crucial importance for wind farm development. The common practice of using sector-wise Weibull distributions has been found inappropriate for wind farm layout optimization. In this study, we propose a simple and easily implementable method to construct joint distributions of wind speed and wind direction, which is based on the parameters of sector-wise Weibull distributions and interpolations between direction sectors. It is applied to the wind measurement data a...

Design of the LRP airfoil series using 2D CFD

DEFF Research Database (Denmark)

Zahle, Frederik; Bak, Christian; Sørensen, Niels N.

2014-01-01

This paper describes the design and wind tunnel testing of a high-Reynolds number, high lift airfoil series designed for wind turbines. The airfoils were designed using direct gradient- based numerical multi-point optimization based on a Bezier parameterization of the shape, coupled to the 2D...... Navier-Stokes flow solver EllipSys2D. The resulting airfoils, the LRP2-30 and LRP2-36, achieve both higher operational lift coefficients and higher lift to drag ratios compared to the equivalent FFA-W3 airfoils....

Design of the LRP airfoil series using 2D CFD

International Nuclear Information System (INIS)

Zahle, Frederik; Bak, Christian; Sørensen, Niels N; Vronsky, Tomas; Gaudern, Nicholas

2014-01-01

This paper describes the design and wind tunnel testing of a high-Reynolds number, high lift airfoil series designed for wind turbines. The airfoils were designed using direct gradient- based numerical multi-point optimization based on a Bezier parameterization of the shape, coupled to the 2D Navier-Stokes flow solver EllipSys2D. The resulting airfoils, the LRP2-30 and LRP2-36, achieve both higher operational lift coefficients and higher lift to drag ratios compared to the equivalent FFA-W3 airfoils

Regulation techniques for smoothing active power in aggregated wind farms distributed within Spain

Energy Technology Data Exchange (ETDEWEB)

Martin-Martinez, Sergio; Vigueras-Rodriguez, Antonio; Gomez-Lazaro, Emilio [Universidad de Castilla-La Mancha, Albacete (Spain). Renewable Energy Research Inst.

2009-07-01

With the increasing production of wind power worldwide, power fluctuations have an impact on power system operation and costs. Power systems with high wind penetration gives rise to concerns about the adverse effects of wind farms on power operations and its staability. The integration of the power produced by wind farms is evaluated through ramp rates calculated as suggested by Parson et al. The worst cases regarding the power system are the most negative ramp rates in the Wind Farm, where the Power System has to compensate such drops in the wind power production. In most onshore wind farms production fluctuates much less than in offshore farms, due to two main reasons. First, offshore wind turbines are collected in a more reduced area, so fluctuations are more correlated. In addition, offshore meteorological conditions are often different than onshore. Furthermore, the variability of wind power is reduced when looking at a large interconnected sytem with geographically dispersed wind power production. This paper deals with a comparison of the smoothed out variability of wind power production time series for the single and aggregated wind farms, parting from their wind power production. The data analyzed come from a 1 year-period measurements of 9 wind farms spread over Spain. (orig.)

GALAXY INTERACTIONS IN COMPACT GROUPS. I. THE GALACTIC WINDS OF HCG16

Energy Technology Data Exchange (ETDEWEB)

Vogt, Frederic P. A.; Dopita, Michael A.; Kewley, Lisa J., E-mail: fvogt@mso.anu.edu.au [Mount Stromlo Observatory, Research School of Astronomy and Astrophysics, Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia)

2013-05-10

Using the WiFeS integral field spectrograph, we have undertaken a series of observations of star-forming galaxies in compact groups. In this first paper dedicated to the project, we present the analysis of the spiral galaxy NGC 838, a member of the Hickson Compact Group 16, and of its galactic wind. Our observations reveal that the wind forms an asymmetric, bipolar, rotating structure, powered by a nuclear starburst. Emission line ratio diagnostics indicate that photoionization is the dominant excitation mechanism at the base of the wind. Mixing from slow shocks (up to 20%) increases further out along the outflow axis. The asymmetry of the wind is most likely caused by one of the two lobes of the wind bubble bursting out of its H I envelope, as indicated by line ratios and radial velocity maps. The characteristics of this galactic wind suggest that it is caught early (a few Myr) in the wind evolution sequence. The wind is also quite different from the galactic wind in the partner galaxy NGC 839 which contains a symmetric, shock-excited wind. Assuming that both galaxies have similar interaction histories, the two different winds must be a consequence of the intrinsic properties of NGC 838 and NGC 839 and their starbursts.

A time-localized response of wave growth process under turbulent winds

Directory of Open Access Journals (Sweden)

Z. Ge

2007-06-01

Full Text Available Very short time series (with lengths of approximately 40 s or 5~7 wave periods of wind velocity fluctuations and wave elevation were recorded simultaneously and investigated using the wavelet bispectral analysis. Rapid changes in the wave and wind spectra were detected, which were found to be intimately related to significant energy transfers through transient quadratic wind-wave and wave-wave interactions. A possible pattern of energy exchange between the wind and wave fields was further deduced. In particular, the generation and variation of the strong wave-induced perturbation velocity in the wind can be explained by the strengthening and diminishing of the associated quadratic interactions, which cannot be unveiled by linear theories. On small time scales, the wave-wave quadratic interactions were as active and effective in transferring energy as the wind-wave interactions. The results also showed that the wind turbulence was occasionally effective in transferring energy between the wind and the wave fields, so that the background turbulence in the wind cannot be completely neglected. Although these effects are all possibly significant over short times, the time-localized growth of the wave spectrum may not considerably affect the long-term process of wave development.

Power system reliability impacts of wind generation and operational reserve requirements

Directory of Open Access Journals (Sweden)

Esteban Gil

2015-06-01

Full Text Available Due to its variability, wind generation integration presents a significant challenge to power system operators in order to maintain adequate reliability levels while ensuring least cost operation. This paper explores the trade-off between the benefits associated to a higher wind penetration and the additional operational reserve requirements that they impose. Such exploration is valued in terms of its effect on power system reliability, measured as an amount of unserved energy. The paper also focuses on how changing the Value of Lost Load (VoLL can be used to attain different reliability targets, and how wind power penetration and the diversity of the wind energy resource will impact quality of supply (in terms of instances of unserved energy. The evaluation of different penetrations of wind power generation, different wind speed profiles, wind resource diversity, and different operational reserve requirements, is conducted on the Chilean Northern Interconnected System (SING using statistical modeling of wind speed time series and computer simulation through a 24-hour ahead unit commitment algorithm and a Monte Carlo simulation scheme. Results for the SING suggest that while wind generation can significantly reduce generation costs, it can also imply higher security costs to reach acceptable reliability levels.