Database on Wind Characteristics L
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ET -AFM - 9901 v_______ _______ ____ ______ ' MASTER Database on Wind Characteristics L. '• K.S. Hansen The Technical University of Denmark (editor) & M.S. Courtney 1 Ris0 National Laboratory, Denmark s (editor) Q 1 % a* ET - ARM - 9901 Database on Wind Characteristics K.S. Hansen1 & M.S.Courtney 2 1The Technical University of Denmark 2Ris0 National Laboratory, Denmark (editors) Contract JOR3-CT95-0061 Final report Resarch funded in part by THE EUROPEAN COMMISSION in the framework of the Non Nuclear Energy Programme JOULE III Department of Energy. Engineering Technical University of Denmark August 1999 DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. Abstract: This report describes the work and results of the project: Database on Wind Characteristics which was sponsered partly by the European Commision within the framework of JOULE III program under contract JOR3-CT95-0061 The organisations that participated in the project consists of five research organisations: MlUU(Sweden), ECN(The Netherlands), CRES(Greece), DTU(Denmark), Rise (Denmark) and one wind turbine manufacturer: Vestas Wind System AZS(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. Keywords: wind, turbulence, windloads, extreme wind conditions, gusts, wind shear, flow measurements, databases. Authors: Kurt S. Hansen, Department of Energy Engineering, Technical University of Denmark Mail: [email protected] Michael S. Courtney MetSupport ApS, Denmark Mail: [email protected] Contents Executive summary ................................................................................................................ 1 1. Introduction ..................................................................................................................2 1.1 Background .......................................................................................................2 1.2 Participants....................................................................................................... 3 2. Overview of the database system...............................................................................6 2.1 Introduction ....................................................................................................... 6 2.2 Server organisation ..........................................................................................6 2.3 Data handling, input ....................................................................................... 7 2.4 Data handling, output - the web interface...................................................9 3. Archiving interesting data..........................................................................................10 3.1 Selecting interesting data............................................................................ 10 3.2 Converting to a standard format .................................................................10 3.3 Data Arrival Procedure ................................................................................ 15 3.4 Checking the quality ..................................................................................... 18 3.5 Characterising the data................................................................................ 19 3.6 Storing the details - the SQL database.................................................. 21 3.7 Technical details............................................................................................26 4. Finding and visualising time series..........................................................................32 4.1 Downloading time series using FTP..........................................................32 4.2 Searching for data using a web browser ...................................................33 4.3 Advanced queries ......................................................................................... 37 4.4 Visualising time series...................................................................................38 5. Contents of the database......................................................................................... 40 5.1 Site information ..............................................................................................42 6. Extremes.......................................................................................................................66 6.1 Mean wind speed and turbulence intensity.............................................. 66 6.2 Wind speed probability density distribution ...............................................67 6.3 Maximum wind speed...................................................................................68 6.4 Maximum gusts ..............................................................................................68 6.5 Wind direction change ...................................................................................69 6.6 Gust directional index...................................................................................70 7. Conclusion .................................................................................................................. 71 Annex A1: Definitions ...................................................................................... A2 Annex B1: Project descriptions ......................................................................A16 Annex B2: Site descriptions ............................................................................A20 Annex B3: Master Sensor file........................................................................A27 Annex B4: Template for common file format ..............................................A36 Executive summary Vast amounts of wind data have been measured in many different locations. Of the thousands of hours of time series collected, only a tiny proportion are available for use by the wind turbine and wind engineering communities. This report describes the project of collecting a small but representative portion of these data and making them available on the World Wide Web. In order to implement a suitable search system we have constructed a database for the detailed registration of field measurements, ranging in scope from the administrative level down to the mounting details of individual sensors. Wind data are quality checked according to a number of different criteria such as presence of spikes, noise and trends. Subsequently data are indexed using a variety of parameters, including conventional statistics and extremes, turbulence intensity, gust, acceleration and wind shear. A wide variety of wind climates and terrain types are represented together with significant amounts of data measured in and close to wind farms. Data have a typical temporal resolution of 1-20 Hz and as such are intended for design and simulation studies (not wind resource applications). Emphasis has been gived to ensure a high level of documentation of the measurement setups which are included in the database. Furthermore, a search and data selection system has been developed that fully utilizes interactive nature of the World Wide Web. After quality control and indexing, the actual wind data are copied in a standard format to CD- ROM’s. All CD-ROM’s reside in a juke box containing up to 150 disks, giving a capacity of around 100 GB (with present CD technology). The juke box is accessible via ftp which also allows direct downloading of data files from a web browser. Data are provided by all the participants of the project, covering most of the countries of the European Union. By spring 1999 we have gathered and included approximately 50.000 hours of wind speed measurements representing more than 20 sites. As an indication of the applicability of the database, we can refer to two projects that are allready benefiting from this rich resource, The Joule NEWGust project, coordinated by Delft University of Technology, uses wind data from the database to verify and calibrate theoretical models for gust shape. A Danish funded project uses wind time series to examine the precise form of the high sped tails of the wind speed distribution and determine how much these deviate from Gaussian form. This has particular relevance to fatigue loading of the wind turbines. In conclusion it should be remembered that the database coordinators welcome offers of new data. We consider the Database on Wind Characteristics to be the natural repository for many of the numerous existing and future wind datasets. 1 1. Introduction. It is now possible for designers of wind turbines to generate simulated time series of turbulence that to a good approximation describe ’normal ’ conditions in situations with reasonably homogeneous terrain. When it