1,721,837 research outputs found
Measurement and simulation of the flow field around a triangular lattice meteorological mast
No full textThe international standard IEC 61400-12-1 “Wind turbines – Part 12-1: Power performance measurements of electricity producing wind turbines” aims to provide a uniform methodology that will ensure consistency, accuracy and reproducibility in the measurement and analysis of power performance by wind turbines [1]. Annex G of this standard provides a methodology for the appropriate arrangement of instruments on the meteorological mast to ensure accurate measurement. For cup anemometers it provides recommendations about their location relative to the mast so that the effect of mast and boom interference on their output may be minimised. These recommendations are given for both tubular masts and lattice masts. This paper compares the flow distortion predicted by the IEC standard and the results of a 3D Computational Fluid Dynamics (CFD) simulation of a triangular lattice mast. Based on the results of wind tunnel and CFD simulation it was found that the flow distortion surrounding the lattice mast was over predicted by the method suggested in appendix G of IEC61400-12-1. Using the CFD data it was possible to determine, for a range of flow directions and mast heights, the distance from the mast that anemometers would need to be in order to be outside the flow distortion field
Measurement and simulation of the flow field around a triangular lattice meteorological mast
No full textThe international standard IEC 61400-12-1 “Wind turbines – Part 12-1: Power performance measurements of electricity producing wind turbines” aims to provide a uniform methodology that will ensure consistency, accuracy and reproducibility in the measurement and analysis of power performance by wind turbines. Annex G of this standard provides a methodology for the appropriate arrangement of instruments on the meteorological mast to ensure accurate measurement. For cup anemometers it provides recommendations about their location relative to the mast so that the effect of mast and boom interference on their output may be minimised. These recommendations are given for both tubular masts and lattice masts.This paper compares the flow distortion predicted by the IEC standard and the results of a 3D Computational Fluid Dynamics (CFD) simulation of a triangular lattice mast. Based on the results of wind tunnel and CFD simulation it was found that the flow distortion surrounding the lattice mast was over predicted by the method suggested in appendix G of IEC61400-12-1. Using the CFD data it was possible to determine, for a range of flow directions and mast heights, the distance from the mast that anemometers would need to be in order to be outside the flow distortion field
Assistance in the development of a wind turbine test facility in accordance with relevant national and international standards
Full text linkThis dissertation assists the National Small Wind Turbine Centre (NSWTC) in the development of a wind turbine test facility and in preparation for the development of a future turbine testing site. The test turbine facility will conduct tests in accordance with relevant national and international standards. Assistance was given in the development of the test facility by the identification of some of the key areas of the initial set up of the wind turbine test facility. The clarity and adequacy of portions of current national and international standards in application to the development of a small wind turbine testing facility was assessed. By the completion of this dissertation assistance was given, which contributed to the progression of the site development aspects in establishment of the test facility. This process gave insight into some of the important factors to consider in the development of a wind turbine test facility. Participation by author in two international tasks that assessed wind turbine test data to selected standards provided exposure to the current wind turbine standards that will be applied in the testing of wind turbines at the facility. This process highlighted the lack of clarity within one of the standards and illustrated the varied results that can be produced if the assessed standards are not understood as intended. Recommendations were given on how the NSWTC might improve the method of site development of the future test facility. The assessment allowed recommendations to be made on the use of the standards and outlines how errors in their application might be avoided
Next Edition of IEC 61400-27: Electrical simulation models for wind power plants
No full textThe purpose of the IEC 61400-27 standards series is to provide dynamic wind power plant models to be used in power system stability studies. This paper provides a brief overview of the state-of-the-art for the development of a new edition of the IEC 61400-27 series which includes generic wind power plant models in addition to the wind turbine models published in the first edition of IEC 61400-27-1
Tuulivoimaloiden melumittaukset IEC 61400-11 -standardin mukaisesti
Full text linkTämä opinnäytetyö on laadittu Kymenlaakson ammattikorkeakoulun energialaboratoriolle. Työ aloitettiin tilanteesta, jossa oli tieto, että Renewtech–hankkeessa tutkitaan tuulivoimaloiden melua. Työn aikana nuo suunnitelmat tarkentuivat. Laboratorio hankki uuden äänenpainetasomittarin tuulivoimaloiden melupäästöjen mittaamiseen, ja työnä oli näitä mittauksia varten laatia ohje, jonka mukaan mittaukset suoritetaan. Ohjeen pohjaksi valittiin IEC:n tekemä standardi 61400-11, joka antaa yksityiskohtaiset kuvaukset, kuinka tuulivoimaloiden melupäästöt mitataan.
Tämä työ aloitettiin perehtymällä standardiin ja muihin virallisiin melumittausohjei-siin. Standardi piti ensiksi kääntää suomen kielelle, jotta sitä pystyi käyttämään. Myöhemmin ilmestyneen VTT:n suomenkielisen luonnoksen avulla tarkistettiin käännöksen tarkkuus. Työhön haluttiin lisätä myös äänen perusteoriaa ja selostus siitä kuinka, tuulivoimalat aiheuttavat melua.
Kun koulun hankkima melumittari saapui, alkoi tutustuminen mittariin ja sen mukana tulleeseen äänen analysointiohjelmaan. Mittaria ja samalla standardia käytiin kokeilemassa Haminan ja Kotkan tuulivoimaloiden luona. Mittauksista tehtiin raportti, johon kirjattiin ylös sekä mittauksen tulokset että mittauspöytäkirja. Matkalta kerätty käytännön kokemus auttoi ymmärtämään, miten standardin monet vaatimukset pystyisi toteuttamaan käytännössä. Tuloksena saatiin ohje, joka käy yksityiskohtaisesti standardin läpi ja antaa samalla ohjeita ja kommentteja standardin käyttöön.This thesis was written for the emission measurement laboratory of Kymenlaakso University of Applied Sciences. The laboratory has acquired a new sound level meter to measure acoustic noise made by wind turbines. To make these measurements accurate, a detailed guide for noise measurement of wind turbines was needed. The IEC Standard 61400-11 was used as a basis for the guide.
The work was started by studying the standard. Other official noise measurement materials were also used. Standard 61400-11 needed to be translated first before it could be used. After the translation was complete, Technical Research Centre of Finland released their own translated version of the standard, which was used as reference to correct any mistakes our translation may have had. Thesis also includes parts of the theories of sound, and wind turbine noise.
When the sound level meter arrived, it was tested in practice. Acoustic noise meas-urements were taken from wind turbines located in Hamina and Kotka. The meas-urements were reported, and the acquired practical experience helped to understand how to utilize the instructions of the standard. The result is a guide that explains the IEC 61400-11 in detail and also gives tips and comments on how to implement the standard in practice
Rational Calibration of Four IEC 61400-1 Extreme External Conditions
No full textBased on a set of asymptotic statistical models on closed form this paper presents a rational and consistent calibration of four extreme external conditions defined in the International Electrotechnical Commission (IEC) 61400-1 standard: extreme operating gust, extreme wind shear, extreme coherent gust with direction change and extreme wind direction change. These four extreme external conditions are used in the definition of six of the IEC 61400-1 ultimate load cases. The statistical models are based on simple and easily accessible mean wind speed and turbulence characteristics of the atmospheric boundary layer. Using the wind climate characteristics prescribed in the IEC 61400-1 standard as input to the set of statistical models ensures consistency between the specified wind climate and the proposed extreme gust magnitudes. Differences and equalities between the present IEC specifications and proposed specifications of the magnitudes of the extreme external wind conditions are highlighted and discussed using an illustrative example based on two selected terrain types. Copyright © 2008 John Wiley & Sons, Ltd
A new approach for harmonic summation using the methodology of IEC 61400-21
No full textThis work verifies, by computational simulations, the harmonic aggregation in the point of common coupling (PCC) of some electrical systems that feed wind turbines. Results show that the harmonic summation estimates using the IEC 61400-21 methodology may present significant errors. In this work, we analyze the IEC 61400-21 methodology and propose adjustments to improve the estimations. Using the proposed adjustments, we note that the errors in the estimates are significantly reduced
Daten-Management für Windparks mit Kommunikation gemäß IEC 61400-25
Full text linkZiel der Diplomarbeit besteht in der Implementation einer Schnittstelle nach IEC 61400-25 mit einer Remote Field Controller der Firma Phoenix Contact GmbH, der zur Steuerung von Windenergieanlagen verwendet werden kann. In Windparks organisierte Windenergieanlagen verschiedenster Hersteller erscheinen beim EVU, neben anderen verteilten Energieresourcen, als sog. virtuelle Kraftwerke. Ihr zunehmender Anteil am Energiemix macht es notwendig, Verhalten und Einflussmöglichkeiten denen konventioneller Kraftwerke gleichzusetzen. Die Erfüllung dieser Forderung macht die dafür erforderliche Anpassung der bisher ausschließlich verfügbaren proprietäre Schnittstellen verschiedener Anlagenhersteller besonders aufwendig. Die IEC 61400-25 unternimmt den Versuch, eine einheitliche Schnittstelle auf Basis eines objektorientierten Ansatzes vorzunehmen. Nach einem Überblick über diese Norm wird ein Implementationsweg unter Verwendung der hauseigenen Automatisierungslösung PCWORX aufgezeigt. Es wird ein Lösungsweg dargestellt und beschrieben, der alle Aspekte durch Transformation objektorientierter Gesichtspunkte nach IEC 61131 umfasst
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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