IEC WIND TURBINES – PART 1: DESIGN REQUIREMENTS. You may have heard that IEC defines wind turbine classes with labels like IIIB, where the roman number refers to a reference wind speed and the index letter. IEC. Second edition. Wind turbine generator systems –. Part 1 : Safety requirements. Aérogénérateurs –. Partie 1: Spécifications de sécurité.
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In complex terrain the wind profile is not a simple increase and additionally a separation of the flow might occur, leading to heavily increased turbulence. IEC started standardizing international certification on the subject inand the first standard appeared in This article includes a list of referencesrelated reading or external linksbut its sources remain unclear because it lacks inline ief. An update for IEC is scheduled for National Renewable Energy Laboratory participates in IEC standards development work,   iex tests equipment according to these standards.
For small wind turbines the global industry has been working towards harmonisation of certification requirements with a “test once, certify everywhere” objective. Wind turbine classes” Vestas. Wind load models are scaled differently for each wind turbine class, thus a class I A turbine is tested for 61400- extreme wind speed and more severe turbulence than a class II B turbine.
Webarchive template wayback links Articles lacking in-text citations from March All articles lacking in-text citations Use British 61400-1 Oxford spelling from January It is also possible to use the IEC standard for turbines of less than m 2 swept area.
Turbine classes are determined by three parameters – the average wind speed, extreme year gust, and turbulence. Wind turbines are capital intensive, and are usually purchased before they are being erected and commissioned. Examples of modes of operation are normal operation, idling, and operation with yaw error.
Archived from the original on 7 October The IEC turbine safety standard. IEC site assessment criteria.
In addition, ice accumulated fatigue damage caused by stochastic forcing is evaluated for a design life time of twenty years and compared to the material strength. Basic Aspects” Suzlon Energy. Wind classes determine which turbine is suitable for the normal wind conditions of a particular site. The standard concerns most aspects of the turbine life from site conditions before construction, to turbine components being tested,  assembled and operated.
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In principle, the aeroelastic simulation could be repeated with local wind conditions at specific turbine positions. Retrieved 7 October Views Read Edit View history. Languages Deutsch Edit links. Wind conditions are specified by extreme wind speed, vertical wind shear, flow inclination, turbulence and rare gust-like events.
This is the definition in IEC edition 2. This imposes simple limits on fifty-year extreme wind, flow inclination and wind shear, see Figure 1, whereas turbulence assessment is more complicated.
Turbine designers will typically model turbine vibrations and dynamic forces on critical components by aeroelastic simulation programs such as HAWC2. During the construction and design phase assumptions are made about the wind climate that the wind turbines will be exposed to.
The IEC 61400-1 turbine safety standard
The load type is either an ultimate load, which might instantly damage the turbine, or a fatigue load. The extreme wind speeds are based on the 3 second average wind speed.
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Small wind turbines are defined as being of up to m 2 swept area and a somewhat simplified IEC standard addresses these. Updated by Heidi Serny Jacobsen. To 614000-1 that a wind turbine belongs to a give wind turbine class, it must be proven safe under a set of predefined load cases. Each load case is specified by combinations of mode of turbine operation, wind conditions, and load type.
Please help to improve this article by introducing more precise citations. Aeroelastic simulations are processed for all IEC load cases, and turbine safety is verified for each of the deterministic load cases. In Canada, the previous national standards were outdated and impeded the wind industry, and they were updated and harmonized with by the Canadian Standards Association with several modifications.
Because the fatigue loads of a number of major components in a wind turbine are mainly caused by turbulence, the knowledge of how turbulent a site is of crucial importance.
Variable atmospheric isc, unsteady wind, and directional variation of upwind terrain will introduce variations in observed turbulence intensity.
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Therefore, the IEC standard applies a representative turbulence intensity for turbine classification, which is defined as a high percentile of the expected natural variation. Material damage has a highly non-linearly relation to load amplitudes and thus to turbulence intensity, so a few situations with extreme turbulence may cause most of the fatigue damage.
Some of these standards provide technical conditions verifiable by an independent, third partyand as such are necessary in order to make business agreements so wind turbines can be financed and erected. The siting engineer must verify the safety of the deployed turbines.
List of International Electrotechnical Commission standards. Depending on the load case, the wind interacting with the turbine is either deterministic or a pseudo-random wind field with realistic turbulence characteristics.
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