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Metocean Study: Reduction of turbulence intensity with increasing height in the conversion of time scales (12 May 2017)

    WOZ_RVO.nl
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    Asked by WOZ_RVO.nl 162 days ago Answers (1)

    This is a question to the Metocean study on Hollandse Kust Wind Farm Zone:

    Chapter 10.1.4 Conversion between time scales:

    You are recommending the ISO 19901 wind spectra (Frøya spectra). You are recommending the same turbulence intensity at both 10 and 100 m above mean sea level?

    Then you will end up with too strong gust at the heights above 10 m?  There is no doubt that wind turbulence shall decrease with height? That means that Figure 10.4 and Table 10.7 only is valid 10 meter above mean sea level?

    This table is used to calculate wind gust at all heights. In my opinion a 1-hour mean wind speed at 100 m of 39.6 m/s corresponds to 10-minute mean of 42.0 m/s (you have 44.3 m/s) and a 3 s gust of 49.2 m/s (you have 58.3 m/s).

    Can you please clarify?

    1 answer

      • WOZ_RVO.nl
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        WOZ_RVO.nl 161 days ago

        Your observations are correct. Netherlands Enterprise Agency and DHI have issued a revised report that has been made public on May 11th, 2017. Please refer to PDF page 16 ‘Revision History’ for the comparison between V2.2 and V2.1.

        Data in the Metocean Database are correct and do not need an update.