Extreme wind fluctuations: joint statistics, extreme turbulence, and impact on wind turbine loads
<p>For measurements taken over a decade at the coastal Danish site Høvsøre, we find the variance associated with wind speed events from the offshore direction to exceed the prescribed extreme turbulence model (ETM) of the International Electrotechnical Commission (IEC) 61400-1 Edition 3 standa...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-06-01
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| Series: | Wind Energy Science |
| Online Access: | https://www.wind-energ-sci.net/4/325/2019/wes-4-325-2019.pdf |
| Summary: | <p>For measurements taken over a decade at the coastal Danish site
Høvsøre, we find the variance associated with wind speed events from
the offshore direction to exceed the prescribed extreme turbulence model
(ETM) of the International Electrotechnical Commission (IEC) 61400-1 Edition 3 standard for wind turbine safety. The
variance of wind velocity fluctuations manifested during these events is not
due to extreme turbulence; rather, it is primarily caused by ramp-like
increases in wind speed associated with larger-scale meteorological
processes. The measurements are both linearly detrended and high-pass
filtered in order to investigate how these events – and such commonly used
filtering – affect the estimated 50-year return period of turbulence levels.
High-pass filtering the measurements with a cutoff frequency of <span class="inline-formula">1∕300</span> Hz
reduces the 50-year turbulence levels below that of IEC ETM class C, whereas
linear detrending does not. This is seen as the high-pass filtering more
effectively removes variance associated with the ramp-like events. The impact
of the observed events on a wind turbine are investigated using aeroelastic
simulations that are driven by constrained turbulence simulation fields.
Relevant wind turbine component loads from the simulations are compared with
the extreme turbulence load case prescribed by the IEC standard. The loads
from the event simulations are on average lower for all considered load
components, with one exception: ramp-like events at wind speeds between 8 and
16 m s<span class="inline-formula"><sup>−1</sup></span>, at which the wind speed rises to exceed rated wind speed, can
lead to high thrust on the rotor, resulting in extreme tower-base fore–aft
loads that exceed the extreme turbulence load case of the IEC standard.</p> |
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| ISSN: | 2366-7443 2366-7451 |