Using wind speed from a blade-mounted flow sensor for power and load assessment on modern wind turbines
In this paper an alternative method to evaluate power performance and loads on wind turbines using a blade-mounted flow sensor is investigated. The hypothesis is that the wind speed measured at the blades has a high correlation with the power and loads such that a power or load assessment can be...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-11-01
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| Series: | Wind Energy Science |
| Online Access: | https://www.wind-energ-sci.net/2/547/2017/wes-2-547-2017.pdf |
| Summary: | In this paper an alternative method to evaluate power performance
and loads on wind turbines using a blade-mounted flow sensor is
investigated. The hypothesis is that the wind speed measured at the blades
has a high correlation with the power and loads such that a power or load
assessment can be performed from a few hours or days of measurements.<br><br>In the present study a blade-mounted five-hole pitot tube is used as the
flow sensor as an alternative to the conventional approach, where the
reference wind speed is either measured at a nearby met mast or on the
nacelle using lidar technology or cup anemometers. From the flow sensor
measurements, an accurate estimate of the wind speed at the rotor plane can
be obtained. This wind speed is disturbed by the presence of the wind
turbine, and it is therefore different from the free-flow wind speed.
However, the recorded wind speed has a high correlation with the actual
power production as well as the flap-wise loads as it is measured close to
the blade where the aerodynamic forces are acting.<br><br>Conventional power curves are based on at least 180 h of 10 min mean
values, but using the blade-mounted flow sensor both the observation average
time and the overall assessment time can potentially be shortened. The basis
for this hypothesis is that the sensor is able to provide more observations
with higher accuracy, as the sensor follows the rotation of the rotor and
because of the high correlation between the flow at the blades and the power
production. This is the research question addressed in this paper.<br><br>The method is first tested using aeroelastic simulations where the
dependence of the radial position and effect of multiple blade-mounted flow
sensors are also investigated. Next the method is evaluated on the basis of
full-scale measurements on a pitch-regulated, variable-speed 3.6 MW wind
turbine.<br><br>It is concluded that the wind speed derived from the blade-mounted flow
sensor is highly correlated with the power and flap-wise bending moment and
that the method has advantages over the traditional approach where the
met-mast wind speed is used as reference, e.g. the capability of measuring
the shear, veer and turbulence. The aeroelastic simulations show that the
assessment time can be reduced, but this reduction cannot be confirmed from
the current measurement database due to sensor problems and practical
circumstances. Measuring the wind speed at the rotor plane comes with a
price as the wind speed is affected by the induction which may be sensitive
to the changes you want to evaluate, e.g. different vortex generator
configurations. Furthermore it is concluded that a robust instrument and
measurement system is required to obtain accurate and reliable wind speed
recordings from pitot-tube measurements. |
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| ISSN: | 2366-7443 2366-7451 |