Real-time rotor effective wind speed estimation based on actuator disc
theory: design and full-scale experimental validation
Abstract
{The use of state estimation techniques offers a means of inferring
rotor effective wind speed from standard measurements of wind turbines.
Typical wind speed estimators rely upon a pre-computed quasi-steady
aerodynamic mapping, which describes the relationship between pitch
angle and tip-speed ratio and the power coefficient. In practice, the
static mapping does not capture the influence of turbine structural
dynamics and atmospheric turbulence, inevitably resulting in poor
performance of the wind speed estimation. In addition, the turbine
aerodynamic properties might not be easily accessible. Thus, this paper
presents a rotor effective wind speed estimation method that obviates
the requirement for prior knowledge of turbine power coefficients.
Specifically, the proposed method exploits a simple actuator disc model,
where the aerodynamic power and thrust coefficients can be characterised
in terms of axial induction factors. Based on this insight and standard
turbine measurements, real-time estimation of rotor effective wind speed
and axial induction factors can then be achieved using a simplified
turbine drive-train model and an extended Kalman filter. In addition,
the actuator disc model can be updated easily over time by calibrating
solely two correction factors. Thus, the proposed algorithm presents an
alternative for estimating the rotor effective wind speed, which is
valuable for numerous applications, for example, LiDAR-assisted control
and coherence studies.