Publishers version - DTU Orbit

Further developments Furthermore, new and improved wind lidar data and measurement
technologies are under development for RS-based power performance measurements from the
ground but also directly from the wind turbines. A conically scanning wind lidar (Control-
ZephIR) has during the summer 2009 been tested in a operating NM80 2.3 MW wind turbine
located at Tjæreborg Enge, Denmark, with the purpose to investigate the use of wind lidars
integrated directly into the wind turbine hubs, blades or spinners. The intention is to improve
the wind turbine’s performance by use of upstream approaching wind speed measurements
from inside the turbines rotor plane as an active input to the wind turbines active control
systems. Wind lidars for turbine yaw control are already nowadays on the market (Vindicator)
and new and smaller wind lidars are in the near-future envisioned to become integrated as
“standard” on wind turbines to provide upstream lead time wind data to the turbines control
system, e.g. for:
• Enhanced wind turbine yaw control.
• Lead-time control for individual pitch control.
• Protection against fatigue from extreme wind shear and wind gusts.
• Prolonging the wind turbines longevity.
• Improving the wind turbine productivity.
1.3.7 Summary of lidar
Since the wind lidar era started at Risø DTU in 2004 new wind lidars have emerged on the
wind energy market, spurred by the telecom technology revolution of the 90’s. Today, wind
lidars, continuous and pulsed, and properly calibrated, aligned, installed and maintained, and
their volume-averaged wind measurements properly interpreted, are indeed very precise wind
measuring devises, capable of matching the wind industry’s needs today and in the future for
precise and reproducible wind profile measurements and resource assessments.
Before, however, lidar measured wind measurements can become fully certified and accredited
to industry standards, new and revised IEC lidar standards have first to be set and come
into effect. It is important, however, here also to apprehend the very different nature of the
previous standards point measurements as obtained from a mast-mounted cup anemometer
and a volume-averaged wind vectors as obtainable from a profiling wind lidar.
Although the first generations of wind lidars, CW and pulsed, indeed had many difficulties
with reliability, this era now seems to have been improved beyond their first children growth
pains. Today’s wind lidars offer realistic and mobile alternatives to the installation of tall
meteorological masts for many wind resource estimation assessment studies, on and offshore.
The near future will inevitably also show turbine mounted wind lidars fully integrated with
the wind turbines control systems for improving the wind turbines productivity and longevity.
Notation
CW continuous wave
C/N carrier-to-noise
lidar light detection and ranging
RS remote sensing
SAR synthetic aperture radar
sodar sound detection and ranging
References
Bingöl F., Mann J., and Foussekis D. (2008) Lidar error estimation with WAsP engineering. IOP Conf. Series:
Earth and Environ. Sci. 1:012058
de Noord M. et al. (2005) Sodar power performance measurements, WISE WP5.
DTU Wind Energy-E-Report-0029(EN) 23