Laser Sensors Improve Efficiency of Wind Turbines

 World of Wind Energy - November 06, 2008

A system that detects gusts before they arrive reduces wear, boosts output. 

Read Full Article: World of Wind Energy.com - News - Laser Sensors for Wind Turbines

A new fiber-optic laser system can measure wind speed and direction up to 1000 meters in front of a wind turbine, giving the massive machines enough precious seconds to proactively adapt to gusts and sudden changes in wind direction. The device, developed by Catch the Wind, a startup based in Manassas, VA, could improve the efficiency of wind turbines and keep them from breaking down. The device could help lower the cost of renewable electricity from wind. Wind turbines lose roughly 1% of their operating efficiency for every degree their blades are out of alignment with the oncoming wind. Catch the Wind claims that its laser system can boost turbine power output by 10% by improving orientation accuracy. The pitch of the blades can also be adjusted in advance of the wind to reduce wear and tear on turbine gearbox components and blades, lowering repair and maintenance costs by up to 10 percent and extending the operating life of a wind farm, the company says.

Current wind-energy measurement systems--both mechanical anemometers and more advanced LIDAR (light detecting and ranging) devices--are used primarily to determine if a location is suitable for a wind farm. The systems are also kept as part of on-site weather stations used for longer-term wind forecasting. Real-time data can also be gathered by mounting a small anemometer on the back of a turbine's nacelle, Kourtoff says. The problem with this setup is that the air is so disturbed after passing by the turbine blades that measurements are often skewed and unreliable. Also, the turbine can only respond to wind changes after its blades have been hit, leaving them vulnerable for a few seconds to a range of punishing forces caused by wind shear, gusts, and turbulence.

Catch the Wind has adapted LIDAR so that it can be mounted on wind turbines and used to measure wind changes in time to make adjustments to the turbine. It pulses three invisible laser beams in front of the turbine that can simultaneously measure both vertical and horizontal wind speeds at different distances, as well as sudden changes in direction. Like conventional LIDAR, it does this using the Doppler principle: when the laser bounces off small dust particles carried in the wind, it changes color. The color of the laser is directly proportional to the speed of the particle. The device uses proprietary algorithms to convert this data into measurements of wind speed and direction before communicating a course of action to the turbine's control system. The device provides 20 seconds' advance notice--enough to turn the nacelle and angle the blades so that the turbine can catch more of the wind energy while reducing strain on its parts.

Related: Laser Sensor Boosts Wind Turbine Efficiency