Laser technology optimises wind turbine energy
A general assumption with wind turbines is that they generate energy when there is sufficient wind to propel the turbine blades. However, wind speeds can vary dramatically, which in turn limits power fluctuations for high wind speeds, and no power at all when wind speeds are below sufficient requirements. Mounted on top of the wind turbine's nacelle, the laser anemometer's laser beam shoots through the rotor blades and measures the upstream along-wind component of the wind field. It does this by measuring the Doppler shift of the light that is scattered backwards from the elongated region where the laser beam is focused. To evaluate the benefits this technology has over the standard mast cup-anemometer, the laser was subjected to various tests. These included evaluating the deviation within the averaging time of the measured signal, the lack of correlation between measured and significant wind speeds and the influence from control response time. The end product is a fully flexible instrument for testing operational principles and quality of measurements. With commercial dimensions of no more than 20x30x50 cm, the laser anemometer will therefore be a cost effective and viable alternative to the current cup anemometers. It is expected to have a manufacturing output of 1000 units per year. The designers further believe that if the laser anemometer is marketed successfully it could soon become a part of the standards for performance testing of the wind turbines. With a revision of the IEC61400-12 standard on performance testing currently underway, participants in the laser anemometer project are seeking ways to permit the application of laser anemometers in the new standard.
