Advanced ground-based wind observations based on scanning Doppler lidars for improving the overall efficiency of the wind energy sector

The wind observations are crucial for ensuring the performances of the wind energy production. From the early stage of wind resource assessment of potential sites for future wind farms to the operational stage of wind nowcasting around wind farms, the wind information are the fuel of the wind energy sector. This is why a huge range of technologies for measuring and modeling the wind speed and direction has been developed and tested since a couple of decades. But new issues of the wind energy sector are requesting more and more accurate and high resolved wind measurements: the developments of bigger wind farms in more complex terrain or offshore are requesting more wind measurements over larger regions with compact sensors capable to be easily deployed everywhere; the wind farms production needs to be forecast accurately with advanced numerical prediction models that are requesting more wind measurements around the production site to be assimilated; bigger wind farms are requesting wind observations like wake turbines in order to optimize its overall efficiency; as the percentage of electrical energy coming from wind energy is increasing worldwide, the electrical grids have to deal with higher variations in the network. In addition to the request for more accurate wind forecasts, optimizing the operations of smart grids is requesting wind measurements along the electricity transportation network since the capacities of the network are highly linked to thermal dissipation and wind speed. To overcome all these issues of the future wind energy sector related to the wind measurements, lidar technology allows to accurately measure the wind speed and direction for site assessment onshore, offshore but also for the power curve verification. Briefly, the lidar consists in a remote sensor that emits photons at a given wavelength (usually in infrared at 1.5 micron) in the atmosphere and the photons are backscattered by the aerosols in the atmosphere to the lidar receiver. In analyzing the frequency shift induced by the Doppler effect of the aerosols motions, wind Doppler lidars are able to measure very accurately wind speed and direction compared to sodars for instance. LEOSPHERE is the worldwide leader of lidar development and manufacturing for wind measurements. Since 6 years, roughly 350 lidars (mainly wind profilers) have been deployed for addressing various operational and research applications of the wind energy sector. The current presentation will focus on the potential benefits of scanning wind Doppler lidars that allows to cover a huge area around a site of interest for wind resource assessment or for providing gusts alarms, active wind turbines control or improving nowcasting. This kind of lidars can also monitor with a fine spatial resolution a given volume of the atmosphere like the flow downstream the wind turbines in order to study the wake turbines. The presentation will give some practical examples of the way to use the lidar wind measurements for improving at different stages the wind energy sector