Ongoing applications and algorithmic advances of scanning Doppler lidars for wind energy

Improvements in lidar technology over the past few decades have resulted in in-expensive modern remote sensing devices using off-the-shelf electronic equipment's and fiber-optic technology. Vertical profiles can capture high vertical and temporal resolution of winds and direction up to the planetary boundary layer, while modern scanning coherent Doppler lidar (CDL) devices can provide high spatial resolution of winds up to 10 km. In this presentation, results from several ongoing scanning lidars deployments along with software solutions to compliment the increasing applications will be presented. The wind energy industries focus on scanning lidar applications are currently more favored in using such devices for wake characterization and wind resource assessment measurements. Below a synopsis of a few results from several such ongoing studies are provided. With regards to wake characterization and power curve, measurements from a campaign conducted using multiple WINDCUBE scanning CDLs, and two nacelle mounted Wind Iris lidars on top of a turbine deployed at an operating offshore wind farm will be presented. Scanning Doppler lidars provide 3D spatial understanding of the wake interaction while nacelle mounted lidars provide high-resolution understanding of winds ahead and behind individual turbines. New data analysis algorithms in analyzing wake measurements and power curve will be presented. Challenges faced with analyzing big data measurements and deployment of multiple lidar based instruments on an operating wind farm will also be discussed. Wind resource assessment using conventional measurement methods derived from terrestrial wind farm development remains an expensive and logistically challenging task (especially offshore). Scanning lidars installed in coastal locations or existing offshore platforms and aimed into wind development project areas, are emerging as a practical method for high resolution and high coverage wind measurements. Results from a scanning CDL deployment conducted at Danish Technical University (DTU) for determining the accuracy of wind speed and direction retrievals compared to tower measurements will be presented. Promising results are obtained (as validated by DTU), which will be valuable for the scientific community in assessing the true potential of scanning CDLs to complement traditional wind resource assessment strategies, especially for large wind parks in coastal regions or in the vicinity of appropriate offshore observation sites. Scanning CDLs also provide the flexibility to alter measurement locations at a later stage of the campaign for improved understanding of the wind flow around the site. The conglomeration of results provided in this presentation would assist wind energy developers in making improved decisions about their wind farm operations and pre-construction analysis using scanning Doppler lidar's.