Pulsed Lasers in Lidar Application: Models for Optimizing Wind Turbine Performance

Abstract

Since the appearance of the first wind turbines at the end of the nineteenth century, wind energy has been considered to be a renewable energy source for not just developed countries but also developing countries as well. Thus, since 2004, there has been a steady rise in wind energy production worldwide, with substantial actively installed capacity in Africa. However, due to the fact that wind turbines are highly dynamic systems that are excited by stochastic loads from the wind, variations in this disturbance usually medium-term (-changes during the space of a few hours or minutes cause variations in power output which must be accepted by the system to which the turbine is connected -) and short-term (typically wind gusts which will introduce cyclic loadings which must be absorbed by the wind turbine with high susceptibility to fatigue damage) negatively impacts heavily on Levelized Cost Of Energy (LCOE) of wind energy (i.e., the average cost per unit of energy over the lifetime of the turbine, including capital costs, operations and maintenance costs, and all other relevant expenses) [1]. As a result, there has been slow progress in the growth and development of more powerful turbines which have some significant advantages such as less visual impact to local people, and projects with more profitability. While traditional wind turbine control design utilize feedback control algorithms such as Artificial Neural Network (AAN) algorithms to address this challenge, this has often proved ineffective because they are only able to react to impacts of wind changes on the turbine dynamics afterthese impacts have already occurred [2]. Consequently, as a promising alternative, Light Detection and Ranging (Lidar) allows preview information about the approaching wind to be used to improve wind turbine control including blade pitch, generator torque, and yaw direction, thereby optimizing operational performance of the wind turbine through increase in energy yield, while keeping structural loads low [3]. Therefore, it is our goal in this thesis to carry out a thorough exposition of modeling associated with this trend. We will first focus on lidar system modeling with particular emphasis on the laser device which is the primary component of the lidar systems. Then we will explore wind and wind turbine modeling through aero-elastic simulations, and then wind field reconstructions with correlations between Lidar systems and Wind turbines [4]. We will end with an insight into what is to be expected with regards to the lidar scanning