Design and evaluation of a short coherence length laser-based Doppler wind Lidar system for wind energy applications

Abstract

Nowadays larger horizontal axis wind turbines (HAWT) are setup in difficult to access locations adding an overhead to the production cost as well as the Operation & Maintenance (O&M) costs. In order to cover those overhead cost, Lidar assisted preview control of wind turbine blade pitch system is prosperous both on research and industry applications. However, there are not a lot of choices to remote sense the wind field inflow. Doppler wind Lidar systems have been proved to be advantageous on such applications. However due to the economical consideration, the state-of-the-art wind Lidar systems are only limited on research. Therefore, developing a cost efficient wind Lidar to support the pitch control of HAWT to reduce the material requirement, lower the O&M cost and decrease the cost of energy (COE) in the long term is our motivation. Our current main focusing of investigations has been laid on the optical design of emitting and receiving system, and the evaluation of the low cost laser system instead of using a high cost fiber laser as a transmitter. The short coherence length lasers brings a higher phase noise into the detection, normally it is not used for the coherent Lidars system. However, such a laser can achieve a higher output power with a low cost which is very important for the market. In order to bring such kind of laser into the application, different sending, receiving, and detection design is simulated and tested. Those testing results are presented in this paper.