Optimizing Lidars for Wind Turbine Control Applications—Results from the IEA Wind Task 32 Workshop

Abstract

IEA Wind Task 32 serves as an international platform for the research community and industry to identify and mitigate barriers to the use of lidars in wind energy applications. The workshop "Optimizing Lidar Design for Wind Energy Applications" was held in July 2016 to identify lidar system properties that are desirable for wind turbine control applications and help foster the widespread application of lidar-assisted control (LAC). One of the main barriers this workshop aimed to address is the multidisciplinary nature of LAC. Since lidar suppliers, wind turbine manufacturers, and researchers typically focus on their own areas of expertise, it is possible that current lidar systems are not optimal for control purposes. This paper summarizes the results of the workshop, addressing both practical and theoretical aspects, beginning with a review of the literature on lidar optimization for control applications. Next, barriers to the use of lidar for wind turbine control are identified, such as availability and reliability concerns, followed by practical suggestions for mitigating those barriers. From a theoretical perspective, the optimization of lidar scan patterns by minimizing the error between the measurements and the rotor effective wind speed of interest is discussed. Frequency domain methods for directly calculating measurement error using a stochastic wind field model are reviewed and applied to the optimization of several continuous wave and pulsed Doppler lidar scan patterns based on commercially-available systems. An overview of the design process for a lidar-assisted pitch controller for rotor speed regulation highlights design choices that can impact the usefulness of lidar measurements beyond scan pattern optimization. Finally, using measurements from an optimized scan pattern, it is shown that the rotor speed regulation achieved after optimizing the lidar-assisted control scenario via time domain simulations matches the performance predicted by the theoretical frequency domain model.

Enhanced estimation of boundary layer advective properties to improve space‐to‐time conversion processes for wind energy applications

“…[14][15][16][17][18][19][20] The feasibility of proactive wind turbine control has been primarily examined using nacelle-mounted look-ahead technologies (eg, lidar), which typically measure the near-upstream portion of the wind field. 16,[19][20][21][22][23] The inflow forecasts were constructed upwards of 60 seconds in advance at one-second time intervals. These high-fidelity turbine inflow previews are generated from the DD wind maps using advection knowledge provided by the spatial correlation technique.…”

“…Potential wind plant proactive control benefits include improvements to power output and a reduction in wind turbine loads . The feasibility of proactive wind turbine control has been primarily examined using nacelle‐mounted look‐ahead technologies (eg, lidar), which typically measure the near‐upstream portion of the wind field . The extent of the upstream wind field measurement inherently limits the preview time available to turbines to enact proactive wind turbine control strategies.…”

Wind sensing with drone-mounted wind lidars: proof of concept

“…This bounds the usability of single lidars to offshore sites (Peña et al, 2008) and sites with simple topography onshore . Therefore, when the flow is complex, as it is the case in more than 50 % of the onshore sites (e.g., hilly terrain) with good wind resources (Bingöl, 2010), multi-lidar instruments, such as long-range (Vasiljević et al, 2016) or short-range (Sjöholm et al, 2014) WindScanner systems, are needed to accurately retrieve the full wind flow. This of course drastically increases costs (several lidars) as well the complexity of measurements (installation, configuration, synchronization and monitoring) and corresponding data analysis (processing and integrating several datasets).…”

A Review of Progress and Applications of Pulsed Doppler Wind LiDARs

“…Wind turbine control is widely used in the wind energy industry to ensure long structural life and efficient performance of wind turbines operating under complex environmental conditions [130]. In recent decades, Doppler LiDAR technique has received considerable interest in the possibility of improving wind turbine control by providing look-ahead wind measurements in front of the rotor plane [131].…”

“…In addition, the torque control strategy led to a dramatic increase in loads on the shaft [140]. Experimental and numerical studies indicated that yaw control and pitch control could benefit from wind fields obtained from LiDAR measurements [131]. Fleming et al [135] estimated an increase of 2.4% in annual energy production if LiDAR data was used to correct wind vane measurements in yaw control.…”