Calibration report for ZephIR Dual Mode lidar (unit 351)

Nacelle-based profiling LiDARs may be the future of power performance assessment. Due to their large rotor size, single-point measurements are insufficient to quantify the power modern wind turbines can harness. The available energy in the wind indeed varies with heights. Improving power performance assessment by measuring simultaneously at different heights has been demonstrated using ground-based profiling LIDARs. Using nacelle lidars avoids the erection of expensive meteorology masts, especially offshore.
As for any other measuring system, lidars measurements have uncertainties. Their estimation is the ultimate goal of a calibration: a relation is established between reference measurements from calibrated instruments and corresponding LiDAR indications. Traceability in the calibration is obtained by transferring measurement uncertainties from the reference instrument through the calibration process.
A generic methodology to calibrate profiling nacelle lidars has been developed and performed on a ZephIR Dual Mode lidar manufactured by ZephIR LiDAR. In essence, the generic methodology calibrates the inputs of the wind reconstruction algorithms rather than their outputs.
This report presents the calibration procedures and results of the ZephIR Dual Mode lidar unit 351. The calibration was performed at DTU’s test site for large wind turbines, Høvsøre, Denmark. The methods to assess line-of-sight velocity uncertainties are detailed together with an example of how to derive reconstructed wind parameters’ uncertainties.