Nacelle-mounted lidars facing upstream of a wind turbine can measure the wind speed through the induction zone. Several nacelle lidar campaigns have indicated that the induction effect may be felt further upstream of the rotor than is commonly assumed in the design of power curve verification campaigns. To understand the magnitude of the induction effect, the freestream wind speed needs to be established. Since freestream velocity may only be reached beyond the measurement range of the nacelle lidar, an extrapolation based on the lidar measurements is necessary. A wind field model of the induction zone combined with the lidar line of sight wind speeds can be used to perform wind field reconstruction and derive not only the freestream wind speed, but also map the variation of the horizontal wind speed at different distances from the rotor.

No consensus exists on the optimal method for the wind field reconstruction in the induction zone that balances fidelity and simplicity. To take the first steps towards a common understanding in the community a round robin was organized to compare different methods and approaches to the wind field reconstruction problem on a common dataset.

More information about the round robin can be found here.