Supervisor: Jakob Mann, DTU Wind Energy
Co-supervisor: Sri Raman, Vestas
Examiner: Lars Landberg, DNVGL
Title: Lidar based wind field estimation techniques for load verification
In the present report, we first performed the measurement data analysis, especially the nacelle-mounted lidar measurement data, and studied the potential issues for applying the lidar based wind estimation methods, of which the constrained simulation is of the most importance. A ZX LIDAR continuous-wave lidar is mounted on a Vestas V150 4.2 MW Mk3E turbine, where the load measurement sensors are also equipped. Wind measurements are also performed on a meteorological mast that is 3.34 rotor diameter distance from the tested turbine. Then the details of the method of Kriging constrained simulation is demonstrated, including the mathematical derivation for understanding the assumptions of the method, as well as the analysis of the constrained wind. In order to combine the constrained simulation with the aeroelastic load simulations, i.e. VTS, we recapitulated the relevant theories regarding the Mann spectral tensor turbulence model, as well as demonstrating the comparison between two turbulence generators, i.e. ’windsimu’ and ’WSimMannGLSys’. It is found that the correctness of the covaraince tensor is required in order to perform the constrained simulation, and thus the Mann parameter fitting procedure is studied. Details are also studied that occur when implementing the constrained simulation onto the Vestas tool chain. We also compared the load estimation results of different scenario, and studied the impact of constraining the meteorological mast measurement respect to the load estimation uncertainty reduction.