Experimental Modal Analysis of a 750 kW Wind Turbine for Structural Model Validation

In this paper the systematic structural modeling approach implemented in DAWIDUM is validated by experimental modal test data. The data were collected from an instrumented Lagerwey LW-50/750 wind turbine. Pre-test analysis was performed on two DAWIDUM models describing the structural dynamics of the Lagerwey LW-50/750, in order to be able to determine the frequency range of interest, the required input force magnitude, the driving point on the tower, and the accelerometer locations. The mechanical structure of the turbine is excited by applying a static load to the tower top of the wind turbine, and suddenly releasing this load via a quick release mechanism. The turbine was parked during all testing. The structure was instrumented with one force transducer in-line with the cable to measure the applied load, and 19 accelerometers on both the tower and the three rotor blades to measure the resulting response. The first results show that it is possible to derive accurate dynamic wind turbine models from design data using the presented modeling approach.