Floquet stability analysis of wind turbines using input-output models

In this work a method is described for the stability analysis of wind turbines. The method uses input-output time histories obtained by suitable excitations of the system. Next, a periodic reduced model is identified from the recorded response, and used for a stability analysis conducted according to Floquet theory. Since only input-output sequences are used, the approach is model-independent in the sense that it is applicable to wind turbine simulation models of arbitrary complexity. The paper describes a formulation capable of handling turbulent disturbances, and verifies its performance with the help of high fidelity numerical simulations.