Analysis of Control-Generator-Structure Interactions in Wind Turbines using an Integrated Simulation Approach

This paper addresses the modelling of the interactions between the generator, the controller and the structural components in wind turbines. Those interactions have a direct influence on the mechanical loads, which need to be evaluated for the design of the machine. Using the sofware Samcef For Wind Turbines, a model is developed which includes a description of the aeroelastic behaviour of the blades, the gearbox dynamics, the tower flexibility, as well as the electrical and control parts. Electrical and control subsystems can be modelled either by linking an external DLL, by a co-simulation approach or by using an integrated and monolithic model. This paper shows that the monolithic approach can be exploited for the reliable analysis of electrical-control-structure interactions in wind turbines. Non-mechanical elements are represented in a modular way using a newly developed library of block diagram elements. The coupled equations of motion are established by numerical assembly and they include a finite element description of the mechanical components and a block diagram description of the generator and its control system. A fully implicit, stable and reliable solver is then exploited to solve the coupled equations of motion. Simulation results are presented for a 2 MW wind turbine with a doubly-fed induction generator and they illustrate the coupling between the power control system and the dynamic structural response.