The OneWind Modelica Library for Wind Turbine Simulation with Flexible Structure - Modal Reduction Method in Modelica

Abstract

The OneWind R Modelica Library1 [15] for coupled wind turbine loads calculation developed at Fraunhofer IWES uses a structural element based on a modal reduction method to model the motion and deformation of flexible wind turbine rotor blades and tower. The degrees of freedom (DOF) are rigid body motions and modal DOF. The ModalElement model allows the simulation of coupling effects like bend-twist coupling in wind turbine rotor blades and the structural behavior is dependent on the selected eigenmodes. This paper gives an overview about the Modelica implementation of the theory of modal elements, the advantages over other methods (finite-elements), how the ModalElement model is included into the OneWind R Modelica Library, and how it is used for load calculation.