Object-Oriented Modelling of a Wind Power Plant in Modelica and Analysis of Loads on Blade Bearings

Abstract: Within this thesis work a strongly simplified yet complete, component-based numerical model for load analysis of a horizontal wind turbine is built up. The model is written in the open-source, object-orientated and equation-based modelling language Modelica and designed in a modular structure which allows integration in OneWind, a specialised Modelica library for components of wind power plants which is being built by Fraunhofer IWES. The model makes continuous use of three-dimensional mechanical elements of the Modelica Standard Library. It comprises all components of an onshore wind turbine including independent subcomponents such as rotor, drivetrain, generator, controls and tower, as well as different wind models. A main focus is put on energy conversion in the rotor. With the established model an analysis of expectable blade root forces in a 5MW turbine under extreme conditions is performed, which are modelled using two different certification load cases. Based on these results a rough preselection of an appropriate blade bearing is carried out.