Code Development for Control Design Applications, Phase I: Structural Modeling

The design of integrated controls for a complex system like a wind turbine relies on a system model in an explicit format, e.g., state-space format. Current wind turbine codes focus on turbine simulation and not on system characterization, which is desired for controls design as well as applications like operating turbine modal analysis, optimal design, and aeroelastic stability analysis. Weinitiated development of a specialized code to provide explicit system models. The code draws heavily from modern multibody modeling concepts as well as advanced features of an existing helicopter code. The code will be implemented in two phases: structural modeling followed by aerodynamic modeling. This paper reviews structural modeling that comprises three major steps: formulation of componentequations, assembly into system equations, and linearization. Linearization provides system equations in descriptive formats, clearly delineating linear and nonlinear parts, which can then be readily used by optimal control schemes.