SymDyn has been developed to aid multivariable control design of horizontal-axis wind turbines.  Its capabilities include:

• Construction of a nonlinear aeroelastic wind turbine model.
• Calculation of periodic steady-state solutions for use as linearization points.
• Aeroelastic system linearization to form first-order state-space matrices.
• Stability analysis through Floquet theory for linear periodic systems.
• Open- and closed-loop time simulation for preliminary control performance analyses.  Simulation output includes joint constraint loads and blade root loads.

Sample code is also included in the package for the design of full-state feedback controllers and state estimators.  Available control inputs include individual (or collective) blade pitch and generator torque.

The structural model is simple, using rigid bodies connected by revolute joints to define a maximum of 8 + Nb degrees-of-freedom (DOFs), where Nb is the number of blades.  The DOFs include tower deflection (fore-aft, side-to-side, and twist), nacelle yaw and tilt, rotor position, drive-train torsion, hub teeter and flapwise deflection of each blade.  A preprocessor is included that calculates the necessary structural parameters from generic wind turbine properties, including distributed mass and stiffness data for the tower and blades. SymDyn uses AeroDyn 12 subroutines for the calculation of aerodynamic loads.

The code runs in MATLAB version 6.5 for Microsoft Windows with Simulink version 2.0. The Controls Toolbox is also recommended to aid controller design. It is assumed that the user is familiar with the MATLAB environment to edit script code (.m files), execute commands and construct Simulink models.  A background in wind turbine dynamics and modern control is also desirable.

SymDyn has been verified using identical models in ADAMS.  Exact agreement was achieved for a system with 8 DOFs.

You may download the following files from our server:

• SymDyn Change Log (v1.20, 5 KB, 16-July-2003)

  This is a list of changes made to the code.  Look at this text file to see if we've made worthwhile changes since you received your previous version of SymDyn.

• SymDyn User's Guide (v1.2, 413 KB, 20-November-2003)

  This is the SymDyn User's Guide.  Please refer to it when trying to understand how the program works.

• SymDyn Archive (v1.20, 1.4 MB, 18-July-2003)

  This is a self-extracting archive of SymDyn.  It contains the SymDyn source code, sample input and output files, change log, and user's guide. 

If you want to refer to the SymDyn website in a report, here is a reference you can use:

NWTC Design Codes (SymDyn by Karl Stol and Gunjit Bir).  http://wind.nrel.gov/designcodes/simulators/symdyn/.  Last modified 26-May-2005; accessed 26-May-2005.