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MBC: Multi-Blade Coordinate

MBC is a set of MATLAB® scripts that performs multi-blade coordinate (MBC) transformation on wind turbine system models.

The dynamics of wind turbine rotor blades are conventionally expressed in rotating frames attached to the individual blades. The tower-nacelle subsystem sees the combined effect of all rotor blades, not the individual blades. This is because the rotor responds as a whole to excitations such as aerodynamic gusts, control inputs, and tower-nacelle motion—all of which occur in a nonrotating frame. MBC helps integrate the dynamics of individual blades and express them in a fixed (nonrotating) frame.

MBC is mandatory to controls and stability analyses—erroneous predictions can result otherwise. A novel feature of this MBC code is that it can handle variable-speed operation and turbines with dissimilar blades. Depending on the analysis objective, a user may generate system models either in the first-order (state-space) form or the second-order (physical-domain) form. MBC3 can handle both types of system models.

Key advantages of MBC are:

  • Capturing cumulative dynamics of the rotor blades and its interaction with the tower-nacelle subsystem
  • Well-conditioning of system matrices by eliminating non-essential periodicity
  • Filtering operation.

This software was developed by Gunjit Bir of NREL.

The archives below are for MBC v1.00. Newer versions and ongoing development now take place in GitHub in the MATLAB Toolbox repository.


MBC User's Guide (v1.00, 150 KB, 16-October-2008)

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