Full Access to initial states of FAST v8 in Simulink

Hi Every one,

It turns out that there are limited state variables in FAST v8 which can be set as initial conditions. I need to set towerinitial conditions for tower fore-aft displacement as well as its rate before I run the simulations ( S-function in Simulink). I can find initial condition variables listed in the files “???_ElasoDyn.dat” line 28 to 44.
TTDspFA is associated with “Initial fore-aft tower-top displacement (meters)” . he question is how I can set the initial value for the tower fore-aft displacement rate(meters/sec) ?

Dear Elham,

The initial conditions for the tower fore-aft rate are assumed to be zero by FAST. For most users, the use of zero initial rate is reasonable because the start-up transients are ignored anyway and the setting of a nonzero initial rate will not greatly speed up this transient.

You’ll have to modify the source code and recompile FAST if you want to set a nonzero initial rate. The change can be made to SUBROUTINE Init_ContStates() in ElastoDyn.f90.

Best regards,

Dear Jason,

I am trying to develop a model-base controller for 5MW wind turbine. My controller uses a simple model of the turbine however, to replicate the real turbine, I need to have the FAST model (in Simulink). For this purpose, I will need to calculate the control signals and apply them to the FAST model at every time-step. This means there are non-zero initial values for the selected turbine states at every time step. Is it even possible to handle this?
Which FAST version do you suggest I should use ? (I personally think FAST 7 is easier because the states are accessible in Simulink but it looks like FAST 7 does not accept non-zero initial values for the states while FAST 8 is not restricted on this issue).
Please let me know your advice.

Also, do you know any other people who have used similar model-based control structure that I can talk to ?

Thanks for your attention.


Dear Elham,

I would suggest upgrading to FAST v8. Like the Simulink interface to FAST v7, the Simulink interface to FAST v8 allows you to set control inputs to FAST from Simulink. The Simulink interface to FAST v8 also resolves many of the issues of the FAST v7 interface e.g. elimination of problems associated with algebraic loops. While the structural states of FAST are not integrated by Simulink in FAST v8 and cannot be input into the FAST v8 block, the states are still available as a standard FAST output (e.g. output Q_TFA1 is the displacement of the 1st tower fore-aft bending mode DOF from the ElastoDyn module).

Many people have used FAST and the Simulink interface for controls design and analysis.

Best regards,