Convergence Problem with BeamDyn

Wind & Water Computer-Aided Engineering Software Tools
1

Hi,

I ran the latest FAST v8 in MATLAB/Simulink coupled with baseline generator-torque and pitch controllers based on the OC3-monopile model using ‘Test19.fst’ in the ‘CertTest’ folder as the primary input file. It ran successfully. Then I set ‘CompElast’ and ‘CompAero’ to 2 to test BeamDyn. I also changed AeroFile to ‘5MW_Baseline/NRELOffshrBsline5MW_OC3Monopile_AeroDyn15.dat’. But it fell and gave the error messages as follows:
“Error using Run_NREL_5MW_MONOPILE (line 22)
Error reported by S-function ‘FAST_SFunc’ in ‘NREL_5MW_MONOPILE/FAST Nonlinear Wind
Turbine/S-Function’:
FAST_Solution:FAST_AdvanceStates:BD_GA2:BD_DynamicSolutionGA2:Solution does not
converge after the maximum number of iterations
FAST_AdvanceStates:BD_GA2:BD_DynamicSolutionGA2:Solution does not converge after the
maximum number of iterations
FAST_AdvanceStates:BD_GA2:BD_DynamicSolutionGA2:Solution does not converge after the
maximum number of iterations”.
Then I increased ‘NRMax’ in ‘NRELOffshrBsline5MW_BeamDyn.dat’ to 10000. But there was no use for convergence and errors reported above still appeared.

I would like to know how I can deal with this problem, without increasing ‘stop_tol’ in ‘NRELOffshrBsline5MW_BeamDyn.dat’. Thank you.

Best wishes,
Xin

2

You should decrease the FAST time step for the BeamDyn simulation. Test 26 in the FAST archive is the same model as Test 18, except Test 26 uses BeamDyn. Compare the time steps of those two models and adjust your Test19 with BeamDyn accordingly.