search

OpenFAST / openfast

Main repository for the NREL-supported OpenFAST whole-turbine and FAST.Farm wind farm simulation codes.
http://openfast.readthedocs.io
Apache License 2.0
691 stars 457 forks source link

Error AeroDyn: The BEM solution is being turned off due to low TSR; There is no valid value of phi #1635

Open jujeonW opened 1 year ago

jujeonW commented 1 year ago

Hello all,

I am running FAST.Farm with NREL 5-MW wind turbines and TurbSim inflow input, and I have encountered this problem several times. Currently, I am running the simulation with 4 identical turbines placed along the x-axis with 7D apart from each other. I ran this simulation with a 10m/s TurbSim input without a problem but when I used a 11.4m/s TurbSim input the following error occurred:

"The BEM solution is being turned off due to low TSR. (TSR = 1.9612). This warning will not be Time: 12 of 1600 seconds. Estimated final completion at 15:28:46.

T2:FARM_UpdateStates:FWrap_Increment:FAST_Solution:FAST_AdvanceStates:AD_UpdateStates:BEMT_UpdateS tates:UpdatePhi(node 5, blade 2):BEMT_UnCoupledSolve:There is no valid value of phi for these operating conditions: Vx = 10.907, Vy = -0.93201, rlocal = 11.73, theta = 0.7679, geometric phi = 1.656. This warning will not be repeated though the condition may persist. (See GeomPhi output channel.) Time: 19 of 1600 seconds. Estimated final completion at _15:33:26."

The result is that while the first turbine works normally with a RotSpeed=12, the second turbine is shut down with T3 and T4 having a RotSpeed over 20 with GenPwr vibrating between 2000 and -2000 kW. Other plots drawn from the output files don't look normal as well, which I've seen on pyDatView.

Trying to solve the problem, I changed the settings in AeroDyn such as WakeMod AFAeroMod and SkewMod, and I changed the layouts in the turbine columns in FAST.Farm input file. None of it helped. The errors just showed up earlier or later on a different turbine/node/blade.

Similar error outputs showed up before while I was running simulations with two turbines 7D apart. The simulations managed to abort with no errors up to a TurbSim input of URef=17m/s. But this time the errors showed up at 11.4m/s with four turbines. This is the rated wind speed of the NREL 5-MW turbine and I would really want to run the simulation at this wind speed. Can someone help me solve the problem? Thanks kindly.

Best regards, Zhizhong

jjonkman commented 1 year ago

Dear @jujeonW,

A similar question was asked and answered in the following OpenFAST issue: https://github.com/OpenFAST/openfast/issues/1488.

Best regards,

May0048 commented 11 months ago

Hello, have you solved this problem yet? I encountered the same problem, but the above method did not solve it.