I was running some simulations on the FOWT without and with TMD. For the uncontrolled case (no TMD), everything was fine. However, for the controlled case (a TMD is used), i get an error. This is the first time i obtained such error.
The following figure shows the obtained error:
I think it comes from MAP++ and i think the number of iterations exceeds the maximum allowable number of iterations, right ?
Please if you could clarify.
Thank u in advance.
What does the FOWT response look like just before this error is reported? Are the floater motions (surge, sway, heave, roll, pitch, and yaw) reasonable?
Thank you for your reply.
In fact, all the floater response were reasonable except for the surge response. It should be noted that the FOWT is subjected to 11.4 m/s steady wind with a sea state having Hs=2.6 m and Tp=12.5 s.
The following figure shows the surge response.
Note that this error disappears when the misalignment between wind and wave is different from zero (i have tried +90 degrees misalignment and the simulation succeeds ! )
You haven’t provided enough information yet to know what the issue might be.
Can you share plots of the time series of all floater motions (surge, sway, heave, roll, pitch, and yaw) with and without the TMD?
Sorry for my late reply and Sorry for my misunderstanding of your demand.
To be more concise, i was simulating the 5 MW barge type FOWT in the case of a sudden gust followed by a fault. The gust occurs at t=200 s. Instantly, the blades are feathered, the rotor is stopped and locked (i.e. a brake of 100 000 Nm is applied) and the generator is turned off. The wave elevation is a stochastic field generated using JONSWAP spectrum and having the following parameters: Hs=2.6 m & Tp=12.5 s. For the same wind and wave, two cases are treated: (i) uncontrolled case and (ii) controlled case. The controlled case consists of using two TMDs placed at the bottom of the platform, i.e. -4 m under mean sea level.
The floater motions are presented in the following:
1- Platform surge
2- Platform sway
3- Platform heave
4- Platform roll
5- Platform pitch
6- Platform yaw
I should also mention that i have changed the mooring line solver (i used MoorDyn instead of MAP) and the simulation succeeds.
Thank you a lot.
If I understand correctly, switching from MAP++ to MoorDyn solved the issue? If so, that’s great!