Thank you Jpfeiffer. I think my problem is quite similar to this post (Are Dynare's stochastic shocks truely random?).
I know now that I have to add set_dynare_seed=(…) to the options of stoch_simul(…) instead of simul_seed (which seems to be outdated).
In the description of set_dynare_seed I see that there are two input argument a,b which correspond to the random number generator and its seed respectively.
According to the dynare manual one can also only put a single integer or double or expression in the argument set_dynare_seed(.).
But how exactly do I use this option. When I used 1 as an integer I got an error message on the mod file:
ERROR: BA_Perturbation_General.mod:40.45-59: syntax error, unexpected NAME
Thanks for your help,
nbt