Genetic Algorithm in system with Pi Controller

Hi Frieands, I work on system that have Pi Controller and want to optimize pi parameters. but this erro is occur:

??? Error using ==> outsim at 10 Derivative input 1 of 'Model07/PMSG/Integraor2'at time 0.67835447282436279 is Inf or NaN.Stopping simulation. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances).

solver type is variable and solver is ode45,also i reduce the step size but this problem don't solve.

please help for this problem.