Derivative of state '1' in block 'test1/Control_DFIG/PID Controller​2/Integrat​or/Continu​ous/Integr​ator' at time 0.0 is not finite. The simulation will be stopped. There may be a singularity in the solution. simulink

In my simulation when I use a synchronous genarator and an asynchronous machine the error message comes. If I replace synchronous generator with a three phase source block, error does not come. I don't get any problem with synchronous generator, because the same generator works fine with a load only (i.e with out assynchronous machine)