Simplified Synchronous Machine with zero mechanical input

Hello,

I am trying to simulate a simplified synchronous machine linked to the ground as shown in the picture below:

I gave Pm=0 and E=0 as an input. Logically, I expected to obtain w=0 because if Pm=0 that mean that the rotor is not turning. But in fact I obtain w=1 pu as shown in the figure below:

Can you please provide me with an explanation about this phenomenon ?