Bhavani, yes this type of simulation is possible in PLECS.
Some of the existing machine models in the PLECS library can be modified to bring out the neutral point for this type of analysis. However, care is required when modifying a machine model to ensure that no assumptions were made in its derivation. Specifically, ia+ib+ic=0 is assumed for the rotor reference frame implementations of the synchronous machine models and all implementations of the Permanent-Magnet Synchronous Machine component. The VBR implementations of the Synchronous Machine (Salient Pole, Saturable), Synchronous Machine (Round Rotor, Saturable), and the Non-Excited Synchronous Machine (Lookup) can be modified in this manner.
For the induction machine with a neutral connection, you can use an the Induction Machine (Open Winding) component from the PLECS Library with the stator windings connected to a common point.
You can modify the library components by right clicking the component and selecting “Subsystem + Break Library Link” and “Subsystem + Unprotect”. Then you can look under the component mask (again by right clicking) to see and modify its implementation. In this case you should add an Electrical Port at the appropriate neutral location.