I went though this example and it seems a good one where we can see how to control the output voltage as described. I have some questions about Transient Stability but I started my investigation with the above question where I wish if there is any way to change the the output signal to be seen as normal ( like when we see 3 phase signal ) sinusoidal ones.
It can be done but it requires post processing of the data. The model will not display it that way in any of its logging. Alternatively, simscape (not specialized power systems) has phasor simulations and will create the sinusoid for you.