Mechanical rotational port of Induction Motor from the specialized power system library

Hello,

I want to build a rotary frequency converter using an induction motor and a synchronous generator, connected to each other via the mechanical rotational port S.

The generator will supplement a grid and has already been modeled and the result was validated (400V and 50Hz on the grid side)

When I connected both machines through the mechanical rotational port, (assuming a perfect connection without a clutch for the first try) I got a warning saying "First solve for initial conditions failed to converge. Trying again with all high priorities relaxed to low." although I don't have any input with high priority, and o.c. I have 0V on the grid side.

It has to bet connected via the mechanical rotational port because the speed w of the induction motor will be controlled (so I can't choose the mechanical input as speed) and the torque varies over the time (so I can't choose the mechanical input as torque either).

I choose squirrel cage model 18 with a positive load flow (which indicates a motor not a generator)

I'm not sure wether simscape can assume the synchronous machine as a generator just by its load flow through the shaft.

Any suggestion why it's not working?

Thank you!

Answer 1

[Steve Miller]

I believe you need to remove the Mechanical Rotational Reference. You have essentially welded the shaft to the earth so it cannot spin. This will make it impossible for the initial speed setting to be achieved, hence the error.

--Steve

[K]

Hello Steve

thank you, yes that was it