Isolated synchronous machine feeding induction machine

Hello everyone

I would like to simulate an isolated synchronous machine feeding an induction motor. But whenever I want to model the line reactance or the transformer of the motor I get the error message:

"The first block, modeled as a current source, cannot be connected in series with the inductive element of the second block. Add a high-value resistance in parallel with one of the two block. You can also specify high-value resistive snubbers if the blocks have a snubber device.You can also avoid the use of the snubbers by selecting the 'Enable use of ideal switching devices' option of powergui block."

What is the "trick to bypass" this problem ? Indeed an reactance cannot be in series with a current source. But if I put an high parallel resistance the simulation takes way to much time to be solved and is not anymore correct.

Does anyone has a convenient solution for this type of problem ?

Thank you

Answer 1

[John Noon]

There isn't a simple trick to bypass this issue. Typically machines are modeled as current sources, but you can use a voltge behind reactance method to model them as a voltage source instead and this will get around the issue. If you search VBR modeling on IEEExplore you will see some papers from the University of British Columbia which are very helpful for you to reformulate the machine models. Also, the simulation speed is inversely related to the value of the snubber resistor. So decreasing the value of the snubber will increase the speed.