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Strange machine angle behaviour in dynamics when breaking up run() calls

asked 2020-05-25 20:30:29 -0500

boat14 gravatar image

I'm seeing deviations in flat runs in dynamics when I break up my commands.

The reason I'm concerned is this behaviour is not expected. My understanding is that I can break a simulation up into multiple segments, even if nothing happens between the two.

For example, if I do a flat 30 second run with just one command, all machine angles are flat and are consistent with each other:  tpause  = 30,
            nprt    = 0,
            nplt    = 5,
            crtplt  = 0

However, if I do a 30 second run, broken up into multiple parts, one of the machine's angles starts to deviate after the first command (for 1 second of initialization):  tpause  = 1.0,
            nprt    = 0,
            nplt    = 5,
            crtplt  = 0
# [Do contingency actions here]  tpause  = 30,
            nprt    = 0,
            nplt    = 5,
            crtplt  = 0

I have a list of contingencies that is used as an input for a dynamics simulation loop. The first "contingency" is a no fault run to compare the other contingencies against. So in the code above, the [Do contingency actions here] segment would be:

  • A non-operation for the "no fault" contingency.
  • A series of actions for other contingency tests.
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answered 2020-05-26 00:05:13 -0500

perolofl gravatar image

A pause shall not affect the simulation results. Something is wrong in your model.

Check the dynamic models for the generators, especially for the generator with changing rotor angle.

If a user model is used, replace it with a library model.

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Thanks - it is a custom model, which makes it a little harder to troubleshoot.

boat14 gravatar imageboat14 ( 2020-05-26 11:01:54 -0500 )edit

What kind of generator is it? Synchronous or RE?

perolofl gravatar imageperolofl ( 2020-05-26 11:16:12 -0500 )edit

After more investigation, it is RE (Renewable Energy?). Which explains why the angle is drifting. I should be disregarding that machine's angle since it's not tied to the system.

boat14 gravatar imageboat14 ( 2020-05-26 12:42:21 -0500 )edit

Yes, for a RE generator rotor angle is meaningless. Check Eterm, Pelec and Qelec for the machine instead.

perolofl gravatar imageperolofl ( 2020-05-26 15:12:17 -0500 )edit

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Asked: 2020-05-25 20:30:29 -0500

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Last updated: May 26