DMC3 Builder. Ramps show abrupt changes in Simulation

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Products: Aspen DMC3 Builder 
Last Updated: 02-Dec-2020
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Article ID: 000097887
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Problem Statement

When simulating ramp CV’s in DMC3 Builder Simulation, you might see the CV steady state values increasing abruptly or a Mismatch between Model and prediction. For example, in the image below, the Steady state value has gone to high violation and MV1(primary handle) has already reached its limit.

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Workaround

The cause of this is that the IPSKIP is much greater than 1. This causes an accuracy problem in the simulation. This does not affect the online behavior of the controller though.
This problem has been reported in V11. There are two workarounds, either one (or both) works:
  1. Make a copy of the application in DMC3 Builder. When you click on Simulation on the original application, select the copy as the plant model. This will force the simulator to work harder but it will greatly increase the accuracy.
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  1. In the Move Settings, don't select the Expanded Blocking setting. This will force IPSKIP = 1.
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Fixed in
V12

Keywords

DMC3 Builder, Ramp, Simulation.
VSTS 570465
VSTS 544162