The step input and external disturbances drive the model away from the
operating point that the linearized model uses. This prevents the response from
reaching steady-state. To correct this problem, find and disable the time-varying
source blocks that interfere with the estimation. Then estimate the frequency
response of the model again.(^7) Find and disable the time-varying sources within the model.
a Open the Options for frequency response estimation dialog box.
In the Estimation tab, in the Options section, click More Options.
5 Frequency Response Estimation