RGA at steady state for integrating system

From: Sigurd Skogestad <skoge@chemeng.ntnu.no>
Date: Wed Jun 12 2002 - 13:46:12 CEST

Hello,

At 13:09 11.06.2002 +0200, you wrote:

Dear Proffesor Skogestad:
 
I am a student of Industrial Engineering from Spain and I have a problem that I'd like to tell you. I am working with a control structure of a distillation column and I'm trying to measure its controllability with the RGA (and other tools). The problem is that, when I have the Model of the column and I obtain the matrix A,B,C and D (state space model), I obtain a integrator (1/s) in some values (as you mention in Modelling and control of distillation columns as a 5 x 5 system). The problem is that I want to calculate G at steady-state (G(w=0)).
 
How can I use the RGA ? Do I have to take the absolute value of every element of my G matrix (in a frequency w near to zero, i.e w=1e-3) and then applicate the RGA matrix?
 

Yes, this should work fine.
Good luck!

-Sigurd Skogestad

Thanks in advance and congratulations for your articles, your books (I have Multivariable feedback Control) and your family!! (I've been looking at your page!!)
 
J.A

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Received on Wed, 12 Jun 2002 13:46:12 +0200