April 2010

In this issue

• Trick
• Courses
• Articles
  

Trick

Reducing Interactions

Last month, we discussed control loop interactions and how to evaluate those interactions. (SeeMarch 2010 Top News)

This month, we present solutions when interactions are present. Three approaches are presented:

1.      Tuning loops at different speeds

2.      Using advanced regulatory control, for example using feedforward

3.      Using MPC (« multivariable process control »)

The first solution is very simple; each loop is tuned at a different speed, using a factor of 3. For example, if a pressure and a flow loop interact, one loop is tuned accordingly to its goal and the other loop is tuned 3 times slower. This approach reduces impacts of interaction.

The second method is to inform each loop when a change occurs. For example, in a header supplying many flow loops, total flow is used as a feedforward signal to improve pressure control.

Finally, the third method uses an advanced controller. This controller is similar to a conductor conducting his orchestra; not only the controller manages interactions but also handles constraints and limits.

 
More to come…

Optimization is a very good investment! Usually, within few weeks, money invested is recovered.

Do not hesitate to contact us; we can help you.


Contact us!

---

Courses

See our calendar: we offer workshops on control strategies, performance supervision, advanced process control, alarm management, etc.

Next classes:

WS-100-2E
Workshop on PID Troubleshooting and Tuning, with Cascade and Feedforward

Atlanta GA,    May 4-5, 2010

To learn more


Articles

Two articles have been added to our  WEB site.

CLOSED LOOP TUNING VS OPEN LOOP TUNING-Tuning all your Loops While the Process is Running is Now Possible, PAPTAC 2010, Montreal, February 2 2010, by Michel Ruel

Tracking performance after optimizing a deinked plant, PAPTAC 2010, Montreal, February 3 2010, by Michel Ruel

To learn more