Industrial & Engineering Chemistry Research, Vol.52, No.18, 6193-6200, 2013
Refinement of Cascade Tuning to Improve Control Performance without Requiring Any Additional Knowledge on the Process
A refinement of cascade control tuning to reduce oscillations in the inner loop without deteriorating performance of the controlled (outer) variable is proposed. It is illustrated that the problem can rise for very common process dynamics and tuning techniques. The basic idea is to perform a balanced retuning of master and slave controllers, by acting on proportional and integral components of the two (PI) controllers. A distinctive feature of the method is that, once the problem shows up, appropriate actions can be performed on the two controllers without any additional knowledge about process dynamics. The effectiveness of the technique is validated in simulation on a significant class of process dynamics and in application on industrial loops.