Given that cascade control loops are everywhere without much consideration as to dynamic requirements, what can we do to make the implementation effective? Here are some specifics by the way of detailed recommendations on the sequence, speed, and setup for tuning PID and digital valve controllers.
Did you know all loops today use cascade control? Do you understand how cascade control can correct for lower loop disturbances before they affect the upper loop and can make the upper loop faster? Do you know what to do to keep the system from oscillating if the lower loop...
A unified approach to tuning has been found that enables a common and simplified method for setting PID tuning parameters. Key features can be used to eliminate the need for retuning to deal with different dynamics and objectives.
We continue this series with the steps for designing control strategies. Simple rules of thumb will be offered for setting up cascade, composition, flow, level, pH, pressure, and temperature control systems. Examples of common unit operations will help provide understanding of the steps involved. The objective is to set the...
Cascade control is an effective way of providing better feedback and feedforward control. The peak error in the primary loop can be reduced by more than an order of magnitude for disturbances originating in the secondary loop.
The value of a key PID feature is increasingly becoming apparent. I got a preview of the importance when I found the 1980s vintage DCS required a fix for override control that was inherently addressed in the next generation of DCS by this feature.