A previous post about the Derivative Term focused on its weaknesses. As noted, the primary challenge associated with the use of Derivative and PID Control is the volatility of the controller’s response when in the presence of noise. Noise is a major stumbling block for Derivative and PID Control as production data is routinely replete with process noise and other sources of variability. The use of PID Control in such an environment can drive frenetic changes in a loop’s Controller Output (CO) and unnecessarily wear out the associated Final Control Element (FCE). In summary: Little to gain; lots to lose.Read More
Effective Disturbance Rejection
“When your only tool is a hammer, every problem looks like a nail” – a concept attributed to Abraham Maslow. Such can be the situation with process control and the PID controller. For decades practitioners have applied the PID to tackle the majority of challenges related to process control. Fortunately for practitioners the PID is more like a Swiss Army Knife as it can take different forms. The focus of this post is on a pair of applications of P-Only Control – or Proportional-Only Control.
Place in Industrial Process Control.
As with most everything in process manufacturing, PID controllers require practitioners to make choices. One of those choices is which form of the controller to apply on a given regulatory control application. In a previous post the pros and cons of Derivative and the full PID were covered, and now the advantages and disadvantages of Proportional-Only control are explored. Due to performance characteristics the selection of a P-Only controller can be relatively straightforward and among a practitioner’s easier choices.