After the process characteristics are identified, the information is then used to calculate the recommended loop tuning. The tuning rules used to derive controller parameters from process characteristics can be chosen as appropriate for the specific process and the desired speed of response. As addressed in Chapter 4 of Advanced Control Foundtion – Tools, Techniques, …
Tag Archive: response
Apr
15
On-Demand Tuning
During the commissioning of feedback control based on the PID algorithm, the PID tuning parameters (that is, the proportional, integral, and derivative gain) must be set to specific values to achieve the best controller response to setpoint and disturbance input changes. To minimize process variations and the response time to setpoint and disturbance input changes …
Mar
18
Impact of Changing Process Gain
From a control perspective, it is highly desirable that the process gain is constant. If the process gain is constant, then the same proportional gain can be used over the entire operating range of the control loop. Using a control valve as an example, if the valve characteristic was not properly selected based on the …
Mar
04
Addressing Incorrect Tuning
A Loop tuning has a significant impact on control loop utilization and performance. Controller tuning parameters can be easily changed over a wide range to adjust loop operation for various process requirements. However, some expertise in tuning is required even when advanced control tools are used, and there is a chance that the behavior of …
Nov
14
Recovery from a Process Saturation Condition
At Emerson Exchange, 2011, I had the pleasure of working with Daniel Coyne, Manager, Automation, BP America Inc., to host a workshop on Recovery from a Process Saturation Condition. The workshop addresses the improved recovery from a process saturation condition that is provided by the PIDPlus option of the PID function block in the DeltaV …
Sep
26
Commissioning Control Systems – Setting Controller Action
The process gain may be negative or positive depending on the process design. To provide the correct response a feedback control block must take into account the process gain direction—whether to increase or decrease the manipulated input to correct for a control error. For example, the inlet flow to a tank may be manipulated to …
Aug
22
Commissioning Control Systems – Control Response
In many processes, it is desirable to have an overdamped response. To achieve that response, the proportional gain used in the PID is typically much less than that required for an underdamped or unstable response. When selecting the PID gain, it is important to consider that the process gain may change with the operating conditions. …
Dec
27
Process Characterization – Inverse Process Response
Process characterization is the identification of the dynamic responses of a process to changes in its inputs. As part of the chapter on process characterization in Chapter 9 of Control Loop Foundation, we address inverse process response. A few processes exhibit a behavior where for a step change in input, the output initially changes in …
