The paper first briefly reviews the analytical procedures for obtaining optimum PID controller settings for minimisation of time weighted integral performance criteria. The approach is then used to obtain formulae for setting the controller parameters for a first-order plus dead time plant model which is a common approximation used in the process industries. These results are further extended to obtain two procedures, which can be used with the relay autotuning approach, to find the required controller parameters for optimisation of the integral of time error squared criterion. Good results have been obtained when these criteria are used with other plant models.

Tuning process controllers

Automatic tuning of optimum PID controllers

A process control system (100) controls a process (110) through a control output signal (u(t)) based on a set point (YSET) and a measured process variable (y(t)). The process control system (100) includes a control circuit having a set point input, a process variable input and a control output. The control circuit generates the control output signal (u(t)) on the control output as a function of the set point (YSET) received on the set point input and the measured process variable (y(t)) received on the process variable input. An auto-tuning circuit (106) excites the process (110), estimates a process model based on a rising dead time, a rising rate-of-change, a falling dead time and a falling rate-of-change in the measured process variable (y(t)) and then tunes the control function to the process (110) based on the process model. The auto-tuning circuit (106) obtains robust results, but is computationally simple such that the circuit can be implemented with hardware or software in low-power and low-memory applications, such as in field-mounted control units.

Field based process control system with auto-tuning

The ability of PI and PID controllers to compensate many practical processes has led to their wide acceptance in industrial applications The requirement to choose two or three controller parameters is most easily done using tuning rules Starting with a general discussion of industrial practice, the chapter will provide an outline of tuning rules for continuous-time PI and PID control of time-delayed single-input, single-output (SISO) processes

An Overview of Tuning Rules for the PI and PID Continuous-Time Control of Time-Delayed Single-Input, Single-Output (SISO) Processes

The implementation of the SCADA system has a positive impact on the operations, maintenance, process improvement and savings for the City of Houston's Wastewater Operations branch. This paper will discuss the system's evolvement, the external/internal architecture, and the human-machine-interface graphical design. Finally, it will demonstrate the system's successes in monitoring the City's sewage and sludge collection/distribution systems, wet-weather facilities and wastewater treatment plants, complying with the USEPA requirements on the discharge, and effectively reducing the operations and maintenance costs.

Application of the SCADA system in wastewater treatment plants.

SUMMARY

In this paper, an algebraic rule for tuning the integer realizations of fractional-order PI controllers is developed, with an integral square error performance index, which outperforms that of an optimal ordinary PI controller. To this end, the PIλ control structure is used in conjunction with a third-order integer approximating filter to provide a three parameter fixed-structure extension of the ordinary PI controller. Next, the extra degree of freedom in setting the order of integration λ is leveraged to introduce a steepest descent direction in the extended controller parameter space. It is then stated that shifting the parameters of an ordinary PI controller along the proposed descent direction will result in a fractional-based three parameter controller with a performance index, which is superior to that of the original PI controller. The stability of the controller parameters derived in this manner is then analyzed, and examples and simulation results are offered to verify the theoretical expectations and analyses. Copyright © 2013 John Wiley & Sons, Ltd.

Tuning process controllers

Citations

Automatic tuning of optimum PID controllers

Field based process control system with auto-tuning

An Overview of Tuning Rules for the PI and PID Continuous-Time Control of Time-Delayed Single-Input, Single-Output (SISO) Processes

Application of the SCADA system in wastewater treatment plants.

Improving integral square error performance with implementable fractional‐order PI controllers

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