Blogs

When do I Use MPC instead of PID for Advanced Regulatory Control - Tips?

For advanced regulatory control, when do I use Model Predictive Control (MPC) instead of PID control? There are many PID techniques for dealing with batch operations, abnormal operation, startups, and transitions. Feedforward, ratio control, and override control are a main stay for PID control.  If desired, PID dead time compensators...

When do I Use PID, MPC, and FLC for Basic Control - Tips?

For basic control, when do I use Fuzzy Logic Control (FLC) and Model Predictive Control (MPC) instead of PID control? The automation and integration of FLC and MPC into distributed control systems makes these a more viable choice. Surprisingly, there may be less decisions and expertise required than for PID control.

How can we provide Mechanical and Process Engineering Regulatory Control Guidance Tips (Part 5)?

In part 5 we finish with a list of my foremost best practices. These practices build on the essential concepts given in Part 3. These practices offer simple fixes in the automation system design. Major improvements in the mechanical design are also introduced.

How can we provide Mechanical and Process Engineering Regulatory Control Guidance Tips (Part 4)?

In part 4 we start a list of best practices. The guidance is the result of decades of experience in plants by industry experts Michel Ruel and Jacques Smuts.  The practices are insightful and apply to almost every control loop. The series will conclude next week with my offering.

How can we provide Mechanical and Process Engineering Regulatory Control Guidance Tips (Part 2)?

In part 2 we evaluate a misleading statement about the amount of derivative to use and provide some better guidance. We take a look at how mechanical and process design and operating conditions affect the need for derivative action.

How can we provide Mechanical and Process Engineering Regulatory Control Guidance Tips (Part 1)?

The mechanical, piping, and process design determines the steady state and integrating process gains and the process deadtimes and lags. The process engineer usually sets the project basis for the control system in the development of the Process Flow Diagram (PFD) and in the writing of the operating and process descriptions.

What are Good Signal Filtering Tips?

Noise in control loops can wear out valves and get amplified by proportional and derivative action. The filter should reduce noise to an acceptable level without appreciably slowing down the loop. I have enlisted the help of key industry experts to provide their guidance.

What Are the Merits of Options to avoid a Kick on a Setpoint Change Tips?

The PID structures with proportional on error cause a step change in the PID output for a large setpoint change. For structures with derivative on error there is also a sharp bump almost looking like a spike unless you zoom in.

Is it better to have a Controller with More or Less Knobs Tips?

What are the relative merits of different PID structures, a setpoint (SP) filter, and analog output (AO) setpoint rate (velocity) limits? Should I seek a general solution I can use all the time and each knob fits a particular purpose, or a controller with fewer knobs that does exactly what...

How do you Effectively Use Anti-Reset Windup Options Tips?

Anti-reset windup (ARW) protection is a standard feature of industrial PID controllers. In some DCS, ARW limits are adjustable besides output limits.  The ARW limits may not be at their best values. ARW default values may not match up with output limits as output scale and engineering units change.