Incatools blog

PID tuning example: tuning for closed loops

Posted by Edwin Weetink on Jun 29, 2021 1:17:33 PM

There are many critical PID loops in an operating plant. Operations managers typically like to minimise changes on tuning parameters on such PID loops, quite often maintaining the status quo, even if improvements are possible or desirable. The performance of such PID loops could be optimised if they could be inserted in manual mode followed by moving the output a few times, collecting data, and calculating PID tuning using PID tuning software. Unfortunately, operations managers may not allow you to insert this critical loop in manual, so how can you calculate PID tuning parameters for such a loop while maintaining it in closed-loop mode? In this PID tuning example, we’ll show the best practices and pitfalls.

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Topics: PID tuning

Why you should implement soon after awarding an APC project

Posted by Edwin Weetink on Jun 29, 2021 10:50:38 AM

Operations managers have many priorities to juggle in their workday. Some of these activities are completing emergency repairs, resolving instrumentation issues, meeting production targets, preparing and presenting reports. When a company purchases a new APC projectit may fall to the bottom of the priority list due to other activities requiring more attention. Why is it important to start APC activities soon after the contract award? What are the convincing arguments for operations managers that will help them move the APC project higher up the priority list and start implementation as soon as possible?

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Topics: PID tuning, Advanced Process Control

Controller configuration for ratio control

Posted by Mubasshir Anwar on Jun 7, 2021 10:33:02 AM

Ratio control is an essential element in the toolbox of control engineers to control various industrial processes. The objective is to maintain the ratio of two flows at a specified value. The desired ratio can be either manually entered by an operator or automatically set by another controller. At least one of the flows needs to be controlled by a PID controller (or at least a valve should be available to control the flow). The ratio can be calculated based on the flow measurements or based on the setpoints of the flow controller(s).  The ratio controller can be configured in different ways in the DCS. The different approaches and their pro’s and con’s are described in this blog.

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Topics: PID tuning

How to configure PID structures for distillation columns

Posted by Christiaan Moons on Jun 7, 2021 10:03:33 AM

As a control engineer, you may get called by plant operators when a PID loop is a “bad actor”, causing problems on a distillation column. The process upset caused by this PID loop may have a destabilising impact on downstream process units as well, potentially causing widespread impact. Quite often, the “quick fix” for process operators is to insert these bad acting PID loops in manual. While this mitigates the immediate issue, the cost of such actions is poor performance of the distillation column. The control engineer is tasked with rectifying the problem. Is this a PID tuning issue or are the PID loops on the distillation column configured incorrectly? How would you ensure that the PID structures on a distillation column are configured correctly? You can read it in this blog.

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Topics: PID tuning

How to successfully configure and tune a split range PID control strategy

Posted by Christiaan Moons on May 31, 2021 4:21:42 PM

A split range control strategy uses software or hardware-based splitter and two or more final control elements to control a process variable. You can find split range strategies in different applications across process industries such as temperature control with heating/cooling media, large and small valves installed in parallel, pressure control with a vent valve, etc. 

Usually, split range applications are tricky and time consuming, and you should know what I’m talking about as a process control engineer.

Oscillations over the entire range of operation and across the split point, typically improperly selected at 50%, are common in real operation. 

This blog will discuss the usual problems you might face when configuring and tuning a split range strategy and the possible and practical solutions to overcome it.

 

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Topics: PID tuning

Low risk investment and guaranteed benefits with APC project

Posted by Christiaan Moons on May 17, 2021 5:02:01 PM

Every operations manager would like to improve the performance of their asset in a safe manner. You need to steer your plant operation through rapid business changes, and maintain products within the specified targets while always maintaining safe plant conditions. Further optimisation of your operation is not feasible with the current tools, and you know that Advanced Process Control (APC) has been successful in making further improvements in similar processes. How do you go about adopting APC for your facility?

 

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Topics: PID tuning, Advanced Process Control

Do I have a PID Tuning Problem?

Posted by Christiaan Moons on May 11, 2021 9:07:08 AM

Engineers are often tasked with troubleshooting and resolving process performance issues. The feedback from operators could be statements such as “this PID loop does not work in Automatic” or “I am always getting alarms in this variable” or “this PID loop has never worked in Automatic”. Understanding how to tackle these issues efficiently and effectively requires a systematic approach along with a good PID tuning tool. This blog explains how to go about achieving success in resolving PID tuning issues.

 

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Topics: PID tuning

Tuning a buffer tank to absorb disturbances

Posted by Gustavo Müller on May 3, 2021 4:24:43 PM

Buffer tanks are built to provide smoother operation to the process, avoiding the propagation of disturbances on the inputs, e.g., temperature, composition, feed rate, to the downstream process. Aggressive tuning methods don't work for buffer tanks since you want to explore the largest volume possible to reduce the disturbances. In this blog, we will explain how you make a compromise with the correct tuning.

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Topics: PID tuning

Did you know a DCS can change your PID equation?

Posted by Edwin Weetink on Apr 7, 2021 10:23:16 AM

Every DCS has its own set of PID loop equations.  A Honeywell Experion DCS features 5 different equations and an Emerson Delta-V DCS can even offer 7 equations. Each equation implies a different formulation of the PID control algorithm. So, each equation might require different tuning parameters to obtain the same or similar closed-loop behaviour. Many control engineers ignore the equation type of a PID loop. Even if you have tuned many different loops, you might not be able to obtain the desired closed-loop performance if you don’t have the right equation selected.

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Topics: PID tuning, Plant performance

Comparison of different tuning methods with INCA Aptitune

Posted by Kamalnayan Singh on Mar 15, 2021 11:39:10 AM

The tuning of Proportional-Integral-Derivative (PID) can be considered a mix of art and science. It's an art where one needs to use their judgment and experience to understand the controller’s behavior. The science of tuning comes into the picture where one uses open-loop mathematical models and different techniques to derive the tuning parameters. The “Art” of tuning helps to understand the how’s and why’s of the process, and the “Science” of tuning provides a roadmap for tuning.

The performance of any PID controller depends on tuning parameters, i.e., gain, integral time, and derivative time that is set in. The tuning parameters are a function of process types, functionality expected from the PID loop, i.e., variance reduction or setpoint tracking, and type of the PID loop.

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Topics: PID tuning methods