Contek Systems Ltd, Aberdeen, UK

Control engineering consultant for the oil and gas industry. Process control, de-bottlenecking, compressors, slugging and control system PID tuning.

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Contek Systems Ltd,
Shampher Cottage,
Strachan,
AB31 6NN

+44  (0)1330 850598

Try my well-known Process Identification and PID Tuning package U-Tune.

Click here for details and screenshot.

See my FREE tuning calculator.

Download here.

I have written several tutorials on the practicalities of process control.

Click here for links to our tutorials.

Check back from time to time. New articles will be added as time permits.
Note: emails can be accessed offshore - telephones can't!
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U-Tune PID Tuning Package (Version 2)

Process measurements in the process industries are typified by excessive noise and disturbances. In these environments, automatic tuning software often fails to identify even the most obvious characteristics of the process response resulting in poor selection of tuning parameters.

U-Tune minimises this inaccuracy by helping you to select the primary elements of the process step or pulse response.

U-Tune calculates the tuning parameters giving options for PI and PID control, all the common controller algorithms and parameter types, and two sets of parameters, one for fast and the other for slow responding loops.

U-Tune lets you compare the results from a series of tests and provides you with the best parameters to enter into the controller.

THIS PRODUCT IS NO LONGER AVAILABLE FOR PURCHASE, BUT MAY BE DOWNLOADED AS A TRIAL VERSION

U-Tune Process Identification and PID Tuning Package
Download To install the software, click on the Download button. When the dialog window opens, select Run and follow the instructions.
 
Process Identification
Click to see full screen version The image on the left shows the Identification view with data captured during the step testing of a compressor anti-surge controller. Click on the image to enlarge.

The upper trend shows the output to the recycle valve (blue line) and the lower trend shows the process variable (also blue line) responding to the increased gas flow. Note the considerable noise on this trend. The valve is clearly also sticking slightly. This meant that automatic tuning packages failed to give consistent results.

By moving the sliders, the start and end of the output step have been identified (magenta line on upper trend) as have the start, end and shape of the process variable (magenta line on lower trend). Note the way the output step has ramped up gradually at first and then faster. This is because the output is driven using up/down pushbuttons on the controller faceplate.

The primary characteristics of the step test are given in the box at the bottom of the screen.

 
Controller Tuning
U-Tune supports self-regulating and integrating processes, two- and three-term controllers (PI and PID), ideal, series and parallel algorithms, and all the common forms of gain, integral and derivative terms. Two sets of tuning parameters are provided, one set for processes needing a slow response such as temperature controllers and the other for processes requiring fast responses such as flare or minimum flow recycle controllers.
Click to see full screen version
 
Model Management
Click to see full screen version One step test is rarely sufficient. Generally, a test must be repeated three or four times. The Manager view collates the test results into a tabular format giving the process characteristics and tuning parameters for each of up to ten tests.

The records can be selected for display, deletion or editing. An average set of process characteristics is calculated from the test results and the corresponding tuning parameters are generated. Records can be included or excluded from this calculation.

The tables in the Manager view can be printed or written to a text file for incorporation in reports etc.

 
Text File Conversion
U-Tune will convert any column-based numeric text file (comma, space or tab delimited fields) into its internal format, so data from many sources can be used. The internal format is the same as the waveform files of the popular DATAQ data acquisition equipment (www.dataq.com), so if this is the device you use to collect data, no extra conversion is necessary.
Click to see full screen version Click to see full screen version
 
Help Pages
U-Tune is simple to use, allowing you to concentrate on the vital controller tuning. But if you do need a helping hand, the U-Tune Help pages are no more than a function keypress away.

Please note that some of the images on this site show data collected while tuning controllers on compressors and other rotating machinery. While Contek has considerable experience in process tuning and optimisation, you are reminded that utmost care must be taken when working with these and other devices.

  Click to see full screen version