Hi Guys,

I'm a BOP commissioning engineer and I'm working for the first time with the ABB 800XA DCS (as you'll figure it out I'm still young in the job). I'm kind a lost with ABB PID tuning parameters.

Does Kp = Proportional Band or is it Kp = 100/Pband ?
Is Ti repetition/second or is it second/repetition ?
(Compared to Foxboro parameters)

I've tried to tune with both and doesn't really seem to fit.

Thanks for tour help.

 

Since there are a few different PID control module/function blocks (CM/FB) can you provide the following info:

1. System version
2. Library(ies) used that contain the PID(s) you are interested in
3. PID CM/FB name(s)

Are you tuning via the extended faceplate, edit tab?
Have you called up the contextual help, specific to that CM/FB by selecting the object and clicking on the "F1" key on the keyboard?

 

For Bailey Infi90 FC156;

Kp: Gain (100/P-Band)
Ki: Reset Rate (Repeats/Min)
Reset Rate= 1/Time constant
Kd: Time Constant (Min)
Ka: Derivative Lag Constant

Reverse Mode(SP-PV) Non-interacting PID Controller

Output= K*(Kp+Ki/60s)*Error - K(60Kds/(60Kds/Ka)+1)

For PI control,

output= K*(Kp+Ki/60s)*Error

Also check this site;
http://cats-fs.rpi.edu/~wenj/ECSE446S05/pidtuningguide.pdf?q=~wenj/ECSE446S05/pidtuningguide.pdf

 

800xA is the operator interface. You need to tell us what type of controller you are using - AC800, AC450, Bailey, MOD, DCI, etc - and which function blocks on that controller.

You have of course already checked the manuals for your controller though haven't you.

If you need to convert tuning numbers from one system to another try http://www.expertune.com/TuningTranslator.html

Rob
www[.]lymac.co.nz

 

First of all thanks a lot guys for quick answers.

Lets see. The controller is the MOD300 and the system version is the number 5.0 (SP2).

Regarding libraries they are specific to this project, for instance my PIDs doesn't include the Auto tune function.

I did, of course checked the documentation but there is nothing really detailed about PIDs, but I should be looking at libraries (kind a difficult to get my hand on it).

We are finishing the steam blow so for the moment everything is pretty stable but will be needing bypass (attemp, HRSG level ctrl...) as soon as outage is done. So I'd like to have all information in hand.

Thanks again guys.

 

OK, There's a large dedicated section in the CCF Manual for PID controller FCM's. You need to check this for the control algorithm because there are several ways in which you can set up a MOD300 PID Controller.

In general, Gain = Gain , not PB. Integral is in repeats per minute and Derivative (PreAct Time) is in minutes.

Watch for the scan rate, especially on faster control loops. PID loops are executed at a multiple of the base controller scan rate. Typically the base scan is around 1 second but can vary. Also, be sure that the Input Channel, Controller FCM and Output channel are actually all in the same controller and not scattered across different controllers. (The MOD300 lets you do all sorts of nasty things like this and not every project engineer is strict enough to avoid these kind of problems)

Sorry, I don't have access to the manuals here to be able to give you more specific information. However, if you are familiar with Foxboro I/A then you shouldn't have too much trouble with the MOD300 as the systems are remarkably similar in many ways.

Rob
www[.]lymac.co.nz

 

There are a wide variety of units and PID algorithms used by control suppliers. Sometimes they even use different approaches on different generations of controllers, or even use different algorithms on the same controller.

ExperTune has a database of over 800 industrial control algorithms. We also produce a "Tuning Converter" software, that allows you to convert tuning constants from any of these controllers to any of the others.

Using your example (Fox I/A to ABB 800XA) in our tuning converter, here is what we see:

Fox I/A, PID uses Proportional Band, minutes/repeat for integral, and
minutes for derivative.

ABB AC800M/C with beta=1, uses Gain, sec/repeat for integral, and
seconds for derivative.

Note: You may not be using these exact algorithms, so your actual answer may be different!

To convert,

ABB gain = 100 / Fox IA PB

ABB Integ = Fox IA Integ x 60

ABB Derivative = Fox IA Derivative x 60

Good Luck!

-George Buckbee
ExperTune, Inc.