windup effect & fb41 (step7)
- Thread starter cetec
- Start date
Peter Nachtwey
Member
Hey, there is one that I can answer.
Simple, the sum of all the control output terms from the proportional gain, integrator gain and derivative gain can never be greater than 100%. If the sum of the proportional and derivative terms is 90% then limit the integrator's contribution to the control output to 10%.
Simple, the sum of all the control output terms from the proportional gain, integrator gain and derivative gain can never be greater than 100%. If the sum of the proportional and derivative terms is 90% then limit the integrator's contribution to the control output to 10%.
bara_hence
Member
If you want you can use a fb from http://www.oscat.de that already has wind-up protection in it..
(oscat.de is a open source community for automation technology wich has a great library with many functions..) you can get the library in either precompiled format for Step7 or you can get it in plain text (ST)
(oscat.de is a open source community for automation technology wich has a great library with many functions..) you can get the library in either precompiled format for Step7 or you can get it in plain text (ST)
Hello cetec,
Peter, by default, always implements windup integral protection. There are a ot of threads discussed earlier, just do a search for "Advanced control".
There are also a lot of Peter's PDF files that can be found here:
ftp://ftp.deltacompsys.com/public/NG
Many of examples are simulated in Mathcad and code can be found in .pdf files. That could give you clear understanding what to do.
If you have further questions, don't hesistate to ask.
Regards,
Pandiani
Peter, by default, always implements windup integral protection. There are a ot of threads discussed earlier, just do a search for "Advanced control".
There are also a lot of Peter's PDF files that can be found here:
ftp://ftp.deltacompsys.com/public/NG
Many of examples are simulated in Mathcad and code can be found in .pdf files. That could give you clear understanding what to do.
If you have further questions, don't hesistate to ask.
Regards,
Pandiani
Thanks for replay, is it true that PID (FB41) has arledy implemented windup protection ?
When I simulated it I set inputs SP = 50, PV = 45 (ER 5), (P - on, I - on, D - on), LMN was rising up, when output (LMN) reached 100 then LMN_I part stoped incrementing value.
When I changed SP to 40 (ER -5), LMN started decreasing value, and LMN_I part started decreasing immediatly.
It work like:
IF LMN > 100
THEN I_SEL = 0
When I simulated it I set inputs SP = 50, PV = 45 (ER 5), (P - on, I - on, D - on), LMN was rising up, when output (LMN) reached 100 then LMN_I part stoped incrementing value.
When I changed SP to 40 (ER -5), LMN started decreasing value, and LMN_I part started decreasing immediatly.
It work like:
IF LMN > 100
THEN I_SEL = 0
Cetec, I'm not sure about this. If you look at block diagram, there is an option to limit controller output. If you tested, then I guess it works by stopping incrementing integral part because there is limit on controller output (which contains integral part).
Regards
Regards
isn't it work like windup protection ? It works by stopping incrementing integral part because there is limit on controller output, when I was testing on simulator I got:
when LMN 100,
LMN_P = 10,
LMN_I = 90 (stopped incrementing on that value)
LMN_D = 0.
"the sum of all the control output terms from the proportional gain, integrator gain and derivative gain can never be greater than 100%"
when LMN 100,
LMN_P = 10,
LMN_I = 90 (stopped incrementing on that value)
LMN_D = 0.
"the sum of all the control output terms from the proportional gain, integrator gain and derivative gain can never be greater than 100%"
zova
Member
There are two kind of integral windup - switching windup and speed windup.
First of them is implemented in FB41, second not.
First of them is implemented in FB41, second not.
Peter Nachtwey
Member
So what happens if LMN_P goes to 20? Is LMN_I set to 80 or is LMN_I frozen at 90.cetec said:
In have never heard of speed and switching wind up. Please explain.zova said:
now I feel that problem, thx for explenation!zova
Member
Because all of us studied in different places and time, probably there is a problem in definitions.
1. When I speak "switching windup" I mean that at transition PID from manual mode back to automatic mode it is necessary to recalculate-back I-part for bumpless switching.
2. When I speak "speed windup" I mean that if the actuator is slow, that I-part shouldn't save up an error when speed of change of PID's exit exceeds really possible speed of change of the actuator.
Whether not so?
1. When I speak "switching windup" I mean that at transition PID from manual mode back to automatic mode it is necessary to recalculate-back I-part for bumpless switching.
2. When I speak "speed windup" I mean that if the actuator is slow, that I-part shouldn't save up an error when speed of change of PID's exit exceeds really possible speed of change of the actuator.
Whether not so?
Peter Nachtwey
Member
I understand
OK. I wouldn't have given the two modes those names but I understand.
OK. I wouldn't have given the two modes those names but I understand.
Similar Topics
Hi all,
I have primary and secondary control loop cascaded together and am using the WindupHIn/Out and WindupLIn/Out to prevent the CV of the...
I have a PLC in a pump station modulating a valve via PID. When the pump station shuts off the valve is supposed to shut. And it does for 3 months...
My colleague and I are having a problem with the use of a PIDE algorithm with external anti-reset windup (ARWU) active. We are using a...
Hi all,
I've been reading about anti-reset windup. For RSLogix 5000 it seems that the PID block takes cares of it automatically. For RSLogix the...
Hi
If I enable INT_Hold when QLMN_HLM or QLMN_LLM are on would this freeze the integrator and prevent the windup of the integrator?
As I see it...