PID Loop windup prevention
- Thread starter FAGARCIA
- Start date
Mickey
Lifetime Supporting Member
Take the output of your flow controller ( 0-100%) and add 1% to it then write that value to the CV Max of the level controller.
kamenges
Member
To make sure we are on the same page, define what you mean by 'wind-up'. I know what I mean but I want to make sure we are talking about the same thing.
Keith
Keith
Peter Nachtwey
Member
Get rid of the ramp function or ....
Obviously the level PID wants to see the level change faster than ramp permits.
Reduce the gains on the level function so the rate in change in the flow SP will not exceed the ability of the pump's ability to accelerate or decelerate.
How do you know the integrator is winding up? This is somewhat related to Keith's question about definition.
My integrators never windup. I use dynamic limits that can adapt to different situations. It is easy to do an I don't see why other people don't do it.
Note...
The velocity or incremental form of the PID doesn't suffer from integrator wind up problems.
Obviously the level PID wants to see the level change faster than ramp permits.
Reduce the gains on the level function so the rate in change in the flow SP will not exceed the ability of the pump's ability to accelerate or decelerate.
How do you know the integrator is winding up? This is somewhat related to Keith's question about definition.
My integrators never windup. I use dynamic limits that can adapt to different situations. It is easy to do an I don't see why other people don't do it.
Note...
The velocity or incremental form of the PID doesn't suffer from integrator wind up problems.
Im new to programming and very interested in PID control and would like to join your disscusion.Does this make sense.If you know the max counts in the PLC for the level PID loop,e.g your output m(t)/m
then use a compare instruction to clip your integrator and stop wind up occuring when the desired value is reached.Hi Im not familiar with your brand of PLC control logic L63 PLC.I use mitsubishi i write my own PID equation instead of the block and to stop wind up I check my output in counts and when it has reached its desiered value or set point I clip the integrator I and PID output M.Are using a PID block in the PLC or writing your own.Hope this is of some help
Liam
and PID output M.Are using a PID block in the PLC or writing your own.Hope this is of some helpLiam
OkiePC
Lifetime Supporting Member
According to a technote I just read:
If the Ladder PID is at the high clamp value, then it will stop integrating in the positive direction.
If the Ladder PID is at the low clamp value, it will stop integrating in the negative direction.
I believe by "clamp values" they're talking about the output high and low limits.
Is this what you are looking for?
If the Ladder PID is at the high clamp value, then it will stop integrating in the positive direction.
If the Ladder PID is at the low clamp value, it will stop integrating in the negative direction.
I believe by "clamp values" they're talking about the output high and low limits.
Is this what you are looking for?
Last edited:
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