PID controller

Good Day! I would like to know if there are any descrepancies or should we say, needs improvement by using PID controller in tuning a boiler
especially resolving deadtime process?
Thanks.
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On Tue, 20 May 2008 09:36:32 -0700, daisyj.rico wrote:

Forgive me, but I'm having a bit of trouble with your English.
Are you asking if there are shortcomings to using a straight PID controller for a boiler?
I'm no expert in boilers, but I'll bet you that the answers are, in turn (a) yes, (b) but it's not usually so bad that it's worthwhile cooking* up a special boiler-control algorithm, and (c) there will be times when it _is_ worth doing so, and there are no doubt innumerable articles in both the trade literature and by fancy-pants academics detailing various methods, with various levels of practicality.
* as it were.
--
Tim Wescott
Control systems and communications consulting
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hmm. e.. all of the above.
Boiler controls are pretty well known about now. At this point, the real issue is what strategy to use to operate the boiler. While the strategy depends on the type of boiler, size, etc, it should be noted that there are several methods other than the ones that are initially obvious. A good analysis of what a boiler really is provides a very good idea on what strategy to use. The optimal boiler strategy is not used on many boilers, in part because too many people are stuck on using PID loops when there are better tools available for many parts of the control.
Michael
Michael
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On Tue, 20 May 2008 23:32:40 -0700, Herman Family wrote:

The attraction of using a PID loop to solve as many problems stems from much of the same impulses that leads every kitchen to have a pair of pliers and a screwdriver: they may not be the _right_ tool for every job, but with them you can usually turn things from disasters to adequate.
So if you're only going to learn how to apply _one_ control strategy, PID would be it.
(My kitchen is better equipped: I have a pair of pliers and _two_ screwdrivers).
--
Tim Wescott
Control systems and communications consulting
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What? no hammer?
I agree. I've seen too many controls which are shoehorned into a PID loop or some sort of cascade of it. PID is a great regulatory control, but supervisory controls are often better off being a model based system that can fully appreciate the complexity of the overall system.
Michael
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