need advice on optimising PID heating controller

[domoticom]

Hi,

Icould need some advice regarding a temp control with PID controller.

The situation:
- a room with radiator and fancoil
- I need to control the temperature of the air inlet from the fancoil.
- the temp. sensor is directly behind the heat sourse, so temp. changes quickly
- controller of Arcus-EDS didn't do the job (lot of over/undershoot, and never stable, keeps swinging)
- now I have disabled this controller and use the PID controller in the H/S
- All variables (p,i,d,cycle) are changable via visu

the result (see graph from QC) is better, but not satisfying. I would like to know what could be better settings than I have now. I already tried some combinations, but maybe somebody here has more experience with PID and heating.

another question about this: does it matter waht value I enter in the input of the PID controller ? I mean: When I enter a value "1" in the nachstelzeit of the PID module, and then change it via an object, does it actualy change, or do I have to put a'" 0" in it as default value. So, is it only a default value that will be overwriten ?

[lobo]

Dear Mike,

I just don't understand (or believe) what I am seeing: is the red color (actual temperature) really changing between 15 and something and 24 °C in one single hour???

What is "klepstand"? Is this the valve value? Why isn't it changing?

Best regards,

Stefan

[domoticom]

no, not only ones, but 5 times in 1 hour. That's what drives me crazy
'klepstand' is vlave, but the resolution of the archive is not ok, that's why is seems like it's not moving. Actualy it goed up and down too.

I will try to fix it, so the valve graph is right, if that helps you analyse it

[lobo]

I can try, but I cannot promise

First, I would recommend to get rid of the D-Part (Vorhaltezeit). I don't know how this is realised in your algorithm, but I would guess to just set it to zero.

What would additionally help is a system response plot (German: Spungantwort, Netherlands: Stap reactie), so set your valve for instance to 20 % and then set it to 50 % and show how the temperature reacts. This would be a good help to find appropriate settings for your regulation.

I do not know which type of valve you have, so if it is only capable to open and close completely, so close it, wait until the temperature has settled, then open ist, wait until temperature reaches equilibrum and close it again.

Cheers,

Stefan