[TRNSYS-users] Questions about PID 23

[LIBIOT, Erwan]

Hello everybody,

I'm a new trnsys user...

 

Currently, I simulates an heating coil (type 670) with fan (type 662)
regulated by a PID type 23. I fixed an input temperature outside,
incoming air flow, HR, pressure and inlet fluid temperature of heating
coil.

 

My goal is to analyze the functioning of the PID 23. It regulates the
heating coil fluid flow rate by comparing the output temperature of the
fan to a set temperature 

(gain Kp = 10 ^-4 and Ti = 10 ^-4; Td = 0).

 

By several simulations, I noticed that:

 

_The time step simulation is significant in the convergence of the
regulator (Doesn't it perform iterations between each time step?). A
large time step does not allow the system converge.

 

 

_Acting on the gain of the PID, convergence can be possible! Do you know
why there is a dependency of these two parameters?

 

 

_PID values, gain and Ti (integration time) are not to my knowledge in
the orders of magnitude of value of real PID of this system... why this
difference in value?

 

If you have some information and/or model working fine about the PID
23...

 

Thanks!!!

 

LIBIOT Erwan

Bouygues Batiment International

service mechanical
01.30.60.56.66
06.78.02.81.97

e.libiot at bouygues-construction.com
<mailto:s.datcu at bouygues-construction.com>  

 


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