[TRNSYS-users] Type2b

David BRADLEY d.bradley at tess-inc.com
Fri Oct 19 12:05:24 PDT 2012


Ciaran,
   It may be that the controller arrived at its oscillation limit during 
that time step. The parameter NSTK limits how many times the controller 
can change states within the iterations of a single time step.
Best,
  David


On 10/19/2012 11:14, Flynn Ciaran wrote:
>
> Hello,
>
> After having read the documentation and online help, I am still having 
> trouble with the type 2b and I was wondering if you could please help 
> me out. My problem is the following:
>
> I used the example file SDHW, where the Type2b is connected as follows:
>
> Upper limit TH= solar collector output temperature
>
> Lower limit TL= tank to heat source temperature
>
> Monitoring temperature TIN= tank to load temperature
>
> Upper deadband ?TH= 15 degrees
>
> Lower deadband ?TL= 0 degrees
>
> Then I went through the documented equations (Eq. 4.1-1 to Eq.4.1-4). 
> However in the simulation results, when I take a look at time steps 
> 4064.25 to 4065 (as an example), I find the following:
>
> Time step
>
> 	
>
> 4064.25
>
> 	
>
> 4064.5
>
> 	
>
> *4064.75*
>
> 	
>
> 4065
>
> (TH-TL)
>
> 	
>
> -1.373
>
> 	
>
> 7.008
>
> 	
>
> *1.618*
>
> 	
>
> 2.304
>
> ?i
>
> 	
>
> 0
>
> 	
>
> 0
>
> 	
>
> *0*
>
> 	
>
> 1
>
> ?o
>
> 	
>
> 0
>
> 	
>
> 0
>
> 	
>
> *1*
>
> 	
>
> 1
>
> From what I see, time step *4064.75* does not agree with *Eq. 4.1-3 
> *since (TH-TL) is still below the upper deadband even though the 
> controller is turned on (it should remain off until (TH-TL) is greater 
> than or equal to the upper deadband). Maybe I am misreading the 
> input/output controller values?**
>
> Any help would be greatly appreciated.
>
> Thanks,
> Ciaran
>
> **
>
>
>
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> TRNSYS-users at cae.wisc.edu
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-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com

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