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Re: [TRNSYS-users] Type2b



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 ΔTH = 15 degrees

Lower deadband ΔTL = 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

γi

0

0

0

1

γo

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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