Re: [TRNSYS-users] question related to type2

Bon dia Angel,

I checked the three points that you mentioned in your previous email and the first option was the one which cause the problem.

I reduced the time step to 30 seconds and the behaviour of the controller improved but as you can imagine the simulations was really slow, so I increased the number of oscillations (controller parameter 1) and now the controller works OK, is it a possibility or I should maintain the number of oscillations in 5?

Thank you very much for your help,

Regards,

Carol

De: Angel Carrera [mailto:angel.carrera@aiguasol.coop]
Enviado el: viernes, 24 de enero de 2014 14:35
Para: TRNSYS users mailing list at the Solar Energy Lab, UW-Madison
Asunto: Re: [TRNSYS-users] question related to type2

Carol,

I forgot one more thing: make sure that the output control function is connected to the same type "input control function", cheers

Angel

2014/1/24 Angel Carrera <angel.carrera@aiguasol.coop>

Egun on Carol,

I think there a two basic reasons for this:

1-The controller gets stuck due to a lack of stability of your model. Parameter 1 sets the number of oscillations that the controller can do in a single time step; if the controller changes of state while trnsys is iterating within a time step, it will never do it (change) more times than the value you have set in parameter 1, so it gets fixed when the number of changes reaches that value. I can't explain it better than it is done in the user help (at least in english), so I recommend you to carefully read the introduction in the controllers section of the mathematical reference on the trnsys help as well as type 2b section. To solve this, usually the best you can do is reduce you time step until you have a coherent behaviour of the controller.

2-The monitoring temperature is governing the controller. If the Input Control Functio (inputs tab of the proforma) exceeds the value of the parameter 2, then the controller output is set to 0.

I imagine that the first possibility is the one explaining that behaviour; reducing the time step is probably a good help for your model, good luck

Angel

2014/1/24 Pascual Ortiz, Carol <carol.pascual@tecnalia.com>

Hi TRNSYS user,

In my last simulation I use type 2 on/off differential controllers and I do not know why sometimes it works ok and others doesn´t.

For example Time step temperature control signal

4016,65 25 0

4016,70 25 1

4016,75 25 0

Do you know what I am doing wrong? Does this ever happen to you?

Thank you in advance,

Best regards,

Carol Pascual

Energía Térmica/Thermal Energy

División de Energía y Medio Ambiente/

Energy and Environment Division

TECNALIA

Área Anardi,5

Laida Bidea, Edificio 204

E-20730 Azpeitia - Gipuzkoa (Spain)

T 902 760 000*

M 667119581

T +34 946 430 850 (International calls)

carol.pascual@tecnalia.com

www.tecnalia.com

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Àngel Carrera

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