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Re: [TRNSYS-users] First message and a couple questions.



Med. Omar FANNAN,

  This list is intended as a place in which users can assist other users although it is often used as a starting point for technical support. If you have specific technical support questions you should email them to the distributor from whom you (or your institution) purchased TRNSYS. If you aren't sure who to contact then please send me an email directly (i.e. not to this list) and include the information from your user17 (which can be opened with a text editor).

  The list and description of TRNSYS access functions such as getIsConvergenceReached() can be found in the 07ProgrammersGuide manual in the ..\Trnsys17\Documentation\ folder.

  Convergence can be impacted by component order. You can change the component order by clicking on the "control cards" tool in the left hand toolbar (where you set the simulation start and stop times) and then switching to the component order tab.

  Convergence problems can be hard to track down because there can be many causes. Here are a few hints about them.

- make sure that your timestep is not too long. TRNSYS can only make one control decision per timestep. If you are using a long timestep and are using a controller model to control a system that has a time constant shorter than your timestep you are going to run into convergence problems. Time steps should typically be on the order of 1 to 5 minutes.

- make sure you have enough thermal capacitance in your system. This is basically the same as the above point; thermal capacitance increases the time constant of the system and causes it to respond more slowly (and more realistically) to control state changes.

- you can look in the *.lst and *.log files to find out which components are failing to converge.

kind regards,

 David



On 06/20/2016 05:12, Med. Omar FANNAN via TRNSYS-users wrote:
Greetings,

First of all, I really don't know if I'm posting in the right section, but it never hurts to try.

I'm only just starting to use TRNSYS, so excuse my questions if they seem silly :
Is there a listing of intrinsic TRNSYS routines (like getIsConvergenceReached and such?)
How can I resolve convergence problems?
Is the order of execution of the UNITS important?

Thank's in advance,

Med. Omar FANNAN (AKA MOF)



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