[TRNSYS-users] simulation time error

[David BRADLEY]

LiaoGang,

  This is quite a common issue and the behavior you are seeing is 
normal. The short answer to your question is: stick to using a small 
time step.

  Remember that TRNSYS iterates at each timestep to find a converged 
solution if there are any control decisions to be made then TRNSYS can 
make one control decision (such as turning on or off a piece of 
equipment) per time step. The equipment must then stay on (or off) for 
the entire duration of the next timestep. If your time step is big then 
the system will be driven a long way from where it started before the 
end of the time step. Imagine if the thermostat in your home could 
decide to turn on heating only once per hour. If the heating had to stay 
on for the entire hour then chances are that the home would be 
uncomfortably hot by the time the thermostat was allowed to make a new 
decision. TRNSYS forsees this (in a way) and can't decide whether it is 
better to leave the heat on or off. If you shorten the time step then 
the on/off decision becomes quite a lot simpler and overheating and 
undercooling become less of a problem.

kind regards,

  David



On 04/19/2018 04:11, 廖刚 via TRNSYS-users wrote:
>
> Dear TRNSYS users,
>
> I met a very strange problem when I run my simulation model, I found 
> that my model works well when the simulation time is relatively small, 
> but when I increase the simulation stop time , it gives warning “The 
> inputs to the listed units have not converged at this timestep “and 
> then corrupted with an fatal error.
>
> I would be very appreciated if someone can help me solve this problem,
>
> Best
>
> LiaoGang
>
>
>
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users at lists.onebuilding.org
> http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org

-- 
***************************
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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