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Re: [EnergyPlus_Support] Re: SystemTimeStep in EMS





And how did you solve that problem? Please paste in the EMS code.

On 8/4/2011 5:08 AM, dgerome06 wrote:
 

Ok,
i have integrated an EMS code to avoid the problem. But i was thinking that it was possible to change parameters to solve it.

Thanks all.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad <RRaustad@...> wrote:
>
> You already have the answer from the previous email.
>
> Here, it has first run a system timestep of 10 minutes (from 8:10 to
> 8:20), then later decided it should be shorter and repeated a system
> timestep that starts at 8:10 (from 8:10 to 8:13). Because of this and
> other iteration/timing issues, you will have a hard time counting up
> time entirely on your own.
>
> The simulation ran at 8:10-8:20 and found that it had to shorten the
> system time step. So it ran that time again, but this time from 8:10 -
> 8:13.333, and then 8:13.333 - 8:16.667, and then 8:16.667 - 8:20. So the
> time 8:10-8:20 was repeated, this is where your error is. You have to
> account for that in your EMS code.
>
> This example should give you an idea of what you need to do.
>
> IF(SystemTimeStep < LastSysTStep)THEN
> SET count = count - LastSysTStep
> END IF
> SET count = count + SystemTimeStep
> SET LastSysTStep = SystemTimeStep
>
> On 8/3/2011 5:34 AM, dgerome06 wrote:
> >
> > I am already using built-in variable SystemTimeStep. My program is
> > simple, just count the time spent during the simulation.
> >
> > Program :
> > SET count = count + SystemTimeStep
> >
> > The program is called "AfterPredictorAfterHVACManagers"
> >
> > The outputvariable "count" is type "summed" and frequency
> > "systemtimestep".
> >
> > My timestep is 10min that is to say 0.167 hours.
> > The right column of the next array is what i expect to have and the
> > left column is what i have in the spreadsheet.
> >
> > 33 33
> > 33,16666667 33,16666667
> > 66,91666667 33,33333333
> > 67,58333333 33,5
> > 68,25 33,66666667
> > 68,91666667 33,83333333
> > 69,58333333 34
> > 70,25 34,16666667
> > 106,3333333 34,33333333
> > 107,3333333 34,5
> > 72,25 34,66666667
> > 36,33333333 34,83333333
> > 36,5 35
> >
> > This problem doesn't happen with a timestep of 2min.
> > I want to work with timestep=10 min so i need to find a solution.
> >
> > I can send the edd file maybe it will be easier to understand.
> >
> >
>
> --
> Richard A. Raustad
> Senior Research Engineer
> Florida Solar Energy Center
> University of Central Florida
> 1679 Clearlake Road
> Cocoa, FL 32922-5703
> Phone: (321) 638-1454
> Fax: (321) 638-1439 or 1010
> Visit our web site at: http://www.fsec.ucf.edu
>
> UCF - From Promise to Prominence: Celebrating 40 Years
>


-- 
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
1679 Clearlake Road
Cocoa, FL  32922-5703
Phone:   (321) 638-1454
Fax:     (321) 638-1439 or 1010
Visit our web site at: http://www.fsec.ucf.edu

UCF - From Promise to Prominence: Celebrating 40 Years


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