Daily time step for 20 years

[Former user]

I tried to run the MODSIM model for 20 years duration with daily time step. The model runs with monthly time step for 20 years simulation (239 time steps in total). But when I change the time step from monthly to daily (7304 time steps in total), MODSIM shows error and stop calculation. I guess this error occurs because 7304 time steps exceeds MODSIM capacity. Is it possible to increase size of array of MODSIM to allow us to have daily time step for 20 years?

[Bob Lounsbury]

My guess is that when you changed the time step from monthly to daily some date somewhere in a node or something did not translate correctly or get populated correctly. Modsim has no time step capacity constraint, 20 years daily is no problem, I've run 80 years daily.

If you wanted to send me your monthly time step model, I could investigate why changing the time step did not appear to work properly. Otherwise, you might simply need to step through some of the model Nodes to look for invalid dates, remember that the first date in a Node timeseries must match the models Data Start Date. With each Nodes data you can right-click on table headers to copy columns or the whole table and also use the 'Varies By Year' checkbox to clear out existing data and set it up for new data.

[Former user]

I currently make a MODSIM model with 13 reservoirs, over 140 non-storage nodes, and around 20 demand nodes. I revise the model as simple as possible to explain the error, and the simplified model is attached above. The model still shows an error when the solver runs.

[Bob Lounsbury]

Thank you for this perfect example! You have indeed found a bug in MODSIM. If the year following the model start date year is a leap year and the model starts in January, the code had a bug. I have fixed the bug and will be closing this issue shortly. To workaround the bug, you can change your simulation start date to 3/1/1991 (easiest solution) or set the data start date back one year or forward one year. Or wait until a new version is released.

Thanks again!

[Bob Lounsbury]

Closes #35. Datetime exception if data start date is in January or February and the following year is a leap year.

→ <<cset 60b2adff651d>>