Using the restart option

[ClaireN]

Dear all,

I am trying to use the restart option without success. I would like to be able to start from a previous solution because my model takes a long time to run and I change very little things across my different runs.

I don't succeed even with the DEMO model so I think I am mystaking somewhere:
- I do a first run (run1) activating the box "Save a solution Information" in the control panel
- I then do run2 (same as run1+ a new tax for example) , selecting run1_p.gdx in the "Restart" box
- I get the "Unexpected termination of run" message.

What am I doing wrong?

Thanks in advance for your help,

Claire

[Antti-L]

Dear Claire,

I think you are not doing anything wrong.  It is a problem in VEDA-FE, not you.

In older versions of VEDA-FE (e.g. 4.3.5001), the restart option still works well (I just verified it):

VEDA-FE inserts $SET LPOINT <gdx_name> into the RUN file, and if BRATIO is set small enough, the solver is able to start directly from the previous solution. If there happens to be no changes in the model, the solution is thus obtained immediately.

In more recent versions of VEDA-FE, this option appears to be broken. VEDA-FE no longer inserts $SET LPOINT <gdx_name> into the RUN file, but instead  $SET RPOINT <gdx_name>, which is a completely different TIMES feature. That also explains the spurious "Unexpected termination of run" message.

However, in TIMES, there is also a second way of restarting a run from a previois solution: $SET SPOINT 2. But that option is neither supported in VEDA-FE.  It seems the whole restart functionality is simply no longer supported by VEDA-FE, because neither $SET LPOINT <gdx_name> nor  $SET SPOINT 2 is supported.

As a side point, as LPOINT is utilized also when fixing initial periods to a previous run, one might think that by fixing the initial periods to some year before BOH would do the trick. Unfortunately it doesn't, because when fixing initial periods, the old solution needs to be cleared for the remaining active years (because the new solution must be merged with the old one). So, with respect to restarting, that will not work either.

[AKanudia]

Apologies for the inconvenience. We will release an update early next week to fix this.

[saleh]

Hi,

I am able to fix the initial years option and use it for the new run successfully, but I want to use restart setting as well (so that the model is able to start from the previous solution). I put $ SET SPOINT 1 in a scenario that I want to save its results to use it later as an initial solution. In the new scenario (i.e. the one that I want to solve it use a previous scenario solution) , I put $ SET RPOINT _p, which does not work. I also tried $ SET LPOINT _p and $ SET LPOINT, but none of them work. Is there anyway that I can use restart option? My TIMES version is 4.4.7, and I am using TIMES 3.4.3. By the way, I don't use FE directly, I just modify dd files and run the model manually.

Thank you

[Antti-L]

Ok, maybe I can briefly comment on this, as you are not using VEDA-FE, at least directly.

The restart option can be easily used with TIMES, but no support can be provided for using such an old version (v3.4.3). 
May I ask why you are not using the latest (or at least a recent) version?

In TIMES v3.9.3, the restart option can be used by using the LPOINT control variable, or using the $SET SPOINT 2 option, as descibed in the documentation.  See the documentation on Control Switches.  You should also make sure that you set the GAMS BRATIO option to a reasonable value for enabling a warm start.

The allowable values for BRATIO range from 0 to 1 with a default value of 0.25. Setting bratio to 1 will always cause the basis to be discarded.
Setting bratio to 0 forces GAMS to always try to construct a basis.

[Antti-L]

Apologies for the inconvenience. We will release an update early next week to fix this.

Where can I download the latest version of VEDA-FE, and the latest database templates supporting the new TIMES input parameters?
(And samilarly for VEDA-BE?).  Like the update mentioned above (it was released "next week", but how?)?

For a long time, I have not been able to download any updates, as the VTI_www_4.exe utility no longer works, and so my version is getting quite old. It would be nice to know what is the current procedure for downloading the VEDA updates for ETSAP partners.