Yes, IMPNRGZ is the dummy import process for energy.  The dummy imports are a VEDA feature.

You have already been advised, that your dummy import prices are too low for your model.  I can only suggest again, that you should increase the dummy import prices in SysSettings. See the ACTCOST values on the sheet Interpol_Extrapol_Defaults in SysSettings. Try e.g. with 10 times higher values 22222 and 88888 for IMP*Z and IMPDEMZ.

You can also disable the dummy imports altogether. For more information, see the VEDA online documentation:

support.kanors-emr.org/VEDA-FE/SubFile_TemplatesBasics_Files/SYSSETTINGS.htm

support.kanors-emr.org/VEDA-FE/SubFile_Overview/Functional.htm

@huichenpku@huichenpku:  A small follow-up:

As you even approached me privately asking for more help, I tested with your model now.

First, I decided to disable the dummy imports, as they seem to be causing many problems in your model, and you have not followed my earlier suggestion to increase the dummy import prices.

The model proved to be infeasible, because you had specified too low upper bounds for the coal imports (and/or electricity imports).

I decided to increase the upper bound for IMPCOA2 to 20,000 ktce. The model was now feasible, and the results showed constantly increasing electricity generating capacity for ELCCOA00, just as expected.

Finally, because you were also so worried about the decreasing "Stock" (which refers to the remaining existing capacity), I added a Stock value of 1000 in 2030, i.e. the Stock  of old capacity will then remain constant from 2012 to 2030.  Again, the model solved fine, and the Stock of old capacity now remained constant, just as specified.

I hope that the above observations can help you make some progress now.