Using subscripts

[walin]

Dear all,

I would like to model different CHP (combined heat and power) installations who in total have to fullfill a certain (provided) energy demand. All generators are initially the same, but store their heat in a heat buffer. CHP's with a full buffer are switched off.
This will lead for example to the folowing (fictional) situation:

5 CHP's with a Power of 1W
which all have a buffer of 100 J
which means they will be full after 100seconds.

The total cluster has to deliver 2W for 150seconds meaning first 2CHP are switched on and when their buffer is filled (after 100sec) than 2other CHP's are switched on for another 50sec.

Is this possible to model in one single sketch with different a subscipt for each household? Because I can only find that you can vary initial variables (which are the same for each CHP in this case) and not that you can apply IF THEN ELSE function for different subscripts...

Does anyone have experience with this?

thanks in advance,

grt Wouter

[tomfid]

One possibility would be to use the allocation function logic for this, assigning different priorities to the various CHP units so that the get used in sequence. See ALLOCATE AVAILABLE, ALLOC P, ALLOCATION BY PRIORITY and Appendix E-Allocation in the help files/manuals.

Also, it is possible to write separate equations for each element of a subscript (User's Guide, Ch. 17), though that is typically more work than using the allocation logic.

Tom