i have been trying to bound input (charging) capacity to (GW) to stored capacity. The suggested 'ACT' index works perfectly in my model to bound discharge capacity and storage capacity.
I followed the same approach described in the advanced models. However, I still don't quite get how to use the AFC to limit the charging capacity of a battery.
04-01-2024, 08:42 PM (This post was last modified: 04-01-2024, 09:26 PM by Antti-L.)
Can you elaborate on the problem you are seeing? Your screenshot defines NCAP_AFC(NRG,DAYNITE) = 1, which limits both the charging capacity (maximum input power level) and the discharging capacity (maximum output power level) to the same value, 1 × VAR_CAP.
Thanks Antti for checking the situation I face. What i want to model is a different limit for charging and discharging. For example, the case in with the battery requires 4 hours to be charged and 1 hour to be discharged.
Hmm... I think the answer was already given in your first screenshot, no?
It is also explained in the documentation, Part II, Section 4.3.7, Availability factors for storage processes.
So, if you would like to define that charging should require 4 times as much time as discharging, it effectively means that the maximum power level of charging should be only 0.25 × the maximum power level of discharging. Therefore, just define the availability factor NCAP_AFC(NRG,DAYNITE) = 0.25 × NCAP_AFC(ELC,DAYNITE).
(05-01-2024, 04:00 PM)Antti-L Wrote: Hmm... I think the answer was already given in your first screenshot, no?
It is also explained in the documentation, Part II, Section 4.3.7, Availability factors for storage processes.
So, if you would like to define that charging should require 4 times as much time as discharging, it effectively means that the maximum power level of charging should be only 0.25 × the maximum power level of discharging. Therefore, just define the availability factor NCAP_AFC(NRG,DAYNITE) = 0.25 × NCAP_AFC(ELC,DAYNITE).
Thanks Antti for the help and feedback. By using the CommGrp = ACT to set up the limit it was possible to constraint the charging capacity.
05-04-2024, 06:00 PM (This post was last modified: 05-04-2024, 06:09 PM by Antti-L.)
Hmm... well maybe indirectly so, but NCAP_AFC(ACT,tslvl) only limits the storage level (and thus implicitly the storage energy capacity. However, the charging capacity can be directly limited by NCAP_AFC(NRG,DAYNITE), as I described above. 'NRG' needs to be used when input = output (same commodity IN and OUT). With different IN/OUT commodities one can of course use the input commodity instead.
Therefore, for battery input capacity constraints, one should not suggest using 'ACT', because it does not in fact limit the charging capacity, but instead it limits the storage level, i.e. the energy capacity. This is easy to verify, by looking at the model equations: when using 'ACT', only the VAR_ACT variable level is constrained, and not the input flow at all.