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Veda Application Installation guide

Storage Interpeting In and Out flows
Dear experts,

I have a storage process (pump) which is defined as STS and is operating at the DAYNITE level. I use the NCAP_AFC for ANNUAL and DAYNITE timeslices and the same in/out commodity (ELC).

The units are GWe for the capacity and PJ for the output commodity, with a CAP2ACT=31.536.

The model has 288 timeslices distinguishing between 4 seasons and 3 typical days with 24 hours each (4*3*24=288).

I would like to report the charging and discharging profile of this process in terms of capacity per hour (during a 24-hour single typical day).

This can be done straightforward for the Var_Fout using the timeslice duration, the capacity and the CAP2ACT coefficient (as the VAR_SOUT variable participates in the capacity availability constraint CAP)

By applying the same procedure for Var_FIn, I get a result that exceeds the process' capacity in GWe for some timeslices.

There are no bounds affecting the result.

Is anyway to adjust Var_Fin (by declaring some additional parameter that I am missing) in order not to report charging power more than the process' capacity in a typical hour? Or do you suspect that I have a model specification error?

I attached the output that I get and the calculation I made to report the charge/discharge capacity in a year.

Thank you for your help,

Attached Files
.zip (Size: 13.96 KB / Downloads: 16)

Just a quick comment (being on holidays):

For storage processes, you can only have a capacity based on the stored amount, or based on either the output or input  flow (when using NCAP_AFC), but not both. Therefore, if you would also want to restrict the charging flows by the same capacity as the output flows, at the moment that is a bit difficult (you would need to define an UC and an auxiliary flow).  But the next TIMES version will allow an easy way for doing that.

However, I am not sure I understood your question correctly, as you were talking about reporting...

Thank you very much Antti,

yes you understood very well the "reporting" (it is just for producing an excel chart).

I will do the UC constraint and AUX flow alternative (if necessary), but I was hopping to avoid it. It is good that it will be considered in the next TIMES version.

Enjoy your vacations ,

FWIW: In fact, you could also require both the input and output flows to be constrained by the capacity by using different electricity commodities for the input and output, because then you can define NCAP_AFC for both. But when using the same commodity for  both input and output, the current code allows only the output flows to be constrained by the capacity. And, as mentioned, this restriction will be relaxed in the next version.
This is related to the use of NCAP_AFC on both the input and output flow. I find this very useful in regards of modelling batteries in a relatively simple manner.

- Have anyone succeeded on doing this for a storage process in Answer-TIMES? I am currently struggling with this.....I know this is a VEDA forum but the questions is highly related to this previous post : ).

So you have the same commodity IN and OUT?
Can you tell what is causing struggling with it? I think ANSWER supports well NCAP_AFC / NCAP_AFCS.

The documentation describes how you can define availability factors for input and output:
If input=output=c, NCAP_AFC('NRG') will define the availability factor for both the input and output flow, while NCAP_AFC(C) will define the availability factor for the output flow only, overriding any NCAP_AFC('NRG') value if that is also specified (assuming NRG is the type of the stored commodity).

This should normally work well on the DAYNITE level, because usually one can assume that charging and discharging occur at different timeslices. Thus you can constrain the charging and discharging power levels to different maximum levels. However, on the SEASON or ANNUAL level one might want to define only an output availability.
Thank you for the fast reply!

Yes, I have the same commodity IN and OUT, and the process is on a storage DAYNITE level.

Since a process activity is defines as either Output-based or Input-based in Answer, I am currently only able to use NCAP_AFC on either the input or output commodity. I assume that there is either something that I have misunderstood, or that Answer-TIMES needs to be modified to be able to use NCAP_AFC on both input and output flows.
Hmm... that sounds strange.  What are you trying to do for using NCAP_AFC on both input and output?  And how does the fact that the process activity is defined as either Output-based or Input-based affect that?

If the input and output commodity is COM, and it is defining the PG, both the input and output will be in the PG.

I just tried it myself in ANSWER, with a storage having ELC as an input and an output.  I was able to define NCAP_AFC(ELC) and NCAP_AFC(NRG) without any problems.  So, that worked well, and then TIMES will define the AFC equation for both input and output, using the different availability factors for charging and discharging. Thus, unless I am missing something, that should work well.
This is good news! Thank you very much, now it works perfectly!

Previously, I did not include NCAP_AFC(NRG), only NCAP_AFC(ELC,) and that is the reason for why it did not work! I apologies for not reading the documentation more thorough.....

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