Questions on storage and CAP_BND

[srchlela]

Hello everyone, 

I am want to implement a storage technology in a model and I have some questions on the parameters: 

- If it's maximum capacity is 50 kW then I should insert a constraint CAP_BND <= 50 kW (or use the NCAP_BND since it is a new tech?) and is STGIN_BND the same as bounding the capacity? 

- Can I use a BND on the activity which is 250 kWh? 

- I am a bit lost with STG and STGTSS when is it better to use STGTSS? 

- I want to evaluate this techno for flexibility (providing elec when consumption is high (peak hours) and charging during the night) so has anyone done the same through constraints? any advice or help are highly appreciated! 

Thank you very much!

Sophie

[Antti-L]

Some quick answers below:

> If it's maximum capacity is 50 kW then I should insert a constraint CAP_BND <= 50 kW

What do you mean by a maximum capacity of 50 kW for a storage?  Storage capacity is normally understood as the maximum amount of energy stored, while kW is a power unit. But yes, you can also define the capacity on the basis of the input / output power level.

> Is STGIN_BND the same as bounding the capacity

No. STGIN_BND bounds the input (charging) flow.

> Can I use a BND on the activity which is 250 kWh?

You can, but it is not straightforward and is thus not recommended, and is normally not needed. One can use availability factors on the activity for bounding the storage level in proportion to the capacity, and if you bound the capacity, you can thus bound the storage level to a desired maximum absolute amount as well. See the documentation, Section 4.3.7 Availability factors for storage processes.

> I am a bit lost with STG and STGTSS when is it better to use STGTSS?

I think VEDA supports both as the process type.  In both cases it means a standard timeslice storage, operating on the timeslice level defined for the process (e.g. DAYNITE).

[srchlela]

Thank you for your reply and explanations, Antti.

You helped figured it out, I was reading a model where Capacity unit for storage is set to kW and it should be kWh so I got confused with the constaints units!

I will check the details on availability factor