Doubt on modeling battery in new version of SAM 2021 Revised 2

paoman
Topic Author

18 Jul 2022 13:50 #11264 by paoman

Doubt on modeling battery in new version of SAM 2021 Revised 2 was created by paoman

Dear, in the new version of SAM 2021 revised 2, when checking the option "Battery Can Charge from System" and "...Charge from Clipped..." it only charges with dc/ac ratio of 1.3, is there any change with modeling? (Note: use perfect day ahead, 6 hours of update, 1 hour frequency).

In the 2020 version, for example, close to the time of highest energy cost, the system charges the battery (100%) with photovoltaic and discharges later, in any ratio.
My model is to always charge the battery close to the time when electricity is more expensive.

So, did the model change? What does he consider the most now to decide to charge the battery?

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pgilman

18 Jul 2022 17:24 #11265 by pgilman

Replied by pgilman on topic Doubt on modeling battery in new version of SAM 2021 Revised 2

Hi Pao,

Please see the SAM release notes for a list of changes between SAM 2021.12.02 and previous versions nrel.github.io/SAM/doc/releasenotes.html#2021-12-02.

For a description of the dispatch options see the Battery Storage topics in help:

Behind-the-meter battery dispatch: samrepo.nrelcloud.org/help/battery_dispatch_btm.htm

Front-of-meter battery dispatch: samrepo.nrelcloud.org/help/battery_dispatch_fom.htm

I'm not sure whether you are modeling a front-of-meter battery or a behind-the-meter one. Please attach a copy of your .sam file so I can see what options you are using.

Best regards,
Paul.

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paoman
Topic Author

18 Jul 2022 19:06 #11266 by paoman

Replied by paoman on topic Doubt on modeling battery in new version of SAM 2021 Revised 2

I am modeling the battery with automatic dispatch (and perfect ahead). My idea is:

1 - Charge with the photovoltaic array close to the time when energy is more expensive;
2 - Discharge for grid at the time when energy is more expensive;
3 - Load with clipped to unload at the most expensive time or at high intermittency.

In previous versions, it worked as desired, but in this new version, the battery charged is zero in relation to DC/AC 1:1. Therefore, I use the price to make a decision in "revenue".

My goal is just to get the loading and unloading and I work in excel with other analyses. I use parametric mode for variations.

Link of simulation: drive.google.com/file/d/1uPuHIXtortRWue-EwM2AEcg78TwktWdR/view?usp=sharing

Att,

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pgilman

20 Jul 2022 18:40 - 01 Aug 2022 22:02 #11273 by pgilman

Replied by pgilman on topic Doubt on modeling battery in new version of SAM 2021 Revised 2

Hi Pao,

Thank you for sharing your file.

As described in the "Battery Dispatch FOM" topic in Help under "Automated Dispatch", (samrepo.nrelcloud.org/help/battery_dispatch_fom.htm), the front-of-meter battery dispatch option responds to power prices defined on the Revenue input page. If the power prices do not vary (TOD factor = 1 for all times), then the dispatch will only respond to available power from the system and the estimated cost of wear on the battery.

In your file, the battery discharges to the grid (Electricity to grid from battery) during TOD Period 3 when TOD factor = 1.667 to maximize revenue.

The battery does not charge from clipped power because the battery is fully charged (Battery state of charge) when inverter power limiting (Inverter clipping loss AC power limit) occurs. The battery is charged by the system (Electricity to battery from system) during TOD Period 1 and 2 when TOD factor = 1.

The battery maximum charge/discharge power of 1.5 MW is smaller than the array capacity (3 MW for DC/AC ratio = 1, 5.4 MW for DC/AC ratio = 1.8), so the array is able to quickly charge the battery during times when the power price is low, and deliver the remaining power to the grid to earn revenue.

Best regards,
Paul.

Last edit: 01 Aug 2022 22:02 by pgilman.

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paoman
Topic Author

01 Aug 2022 14:46 #11306 by paoman

Replied by paoman on topic Doubt on modeling battery in new version of SAM 2021 Revised 2

Hi Paul, thanks for your attention. I understand the way you said it. However, in the current version of SAM the battery never operated for 1.1 DC/AC, in previous versions it worked. And it was supposed to work. I don't know if it was a bug here.

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pgilman

01 Aug 2022 22:16 #11307 by pgilman

Replied by pgilman on topic Doubt on modeling battery in new version of SAM 2021 Revised 2

Hi Pao,

Attached is a version of your file with one case where the DC/AC ratio is 1 and one case where the DC/AC ratio is 1.8. For the DC/AC ratio = 1 case, the battery does charge and discharge in response to the TOD factors. This graph shows the battery state of charge in blue and TOD factor in orange for the first seven days of the year: