Issue with BESS not charging from curtailed power under interconnection limit in

Dear Paul: I hope this message finds you well.I have a question regarding the operation of a PV plus BESS plant located in Chile. I would like to simulate the dispatch of a 100 MW × 5-hour battery by discharging at 100% of its rated capacity for the first 2 or 3 hours, and then at 50% of its rated capacity (50 MW) for the following hours.When I set this up in the Manual Dispatch section in SAM and run the simulation, the results do not match my expectations. Specifically, the model does not dispatch at the hours I assigned for the 50% discharge.For your reference, I have attached both the SAM file and the TMY file for PV.Kind Regards,
 

Hi Nicolas,

For the battery dispatch schedule, the battery can discharge at 50% for Period 3, but in the dispatch schedule, Period 3 starts at 6 am. The battery is not allowed to charge or discharge in Period 4 from 10 pm to 5 am:

 

Best regards,
Paul.

Thanks for the quick reply, Paul. Sorry, I usually use period 3 for the standby period and forgot to fix it. I reconfigured the dispatch, but it still isn't discharging 50% of the total power at 10 p.m., even though the battery should have stored energy. I've attached screenshots of the new configuration I've set in the same .sam file.

Regards

Hi Nicolas,

The manual dispatch charge and discharge percentages are intended to limit the charge/discharge rate to avoid damaging the battery. If you use 25% and 12.5% rates instead of 100% and 50%, I think you will see the behavior you want.

Best regards,
Paul.

Hello Pauls, I am modeling a PV + BESS system in SAM and have encountered a problem with battery dispatch under grid interconnection limits. My PV plant is 40 MW with a grid export limit of 28 MW, and the BESS is 4 MW / 8 MWh (2-hour system), DC-connected. I enabled both “Battery can charge from grid-limited system power” and “Battery can charge from clipped system power”. However, in Manual dispatch mode, the battery does not charge from curtailed (clipped) energy even though those options are checked.What I expect is for the battery to charge from curtailed PV energy during the daytime and then discharge later in the evening (e.g., 17:00–20:00). My question is whether this is possible in Manual dispatch, or if it only works with Automated or Custom time series dispatch.Nice to know you and thank you for your guidance!

Ms. Loan, from Vietnam.

Thanks, Paul.

I ran the model setting the discharge rate in period 2 at 20%. I was expecting a discharging power of 20 MW, but for some reason it’s still discharging at full capacity. From my understanding, charging or discharging the battery at a lower rate shouldn’t cause any damage. The only way I’ve found to change the rate on an hourly basis is by importing a curtailment time series.

Is there not other way?
Kind regards