We will be performing a major infrastructure and web site ugprades on Friday, September 27th 8:00 am - 5:00 pm MST (UTC -7).

The website will be down during that time.

System Advisor Model (SAM)

DNI PARAMETRIC

Start
Prev
1
Next
End

jqcano
Topic Author

06 Jul 2019 16:00 #7516 by jqcano

DNI PARAMETRIC was created by jqcano

Dear Sir,

I'm simulating a CSP Molten Salt Power Tower, and I'm trying to make a parametric study varying different variables. One of them I'm changing is DNI at design point, but I'm realising any parameter is changing when I vary it.
Is that right? I suppose I need to change some other values when varying DNI, but I'm not sure which ones should I select.

Thanks for your help,
Javier.

Please Log in or Create an account to join the conversation.

pgilman

08 Jul 2019 14:53 #7519 by pgilman

Replied by pgilman on topic DNI PARAMETRIC

Hi Javier,

When you change the value of an input value, SAM generally does not change the value of other interdependent inputs, so you have to change the values of all related input variables.

SAM uses design DNI value along with other design parameter values to determine the nominal capacities of the solar field and other components in the system.

I am not sure exactly what you mean by "...I'm changing is DNI at design point, but I'm realizing any parameter is changing when I vary it."

Can you tell me more about what you are expecting to see?

Best regards,
Paul.

Please Log in or Create an account to join the conversation.

jqcano
Topic Author

09 Jul 2019 08:03 #7523 by jqcano

Replied by jqcano on topic DNI PARAMETRIC

Hi Paul!

First of all, thanks for your answer.

I'm trying to analyze how the plant performance is influenced by DNI. I'm not expecting SAM to change any input (sorry, I expressed myself wrong), but some outputs should vary, shouldn't they? I mean, annual energy production and hourly production should change for an array of DNI values. Am I wrong?
For your info, I'm simulating an existing plant, so there are many inputs I cannot change (number of heliostats, receiver and cycle power...).

Thanks again,
Javier

Please Log in or Create an account to join the conversation.

pgilman

09 Jul 2019 14:36 #7524 by pgilman

Replied by pgilman on topic DNI PARAMETRIC

Dear Javier,

The design DNI is different from the hourly DNI values in the weather file. The design DNI is used to calculate the nameplate capacities. For example, a system with a 100 MW nameplate capacity and design DNI of 950 W/m2 means that the solar field and power block will generate 100 MW during times when the DNI is 950 W/m2 (and when other design conditions are met).

The weather files has DNI, ambient temperature, wind speed, and other hourly data that SAM uses during the simulation to calculate the system's electrical output in each hour of the year based on the solar resource and meteorological conditions.

These videos about SAM's CSP models explain more about how they work:

sam.nrel.gov/concentrating-solar-power/csp-videos.html

Best regards,
Paul.

Please Log in or Create an account to join the conversation.