Optimisation methodology | objective function(s) | Combined Cases

Hello,

I am writing to ask about,

1. What is the optimisation methodology/technique/algorithm used by SAM models? 
2. What kind of objective function(s) (e.g. LCOE) are maximised/minimised to produce the results for each simulation case?
3. Is it possible to conduct the 3 kinds of analysis (parametric, stochastic and P50/P90) on multiple cases that have been combined using the "Combined Cases" macros?

This query relates more specifically to the following systems: PV+fuel cell, Wind, hydrogen production, battery. 

Kind regards,
Vedika 

Hi Vedika,

In general, SAM is not an optimization model. It runs a performance model simulation to calculate the electrical output of a power system and a financial model simulation to calculate the cash flow of an energy project. There are some optimization algorithms built in to some of the models, for example, the CSP Power Tower model can optimize the field layout or storage dispatch, and the PPA financial models can calculate the PPA price to meet a target internal rate of return (IRR).

You can use SAM for optimization, either by running several simulations to find the maximum or minimum value of an output metric in order to determine optimal value of an input parameter. You can use SAM's simulation tools like parametric simulations, stochastic simulations to automate the process of running multiple simulations, or you can write a script in SAM's LK Script language to do the automation. You can learn more about these options here: sam.nrel.gov/simulation-options.html .

When you use the combine cases macro, you may be able to do a cost or financial optimization on the Generic System case that represents the "combined system." Once you use the Combine Systems macro to create the generation profile for the combined systems that is used as input to that case, you can make changes to the financial parameters in that case. To optimize performance parameters of a part of the system, you would have to do the optimization in the case that represents that part and then run the Combine Systems macro again to create a new generation profile.

UPDATE: As of SAM 2021.12.02, the Combine Cases macro is replaced by the Calculate generation profiles and nameplate capacity from open cases option on the Power Plant page for the Generic System model and Generic Battery model. See the SAM YouTube channel for a short tutorial .

I hope that helps.

Best regards,
Paul.