Dear Andrés,
The collector incidence angle table (and incidence angle modifier equations) are independent of the location of the plant, and represent the geometry of the collectors in the field. The longitudinal and transversal values would be the same for a given field geometry in any location.
During simulations, SAM calculates the solar position for each time step based on the time of year and latitude and longitude from the weather file. SAM then calculates the incidence angle in that time step based on the solar angles and collector angles. Finally, SAM determines the optical efficiency in the time step by looking up the efficiency value in the table for that time step. For angles between those in the table, SAM uses extrapolation to estimate the efficiency value.
Best regards,
Paul.