What do you mean by Grid Impact Study?
Are you talking N-1 criteria, or day-ahead system studies to ensure acceptable system load, generation voltage profiles based on projected planned outages, or the impact of storms on your grid, or your MSSC [ Most Severe Single Contingency ], or system stability limits, or...
CR
"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]