System impact studies for PV units what to model?

Interconnection procedures for conventional generation and wind turbine generators are considered common practice with several Planning Standards across the US clearly addressing the studies to be conducted. Currently the PV market is regulated by IEEE 1547 [1] and UL1741 interconnection and safety standards for distributed generation and do not addressed the largest interconnected PV units. With the introduction of large solar units to the bulk electric grid, determining the studies to be conducted and the appropriate models to be used is a new challenge facing the electric industry. In 2010 Mott MacDonald Inc. (MMI) conducted a system impact study for a solar project with a maximum generating capacity of 32 MW. This paper discusses in detail the electric power system studies and modeling methodology adopted for the impact analysis of a large PV solar plant on the bulk electrical system.