  This study explores the impact of high PV penetration on the inter-area
oscillation modes of large-scale power grids. A series of dynamic models with
various PV penetration levels are developed based on a detailed model
representing the U.S. Eastern Interconnection (EI). Transient simulations are
performed to investigate the change of inter-area oscillation modes with PV
penetration. The impact of PV control strategies and parameter settings on
inter-area oscillations is studied. This study finds that as PV increases, the
damping of the dominant oscillation mode decreases monotonically. It is also
observed that the mode shape varies with the PV control strategy and new
oscillation modes may emerge under inappropriate parameter settings in PV plant
controls.
