As large-scale photovoltaic (PV) generation reaches higher penetration levels, there is a greater need to meet the certain grid code requirements for interconnection. Ultracapacitor, battery energy storage system (BESS) or shunt capacitor have recently been used as auxiliary devices for large-scale PV generator system to meet the grid code requirements for interconnection. Although the individual auxiliary devices are well documented, a comparative study of these devices impact on the damping of electromechanical (EM) modes and oscillatory instability problem has not been reported so far. This paper aims to fill in the gap, and provides a comparative analysis of these auxiliary devices performance along with PV plant on the damping of EM modes. The oscillation problem is analyzed by considering different types of synchronous generator (e.g. hydro, thermal) as the non-electrical components of hydro and thermal units have major influences on system dynamics. The comparisons are based on the results obtained from two-area test system and New England-New York test system (16 machine 68 bus system), which are the benchmark systems for angular stability analysis. (C) 2011 Elsevier Ltd. All rights reserved.