Prompted by the need for clean energy sources, increasing amounts of photovoltaic (PV) generator is connected to the power system around the world, hence, affects many aspects the dynamic and operational characteristics of synchronous generator dominated power system. In this paper, the impact of large-scale PV generation on power system oscillation, especially the inter-area oscillation is studied. The effect of PV on inter-area mode is investigated in New England-New York test system for different level of penetrations and operating conditions. Analysis in the paper reveals that increased PV penetration could affect the critical inter-area mode detrimentally. A trajectory sensitivity based rotor angle norm is evaluated to explore the reason why PV generators are interacting negatively on critical inter-area mode. The primary basis of the method is to convert the PV generator with equivalent sized synchronous generator and evaluate the sensitivity by real power perturbation. The analysis reveals that integration of PV to the system creates higher angular separation among synchronous generators, results inter-area oscillations. A generator ranking based operating point adjustment method is proposed in this paper to minimize the angular separation. The results obtained indicate that the proposed method can effectively minimize the angular separation, hence, enhance the damping of inter-area mode. (C) 2012 Elsevier Ltd. All rights reserved.