In order to investigate the influences of grid-connected photovoltaic(PV)power plants on the low frequency oscillation of multi-machine power systems

detailed derivations are made and the state equation and the linearized model of the multi-machine power system containing PV power plants are set up based on the dynamic model of grid-connected PV power plant. On this basis

the influences of different locations and penetrations of PV on low frequency oscillation of a two-area four-generator system are analyzed systematically by using the modal analysis method

when the system rotational inertia is changed or unchanged. The influences are then validated by time domain simulations. The simulation results show that the PV power plant will not generate additional low frequency oscillation modes. There exist significant differences in influences of PV integration on low frequency oscillation when the system rotational inertia is changed or unchanged. The influences of PV integration depend on the location and penetration of PV power plant. Finally

the influences of PV location and penetration on inter-area low frequency oscillation mode are further validated by eigenvalue sensitivity analysis. This work is supported by State Grid Corporation of China and Sydney University Bridging Funding.