With the increase of grid-connected photovoltaic generation capacity,the inherent characteristics of fluctuation and intermittence of the photovoltaic generation lead to the result that large-scale PV integration will change the distribution of power flow and even reverse it,influencing the stability and security of power grid.A steady-state model of PV generation system is established in the paper.Based on the IEEE 14-bus system and power grid of a province in Northwest China,probabilistic load flow calculation of power grid connected with photovoltaic generation system has been carried out.The influence of large scale grid-connected PV generation on load flow of power system is fully analyzed under the circumstances of different grid-connected capacity,different grid-connected spots and different output correlations of the PV generation system.The results indicate that the fluctuations and limit violation probabilities of power system voltage and load flow increase with the addition of PV capacity.What's more,power loss as well as PV penetration level is influenced by grid-connected spots and the impact of PV on load flow is directional.Additionally,the correlations among PV power stations cannot be ignored.The research does provide reference for the planning and operation of power system with large integration of renewable energy.