With the continuous expansion of the interconnection scale of power grids,the number of the power electronics integrated to the power grid continues to increase,bringing new challenges to the operation reliability of the grid.As the equipment for flexible AC transmission system (FACTS) which has the strongest ability of adjusting power flow,the unified power flow controller (UPFC) has been designed,developed and applied to Nanjing western power grid successfully.In this paper,the operational reliability model considering UPFC is established and applied to perform the operation reliability analysis and benefit evaluation of Nanjing western power grid.The analysis results of the example demonstrate that UPFC can effectively improve the reliability of regional power network and positively contribute to economic benefits.