An algorithm of calculating the capacity of UPFC based on both system and converter strategy is proposed.The comparison of effect in normal and N-1 situation is researched.Control strategy of Nanjing UPFC project is introduced,while power flow is calculated based on UPFC parameters,voltage and reactive power control modes.Control range of UPFC is computed by PSS/E and Python with the real-time data of Jiangsu Power Grid.The result can improve the safety and reliability of Jiangsu Power Grid.