Application of the injection modeling approach to power flow analysis for systems with unified power flow controller

This paper proposes an improved injection modeling approach for power flow analysis of unified power flow controller (UPFC) embedded power systems. With the UPFC injection models, an equivalent network without UPFCs can be obtained easily according to four basic scheduled control objectives of UPFCs. For the equivalent network, conventional techniques such as Newton-Raphson method and even commercial software can be directly employed for power flow solutions of original systems with UPFCs. Hence, it inherits all advantages of conventional techniques both in convergence and in speed. With the power flow solution, control parameters of each UPFC are then evaluated using the equations derived in this paper. Case studies on the IEEE 14-bus system and on North China power network are given to indicate that the approach is reliable and efficient.