A current based model for load flow studies with UPFC

This paper deals with an alternative proposition for the steady state modeling of unified power flow controller (UPFC). Since current limitations are determinant to FACTS apparatus design, the proposed current based model (CBM) assumes the current as variable, allowing easy manipulation of current restrictions in optimal power flow evaluations. The performance of the proposed model and of the power injection model (PIM) are compared through a Quasi-Newton optimization approach. Two operating situations of a medium size network with 39 busbars were studied from the point of view of optimization and current limits, observing the performance of the UPFC modeling.