This paper introduces a modified power flow model for Hybrid Flow Controller (HFC) as an energy flow controller. The existing power flow models for Hybrid Flow Controller are suitable only for conventional power flow analysis, and are not applicable for OPF and optimal location analysis of FACTS devices. In this paper, some modifications were applied to the existing models to promote the accuracy and improve their conformability on any power system and hence leading to a precise steady-state analysis. The modified model and the existing model are investigated using different IEEE test systems and the results are compared together. The optimization method is numerically solved using Matlab and General Algebraic Modelling System (GAMS) software environments. The solution procedure uses Mixed Integer Non-Linear Programming (MINLP) and Relaxed Mixed Integer Non-Linear Programming (RMINLP) to solve the optimal location and setting of HFC incorporated in OPF problem considering the total fuel cost, power losses, and the system loadability as objective functions for single objective optimization problem and improve the power system operation. (C) 2010 Elsevier Ltd. All rights reserved.