Optimal placement of Unified Power Flow Controllers (UPFCs) using Mixed-Integer Non-Linear Programming (MINLP) method

Utilization of unified power flow controllers (UPFCs) can be more beneficial in the restructured power systems due to their capabilities in increasing the transmission line capacities as well as shunt reactive compensation. So, these devices should be installed such that the most benefit can be gained. In this paper, the problem of optimal placement of UPFCs is solved using Mixed-Integer Non-Linear Programming (MINLP) method. Hence, the problem is completely formulated based on this method and is solved using available commercial solvers. The salient feature of this method is having potential to simultaneously determine the optimal location of multi UPFCs. Also, since a full AC Optimal Power Flow (AC-OPF) is fulfilled during this process, functional parameters of UPFCs and results of OPF are obtained finally. Some case studies are examined to illustrate the effectiveness of the proposed formulation.