Article Preview
Top1. Introduction
Optimal power flow (OPF) is an important tool for power system operators both in planning and operation in the present day power systems. The main aspect of OPF is to minimize the costs of meeting the load demand for the power system while satisfying all the security constraints like the various equality and inequality constraints. On the other hand, Flexible AC transmission systems (FACTS) devices are power electronic controlled devices, which are integrated in power systems to increase the transmission line capability to its thermal limit, control the power flow in specific lines and improve the security of transmission system. FACTS devices could also be used to minimize the total generation cost of OPF problem. These devices also reduce unwanted loop flows in the heavily loaded lines thereby resulting in an increase of load ability, improved security and stability of the network.
Some conventional approaches have been used to solve the OPF problem with FACTS like linear programming (LP) (Ge, & Chung, 1999); (Sundar, & Ravikumar, 2012), quadratic programming (QP) (Chung, & Yun, 1998), interior point method (IPM) (Rakpenthai, Premrudeepreechacharn, & Uatrongjit, 2009) and Newton’s method (NM) (Ambriz-Perez, Acha, Fuerte-Esquivel, & Torre, 1998); (Ambriz-Perez, Acha, Fuerte-Esquivel, 2000) by linearizing the objective function and the system constraints around an operating point assuming differentiable, continuous, analytical and monotonically increasing cost function. Unfortunately, the problems of FACTS based OPF are highly non-convex and non-linear optimization problems and so these methods tends to stuck at local optimal solutions.