In the past decade, the problem of optimal power flow (OPF) for improving economy and security of power system operation has received much attention. The OPF problem solution aims to optimize an objective function such as the fuel cost via optimal adjustment of the power system control variables, while at the same time satisfying various equality and inequality constraints. Generally, the OPF problem is a large- scale highly constrained nonlinear nonconvex optimization problem with several objectives. In deregulated environment, OPF is of current interest of many utilities and it has been marked as one of the most operational needs with additional objectives of minimization of wheeling cost and managing the congestion problem using FACTS controllers. This book adds the deregulation perspectives to conventional OPF problem and handles the OPF as a multiobjective optimization problem. This book is suitable for readers from different disciplines, including college students and instructors, electricity traders, consulting companies, electric utilities, and researchers.