Optimisation is the systematised search for the best action, the procedure used to make a system as effective or functional as possible. In the last two decades, optimisation techniques have extended in the electric industry. The present book includes some of the most significant present and foreseen optimisation applications in electric power systems. Four Fellow Members of IEEE and other relevant academia and industry authors developed optimisation techniques in the following areas: state estimation, transmission expansion planning, electricity markets, voltage control, wind power, security stability, optimal placement of equipments, distributed generation and others. All the chapters include algorithms, methods, know-how and examples of applications in real and test systems.