The term power systems control is used to define the application of control theorems and relevant technologies to enhance the power system functions during normal and abnormal operations. Power system control refers to keeping a desired performance and stabilizing power system following various disturbances, such as short circuits and loss of generation and/or load. Power system stability and control was first recognized as an important problem in the 1920s [1,2]. Over the years, numerous modeling/simulation programs, synthesis/analysis methodologies, and protection schemes have been developed. Power system control can take different forms, which are influenced by the type of instability phenomena. A survey on the basics of power system controls, literature, and achievements is given in Refs [3,4].
In this chapter, fundamental concepts and definitions of power system stability and control are emphasized. The role of power system control in preserving system integrity and restoring the normal operation subjected to physical disturbances is described and some challenges, opportunities, and new perspectives concerning the integration of renewable energy options and distributed generators are introduced.
5.1 Power System Stability and Control 
Power system stability is defined as “the ability of an electric power system, for a given initial operating condition, to regain a state of operating equilibrium after being subjected ...