The book covers the fundamentals and application of recently developed methodologies for assessment and enhancement of power system security in short term operational planning (e.g. intra-day, day-ahead, week ahead, and monthly time horizons) and real-time operation. The methodologies employ advanced data mining and probabilistic theory algorithms to provide knowledge-based support for monitoring, control (preventive and corrective), and decision making tasks. Among the topics to be covered are big analytics for feature selection and extraction, computational intelligence for wide-area monitoring, protection and control, risk-based security assessment, model predictive control, dynamic vulnerability assessment, multi-agent and distributed control systems.