"Power System Coherency and Model Reduction" provides a comprehensive treatment for understanding interarea modes in large power systems and obtaining reduced-order models using the coherency concept and selective modal analysis method. Both linear and nonlinear analysis methods are covered. The ideas in this book are important for designing damping control of interarea modes. Small system examples to illustrate the concepts and large power system examples to illustrate practical applications of the method are included. This is an important reference book for researchers interested in interarea oscillations and model reduction, and power engineers in developing reduced models for power system studies and control design.