One of the main concerns with the introduction of competition in the power sector is the strategic behaviour of market participants. Computable models of strategic behaviour are becoming increasingly important to understand the complexities of competition. Such models can help analyze market designs and regulatory policies. Although many models of imperfect competition have been developed to analyze market power in the energy market, comprehensive models are still needed to capture more realistic conditions that suppliers face within electricity markets, and more important is that such models can be applied to large systems. On one hand, operational constraints have been neglected in the modelling. On the other hand, the study of competition has been focused on merely on the energy market, disregarding the incentives from other markets and commodities. In this book, further developments on the modelling and economics of competition in electricity markets are presented by introducing more detailed elements of power systems and using innovative mathematical frameworks of market equilibrium.