Introduction—Advances and Challenges in Active Distribution Systems

Many drivers are determining continuous changes in the structure and operation of distribution grids. In addition to the now long-lasting effects introduced by the smart grid paradigm, a number of new trends are emerging. This chapter provides an overview of how distribution systems are changing. Modernisation is the key point to pass from network infrastructures designed in a rather different context to new solutions that incorporate advanced features. For this purpose, the concepts of passive user, active user, and prosumer, and their role in emerging distribution systems, are introduced and discussed. Relevant aspects addressed include the impact of the diffusion of renewable energy sources in the operation of distribution systems and microgrids, as well as the current trends towards establishing local energy markets and energy communities. Further aspects refer to the development of local solutions for the generation, management and storage of energy at small- and micro-scale, the increasing attention towards grid-side and demand-side flexibility, and the provision of grid services.