The book is a collection of manuscripts proposing original and innovative solutions for accurate distributed monitoring systems, related innovative measurement instruments, distribution grid state forecast algorithms, power flow analysis, frequency and voltage control for stability and quality of service of active networks with distributed generation, and communication systems to acquire distributed measurement data, send commands and receive alarms. The introduction of these innovative solutions can pave the way for the effective transformation of MV and LV distribution networks into smart grids. The book aims to provide readers, Ph.D. students as well as research personnel and professional engineers with information not only on theoretical studies of the recent developments but also the practical application of the proposed solutions for smart grid applications both in LV and MV networks.