This paper presents a novel architecture for electrical distribution networks based on a decentralized control system where a Substation Automation and Control System plays a key role. This new control element brings additional control and management functionalities that are crucial for future distribution networks with high levels of Dispersed Energy Resources in both interconnected and islanded operating modes. Several coordination and control issues are addressed with the aim of optimizing grid operation in interconnected mode and simulation results are shown for voltage and reactive power control.