A centralized voltage optimization function exploiting DERs for distribution systems

Renewable energy sources have reached such a high penetration level that significantly impacts on power system operation, in particular for medium and low voltage distribution systems where the vast majority of renewable energy generators are being connected. To cope with such an impact, higher levels of flexibility must be introduced in system operation, so as to avoid massive infrastructural investments to reinforce the network, and to assure system stability and security of supply. Introducing flexibility of both demand and distributed generation is the key to make distribution systems smarter. The installation of energy storage systems, for their inherent operational characteristics, may further favor this process. In this paper the flexibility potentially offered by distributed energy resources (DERs), that are active demand, distributed generators and energy storage systems, is properly modeled and exploited to tackle voltage regulation issues. In particular, the network is partitioned into zones to identify a limited number of pilot nodes whose voltage deviations are monitored and then minimized using a specific optimization function by acting on the flexibility offered by DERs. For demonstrating the effectiveness of the proposed approach, the optimization function has been applied to a 24-nodes LV network in different operating conditions.