Maximizing PV hosting capacity of distribution feeder microgrid

To meet energy and environmental goals and challenging reliability and resiliency targets, the electric grid is transitioning from solely central generation to the inclusion of distributed energy resources (DERs). With a high penetration of DERs on primary circuits (feeders), utility substation communication, automation, and control must adopt to this new paradigm. In principle, utility substations can transition to and operate the feeder circuits in an islanded mode, effectively as Distribution Feeder Microgrids. This creates the need for research to address the challenges associated with integrating and managing significant deployment of DERs on circuits served by distribution substations. In response, this study addresses substation control to manage circuits emanating from utility substations as a microgrid. To this end, a model for substation automatic control using a Generic Microgrid Controller compliant with the IEEE 2030.7 standard was developed, and the role and impact of substation control to improve energy management, increase renewable penetration, and reduce greenhouse gas emissions were evaluated. The detailed digital simulation model developed encompassed two 12 kV distribution circuits emanating from a utility distribution substation. Individual homes were modeled and results verified using field data collected from a previous study. Various scenarios were simulated in order to determine PV hosting capability of the circuits equipped with a controller at the substation and with three energy storage configurations: (1) A residential energy storage unit (RESU) where all customers own a battery energy storage behind the meter, (2) a community energy storage (CES) unit where a utility-owned battery energy storage is deployed near each transformer, and (3) a circuit battery where a relatively large battery is deployed at the substation serving the entire feeder microgrid. Results show that substation automation and control can increase renewable penetration and reduce emissions without any necessary upgrades to the grid infrastructure. Moreover, the CES configuration was found to be a more economic approach for achieving high PV penetration and GHG reduction than residential storage, achieving a 660 mTCO(2eq) reduction per MWh of installed energy storage and overall 32% reduction in greenhouse gas emissions.