Distribution System EV-hosting Capacity Assessment Considering Decentralized Smart Charging and Static Pricing Rates

This paper presents a distribution system Electric Vehicle (EV) hosting capacity assessment considering Decentralized Smart Charging (DSC) and static pricing rates. The EV hosting capacity, computed using the perturb-and-observe technique, is the number of EVs a particular feeder can host before grid violations are encountered. We consider voltage limit violations for every node, as well as line and transformer current violations. The proposed DSC algorithm is formulated as a multi-objective optimization problem considering Bill Minimization, Fast Charging, or a weighted combination of both. We include a regularization term to each objective to force low amplitude and temporally flat charging profiles. Also, we consider three different static pricing rates available to customers in the Southeastern US: Plug-In EV, Smart Usage, and Residential Service. Results on the EPRI Secondary Test Circuit show that static pricing rates have minimal impact in terms of the hosting capacity of the feeder. Also, we demonstrate that the proposed regularization term increases customer cost but helps to boost the feeder hosting capacity to its maximum. Finally, we found that transformer ampere ratings are binding constraints for EV-hosting capacity assessments.