Integrating energy communities with electric vehicle fleets into flexibility markets

Abstract

The increasing penetration of renewable energy and electric vehicle (EV) fleets intensifies the need for system flexibility to ensure reliable and economical operation. Energy communities (ECs), equipped with distributed energy resources (DERs), thermostatically controlled loads (TCLs), and vehicle-to-grid (V2G) enabled EV fleets, represent a promising source of distributed flexibility. However, fully harnessing this potential requires coordinated interaction across multiple system layers while preserving the autonomy of local actors. Hence, this paper proposes a tri-level hierarchical optimization framework that coordinates the operation of ECs, distribution system operators (DSOs), and transmission system operators (TSOs) in day-ahead energy and intra-day flexibility markets. The proposed framework preserves privacy in an operational sense by limiting information exchange to boundary variables, while explicitly capturing the contribution of EV fleets alongside TCLs, batteries, and renewable generation. Case studies on a coupled 57-bus transmission and 33-node distribution system with ten ECs demonstrate that EV fleets significantly enhance local resilience and cost efficiency by reducing reliance on transmission-level reserves. Results across six case studies show that fully activating distributed flexibility, including EV fleets, reduces DSO operational costs by 13.13% and lowers total system flexibility expenditures, while shifting the provision of services from centralized units to decentralized resources. The findings highlight EV fleets as a cornerstone of distributed flexibility and confirm the effectiveness of the proposed three-level hierarchical market coordination framework in renewable-rich power systems.