Hierarchical energy flexibility coordination of all-electric buildings for deliverable grid services

Building electrification, combined with smart technologies and distributed energy resources, not only reduces the carbon footprint of buildings but also transforms them into active participants in grid operations by providing essential flexibility services and grid support. This paper proposes a hierarchical optimization framework that effectively bridges the gap between the energy flexibility potential of all-electric buildings and power grid support by ensuring that the available energy flexibility is transformed into technically feasible and deliverable energy services through distribution networks while respecting both network constraints and occupant comfort requirements. Local controllers operated by aggregators first optimize zone-level energy flexibility in a day-ahead scheduling framework by coordinating cold-climate air source heat pumps (ccASHPs), heat pump water heaters (HPWHs), photovoltaic (PV) systems, and energy storage systems across multiple all-electric buildings within their respective zones. A central controller operated by the distribution system operator (DSO) then optimizes the energy flexibility offered to the day-ahead energy market by aggregating zone-level energy flexibility and considering distribution network constraints including voltage limits, line capacity restrictions, and power losses to ensure deliverable energy flexibility to the Independent System Operator (ISO). The approach integrates thermal dynamics of heating and cooling loads with electrical characteristics of distributed energy resources to enable coordinated energy flexibility provision that maintains occupant comfort through controlled indoor and water temperatures. The simulation results show reductions in DSO operation costs and electricity bills of the buildings while enabling the provision of deliverable energy flexibility to the ISO. • Proposes a hierarchical model for all-electric building energy flexibility coordination. • Integrates thermal dynamics with DERs to optimize flexible energy services. • Ensures deliverability of flexibility through distribution network constraints. • Validates cost benefits for both DSO and buildings through hierarchical control. • Quantifies energy flexibility from building to ISO through DSO coordination.