“…For decades, the operating paradigm has been supply follows demand, which has been implemented via the hierarchical primary, secondary, and tertiary frequency regulation schemes. However, with increasing penetrations of variable renewable generation, such as solar PV and wind, and internet-enabled, connected, and controllable appliances (e.g., distributed energy resources or DERs), it is now technically and economically feasible for flexible demand to follow a variable supply (i.e., provide dynamic grid services) [1]- [3]. However, to control large fleets of DERs to provide grid services requires a distributed controller implementation, which has been known since the late 1970s [4], [5].…”