A hierarchical demand-response algorithm for optimal vehicle-to-grid coordination

We propose an algorithm to deal with the problem of decentralized coordination of charging/discharging of a large population of plug-in electric vehicles (PEVs). We introduce a framework in which the power grid is modeled as an undirected rooted tree. The root of the tree represents the generation/transmission side of the system and the leaves represent PEVs. Intermediate nodes represent congestible elements on the distribution side (e.g., transformers), which have a bound on the demand they can attend. In the proposed algorithm, the root generates a control signal based on the price per unit of power according to the demand for each time. Intermediate nodes modify the control signal according to the difference between the demand they take care of, and its capacity upper bound. PEVs update their charging/discharging strategies according to this pricing signal. Simulations demonstrate the algorithm performance for a particular example.