Stochastic Centralized Dispatch Scheme for AC/DC Hybrid Smart Distribution Systems

This paper presents a two-stage stochastic centralized dispatch scheme for AC/DC hybrid smart grids. The developed dispatch scheme coordinates the operations of a variety of distributed energy resources (DERs), such as distributed generators (DGs) and energy storage systems (ESSs). It also ensures the coordinated charging of electric vehicles (EVs) and models the degradation of their batteries that occurs due to vehicle-to-grid (V2G). The energy coordination problem has been formulated as a two-stage day-ahead resource scheduling problem, with the intermittent supply; the variable demand, which includes EVs; and the fluctuating real-time energy price modeled as random variables. The first stage produces day-ahead dispatch decisions for the dispatchable DG units. For a set of possible scenarios over the next 24 h, the second stage determines appropriate corrective decisions with respect to the import/export schedule, storage charging/discharging cycles, and EV charging/discharging patterns. The objective is to minimize the expected total operating cost while satisfying operational and technical constraints. The new two-stage stochastic centralized dispatch model has been tested on a 38-bus AC/DC hybrid distribution system. The simulation results demonstrate the effectiveness of the developed scheme for optimally coordinating the various components of future AC/DC hybrid smart grids. To demonstrate the necessity for uncertainty modeling, the value of the stochastic solution (VSS) and the expected value of perfect information (EVPI) have been applied for comparing the stochastic solution obtained and the deterministic one.