Participation of Microgrids in Frequency Regulation Markets

Abstract

The increasing ubiquity of distributed energy resources (DERs) in the power grid provides an opportunity for them to collectively participate in frequency regulation. In this paper, we propose a framework for the participation of microgrids, each acting as an aggregator of certain number of DERs, in the frequency regulation market when operating in grid-connected mode. Our treatment covers both the determination of bids for the market clearance stage and mechanisms for the real-time allocation of the regulation signal. Regarding market clearance, we develop abstractions of the microgrid capabilities regarding capacity, cost of generation, and ramp rates as a function of the individual energy resources that comprise it. Regarding real-time allocation of the regulation signal, we formulate an optimization problem that seeks to minimize the collective cost of the microgrids while respecting operational constraints. Since this problem is not always feasible due to the ramp rate constraints of the microgrids, we provide an alternative formulation that incorporates the minimization of the deviation between the procured collective regulation and the required one. We synthesize an algorithm whose execution involves the coordination of the system operator and the microgrids, and establish its asymptotic convergence to the desired optimizers. Simulations illustrate our results.