Decomposing Loosely Coupled Mixed-Integer Programs for Optimal Microgrid Design

Zolan, Alexander J.; Scioletti, Michael S.; Morton, David P.; Newman, Alexandra M.

Decomposing Loosely Coupled Mixed-Integer Programs for Optimal Microgrid Design

Date

2021

Authors

Zolan, Alexander J.

Scioletti, Michael S.

Morton, David P.

Newman, Alexandra M.

Publisher

INFORMS Journal on Computing

Abstract

Microgrids are frequently employed in remote regions, in part because access to a larger electric grid is impossible, difficult, or compromise's reliability and independence. Although small microgrids often employ spot generation, in which a diesel generator is attached directly to a load, microgrids that combine these individual loads and augment generators with photovoltaic cells and batteries as a distributed energy system are emerging as a safer, less costly alternative. We present a model that seeks the minimum-cost microgrid design and ideal dispatched power to support a small remote site for one year with hourly fidelity under a detailed battery model; this mixed-integer nonlinear program (MINLP) is intractable with commercial solvers but loosely coupled with respect to time. A mixed-integer linear program (MIP) approximates the model, and a partitioning scheme linearizes the bilinear terms. We introduce a novel policy for loosely coupled MIPs in which the system reverts to equivalent conditions at regular time intervals; this separates the problem into subproblems that we solve in parallel. We obtain solutions within 5% of optimality in at most six minutes across 14 MIP instances from the literature and solutions within 5% of optimality to the MINLP instances within 20 minutes.

Keywords

Mixed-integer programming, Decomposition, Microgrid, Design and Dispatch

Citation

Alexander J. Zolan, Michael S. Scioletti, David P. Morton, Alexandra M. Newman (2021) Decomposing Loosely Coupled Mixed-Integer Programs for Optimal Microgrid Design. INFORMS Journal on Computing 33(4):1300-1319.