Optimal scheduling of time-shiftable electric loads in expeditionary power grids

Abstract

Environmental control on the battlefield enhances readiness, reduces casualties, and protects the sensitive equipment upon which U.S. doctrine relies. Purchase and delivery of fuel necessary to provide this service was responsible for an estimated $1.4 billion in costs and 33 resupply convoy casualties per year at the peak of U.S. wars in Iraq and Afghanistan. It is well understood that the current semi-autonomous mode of environmental control unit (ECU) operation results in gener-ators operating at low average loads—and low fuel efficiency—to accommodate periodic unmanaged spikes in peak load.We propose a mechanism to reduce costs through optimal prescriptive management of these ECUs. We exploit the fact that ECU operation is time-shiftable to develop a mixed-integer linear programming (MILP) model that optimally schedules ECUs to eliminate unmanaged peak demand, reduce generator peak-to-average power ratios, and facilitate a persistent shift to higher fuel efficiency. Using sensitivity analysis, we quantitatively demonstrate how grid composition, temperature band tolerance, and energy storage capabilities contribute to fuel efficiency under this approach.