Optimal management of electric power in microgrids under a strategic multi-objective decision-making approach and operational proportional adjustment

Abstract

In energy management systems in microgrids, the combined and on-line use of optimisation and prediction rolling horizons of renewable power and demand may compromise the optimal performance. Usually, the medium-term optimal behaviour improves with additional available convergence time, while the error in predictions worsens with a broader horizon, against the using short-term predictions, which usually contributes to more accurate management. To address this problem, this study proposes the strategical and operational energy management system (SO-EMS) approach, which is based on three complementary management processes: (i) strategic energy management, based on off-line multi-objective optimisation on a rolling horizon, (ii) asynchronous decision making, which offers the ability to incorporate multiple criteria of a microgrid operator in the selection of an optimised energy plan, and (iii) operational power management, as an on-line proportional redistribution and redispatch process based on rules. The SO-EMS evaluation performed on a connected microgrid shows its ability to provide optimised plans on a rolling horizon of 24-h predictions and to adjust them to 1-m predictions. The evaluations made of the scheme also show flexibility because it is possible to redistribute the power assignments of units that are out of service. These features empower the SO-EMS in the broad power management of various connected microgrids.