Lexicographic multi-objective optimization for the unit commitment problem and economic dispatch in a microgrid

Abstract

In this paper, we present a multi-objective approach for the optimal control of dispatchable loads and bi-directional energy storages in a microgrid, commonly referred as the unit commitment problem and economic dispatch problem. We consider two different and possibly conflicting objectives: the minimization of the end user energy bill price and the maximization of the system stability as a function of the overall system's load. We propose a lexicographic ordering of the objectives so that the end user's energy cost is considered as the primary objective and the system's stability is the secondary objective. In order to evaluate the performances, we provide a comprehensive micro-simulation environment used to study different demand response (DR) price profiles. The proposed multi-objective approach mitigates the network instability effects introduced by static DR programs with high price volatility. We conclude that almost flat DR price profiles with higher rates during high-peak periods should be preferred instead of high volatile profiles. With flat DR price profiles, both the end user and the utility company can benefit from smart-control algorithms adopting a lexicographic multi-objective optimization scheme. © 2011 IEEE.