A Multi-Scale Supply Operation of Grid-connected Micro-Grid

Abstract

We introduce a design of supply management system for a grid-connected Micro-Grid (MG) which we term the Multi-Scale Supply Operation. The concept of MG has been developed as an effective method for utilizing distributed generation units including renewable energy resources. Multi-Scale Supply Operation aims to enhance the economic efficiency of a grid-connected MG and to contribute to the long-term supply-demand balancing of the commercial grid. The operation system consists of the three layers for optimization and control: long-scale supply planning, medium-scale supply planning, and short-scale control. In particular, we introduce the medium-scale supply planning to manage the imbalance (i.e. the difference between planned and actual amounts of electric energy from the commercial grid) and thus to enhance the economic efficiency. We also introduce a formulation of the long-scale supply planning to consider a physical constraint in the short-scale control. Performance of the proposed design is evaluated with numerical simulations of MG using a set of practical parameters and measured time-series data.