Unit Commitment Scheduling Including Transmission Constraints: a MILP Formulation

Abstract

The benefits of good scheduling of electrical units are widely known (De la Torre et al, 2008). In this paper, a new approach to account for the Security-Constrained Unit Commitment (SCUC) is presented. A model is developed as a deterministic optimization problem, giving rise to a MILP formulation. Demand, reserve, and unit constraints are taken from a previous paper (Marcovecchio et al, 2014). Transmission constraints including buses balance, lower and upper bound for line power flows, and bus voltage angle constraints are included in this paper. Identification of loops matrix is not necessary as it is the case in several formulations (Stagg et al, 1968). Scheduling was solved for a 6-bus 3-generator and 11 transmission line problem and a 31-bus 16-generator and 43-transmission line problem. Computational times are very low, being 0.189 and 118.160 CPU sec. respectively. Relationship between capacity usage and occupied time for all generators is analyzed. In a similar way, power flow in each line related to the power flow in output and input bus connected to each line is addressed. This information is depicted by simple graphs.