Network-constrained unit commitment with piecewise linear AC power flow constraints.

• New MILP-based UC model with embedded ac power flow constraints. • Piecewise linear ac power flow equations introduced, compatible with MILP models. • UC model perfectly applicable to small power systems containing tens of system buses. This paper presents a new network-constrained unit commitment (UC) model, which is formulated as a mixed-integer linear programming (MILP) optimization problem with embedded ac power flow (AC-PF) constraints. Piecewise linear AC-PF equations are formulated, which constrain the UC dispatch schedule within permissible transmission capacity and voltage deviation limits, solely by executing the main optimization problem. The proposed model is tested on a six-bus and the IEEE RTS-79 test systems, using GAMS software, whereas the obtained AC-PF results are validated against DIgSILENT/Powerfactory package. The UC schedules are comparatively assessed with detailed results presented in the relevant literature for the same test systems, employing different UC+AC-PF models. [ABSTRACT FROM AUTHOR]