Transmission and ramp constrained unit commitment using enhanced adaptive Lagrangian relaxation

This paper proposes an enhanced adaptive Lagrangian relaxation (ELR) for transmission and ramp constrained unit commitment (TRUC) problem. ELR minimizes the total supply cost subject to the power balance, up and down 15 minute spinning reserve response time constraint, generation ramp limit constraints, on/off line minimum level constraints, minimum up and new down time constraints, generator operating constraints, and transmission lines constraints. ELR is enhanced by new minimum down time to account for startup and shut down ramp constraints, new initialization to obtain a high quality initial solution, transmission constrained dynamic economic dispatch to include the operating ramping limits, and adaptive Lagrangian multipliers to speedup the convergence. If the 24 hour schedule is feasible, transmission constrained dynamic economic dispatch by quadratic programming is used to minimize the production cost subject to the power balance, new generation ramp operating frame limit, and transmission line constraints. In addition, the alleviating congestion index is proposed for congestion management. For hours with insufficient 15 minute response time spinning reserves, repairing strategy by quadratic programming is used. The proposed ELR algorithm is tested on the 26 unit IEEE reliability test system. It is shown that ELR could obtain a higher quality solution than both dynamic economic dispatch based on artificial neural network and dynamic priority list.