Transmission constrained generation scheduling in a centralized electricity market by improved Lagrangian relaxation

This paper proposes an improved Lagrangian relaxation (ILR) for centralized dispatch of transmission constrained generation scheduling (TCGS) problem in a centralized electricity market. ILR minimizes the consumer payment rather than the total supply cost subject to the power balance, spinning reserve, transmission lines, and generator operating constraints. ILR algorithm is improved by new initialization of Lagrangian multipliers and adaptive adjustment of Lagrangian multipliers. If congestion exists, the alleviating congestion index is proposed for congestion management. Finally, the unit decommitment is performed to prevent excessive spinning reserve. The ILR for TCGS is tested on the 4 unit and the IEEE 24 bus reliability test systems. The proposed system electricity price including the uniform distributed side payment could ensure generator revenue adequacy leading to a lower consumer payment than system marginal price based on uniformly fixed cost amortized allocation.