Redundant and Nonbinding Transmission Constraints Identification Method Combining Physical and Economic Insights of Unit Commitment

Abstract

There is a continuous need to improve the computational efficiency of the Unit Commitment (UC) in the power system and electricity market operations. Studies show that most of the transmission constraints are inactive in the UC. If the inactive constraints can be identified and curtailed from the model, the computational time can be significantly reduced. A redundant and nonbinding transmission constraints identification method combining the economic and physical insights of the UC is proposed in this paper. The economic insights are reflected in the cost-based schedule without transmission constraints, which is solved as the base result. The output and power flow transfer caused by congestion management, which shows the physical insight, are simulated based on the cost-based schedule to identify the inactive constraints. The inactive constraints can be efficiently identified by solving the problem without transmission constraints once instead of using several iterations. A case study shows that the proposed method can identify many inactive constraints that cannot be identified by the CPLEX presolving process, which can significantly improve the computational efficiency.