Efficient Location of Unsatisfiable Transmission Constraints in Look-Ahead Dispatch via an Enhanced Lagrangian Relaxation Framework

Unsatisfiable transmission constraints (UTCs) may lead to failures in look-ahead dispatch. Hence, the detection of UTCs is a critical issue in power systems, and it may also aid in the discovery of unavailable transmission resources in online look-ahead dispatch. The Lagrangian relaxation (LR) algorithm is a rapid and efficient approach to solving look-ahead dispatch (LD) problems; however, it does not readily handle infeasible problems. Here, we describe criteria and procedures for detecting infeasible LD and for locating and addressing UTCs via an LR framework. The proposed procedures for detecting infeasibility and locating unsatisfiability are incorporated into a conventional LR framework to develop an enhanced LR solution framework without affecting the original computational efficiency. Numerical simulations are carried out using an IEEE 24-bus system, 31-bus system, and several large-scale power systems; the results demonstrate the accuracy, efficiency, and reliability of the methods.