Maximizing Transmission Efficiency Using the National Grid Electricity Balancing System

Security constrained scheduling has been widely implemented in various power system operations and electricity markets. The practice of securing post-contingency flows preventively to long-term ratings has resulted in transmission network under-utilization. This paper presents a security constrained scheduling process that has been implemented in the National Grid Electricity Balancing System. The process is designed to exploit short-term ratings when determining precontingency and post-contingency actions thereby maximizing transmission efficiency. A functional overview is provided. The security criteria adopted, the actions used to secure contingencies, and the logic used to determine corrective time are described. Computational efficiency and results of the implementation are presented.