A novel margin sensitivity based method for transient stability constrained optimal power flow

Transient stability constrained optimal power flow (TSCOPF) is still a difficult but important problem in power system planning and operation. In this paper, the challenging TSCOPF problem is divided into optimal power flow (OPF) and stability analysis processes, and solved iteratively by the interior point method (IPM). The novelty of the proposed approach is that the transient stability constraints for each contingency are incorporated into the OPF model as a single stability constraint derived from the minimum kinetic energy for normal unstable case or the minimum accelerating power distance for extreme unstable case using the time domain simulation based single machine equivalent (SIME) method. The proposed constraint is robust and scalable for large power systems as well as applicable to multi-swing unstable, normal unstable and extreme unstable cases. In addition, this stability constraint is further refined to overcome the issue of over-stabilization by guiding the solution gradually across the stability boundary. As a whole, a complete solution method capable to solve multi-contingency TSCOPF problems is presented in this paper. The effectiveness and computation performance of the proposed approach have been fully studied and extensively validated using the New England 10-generator system and the IEEE 50-generator 145-bus system.