This paper presents an algorithm for the parallel solution of the security constrained optimal power flow (SCOPF) problem in a decentralized framework, consisting of regions, using a price-based mechanism that models each region as an economic unit. We first solve the distributed optimal power flow (OPF) problem to determine the maximum secure simultaneous transfer capability of each tie-line between adjacent regions by taking only the security constraints imposed on the tie-lines into account. In this study, the line outage distribution factors (LODF) calculated at the current state are used to formulate the appended constraints. Once the secure transfer capability of each tie-line is determined, the maximum secure transfer capability of tie-lines joining two regions is solved in such a way that the transmission system can also stay within limits in the event of turning generation units off when they are not needed. A description on the inclusion of security constraints with distributed optimal power flow algorithm is given, followed by case studies for Korea power system.
