Application of Dynamic Equivalents in Determining Practical Dynamic Security Region

In our previous studies, it has been demonstrated that the boundary of transient stability can be approximated by hyper planes (HPs) in power injection space over quite large range. In this paper, an effective method to compute such HP of large scale power systems is proposed. Based on coherence identification of generators for a given fault, the proposed method first reduces the original system to an equivalent system using dynamic equivalents of transient stability. Then, we can quickly compute the critical HP of the equivalent system. Finally, the critical HP of original system is reconstructed and adjusted. Case studies on New England Test System and WSCC Test System show that this approach can save significant amount of computation time without scarifying accuracy.