Overlapping decomposition for small disturbance stability analysis of interconnected power networks

The assessment of small disturbance (SD) stability in large interconnected power networks may become computationally more tractable if decomposition procedures are applied. However, standard disjoint decomposition techniques can prove inadequate if too many interacting machines are present in the system. This paper shows that in such cases the use of overlapping decomposition techniques can be a valid and feasible alternative. Particularly, an approach is suggested which, by suitably expanding the system model, provides a system representation into several weakly connected subsystems which may have common parts. Then, a procedure is developed for decomposing the expanded model into the recognized overlapping subsystems. The method can be carried out systematically and allows the investigation of the SD stability of large power networks through the analysis of the subsystems with a considerable reduction of the computational burden. A numerical example involving a ten-generator system illustrates the capability of the proposed approach.