Modeling of External Networks for On-Line Security Analysis

The larger power system control centers of today routinely incorporate functions for on-line security analysis. In the last decade, advancement in the techniques for state estimation and static contingency analysis has made this feasible. However, the modeling of those portions of the network that are unobservable to the state estimator, but affect the contingency analysis results, remains a problem that hinders the usefulness of these functions. In this paper the state of the art for on-line external network modeling is examined. The problems with the existing methods from the point of view of practical implementation are identified. Some short term research directions are suggested to alleviate these modeling problems that introduce errors in the security analysis results.