State Estimation Based External Network Solution for on-line Security Analysis

A major difficulty in on-line security analysis of power systems is the representation of the external but interconnected network from which very little or no real time data are available. One method used for the determination of the external system state is to extrapolate or assume real time data for a large external network representation, which is then solved by a power flow in such a way that the mismatches at the boundary between this external system solution and the state estimated internal network is minimized. This paper presents a method that extends the state estimation techniques, instead of using the power flow for the external network solution. The results indicate improved solution flexibility, sensitivity, error detection and location abilities, and significant reduction in boundary errors.